fix: cleanup and small improvements

- added empty check in inventory alerts
- corrected parts cost calculation
- removed unused getUser method
- updated default admin password
- fixed missing includes in menus
- cleaned up MenuHelper comments

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem.cpp

@@ -1,7 +1,24 @@
+/*
+File: Trenser.VehicleServiceSystem.cpp
+Description: Entry point for the Vehicle Service Management System.
+			 Initializes the UserInterface and starts the application loop.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #include "UserInterface.h"
 
+/*
+Function: main
+Description: The main entry point of the application.
+			 Creates a UserInterface object and invokes the run method to start the system.
+Parameters:
+	- None
+Returns:
+	- int: Exit status code (0 for successful execution).
+*/
 int main()
 {
 	UserInterface userInterface;
 	userInterface.run();
-}
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem.vcxproj

@@ -171,16 +171,21 @@
     <ClInclude Include="services\PaymentManagementService.h" />
     <ClInclude Include="services\ServiceManagementService.h" />
     <ClInclude Include="services\UserManagementService.h" />
+    <ClInclude Include="utilities\Config.h" />
     <ClInclude Include="utilities\Enums.h" />
+    <ClInclude Include="utilities\FileHelper.h" />
+    <ClInclude Include="utilities\FileManager.h" />
     <ClInclude Include="utilities\InputHelper.h" />
     <ClInclude Include="utilities\Map.h" />
     <ClInclude Include="utilities\OutputHelper.h" />
+    <ClInclude Include="utilities\StringHelper.h" />
     <ClInclude Include="utilities\Timestamp.h" />
     <ClInclude Include="utilities\Utility.h" />
     <ClInclude Include="utilities\Validator.h" />
     <ClInclude Include="utilities\Vector.h" />
     <ClInclude Include="views\AdminMenu.h" />
     <ClInclude Include="views\CustomerMenu.h" />
+    <ClInclude Include="views\MenuHelper.h" />
     <ClInclude Include="views\TechnicianMenu.h" />
     <ClInclude Include="views\UserInterface.h" />
   </ItemGroup>

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem.vcxproj.filters

@@ -233,8 +233,23 @@
     <ClInclude Include="models\ComboPackage.h">
       <Filter>Header Files\Models</Filter>
     </ClInclude>
+    <ClInclude Include="utilities\Config.h">
+      <Filter>Header Files\Utilities</Filter>
+    </ClInclude>
+    <ClInclude Include="utilities\FileManager.h">
+      <Filter>Header Files\Utilities</Filter>
+    </ClInclude>
+    <ClInclude Include="utilities\StringHelper.h">
+      <Filter>Header Files\Utilities</Filter>
+    </ClInclude>
+    <ClInclude Include="utilities\FileHelper.h">
+      <Filter>Header Files\Utilities</Filter>
+    </ClInclude>
     <ClInclude Include="utilities\Utility.h">
       <Filter>Header Files\Utilities</Filter>
     </ClInclude>
+    <ClInclude Include="views\MenuHelper.h">
+      <Filter>Header Files\Views</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/controllers/Controller.cpp

@@ -1,24 +1,37 @@
 /*
 File: Controller.cpp
 Description: Implementation file containing the method definitions of the
-             Controller class, which manages authentication, users, services,
-             combo packages, and inventory operations.
+             Controller class, including authentication, user creation,
+             service purchasing, and system checks.
 Author: Trenser
 Date:19-May-2026
 */
-#include "Controller.h"
 #include "ComboPackage.h"
+#include "Controller.h"
+#include "Enums.h"
+#include "InventoryItem.h"
+#include "Invoice.h"
+#include "JobCard.h"
+#include "Service.h"
+#include "ServiceBooking.h"
 #include "User.h"
+#include <stdexcept>
 
+/*
+Function: login
+Description: Authenticates a user by delegating to the authentication management service.
+Parameter: const std::string& username - user’s username
+           const std::string& password - user’s password
+Return type: bool - true if login successful, false otherwise
+*/
 bool Controller::login(const std::string& username, const std::string& password)
 {
-    return false;
+    return m_authenticationManagementService.login(username, password);
 }
 
 /*
 Function: logout
-Description: Logs out the currently authenticated user by delegating
-             to the authentication management service.
+Description: Logs out the currently authenticated user.
 Parameter: None
 Return type: void
 */
@@ -29,9 +42,8 @@ void Controller::logout()
 
 /*
 Function: changePassword
-Description: Updates the password of the authenticated user by delegating
-             to the authentication management service.
-Parameter: const std::string& newPassword - the new password to set
+Description: Changes the password of the currently authenticated user.
+Parameter: const std::string& newPassword - new password to set
 Return type: void
 */
 void Controller::changePassword(const std::string& newPassword)
@@ -39,13 +51,31 @@ void Controller::changePassword(const std::string& newPassword)
     m_authenticationManagementService.changePassword(newPassword);
 }
 
-void Controller::createCustomer(const std::string& username, const std::string& password, const std::string& email, const std::string& phone)
+/*
+Function: createCustomer
+Description: Creates a new customer account with the provided details.
+Parameter: const std::string& username - customer’s username
+           const std::string& name - customer’s name
+           const std::string& password - customer’s password
+           const std::string& email - customer’s email
+           const std::string& phone - customer’s phone number
+Return type: void
+*/
+
+void Controller::createCustomer(const std::string& username, const std::string& name, const std::string& password, const std::string& email, const std::string& phone)
 {
+    m_userManagementService.createUser(username, name, password, email, phone, util::UserType::CUSTOMER);
 }
 
+/*
+Function: getAuthenticatedUser
+Description: Retrieves the currently authenticated user.
+Parameter: None
+Return type: const User* - pointer to the authenticated user
+*/
 const User* Controller::getAuthenticatedUser()
 {
-    return nullptr;
+    return m_authenticationManagementService.getAuthenticatedUser();
 }
 
 /*
@@ -63,13 +93,40 @@ void Controller::createTechnician(const std::string& username, const std::string
     m_userManagementService.createUser(username, name, password, email, phoneNumber, util::UserType::TECHNICIAN);
 }
 
+/*
+Function: updateUserDetails
+Description: Updates the email and phone details of the currently authenticated user.
+Parameter: const std::string& email - new email address
+           const std::string& phone - new phone number
+Return type: void
+*/
 void Controller::updateUserDetails(const std::string& email, const std::string& phone)
 {
+    User* authenticatedUser = m_authenticationManagementService.getAuthenticatedUser();
+    if (authenticatedUser == nullptr)
+    {
+        throw std::runtime_error("No user currently logged in!");
+    }
+    m_userManagementService.updateUserDetails(authenticatedUser->getId(), email, phone);
 }
 
+/*
+Function: getServices
+Description: Retrieves all available services in read-only form.
+Parameters:
+    - None
+Returns:
+    - util::Map<std::string, const Service*> containing all services
+*/
 util::Map<std::string, const Service*> Controller::getServices()
 {
-    return util::Map<std::string, const Service*>();
+    util::Map<std::string, Service*> currentServices = m_serviceManagementService.getServices();
+    util::Map<std::string, const Service*> readOnlyServices;
+    for (int iterator = 0; iterator < currentServices.getSize(); iterator++)
+    {
+        readOnlyServices.insert(currentServices.getValueAt(iterator)->getId(), currentServices.getValueAt(iterator));
+    }
+    return readOnlyServices;
 }
 
 /*
@@ -94,40 +151,136 @@ util::Map<std::string, const ComboPackage*> Controller::getComboPackages()
     return readOnlyComboPackages;
 }
 
+/*
+Function: purchaseService
+Description: Purchases one or more services for a vehicle by delegating to the service management service.
+Parameter: const util::Vector<std::string>& serviceIDs - IDs of services to purchase
+           const std::string& vehicleNumber - vehicle registration number
+           const std::string& vehicleBrand - brand of the vehicle
+           const std::string& vehicleModel - model of the vehicle
+Return type: void
+*/
 void Controller::purchaseService(const util::Vector<std::string>& serviceIDs, const std::string& vehicleNumber, const std::string& vehicleBrand, const std::string& vehicleModel)
 {
+    m_serviceManagementService.purchaseService(serviceIDs, vehicleNumber, vehicleBrand, vehicleModel);
 }
 
+/*
+Function: purchaseComboPackage
+Description: Purchases a combo package for a vehicle by delegating to the service management service.
+Parameter: const std::string& comboPackageID - ID of the combo package
+           const std::string& vehicleNumber - vehicle registration number
+           const std::string& vehicleBrand - brand of the vehicle
+           const std::string& vehicleModel - model of the vehicle
+Return type: void
+*/
 void Controller::purchaseComboPackage(const std::string& comboPackageID, const std::string& vehicleNumber, const std::string& vehicleBrand, const std::string& vehicleModel)
 {
+    m_serviceManagementService.purchaseComboPackage(comboPackageID, vehicleNumber, vehicleBrand, vehicleModel);
 }
 
+/*
+Function: getInventoryItems
+Description: Retrieves all inventory items from the inventory management service
+             and constructs a read-only map for external use.
+Parameter: None
+Return type: util::Map<std::string, const InventoryItem*>
+*/
 util::Map<std::string, const InventoryItem*> Controller::getInventoryItems()
 {
-    return util::Map<std::string, const InventoryItem*>();
+    auto inventoryItems = m_inventoryManagementService.getInventoryItems();
+    util::Map<std::string, const InventoryItem*> readOnlyInventoryItems;
+    int inventoryItemsMapSize = inventoryItems.getSize();
+    for (int index = 0; index < inventoryItemsMapSize; index++)
+    {
+        readOnlyInventoryItems.insert(inventoryItems.getKeyAt(index), inventoryItems.getValueAt(index));
+    }
+    return readOnlyInventoryItems;
 }
 
+/*
+Function: getInventoryItem
+Description: Retrieves a specific inventory item by its ID from the inventory management service.
+Parameter: const std::string& inventoryItemID - ID of the inventory item
+Return type: const InventoryItem*
+*/
 const InventoryItem* Controller::getInventoryItem(const std::string& inventoryItemID)
 {
-    return nullptr;
+    return m_inventoryManagementService.getInventoryItem(inventoryItemID);
 }
 
+/*
+Function: addInventoryItem
+Description: Adds a new inventory item with specified details to the inventory management service.
+Parameter: const std::string& partName - name of the part
+           int quantity - quantity of the part
+           double price - price of the part
+Return type: void
+*/
 void Controller::addInventoryItem(const std::string& partName, int quantity, double price)
 {
+    m_inventoryManagementService.addInventoryItem(partName, quantity, price);
 }
 
+/*
+Function: removeInventoryItem
+Description: Removes an inventory item from the inventory management service by its ID.
+Parameter: const std::string& inventoryItemID - ID of the inventory item
+Return type: void
+*/
 void Controller::removeInventoryItem(const std::string& inventoryItemID)
 {
+    m_inventoryManagementService.removeInventoryItem(inventoryItemID);
 }
 
+/*
+Function: addInventoryItemStock
+Description: Adds stock to an existing inventory item in the inventory management service.
+Parameter: const std::string& selectedItemId - ID of the inventory item
+           int quantity - quantity to add
+Return type: void
+*/
+void Controller::addInventoryItemStock(const std::string& selectedItemId, int quantity)
+{
+    m_inventoryManagementService.addInventoryItemStock(selectedItemId, quantity);
+}
+
+/*
+Function: getServiceBookings
+Description: Retrieves all service bookings in read-only form.
+Parameters:
+    - None
+Returns:
+    - util::Map<std::string, const ServiceBooking*> containing service bookings
+*/
 util::Map<std::string, const ServiceBooking*> Controller::getServiceBookings()
 {
-    return util::Map<std::string, const ServiceBooking*>();
+    auto serviceBookings = m_serviceManagementService.getServiceBookings();
+    util::Map<std::string, const ServiceBooking*> readOnlyServiceBookings;
+    for (int iterator = 0; iterator < serviceBookings.getSize(); iterator++)
+    {
+        readOnlyServiceBookings.insert(serviceBookings.getKeyAt(iterator), serviceBookings.getValueAt(iterator));
+    }
+    return readOnlyServiceBookings;
 }
 
+/*
+Function: getServiceBookingsByUser
+Description: Retrieves all service bookings for a specific user.
+Parameters:
+    - userID: std::string, the user ID
+Returns:
+    - util::Map<std::string, const ServiceBooking*> containing bookings for the user
+*/
 util::Map<std::string, const ServiceBooking*> Controller::getServiceBookingsByUser(const std::string userID)
 {
-    return util::Map<std::string, const ServiceBooking*>();
+    util::Map<std::string, const ServiceBooking*> readOnlyServiceBookingsByUserMap;
+    util::Map<std::string, ServiceBooking*> currentServiceBookingsByUser = m_serviceManagementService.getServiceBookings(userID);
+    for (int iterator = 0; iterator < currentServiceBookingsByUser.getSize(); iterator++)
+    {
+        readOnlyServiceBookingsByUserMap.insert(currentServiceBookingsByUser.getValueAt(iterator)->getId(), currentServiceBookingsByUser.getValueAt(iterator));
+    }
+    return readOnlyServiceBookingsByUserMap;
 }
 
 /*
@@ -148,30 +301,100 @@ util::Map<std::string, const User*> Controller::getUsers()
     return readOnlyUserList;
 }
 
+/*
+Function: getUsers
+Description: Retrieves users filtered by user type.
+Parameters:
+    - userType: util::UserType, type of user (CUSTOMER, TECHNICIAN, ADMIN)
+Returns:
+    - util::Map<std::string, const User*> containing users of the specified type
+*/
 util::Map<std::string, const User*> Controller::getUsers(util::UserType userType)
 {
-    return util::Map<std::string, const User*>();
+    auto userMap = m_userManagementService.getUsers(userType);
+    util::Map<std::string, const User*> readOnlyUserMap;
+    for (int iterator = 0; iterator < userMap.getSize(); iterator++)
+    {
+        readOnlyUserMap.insert(userMap.getKeyAt(iterator), userMap.getValueAt(iterator));
+    }
+    return readOnlyUserMap;
 }
 
+/*
+Function: createJobCard
+Description: Creates a job card for a service booking assigned to a technician.
+Parameters:
+    - bookingID: std::string, ID of the service booking
+    - technicianID: std::string, ID of the technician
+    - serviceID: std::string, ID of the service
+Returns:
+    - void
+*/
 void Controller::createJobCard(const std::string& bookingID, const std::string& technicianID, const std::string& serviceID)
 {
+    m_serviceManagementService.createJobCard(bookingID, technicianID, serviceID);
 }
 
+/*
+Function: createService
+Description: Creates a new service with associated inventory items and labor cost.
+Parameters:
+    - name: std::string, name of the service
+    - inventoryItemIDs: Vector of inventory item IDs
+    - laborCost: double, labor cost
+Returns:
+    - void
+*/
 void Controller::createService(const std::string& name, const util::Vector<std::string>& inventoryItemIDs, double laborCost)
 {
+    m_serviceManagementService.createService(name, inventoryItemIDs, laborCost);
 }
 
+/*
+Function: removeService
+Description: Removes a service from the system by ID.
+Parameters:
+    - serviceID: std::string, ID of the service
+Returns:
+    - void
+*/
 void Controller::removeService(const std::string& serviceID)
 {
+    m_serviceManagementService.removeService(serviceID);
 }
 
+/*
+Function: getJobCardsByUser
+Description: Retrieves job cards assigned to the authenticated technician.
+Parameters:
+    - None
+Returns:
+    - util::Map<std::string, const JobCard*> containing job cards
+*/
 util::Map<std::string, const JobCard*> Controller::getJobCardsByUser()
 {
-    return util::Map<std::string, const JobCard*>();
+    const User* currentUser = getAuthenticatedUser();
+    auto jobCardsAssignedToTechnician = m_serviceManagementService.getJobCards(currentUser->getId());
+    util::Map<std::string, const JobCard*> readOnlyJobCardMap;
+    for (int iterator = 0; iterator < jobCardsAssignedToTechnician.getSize(); iterator++)
+    {
+        JobCard* currentJobCard = jobCardsAssignedToTechnician.getValueAt(iterator);
+        readOnlyJobCardMap.insert(currentJobCard->getId(), currentJobCard);
+    }
+    return readOnlyJobCardMap;
 }
 
+/*
+Function: completeJob
+Description: Marks a job card as completed.
+Parameters:
+    - jobID: std::string, ID of the job card
+Returns:
+    - void
+*/
 void Controller::completeJob(const std::string& jobID)
 {
+    m_serviceManagementService.completeJob(jobID);
 }
 
 /*
@@ -219,29 +442,178 @@ void Controller::removeComboPackage(const std::string& comboPackageID)
     m_serviceManagementService.removeComboPackage(comboPackageID);
 }
 
+/*
+Function: getInvoicesByUser
+Description: Retrieves all invoices associated with the currently authenticated user.
+             Converts them into a read-only map before returning.
+Parameters:
+    - None
+Returns:
+    - util::Map<std::string, const Invoice*> containing the user’s invoices
+*/
 util::Map<std::string, const Invoice*> Controller::getInvoicesByUser()
 {
-    return util::Map<std::string, const Invoice*>();
+    User* currentUser = m_authenticationManagementService.getAuthenticatedUser();
+    util::Map<std::string, Invoice*> currentUserInvoices =  m_paymentManagementService.getInvoices(currentUser->getId());
+    util::Map<std::string, const Invoice*> userInvoicesReadOnly;
+    for (int iterator = 0; iterator < currentUserInvoices.getSize(); iterator++)
+    {
+        Invoice* currentInvoice = currentUserInvoices.getValueAt(iterator);
+        userInvoicesReadOnly.insert(currentInvoice->getId(), currentInvoice);
+    }
+    return userInvoicesReadOnly;
 }
 
+/*
+Function: completePayment
+Description: Completes payment for a specific invoice using the given payment mode.
+Parameters:
+    - invoiceID: std::string, ID of the invoice to be paid
+    - paymentMode: util::PaymentMode, mode of payment (e.g., ONLINE, OFFLINE)
+Returns:
+    - void
+*/
 void Controller::completePayment(const std::string& invoiceID, util::PaymentMode paymentMode)
 {
+    m_paymentManagementService.completePayment(invoiceID, paymentMode);
 }
 
+/*
+Function: getNotifications
+Description: Retrieves all notifications for the currently authenticated user.
+             Converts them into a read-only vector before returning.
+Parameters: None
+Return type: util::Vector<const Notification*>
+*/
 util::Vector<const Notification*> Controller::getNotifications()
 {
-    return util::Vector<const Notification*>();
+    const User* authenticatedUser = m_authenticationManagementService.getAuthenticatedUser();
+    if (!authenticatedUser)
+    {
+        throw std::runtime_error("No user is currently logged in!");
+    }
+    auto notifications = m_userManagementService.getUserNotifications(authenticatedUser->getId());
+    int numberOfNotifications = notifications.getSize();
+    util::Vector<const Notification*> readOnlyNotifications;
+    for (int index = 0; index < numberOfNotifications; index++)
+    {
+        readOnlyNotifications.push_back(notifications[index]);
+    }
+    return readOnlyNotifications;
 }
 
+/*
+Function: deleteNotification
+Description: Deletes a specific notification for the currently authenticated user.
+Parameters:
+    - notificationID: std::string, the unique identifier of the notification
+Return type: void
+*/
 void Controller::deleteNotification(const std::string& notificationID)
 {
+    const User* authenticatedUser = m_authenticationManagementService.getAuthenticatedUser();
+    if (!authenticatedUser)
+    {
+        throw std::runtime_error("No user is currently logged in!");
+    }
+    m_userManagementService.deleteNotification(notificationID, authenticatedUser->getId());
 }
 
-void Controller::configureNotifications(const std::string& userID, bool paymentNotifications, bool serviceNotifications)
+/*
+Function: configureNotifications
+Description: Configures notification preferences for the authenticated user.
+             Attaches or detaches the user from payment and service notifications.
+Parameters:
+    - paymentNotifications: bool, enable/disable payment notifications
+    - serviceNotifications: bool, enable/disable service notifications
+Return type: void
+*/
+void Controller::configureNotifications(bool paymentNotifications, bool serviceNotifications)
 {
+    User* authenticatedUser = m_authenticationManagementService.getAuthenticatedUser();
+    if (authenticatedUser)
+    {
+        if (paymentNotifications)
+        {
+            m_paymentManagementService.attach(authenticatedUser);
+        }
+        else
+        {
+            m_paymentManagementService.detach(authenticatedUser);
+        }
+        if (serviceNotifications)
+        {
+            m_serviceManagementService.attach(authenticatedUser);
+        }
+        else
+        {
+            m_serviceManagementService.detach(authenticatedUser);
+        }
+    }
+    else
+    {
+        throw std::runtime_error("No user is currently logged in!");
+    }
 }
 
+/*
+Function: loadSystemData
+Description: Loads all system data from persistent storage into memory.
+             Invokes the respective management services to load users, inventory items, services,
+             combo packages, service bookings, job cards, invoices, and observers.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void Controller::loadSystemData()
+{
+    m_userManagementService.loadUsers();
+    m_inventoryManagementService.loadInventoryItems();
+    m_serviceManagementService.loadServices();
+    m_serviceManagementService.loadComboPackages();
+    m_serviceManagementService.loadServiceBookings();
+    m_serviceManagementService.loadJobCards();
+    m_paymentManagementService.loadInvoices();
+    m_serviceManagementService.loadObservers();
+    m_paymentManagementService.loadObservers();
+    m_inventoryManagementService.loadObservers();
+}
+
+/*
+Function: saveSystemData
+Description: Saves all system data from memory back to persistent storage.
+             Invokes the respective management services to save users, inventory items, services,
+             combo packages, service bookings, job cards, invoices, and observers.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void Controller::saveSystemData()
+{
+    m_userManagementService.saveUsers();
+    m_inventoryManagementService.saveInventoryItems();
+    m_serviceManagementService.saveServices();
+    m_serviceManagementService.saveComboPackages();
+    m_serviceManagementService.saveServiceBookings();
+    m_serviceManagementService.saveJobCards();
+    m_paymentManagementService.saveInvoices();
+    m_serviceManagementService.saveObservers();
+    m_paymentManagementService.saveObservers();
+    m_inventoryManagementService.saveObservers();
+}
+
+/*
+Function: runSystemChecks
+Description: Runs system checks to ensure critical configurations, such as verifying admin existence.
+Parameter: None
+Return type: void
+*/
 void Controller::runSystemChecks()
 {
+    m_userManagementService.ensureAdminExists();
+    m_inventoryManagementService.sendLowStockAlerts();
+    m_paymentManagementService.sendPaymentReminders();
 }
 

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/controllers/Controller.h

@@ -6,13 +6,16 @@ Description: Header file declaring the Controller class, which manages
 Author: Trenser
 Date:19-May-2026
 */
+
 #pragma once
 #include <string>
-#include "Map.h"
-#include "Enums.h"
-#include "UserManagementService.h"
-#include "ServiceManagementService.h"
 #include "AuthenticationManagementService.h"
+#include "Enums.h"
+#include "InventoryManagementService.h"
+#include "Map.h"
+#include "PaymentManagementService.h"
+#include "ServiceManagementService.h"
+#include "UserManagementService.h"
 
 class Service;
 class ComboPackage;
@@ -29,13 +32,15 @@ private:
     AuthenticationManagementService  m_authenticationManagementService;
     UserManagementService m_userManagementService;
     ServiceManagementService m_serviceManagementService;    
+    InventoryManagementService m_inventoryManagementService;
+    PaymentManagementService m_paymentManagementService;
 public:
     bool login(const std::string& username, const std::string& password);
     void logout();
     void changePassword(const std::string& newPassword);
-    void createCustomer(const std::string& username, const std::string& password, const std::string& email, const std::string& phone);
+    void createCustomer(const std::string& username, const std::string& name, const std::string& password, const std::string& email, const std::string& phone);
     const User* getAuthenticatedUser();
-    void createTechnician(const std::string& username, const std::string& name, const std::string& password, const std::string& email, const std::string& phoneNumber);
+    void createTechnician(const std::string& username, const std::string& name, const std::string& password, const std::string& email, const std::string& phone);
     void updateUserDetails(const std::string& email, const std::string& phone);
     util::Map<std::string, const Service*> getServices();
     util::Map<std::string, const ComboPackage*> getComboPackages();
@@ -44,6 +49,7 @@ public:
     util::Map<std::string, const InventoryItem*> getInventoryItems();
     const InventoryItem* getInventoryItem(const std::string& inventoryItemID);
     void addInventoryItem(const std::string& partName, int quantity, double price);
+    void addInventoryItemStock(const std::string& selectedItemId, int quantity);
     void removeInventoryItem(const std::string& inventoryItemID);
     util::Map<std::string, const ServiceBooking*> getServiceBookings();
     util::Map<std::string, const ServiceBooking*> getServiceBookingsByUser(const std::string userID);
@@ -61,6 +67,8 @@ public:
     void completePayment(const std::string& invoiceID, util::PaymentMode paymentMode);
     util::Vector<const Notification*> getNotifications();
     void deleteNotification(const std::string& notificationID);
-    void configureNotifications(const std::string& userID, bool paymentNotifications, bool serviceNotifications);
+    void configureNotifications(bool paymentNotifications, bool serviceNotifications);
+    void loadSystemData();
+    void saveSystemData();
     void runSystemChecks();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/core/patterns/Observer.h

@@ -1,3 +1,10 @@
+/*
+File: Observer.h
+Description: Declares the Observer interface for handling notifications in the Vehicle Service Management System.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #pragma once
 
 class Notification;
@@ -6,5 +13,5 @@ class Observer
 {
 public:
     virtual ~Observer() = default;
-    virtual void update(Notification* notification) = 0;
+    virtual void addNotification(Notification* notification) = 0;
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/core/patterns/Subject.h

@@ -1,6 +1,14 @@
+/*
+File: Subject.h
+Description: Declares the Subject interface for managing user attachments and detachments in the Observer design pattern within the Vehicle Service Management System.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 
 class User;
 class Notification;

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStore.cpp

@@ -1,46 +1,128 @@
+/*
+File: DataStore.cpp
+Description: Implements the DataStore class which provides a centralized singleton repository
+             for managing system data in the Vehicle Service Management System.
+             Includes accessors for users, services, combo packages, service bookings,
+             job cards, inventory items, invoices, and payments.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #include "DataStore.h"
 
+/*
+Function: getInstance
+Description: Provides a singleton instance of the DataStore class.
+Parameters:
+    - None
+Returns:
+    - Reference to the single DataStore instance.
+*/
 DataStore& DataStore::getInstance()
 {
     static DataStore dataStore;
     return dataStore;
 }
 
+/*
+Function: getUsers
+Description: Retrieves the internal map of users.
+Parameters:
+    - None
+Returns:
+    - Reference to util::Map<std::string, User*> containing all users.
+*/
 util::Map<std::string, User*>& DataStore::getUsers()
 {
     return m_users;
 }
 
+/*
+Function: getServices
+Description: Retrieves the internal map of services.
+Parameters:
+    - None
+Returns:
+    - Reference to util::Map<std::string, Service*> containing all services.
+*/
 util::Map<std::string, Service*>& DataStore::getServices()
 {
     return m_services;
 }
 
+/*
+Function: getComboPackages
+Description: Retrieves the internal map of combo packages.
+Parameters:
+    - None
+Returns:
+    - Reference to util::Map<std::string, ComboPackage*> containing all combo packages.
+*/
 util::Map<std::string, ComboPackage*>& DataStore::getComboPackages()
 {
     return m_comboPackages;
 }
 
+/*
+Function: getServiceBookings
+Description: Retrieves the internal map of service bookings.
+Parameters:
+    - None
+Returns:
+    - Reference to util::Map<std::string, ServiceBooking*> containing all service bookings.
+*/
 util::Map<std::string, ServiceBooking*>& DataStore::getServiceBookings()
 {
     return m_serviceBookings;
 }
 
+/*
+Function: getJobCards
+Description: Retrieves the internal map of job cards.
+Parameters:
+    - None
+Returns:
+    - Reference to util::Map<std::string, JobCard*> containing all job cards.
+*/
 util::Map<std::string, JobCard*>& DataStore::getJobCards()
 {
     return m_jobCards;
 }
 
+/*
+Function: getInventoryItems
+Description: Retrieves the internal map of inventory items.
+Parameters:
+    - None
+Returns:
+    - Reference to util::Map<std::string, InventoryItem*> containing all inventory items.
+*/
 util::Map<std::string, InventoryItem*>& DataStore::getInventoryItems()
 {
     return m_inventoryItems;
 }
 
+/*
+Function: getInvoices
+Description: Retrieves the internal map of invoices.
+Parameters:
+    - None
+Returns:
+    - Reference to util::Map<std::string, Invoice*> containing all invoices.
+*/
 util::Map<std::string, Invoice*>& DataStore::getInvoices()
 {
     return m_invoices;
 }
 
+/*
+Function: getPayments
+Description: Retrieves the internal map of payments.
+Parameters:
+    - None
+Returns:
+    - Reference to util::Map<std::string, Payment*> containing all payments.
+*/
 util::Map<std::string, Payment*>& DataStore::getPayments()
 {
     return m_payments;

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStore.h

@@ -1,5 +1,11 @@
-#pragma once
+/*
+File: DataStore.h
+Description: Declares the DataStore singleton class responsible for managing collections of users, services, combo packages, service bookings, job cards, inventory items, invoices, and payments in the Vehicle Service Management System.
+Author: Trenser
+Date: 19-May-2026
+*/
 
+#pragma once
 #include <string>
 #include "Map.h"
 

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/files/README.md

@@ -0,0 +1 @@
+Place files here.

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/ComboPackage.cpp

@@ -1,65 +1,341 @@
+/*
+File: ComboPackage.cpp
+Description: Implements the ComboPackage class which represents a bundled set of services in the Vehicle Service Management System.
+             Provides constructors, accessors, and mutators for package details such as ID, name, discount percentage, state,
+             and associated services.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+#include <sstream>
+#include <stdexcept>
 #include "ComboPackage.h"
+#include "Service.h"
+#include "Factory.h"
+#include "StringHelper.h"
 
 int ComboPackage::m_uid = 0;
 
+/*
+Function: ComboPackage
+Description: Default constructor that initializes a new combo package with a unique ID,
+             active state, and zero discount percentage.
+Parameters:
+    - None
+Returns:
+    - A new ComboPackage object.
+*/
 ComboPackage::ComboPackage()
     : m_id("CMP" + std::to_string(++m_uid)),
     m_status(util::State::ACTIVE),
     m_discountPercentage(0.0) {}
 
+/*
+Function: ComboPackage
+Description: Parameterized constructor that initializes a new combo package with a unique ID,
+             specified package name, discount percentage, active state, and associated services.
+Parameters:
+    - packageName: Name of the combo package.
+    - discountPercentage: Discount percentage applied to the package.
+    - services: Map of services included in the package.
+Returns:
+    - A new ComboPackage object.
+*/
 ComboPackage::ComboPackage(const std::string& packageName, double discountPercentage, const util::Map<std::string, Service*>& services)
     : m_id("CMP" + std::to_string(++m_uid)),
     m_packageName(packageName),
     m_discountPercentage(discountPercentage),
     m_status(util::State::ACTIVE),
-    m_services(services) {}
+    m_services(services)
+{
+    int numberOfServices = m_services.getSize();
+    auto servicePointers = m_services.getValues();
+    for (int index = 0; index < numberOfServices; index++)
+    {
+        m_serviceIDs.push_back(servicePointers[index]->getId());
+    }
+}
 
+/*
+Function: ComboPackage (parameterized constructor with ID)
+Description: Initializes a combo package with an existing ID, name, discount percentage,
+             service IDs, and state. Updates UID tracking based on ID.
+Parameters:
+    - id: const std::string&, unique ID of the package
+    - packageName: const std::string&, name of the package
+    - discountPercentage: double, discount percentage applied
+    - serviceIDs: const util::Vector<std::string>&, IDs of services included
+    - status: util::State, state of the package (ACTIVE/INACTIVE)
+Returns:
+    - A new ComboPackage object
+*/
+ComboPackage::ComboPackage(const std::string& id, const std::string& packageName, double discountPercentage, const util::Vector<std::string>& serviceIDs, util::State status)
+    : m_id(id),
+    m_packageName(packageName),
+    m_discountPercentage(discountPercentage),
+    m_serviceIDs(serviceIDs),
+    m_status(status)
+{
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
+    {
+        m_uid = idNumber;
+    }
+}
+
+/*
+Function: getId
+Description: Retrieves the unique ID of the combo package.
+Parameters:
+    - None
+Returns:
+    - const std::string& representing the package ID.
+*/
 const std::string& ComboPackage::getId() const
 {
     return m_id;
 }
 
+/*
+Function: getPackageName
+Description: Retrieves the name of the combo package.
+Parameters:
+    - None
+Returns:
+    - const std::string& representing the package name.
+*/
 const std::string& ComboPackage::getPackageName() const
 {
     return m_packageName;
 }
 
+/*
+Function: getDiscountPercentage
+Description: Retrieves the discount percentage applied to the combo package.
+Parameters:
+    - None
+Returns:
+    - double representing the discount percentage.
+*/
 double ComboPackage::getDiscountPercentage() const
 {
     return m_discountPercentage;
 }
 
+/*
+Function: getState
+Description: Retrieves the current state (ACTIVE/INACTIVE) of the combo package.
+Parameters:
+    - None
+Returns:
+    - util::State representing the package state.
+*/
 util::State ComboPackage::getState() const
 {
     return m_status;
 }
 
+const util::Vector<std::string>& ComboPackage::getServiceIDs() const
+{
+    return m_serviceIDs;
+}
+
+/*
+Function: getServices
+Description: Retrieves the map of services included in the combo package.
+Parameters:
+    - None
+Returns:
+    - const util::Map<std::string, Service*>& representing the services.
+*/
 const util::Map<std::string, Service*>& ComboPackage::getServices() const
 {
     return m_services;
 }
 
+/*
+Function: setId
+Description: Sets the unique ID of the combo package.
+Parameters:
+    - id: New ID string.
+Returns:
+    - void
+*/
 void ComboPackage::setId(const std::string& id)
 {
     m_id = id;
 }
 
+/*
+Function: setPackageName
+Description: Sets the name of the combo package.
+Parameters:
+    - packageName: New package name string.
+Returns:
+    - void
+*/
 void ComboPackage::setPackageName(const std::string& packageName)
 {
     m_packageName = packageName;
 }
 
+/*
+Function: setDiscountPercentage
+Description: Sets the discount percentage for the combo package.
+Parameters:
+    - discountPercentage: New discount percentage value.
+Returns:
+    - void
+*/
 void ComboPackage::setDiscountPercentage(double discountPercentage)
 {
     m_discountPercentage = discountPercentage;
 }
 
+/*
+Function: setServices
+Description: Sets the services included in the combo package.
+Parameters:
+    - services: Map of services to be associated with the package.
+Returns:
+    - void
+*/
 void ComboPackage::setServices(const util::Map<std::string, Service*>& services)
 {
     m_services = services;
+    m_serviceIDs.clear();
+    int numberOfServices = m_services.getSize();
+    auto servicePointers = m_services.getValues();
+    for (int index = 0; index < numberOfServices; index++)
+    {
+        m_serviceIDs.push_back(servicePointers[index]->getId());
+    }
 }
 
+/*
+Function: setState
+Description: Sets the state (ACTIVE/INACTIVE) of the combo package.
+Parameters:
+    - status: New state value.
+Returns:
+    - void
+*/
 void ComboPackage::setState(util::State status)
 {
     m_status = status;
 }
+
+/*
+Function: getServiceIDsAsString (static helper)
+Description: Converts a vector of service IDs into a single string separated by '|'.
+Parameters:
+    - serviceIDs: const util::Vector<std::string>&, vector of service IDs
+Returns:
+    - std::string: Concatenated service IDs string
+*/
+static std::string getServiceIDsAsString(const util::Vector<std::string>& serviceIDs)
+{
+    int numberOfServices = serviceIDs.getSize();
+    std::string serviceIDsString;
+    for (int index = 0; index < numberOfServices; index++)
+    {
+        serviceIDsString += serviceIDs[index];
+        if (index < numberOfServices - 1)
+        {
+            serviceIDsString += '|';
+        }
+    }
+    return serviceIDsString;
+}
+
+/*
+Function: getServiceIDsAsVector (static helper)
+Description: Converts a string of service IDs separated by '|' into a vector.
+Parameters:
+    - serviceIDsString: const std::string&, concatenated service IDs string
+Returns:
+    - util::Vector<std::string>: Vector of service IDs
+*/
+static util::Vector<std::string> getServiceIDsAsVector(const std::string& serviceIDsString)
+{
+    util::Vector<std::string> serviceIDs;
+    std::string serviceID;
+    std::istringstream serializedServiceIDs(serviceIDsString);
+    while (getline(serializedServiceIDs, serviceID, '|'))
+    {
+        serviceIDs.push_back(serviceID);
+    }
+    return serviceIDs;
+}
+
+/*
+Function: serialize
+Description: Serializes the combo package into a CSV-formatted string.
+Parameters:
+    - None
+Returns:
+    - std::string: Serialized combo package record
+*/
+std::string ComboPackage::serialize() const
+{
+    std::ostringstream serializedComboPackage;
+    serializedComboPackage << m_id << ','
+        << m_packageName << ','
+        << m_discountPercentage << ','
+        << getServiceIDsAsString(m_serviceIDs) << ','
+        << util::getStateString(m_status);
+    return serializedComboPackage.str();
+}
+
+/*
+Function: deserialize
+Description: Deserializes a CSV-formatted string into a ComboPackage object.
+Parameters:
+    - record: const std::string&, serialized combo package record
+Returns:
+    - ComboPackage*: Pointer to the deserialized ComboPackage object
+Throws:
+    - std::runtime_error if data is invalid
+*/
+ComboPackage* ComboPackage::deserialize(const std::string& record)
+{
+    std::string id, packageName;
+    std::string discountPercentageString, serviceIDsString, statusString;
+    double discountPercentage;
+    std::istringstream serializedComboPackage(record);
+    getline(serializedComboPackage, id, ',');
+    getline(serializedComboPackage, packageName, ',');
+    getline(serializedComboPackage, discountPercentageString, ',');
+    getline(serializedComboPackage, serviceIDsString, ',');
+    getline(serializedComboPackage, statusString, ',');
+    try
+    {
+        discountPercentage = std::stod(discountPercentageString);
+    }
+    catch (...)
+    {
+        throw std::runtime_error("Invalid combo package data");
+    }
+    util::Vector<std::string> serviceIDs = getServiceIDsAsVector(serviceIDsString);
+    util::State status = util::getState(statusString);
+    return Factory::getObject<ComboPackage>(
+        id,
+        packageName,
+        discountPercentage,
+        serviceIDs,
+        status
+    );
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for combo package serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,PackageName,DiscountPercentage,ServiceIDs,Status")
+*/
+std::string ComboPackage::getHeaders()
+{
+    return "ID,PackageName,DiscountPercentage,ServiceIDs,Status";
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/ComboPackage.h

@@ -1,6 +1,14 @@
+/*
+File: ComboPackage.h
+Description: Declares the ComboPackage class which represents a service package with a unique ID, package name, discount percentage, associated services, and status in the Vehicle Service Management System.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "Enums.h"
 
 class Service;
@@ -12,14 +20,17 @@ private:
     std::string m_id;
     std::string m_packageName;
     double m_discountPercentage;
+    util::Vector<std::string> m_serviceIDs;
     util::Map<std::string, Service*> m_services;
     util::State m_status;
 public:
     ComboPackage();
     ComboPackage(const std::string& packageName, double discountPercentage, const util::Map<std::string, Service*>& services);
+    ComboPackage(const std::string& id, const std::string& packageName, double discountPercentage, const util::Vector<std::string>& serviceIDs, util::State status);
     const std::string& getId() const;
     const std::string& getPackageName() const;
     double getDiscountPercentage() const;
+    const util::Vector<std::string>& getServiceIDs() const;
     const util::Map<std::string, Service*>& getServices() const;
     util::State getState() const;
     void setId(const std::string& id);
@@ -27,4 +38,7 @@ public:
     void setDiscountPercentage(double discountPercentage);
     void setServices(const util::Map<std::string, Service*>& services);
     void setState(util::State status);
+    std::string serialize() const;
+    static ComboPackage* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/InventoryItem.cpp

@@ -1,13 +1,45 @@
+/*
+File: InventoryItem.cpp
+Description: Implements the InventoryItem class which represents an inventory item in the Vehicle Service Management System.
+             Provides constructors, accessors, and mutators for item details such as ID, part name, quantity, price, and state.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+#include <sstream>
+#include <stdexcept>
+#include "Factory.h"
+#include "StringHelper.h"
 #include "InventoryItem.h"
 
 int InventoryItem::m_uid = 0;
 
+/*
+Function: InventoryItem
+Description: Default constructor that initializes a new inventory item with a unique ID,
+             active state, zero quantity, and zero price.
+Parameters:
+    - None
+Returns:
+    - A new InventoryItem object.
+*/
 InventoryItem::InventoryItem()
     : m_id("IIM" + std::to_string(++m_uid)),
     m_quantity(0),
     m_status(util::State::ACTIVE),
     m_price(0.0) {}
 
+/*
+Function: InventoryItem
+Description: Parameterized constructor that initializes a new inventory item with a unique ID,
+             specified part name, quantity, price, and active state.
+Parameters:
+    - partName: Name of the inventory item.
+    - quantity: Initial quantity of the item.
+    - price: Price of the item.
+Returns:
+    - A new InventoryItem object.
+*/
 InventoryItem::InventoryItem(const std::string& partName, int quantity, double price)
     : m_id("IIM" + std::to_string(++m_uid)),
     m_partName(partName),
@@ -15,52 +47,232 @@ InventoryItem::InventoryItem(const std::string& partName, int quantity, double p
     m_status(util::State::ACTIVE),
     m_price(price) {}
 
+/*
+Function: InventoryItem (parameterized constructor with ID)
+Description: Initializes an inventory item with an existing ID, part name, quantity,
+             price, and state. Updates UID tracking based on ID.
+Parameters:
+    - id: const std::string&, unique ID of the item
+    - partName: const std::string&, name of the part
+    - quantity: int, quantity of the part
+    - price: double, price of the part
+    - status: util::State, state of the item (ACTIVE/INACTIVE)
+Returns:
+    - A new InventoryItem object
+*/
+InventoryItem::InventoryItem(const std::string& id, const std::string& partName, int quantity, double price, util::State status)
+    : m_id(id),
+    m_partName(partName),
+    m_quantity(quantity),
+    m_status(status),
+    m_price(price)
+{
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
+    {
+        m_uid = idNumber;
+    }
+}
+
+/*
+Function: getId
+Description: Retrieves the unique ID of the inventory item.
+Parameters:
+    - None
+Returns:
+    - const std::string& representing the item ID.
+*/
 const std::string& InventoryItem::getId() const
 {
     return m_id;
 }
 
+/*
+Function: getPartName
+Description: Retrieves the part name of the inventory item.
+Parameters:
+    - None
+Returns:
+    - const std::string& representing the part name.
+*/
 const std::string& InventoryItem::getPartName() const
 {
     return m_partName;
 }
 
+/*
+Function: getQuantity
+Description: Retrieves the current quantity of the inventory item.
+Parameters:
+    - None
+Returns:
+    - int representing the quantity.
+*/
 int InventoryItem::getQuantity() const
 {
     return m_quantity;
 }
 
+/*
+Function: getPrice
+Description: Retrieves the price of the inventory item.
+Parameters:
+    - None
+Returns:
+    - double representing the price.
+*/
 double InventoryItem::getPrice() const
 {
     return m_price;
 }
 
+/*
+Function: getState
+Description: Retrieves the current state (ACTIVE/INACTIVE) of the inventory item.
+Parameters:
+    - None
+Returns:
+    - util::State representing the item state.
+*/
 util::State InventoryItem::getState() const
 {
     return m_status;
 }
 
+/*
+Function: setId
+Description: Sets the unique ID of the inventory item.
+Parameters:
+    - id: New ID string.
+Returns:
+    - void
+*/
 void InventoryItem::setId(const std::string& id)
 {
     m_id = id;
 }
 
+/*
+Function: setPartName
+Description: Sets the part name of the inventory item.
+Parameters:
+    - partName: New part name string.
+Returns:
+    - void
+*/
 void InventoryItem::setPartName(const std::string& partName)
 {
     m_partName = partName;
 }
 
+/*
+Function: setQuantity
+Description: Sets the quantity of the inventory item.
+Parameters:
+    - quantity: New quantity value.
+Returns:
+    - void
+*/
 void InventoryItem::setQuantity(int quantity)
 {
     m_quantity = quantity;
 }
 
+/*
+Function: setPrice
+Description: Sets the price of the inventory item.
+Parameters:
+    - price: New price value.
+Returns:
+    - void
+*/
 void InventoryItem::setPrice(double price)
 {
     m_price = price;
 }
 
+/*
+Function: setState
+Description: Sets the state (ACTIVE/INACTIVE) of the inventory item.
+Parameters:
+    - status: New state value.
+Returns:
+    - void
+*/
 void InventoryItem::setState(util::State status)
 {
     m_status = status;
+}
+
+/*
+Function: serialize
+Description: Serializes the inventory item into a CSV-formatted string.
+Parameters:
+    - None
+Returns:
+    - std::string: Serialized inventory item record
+*/
+std::string InventoryItem::serialize() const
+{
+    std::ostringstream serializedInventoryItem;
+    serializedInventoryItem << m_id << ','
+        << m_partName << ','
+        << m_quantity << ','
+        << m_price << ','
+        << util::getStateString(m_status);
+    return serializedInventoryItem.str();
+}
+
+/*
+Function: deserialize
+Description: Deserializes a CSV-formatted string into an InventoryItem object.
+Parameters:
+    - record: const std::string&, serialized inventory item record
+Returns:
+    - InventoryItem*: Pointer to the deserialized InventoryItem object
+Throws:
+    - std::runtime_error if data is invalid
+*/
+InventoryItem* InventoryItem::deserialize(const std::string& record)
+{
+    std::string id, partName;
+    std::string quantityString, priceString, statusString;
+    int quantity;
+    double price;
+    std::istringstream serializedInventoryItem(record);
+    getline(serializedInventoryItem, id, ',');
+    getline(serializedInventoryItem, partName, ',');
+    getline(serializedInventoryItem, quantityString, ',');
+    getline(serializedInventoryItem, priceString, ',');
+    getline(serializedInventoryItem, statusString, ',');
+    try
+    {
+        quantity = std::stoi(quantityString);
+        price = std::stod(priceString);
+    }
+    catch (...)
+    {
+        throw std::runtime_error("Invalid inventory item data");
+    }
+    util::State status = util::getState(statusString);
+    return Factory::getObject<InventoryItem>(
+        id,
+        partName,
+        quantity,
+        price,
+        status
+    );
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for inventory item serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,PartName,Quantity,Price,Status")
+*/
+std::string InventoryItem::getHeaders()
+{
+    return "ID,PartName,Quantity,Price,Status";
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/InventoryItem.h

@@ -1,3 +1,12 @@
+/*
+File: InventoryItem.h
+Description: Declares the InventoryItem class which represents parts in the Vehicle Service Management System.
+             Each item has a unique ID, part name, quantity, price, and status.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+
 #pragma once
 #include <string>
 #include "Enums.h"
@@ -14,6 +23,7 @@ private:
 public:
     InventoryItem();
     InventoryItem(const std::string& partName, int quantity, double price);
+    InventoryItem(const std::string& id, const std::string& partName, int quantity, double price, util::State status);
     const std::string& getId() const;
     const std::string& getPartName() const;
     int getQuantity() const;
@@ -24,4 +34,7 @@ public:
     void setQuantity(int quantity);
     void setPrice(double price);
     void setState(util::State status);
+    std::string serialize() const;
+    static InventoryItem* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/Invoice.cpp

@@ -1,7 +1,31 @@
+/*
+File: Invoice.cpp
+Description: Implements the Invoice class which represents an invoice in the Vehicle Service Management System.
+             Provides constructors, accessors, and mutators for invoice details such as ID, booking, costs,
+             discount percentage, total amount, payment details, and status.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+#include <sstream>
+#include <stdexcept>
 #include "Invoice.h"
+#include "Factory.h"
+#include "InventoryItem.h"
+#include "StringHelper.h"
 
 int Invoice::m_uid = 0;
 
+/*
+Function: Invoice
+Description: Default constructor that initializes a new invoice with a unique ID,
+             null booking, zero costs, zero discount, zero total amount,
+             and default payment method and status.
+Parameters:
+    - None
+Returns:
+    - A new Invoice object.
+*/
 Invoice::Invoice()
     : m_id("INV" + std::to_string(++m_uid)),
     m_booking(nullptr),
@@ -12,12 +36,30 @@ Invoice::Invoice()
     m_paymentMethod(util::PaymentMode()),
     m_status(util::PaymentStatus()) {}
 
+/*
+Function: Invoice
+Description: Parameterized constructor that initializes a new invoice with a unique ID and specified details.
+Parameters:
+    - bookingId: ID of the associated service booking.
+    - booking: Pointer to the ServiceBooking object.
+    - invoiceDate: Timestamp of when the invoice was created.
+    - laborCost: Cost of labor for the service.
+    - parts: Map of inventory items used in the service.
+    - partsCost: Total cost of parts.
+    - discountPercentage: Discount applied to the invoice.
+    - totalAmount: Final total amount after discount.
+    - paymentDate: Timestamp of when payment was made.
+    - paymentMethod: Payment mode (ONLINE/OFFLINE).
+    - status: Payment status (PENDING/COMPLETED).
+Returns:
+    - A new Invoice object.
+*/
 Invoice::Invoice(
     const std::string& bookingId,
     ServiceBooking* booking,
     const util::Timestamp& invoiceDate, 
-    double laborCost, const util::Map<int,
-    InventoryItem*>& parts,
+    double laborCost, 
+    const util::Map<std::string, InventoryItem*>& parts,
     double partsCost,
     double discountPercentage, 
     double totalAmount, 
@@ -36,124 +78,495 @@ Invoice::Invoice(
     m_totalAmount(totalAmount),
     m_paymentDate(paymentDate),
     m_paymentMethod(paymentMethod),
-    m_status(status) {}
+    m_status(status) 
+{
+    int numberOfParts = m_parts.getSize();
+    auto partPointers = m_parts.getValues();
+    for (int index = 0; index < numberOfParts; index++)
+    {
+        m_partIDs.push_back(partPointers[index]->getId());
+    }
+}
+Invoice::Invoice(
+    const std::string& id,
+    const std::string& bookingId,
+    const util::Timestamp& invoiceDate,
+    const util::Vector<std::string>& partIDs,
+    double laborCost,
+    double partsCost,
+    double discountPercentage,
+    double totalAmount,
+    const util::Timestamp& paymentDate,
+    util::PaymentMode paymentMethod,
+    util::PaymentStatus status
+)
+    : m_id(id),
+    m_bookingId(bookingId),
+    m_booking(nullptr),
+    m_invoiceDate(invoiceDate),
+    m_partIDs(partIDs),
+    m_laborCost(laborCost),
+    m_partsCost(partsCost),
+    m_discountPercentage(discountPercentage),
+    m_totalAmount(totalAmount),
+    m_paymentDate(paymentDate),
+    m_paymentMethod(paymentMethod),
+    m_status(status)
+{
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
+    {
+        m_uid = idNumber;
+    }
+}
 
+/*
+Function: getId
+Description: Retrieves the unique ID of the invoice.
+Returns:
+    - const std::string& representing the invoice ID.
+*/
 const std::string& Invoice::getId() const
 {
     return m_id;
 }
 
+/*
+Function: getBookingId
+Description: Retrieves the booking ID associated with the invoice.
+Returns:
+    - const std::string& representing the booking ID.
+*/
 const std::string& Invoice::getBookingId() const
 {
     return m_bookingId;
 }
 
+/*
+Function: getBooking
+Description: Retrieves the pointer to the associated ServiceBooking.
+Returns:
+    - ServiceBooking* representing the booking.
+*/
 ServiceBooking* Invoice::getBooking() const
 {
     return m_booking;
 }
 
+/*
+Function: getInvoiceDate
+Description: Retrieves the timestamp of the invoice creation date.
+Returns:
+    - const util::Timestamp& representing the invoice date.
+*/
 const util::Timestamp& Invoice::getInvoiceDate() const
 {
     return m_invoiceDate;
 }
 
+/*
+Function: getLaborCost
+Description: Retrieves the labor cost associated with the invoice.
+Returns:
+    - double representing the labor cost.
+*/
 double Invoice::getLaborCost() const
 {
     return m_laborCost;
 }
 
-const util::Map<int, InventoryItem*>& Invoice::getParts() const
+/*
+Function: getPartIDs
+Description: Retrieves the IDs of parts used in the invoice.
+Parameters:
+    - None
+Returns:
+    - const util::Vector<std::string>&: Part IDs
+*/
+const util::Vector<std::string>& Invoice::getPartIDs() const
+{
+    return m_partIDs;
+}
+
+/*
+Function: getParts
+Description: Retrieves the map of inventory items used in the service.
+Returns:
+    - const util::Map<int, InventoryItem*>& representing the parts.
+*/
+const util::Map<std::string, InventoryItem*>& Invoice::getParts() const
 {
     return m_parts;
 }
 
+/*
+Function: getPartsCost
+Description: Retrieves the total cost of parts used in the service.
+Returns:
+    - double representing the parts cost.
+*/
 double Invoice::getPartsCost() const
 {
     return m_partsCost;
 }
 
+/*
+Function: getDiscountPercentage
+Description: Retrieves the discount percentage applied to the invoice.
+Returns:
+    - double representing the discount percentage.
+*/
 double Invoice::getDiscountPercentage() const
 {
     return m_discountPercentage;
 }
 
+/*
+Function: getTotalAmount
+Description: Retrieves the total amount of the invoice after discount.
+Returns:
+    - double representing the total amount.
+*/
 double Invoice::getTotalAmount() const
 {
     return m_totalAmount;
 }
 
+/*
+Function: getPaymentDate
+Description: Retrieves the timestamp of the payment date.
+Returns:
+    - const util::Timestamp& representing the payment date.
+*/
 const util::Timestamp& Invoice::getPaymentDate() const
 {
     return m_paymentDate;
 }
 
+/*
+Function: getPaymentMethod
+Description: Retrieves the payment mode used for the invoice.
+Returns:
+    - util::PaymentMode representing the payment method.
+*/
 util::PaymentMode Invoice::getPaymentMethod() const
 {
     return m_paymentMethod;
 }
 
+/*
+Function: getStatus
+Description: Retrieves the payment status of the invoice.
+Returns:
+    - util::PaymentStatus representing the payment status.
+*/
 util::PaymentStatus Invoice::getStatus() const
 {
     return m_status;
 }
 
+/*
+Function: setId
+Description: Sets the unique ID of the invoice.
+Parameters:
+    - id: New invoice ID string.
+Returns:
+    - void
+*/
 void Invoice::setId(const std::string& id)
 {
     m_id = id;
 }
 
+/*
+Function: setBookingId
+Description: Sets the booking ID associated with the invoice.
+Parameters:
+    - bookingId: New booking ID string.
+Returns:
+    - void
+*/
 void Invoice::setBookingId(const std::string& bookingId)
 {
     m_bookingId = bookingId;
 }
 
+/*
+Function: setBooking
+Description: Sets the associated ServiceBooking pointer.
+Parameters:
+    - booking: Pointer to the ServiceBooking object.
+Returns:
+    - void
+*/
 void Invoice::setBooking(ServiceBooking* booking)
 {
     m_booking = booking;
 }
 
+/*
+Function: setInvoiceDate
+Description: Sets the invoice creation date.
+Parameters:
+    - invoiceDate: New timestamp for the invoice date.
+Returns:
+    - void
+*/
 void Invoice::setInvoiceDate(const util::Timestamp& invoiceDate)
 {
     m_invoiceDate = invoiceDate;
 }
 
+/*
+Function: setLaborCost
+Description: Sets the labor cost for the invoice.
+Parameters:
+    - laborCost: New labor cost value.
+Returns:
+    - void
+*/
 void Invoice::setLaborCost(double laborCost)
 {
     m_laborCost = laborCost;
 }
 
-void Invoice::setParts(const util::Map<int, InventoryItem*>& parts)
+/*
+Function: setParts
+Description: Sets the inventory items used in the service.
+Parameters:
+    - parts: Map of inventory items.
+Returns:
+    - void
+*/
+void Invoice::setParts(const util::Map<std::string, InventoryItem*>& parts)
 {
     m_parts = parts;
+    m_partIDs.clear();
+    int numberOfParts = m_parts.getSize();
+    auto partPointers = m_parts.getValues();
+    for (int index = 0; index < numberOfParts; index++)
+    {
+        m_partIDs.push_back(partPointers[index]->getId());
+    }
 }
 
+/*
+Function: setPartsCost
+Description: Sets the total cost of parts used in the service.
+Parameters:
+    - partsCost: New parts cost value.
+Returns:
+    - void
+*/
 void Invoice::setPartsCost(double partsCost)
 {
     m_partsCost = partsCost;
 }
 
+/*
+Function: setDiscountPercentage
+Description: Sets the discount percentage applied to the invoice.
+Parameters:
+    - discountPercentage: New discount percentage value.
+Returns:
+    - void
+*/
 void Invoice::setDiscountPercentage(double discountPercentage)
 {
     m_discountPercentage = discountPercentage;
 }
 
+/*
+Function: setTotalAmount
+Description: Sets the total amount of the invoice.
+Parameters:
+    - totalAmount: New total amount value.
+Returns:
+    - void
+*/
 void Invoice::setTotalAmount(double totalAmount)
 {
     m_totalAmount = totalAmount;
 }
 
+/*
+Function: setPaymentDate
+Description: Sets the payment date for the invoice.
+Parameters:
+    - paymentDate: New timestamp for the payment date.
+Returns:
+    - void
+*/
 void Invoice::setPaymentDate(const util::Timestamp& paymentDate)
 {
     m_paymentDate = paymentDate;
 }
 
+/*
+Function: setPaymentMethod
+Description: Sets the payment mode for the invoice.
+Parameters:
+    - paymentMethod: New payment mode value.
+Returns:
+    - void
+*/
 void Invoice::setPaymentMethod(util::PaymentMode paymentMethod)
 {
     m_paymentMethod = paymentMethod;
 }
 
+/*
+Function: setStatus
+Description: Sets the payment status of the invoice.
+Parameters:
+    - status: New payment status value.
+Returns:
+    - void
+*/
 void Invoice::setStatus(util::PaymentStatus status)
 {
     m_status = status;
 }
+
+/*
+Function: getPartIDsAsString (static helper)
+Description: Converts a vector of part IDs into a single string separated by '|'.
+Parameters:
+    - partIDs: const util::Vector<std::string>&, vector of part IDs
+Returns:
+    - std::string: Concatenated part IDs string
+*/
+static std::string getPartIDsAsString(const util::Vector<std::string>& partIDs)
+{
+    int numberOfParts = partIDs.getSize();
+    std::string partIDsString;
+    for (int index = 0; index < numberOfParts; index++)
+    {
+        partIDsString += partIDs[index];
+        if (index < numberOfParts - 1)
+        {
+            partIDsString += '|';
+        }
+    }
+    return partIDsString;
+}
+
+/*
+Function: getPartIDsAsVector (static helper)
+Description: Converts a string of part IDs separated by '|' into a vector.
+Parameters:
+    - partIDsString: const std::string&, concatenated part IDs string
+Returns:
+    - util::Vector<std::string>: Vector of part IDs
+*/
+static util::Vector<std::string> getPartIDsAsVector(const std::string& partIDsString)
+{
+    util::Vector<std::string> partIDs;
+    std::string partID;
+    std::istringstream serializedPartIDs(partIDsString);
+    while (getline(serializedPartIDs, partID, '|'))
+    {
+        partIDs.push_back(partID);
+    }
+    return partIDs;
+}
+
+/*
+Function: serialize
+Description: Serializes the invoice into a CSV-formatted string.
+Parameters:
+    - None
+Returns:
+    - std::string: Serialized invoice record
+*/
+std::string Invoice::serialize() const
+{
+    std::ostringstream serializedInvoice;
+    serializedInvoice << m_id << ','
+        << m_bookingId << ','
+        << m_invoiceDate.toString() << ','
+        << m_laborCost << ','
+        << getPartIDsAsString(m_partIDs) << ','
+        << m_partsCost << ','
+        << m_discountPercentage << ','
+        << m_totalAmount << ','
+        << m_paymentDate.toString() << ','
+        << util::getPaymentModeString(m_paymentMethod) << ','
+        << util::getPaymentStatusString(m_status);
+    return serializedInvoice.str();
+}
+
+/*
+Function: deserialize
+Description: Deserializes a CSV-formatted string into an Invoice object.
+Parameters:
+    - record: const std::string&, serialized invoice record
+Returns:
+    - Invoice*: Pointer to the deserialized Invoice object
+Throws:
+    - std::runtime_error if data is invalid
+*/
+Invoice* Invoice::deserialize(const std::string& record)
+{
+    std::string id, bookingId;
+    std::string invoiceDateString, laborCostString, partIDsString;
+    std::string partsCostString, discountPercentageString, totalAmountString;
+    std::string paymentDateString, paymentMethodString, statusString;
+    double laborCost, partsCost, discountPercentage, totalAmount;
+    std::istringstream serializedInvoice(record);
+    getline(serializedInvoice, id, ',');
+    getline(serializedInvoice, bookingId, ',');
+    getline(serializedInvoice, invoiceDateString, ',');
+    getline(serializedInvoice, laborCostString, ',');
+    getline(serializedInvoice, partIDsString, ',');
+    getline(serializedInvoice, partsCostString, ',');
+    getline(serializedInvoice, discountPercentageString, ',');
+    getline(serializedInvoice, totalAmountString, ',');
+    getline(serializedInvoice, paymentDateString, ',');
+    getline(serializedInvoice, paymentMethodString, ',');
+    getline(serializedInvoice, statusString, ',');
+    util::Timestamp invoiceDate;
+    util::Timestamp paymentDate;
+    try
+    {
+        invoiceDate = util::Timestamp::fromString(invoiceDateString);
+        paymentDate = util::Timestamp::fromString(paymentDateString);
+        laborCost = std::stod(laborCostString);
+        partsCost = std::stod(partsCostString);
+        discountPercentage = std::stod(discountPercentageString);
+        totalAmount = std::stod(totalAmountString);
+    }
+    catch (...)
+    {
+        throw std::runtime_error("Invalid invoice data");
+    }
+    util::Vector<std::string> partIDs = getPartIDsAsVector(partIDsString);
+    util::PaymentMode paymentMethod = util::getPaymentMode(paymentMethodString);
+    util::PaymentStatus status = util::getPaymentStatus(statusString);
+    return Factory::getObject<Invoice>(
+        id,
+        bookingId,
+        invoiceDate,
+        partIDs,
+        laborCost,
+        partsCost,
+        discountPercentage,
+        totalAmount,
+        paymentDate,
+        paymentMethod,
+        status
+    );
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for invoice serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,BookingID,InvoiceDate,LaborCost,PartIDs,PartsCost,DiscountPercentage,TotalAmount,PaymentDate,PaymentMethod,Status")
+*/
+std::string Invoice::getHeaders()
+{
+    return "ID,BookingID,InvoiceDate,LaborCost,PartIDs,PartsCost,DiscountPercentage,TotalAmount,PaymentDate,PaymentMethod,Status";
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/Invoice.h

@@ -1,6 +1,16 @@
+/*
+File: Invoice.h
+Description: Declares the Invoice class which represents billing details for a service booking in the Vehicle Service Management System.
+             Each invoice includes booking information, labor cost, parts used, discount percentage, total amount, payment details, and status.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "Timestamp.h"
 #include "Enums.h"
 
@@ -16,22 +26,22 @@ private:
     ServiceBooking* m_booking;
     util::Timestamp m_invoiceDate;
     double m_laborCost;
-    util::Map<int, InventoryItem*> m_parts;
+    util::Vector<std::string> m_partIDs;
+    util::Map<std::string, InventoryItem*> m_parts;
     double m_partsCost;
     double m_discountPercentage;
     double m_totalAmount;
     util::Timestamp m_paymentDate;
     util::PaymentMode m_paymentMethod;
     util::PaymentStatus m_status;
-
 public:
     Invoice();
     Invoice(
         const std::string& bookingId,
         ServiceBooking* booking,
         const util::Timestamp& invoiceDate, 
-        double laborCost, const util::Map<int,
-        InventoryItem*>& parts,
+        double laborCost, 
+        const util::Map<std::string,InventoryItem*>& parts,
         double partsCost,
         double discountPercentage, 
         double totalAmount, 
@@ -39,12 +49,26 @@ public:
         util::PaymentMode paymentMethod, 
         util::PaymentStatus status
     );
+    Invoice(
+        const std::string& id,
+        const std::string& bookingId,
+        const util::Timestamp& invoiceDate,
+        const util::Vector<std::string>& partIDs,
+        double laborCost,
+        double partsCost,
+        double discountPercentage,
+        double totalAmount,
+        const util::Timestamp& paymentDate,
+        util::PaymentMode paymentMethod,
+        util::PaymentStatus status
+    );
     const std::string& getId() const;
     const std::string& getBookingId() const;
     ServiceBooking* getBooking() const;
     const util::Timestamp& getInvoiceDate() const;
     double getLaborCost() const;
-    const util::Map<int, InventoryItem*>& getParts() const;
+    const util::Vector<std::string>& getPartIDs() const;
+    const util::Map<std::string, InventoryItem*>& getParts() const;
     double getPartsCost() const;
     double getDiscountPercentage() const;
     double getTotalAmount() const;
@@ -56,11 +80,14 @@ public:
     void setBooking(ServiceBooking* booking);
     void setInvoiceDate(const util::Timestamp& invoiceDate);
     void setLaborCost(double laborCost);
-    void setParts(const util::Map<int, InventoryItem*>& parts);
+    void setParts(const util::Map<std::string, InventoryItem*>& parts);
     void setPartsCost(double partsCost);
     void setDiscountPercentage(double discountPercentage);
     void setTotalAmount(double totalAmount);
     void setPaymentDate(const util::Timestamp& paymentDate);
     void setPaymentMethod(util::PaymentMode paymentMethod);
     void setStatus(util::PaymentStatus status);
+    std::string serialize() const;
+    static Invoice* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/JobCard.cpp

@@ -6,7 +6,13 @@ Description: Implementation file containing the method definitions of the
 Author: Trenser
 Date:19-May-2026
 */
+
+#include <sstream>
+#include <stdexcept>
 #include "JobCard.h"
+#include "Factory.h"
+#include "StringHelper.h"
+#include "Enums.h"
 
 int JobCard::m_uid = 0;
 
@@ -26,18 +32,19 @@ JobCard::JobCard()
 
 /*
 Function: JobCard
-Description: Parameterized constructor that initializes a job card with
-             booking, service, technician, and status details.
-Parameter: const std::string& bookingId - ID of the booking
-           ServiceBooking* booking - pointer to the booking object
-           Service* service - pointer to the service object
-           const std::string& serviceId - ID of the service
-           const std::string& technicianId - ID of the technician
-           User* technician - pointer to the technician object
-           const util::Timestamp& assignedDate - date when job was assigned
-           util::ServiceJobStatus status - current status of the job
-           const util::Timestamp& completionDate - date when job was completed
-Return type: Constructor
+Description: Parameterized constructor that initializes a new job card with a unique ID and specified details.
+Parameters:
+    - bookingId: ID of the associated service booking.
+    - booking: Pointer to the ServiceBooking object.
+    - service: Pointer to the Service object.
+    - serviceId: ID of the associated service.
+    - technicianId: ID of the assigned technician.
+    - technician: Pointer to the User object representing the technician.
+    - assignedDate: Timestamp of when the job was assigned.
+    - status: Current status of the job (STARTED/COMPLETED).
+    - completionDate: Timestamp of when the job was completed.
+Returns:
+    - A new JobCard object.
 */
 JobCard::JobCard(const std::string& bookingId,
     ServiceBooking* booking,
@@ -60,11 +67,53 @@ JobCard::JobCard(const std::string& bookingId,
     m_status(status),
     m_completionDate(completionDate) {}
 
+/*
+Function: JobCard (parameterized constructor with ID)
+Description: Initializes a job card with an existing ID, booking ID, service ID,
+             technician ID, assignment date, completion date, and status.
+             Updates UID tracking based on ID.
+Parameters:
+    - id: const std::string&, unique job card ID
+    - bookingId: const std::string&, ID of the booking
+    - serviceId: const std::string&, ID of the service
+    - technicianId: const std::string&, ID of the technician
+    - assignedDate: const util::Timestamp&, date of assignment
+    - status: util::ServiceJobStatus, job status
+    - completionDate: const util::Timestamp&, date of completion
+Returns:
+    - A new JobCard object
+*/
+JobCard::JobCard(const std::string& id,
+    const std::string& bookingId,
+    const std::string& serviceId,
+    const std::string& technicianId,
+    const util::Timestamp& assignedDate,
+    util::ServiceJobStatus status,
+    const util::Timestamp& completionDate
+)
+    : m_id(id),
+    m_bookingId(bookingId),
+    m_booking(nullptr),
+    m_service(nullptr),
+    m_serviceId(serviceId),
+    m_technicianId(technicianId),
+    m_technician(nullptr),
+    m_assignedDate(assignedDate),
+    m_status(status),
+    m_completionDate(completionDate)
+{
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
+    {
+        m_uid = idNumber;
+    }
+}
+
 /*
 Function: getId
-Description: Retrieves the unique identifier of the job card.
-Parameter: None
-Return type: const std::string&
+Description: Retrieves the unique ID of the job card.
+Returns:
+    - const std::string& representing the job card ID.
 */
 const std::string& JobCard::getId() const
 {
@@ -74,8 +123,8 @@ const std::string& JobCard::getId() const
 /*
 Function: getBookingId
 Description: Retrieves the booking ID associated with the job card.
-Parameter: None
-Return type: const std::string&
+Returns:
+    - const std::string& representing the booking ID.
 */
 const std::string& JobCard::getBookingId() const
 {
@@ -84,9 +133,9 @@ const std::string& JobCard::getBookingId() const
 
 /*
 Function: getBooking
-Description: Retrieves the booking object associated with the job card.
-Parameter: None
-Return type: ServiceBooking*
+Description: Retrieves the pointer to the associated ServiceBooking.
+Returns:
+    - ServiceBooking* representing the booking.
 */
 ServiceBooking* JobCard::getBooking() const
 {
@@ -95,9 +144,9 @@ ServiceBooking* JobCard::getBooking() const
 
 /*
 Function: getService
-Description: Retrieves the service object associated with the job card.
-Parameter: None
-Return type: Service*
+Description: Retrieves the pointer to the associated Service.
+Returns:
+    - Service* representing the service.
 */
 Service* JobCard::getService() const
 {
@@ -107,8 +156,8 @@ Service* JobCard::getService() const
 /*
 Function: getServiceId
 Description: Retrieves the service ID associated with the job card.
-Parameter: None
-Return type: const std::string&
+Returns:
+    - const std::string& representing the service ID.
 */
 const std::string& JobCard::getServiceId() const
 {
@@ -117,9 +166,9 @@ const std::string& JobCard::getServiceId() const
 
 /*
 Function: getTechnicianId
-Description: Retrieves the technician ID assigned to the job card.
-Parameter: None
-Return type: const std::string&
+Description: Retrieves the technician ID associated with the job card.
+Returns:
+    - const std::string& representing the technician ID.
 */
 const std::string& JobCard::getTechnicianId() const
 {
@@ -128,9 +177,9 @@ const std::string& JobCard::getTechnicianId() const
 
 /*
 Function: getTechnician
-Description: Retrieves the technician object assigned to the job card.
-Parameter: None
-Return type: User*
+Description: Retrieves the pointer to the assigned technician.
+Returns:
+    - User* representing the technician.
 */
 User* JobCard::getTechnician() const
 {
@@ -139,9 +188,9 @@ User* JobCard::getTechnician() const
 
 /*
 Function: getAssignedDate
-Description: Retrieves the date when the job was assigned.
-Parameter: None
-Return type: const util::Timestamp&
+Description: Retrieves the timestamp of when the job was assigned.
+Returns:
+    - const util::Timestamp& representing the assigned date.
 */
 const util::Timestamp& JobCard::getAssignedDate() const
 {
@@ -150,9 +199,9 @@ const util::Timestamp& JobCard::getAssignedDate() const
 
 /*
 Function: getStatus
-Description: Retrieves the current status of the job card.
-Parameter: None
-Return type: util::ServiceJobStatus
+Description: Retrieves the current status of the job.
+Returns:
+    - ServiceJobStatus representing the job status.
 */
 util::ServiceJobStatus JobCard::getStatus() const
 {
@@ -161,9 +210,9 @@ util::ServiceJobStatus JobCard::getStatus() const
 
 /*
 Function: getCompletionDate
-Description: Retrieves the completion date of the job card.
-Parameter: None
-Return type: const util::Timestamp&
+Description: Retrieves the timestamp of when the job was completed.
+Returns:
+    - const util::Timestamp& representing the completion date.
 */
 const util::Timestamp& JobCard::getCompletionDate() const
 {
@@ -172,9 +221,11 @@ const util::Timestamp& JobCard::getCompletionDate() const
 
 /*
 Function: setId
-Description: Sets the unique identifier of the job card.
-Parameter: const std::string& id - new job card ID
-Return type: void
+Description: Sets the unique ID of the job card.
+Parameters:
+    - id: New job card ID string.
+Returns:
+    - void
 */
 void JobCard::setId(const std::string& id)
 {
@@ -183,9 +234,11 @@ void JobCard::setId(const std::string& id)
 
 /*
 Function: setBookingId
-Description: Sets the booking ID for the job card.
-Parameter: const std::string& bookingId - new booking ID
-Return type: void
+Description: Sets the booking ID associated with the job card.
+Parameters:
+    - bookingId: New booking ID string.
+Returns:
+    - void
 */
 void JobCard::setBookingId(const std::string& bookingId)
 {
@@ -194,9 +247,11 @@ void JobCard::setBookingId(const std::string& bookingId)
 
 /*
 Function: setBooking
-Description: Sets the booking object for the job card.
-Parameter: ServiceBooking* booking - pointer to the booking object
-Return type: void
+Description: Sets the associated ServiceBooking pointer.
+Parameters:
+    - booking: Pointer to the ServiceBooking object.
+Returns:
+    - void
 */
 void JobCard::setBooking(ServiceBooking* booking)
 {
@@ -205,9 +260,11 @@ void JobCard::setBooking(ServiceBooking* booking)
 
 /*
 Function: setService
-Description: Sets the service object for the job card.
-Parameter: Service* service - pointer to the service object
-Return type: void
+Description: Sets the associated Service pointer.
+Parameters:
+    - service: Pointer to the Service object.
+Returns:
+    - void
 */
 void JobCard::setService(Service* service)
 {
@@ -216,9 +273,11 @@ void JobCard::setService(Service* service)
 
 /*
 Function: setServiceId
-Description: Sets the service ID for the job card.
-Parameter: const std::string& serviceId - new service ID
-Return type: void
+Description: Sets the service ID associated with the job card.
+Parameters:
+    - serviceId: New service ID string.
+Returns:
+    - void
 */
 void JobCard::setServiceId(const std::string& serviceId)
 {
@@ -227,9 +286,11 @@ void JobCard::setServiceId(const std::string& serviceId)
 
 /*
 Function: setTechnicianId
-Description: Sets the technician ID for the job card.
-Parameter: const std::string& technicianId - new technician ID
-Return type: void
+Description: Sets the technician ID associated with the job card.
+Parameters:
+    - technicianId: New technician ID string.
+Returns:
+    - void
 */
 void JobCard::setTechnicianId(const std::string& technicianId)
 {
@@ -238,9 +299,11 @@ void JobCard::setTechnicianId(const std::string& technicianId)
 
 /*
 Function: setTechnician
-Description: Sets the technician object for the job card.
-Parameter: User* technician - pointer to the technician object
-Return type: void
+Description: Sets the pointer to the assigned technician.
+Parameters:
+    - technician: Pointer to the User object.
+Returns:
+    - void
 */
 void JobCard::setTechnician(User* technician)
 {
@@ -249,9 +312,11 @@ void JobCard::setTechnician(User* technician)
 
 /*
 Function: setAssignedDate
-Description: Sets the assigned date for the job card.
-Parameter: const util::Timestamp& assignedDate - new assigned date
-Return type: void
+Description: Sets the timestamp of when the job was assigned.
+Parameters:
+    - assignedDate: New timestamp for the assigned date.
+Returns:
+    - void
 */
 void JobCard::setAssignedDate(const util::Timestamp& assignedDate)
 {
@@ -260,9 +325,11 @@ void JobCard::setAssignedDate(const util::Timestamp& assignedDate)
 
 /*
 Function: setStatus
-Description: Sets the status of the job card.
-Parameter: util::ServiceJobStatus status - new job status
-Return type: void
+Description: Sets the current status of the job.
+Parameters:
+    - status: New job status value.
+Returns:
+    - void
 */
 void JobCard::setStatus(util::ServiceJobStatus status)
 {
@@ -271,11 +338,92 @@ void JobCard::setStatus(util::ServiceJobStatus status)
 
 /*
 Function: setCompletionDate
-Description: Sets the completion date for the job card.
-Parameter: const util::Timestamp& completionDate - new completion date
-Return type: void
+Description: Sets the timestamp of when the job was completed.
+Parameters:
+    - completionDate: New timestamp for the completion date.
+Returns:
+    - void
 */
 void JobCard::setCompletionDate(const util::Timestamp& completionDate)
 {
     m_completionDate = completionDate;
+}
+
+/*
+Function: serialize
+Description: Serializes the job card into a CSV-formatted string.
+Parameters:
+    - None
+Returns:
+    - std::string: Serialized job card record
+*/
+std::string JobCard::serialize() const
+{
+    std::ostringstream serializedJobCard;
+    serializedJobCard << m_id << ','
+        << m_bookingId << ','
+        << m_serviceId << ','
+        << m_technicianId << ','
+        << m_assignedDate.toString() << ','
+        << util::getServiceJobStatusString(m_status) << ','
+        << m_completionDate.toString();
+    return serializedJobCard.str();
+}
+
+/*
+Function: deserialize
+Description: Deserializes a CSV-formatted string into a JobCard object.
+Parameters:
+    - record: const std::string&, serialized job card record
+Returns:
+    - JobCard*: Pointer to the deserialized JobCard object
+Throws:
+    - std::runtime_error if timestamp parsing fails
+*/
+JobCard* JobCard::deserialize(const std::string& record)
+{
+    std::string id, bookingId, serviceId, technicianId;
+    std::string assignedDateString, statusString, completionDateString;
+    std::istringstream serializedJobCard(record);
+    getline(serializedJobCard, id, ',');
+    getline(serializedJobCard, bookingId, ',');
+    getline(serializedJobCard, serviceId, ',');
+    getline(serializedJobCard, technicianId, ',');
+    getline(serializedJobCard, assignedDateString, ',');
+    getline(serializedJobCard, statusString, ',');
+    getline(serializedJobCard, completionDateString, ',');
+    util::Timestamp assignedDate;
+    util::Timestamp completionDate;
+    try
+    {
+        assignedDate = util::Timestamp::fromString(assignedDateString);
+        completionDate = util::Timestamp::fromString(completionDateString);
+    }
+    catch (...)
+    {
+        throw std::runtime_error("Invalid timestamp");
+    }
+    util::ServiceJobStatus status = util::getServiceJobStatus(statusString);
+    return Factory::getObject<JobCard>(
+        id,
+        bookingId,
+        serviceId,
+        technicianId,
+        assignedDate,
+        status,
+        completionDate
+    );
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for job card serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,BookingID,ServiceID,TechnicianID,AssignedDate,Status,CompletionDate")
+*/
+std::string JobCard::getHeaders()
+{
+    return "ID,BookingID,ServiceID,TechnicianID,AssignedDate,Status,CompletionDate";
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/JobCard.h

@@ -6,10 +6,11 @@ Description: Header file declaring the JobCard class, which represents
 Author: Trenser
 Date:19-May-2026
 */
+
 #pragma once
 #include <string>
-#include "Timestamp.h"
 #include "Enums.h"
+#include "Timestamp.h"
 
 class ServiceBooking;
 class Service;
@@ -41,6 +42,14 @@ public:
         util::ServiceJobStatus status,
         const util::Timestamp& completionDate
     );
+    JobCard(const std::string& id,
+        const std::string& bookingId,
+        const std::string& serviceId,
+        const std::string& technicianId,
+        const util::Timestamp& assignedDate,
+        util::ServiceJobStatus status,
+        const util::Timestamp& completionDate
+    );
     const std::string& getId() const;
     const std::string& getBookingId() const;
     ServiceBooking* getBooking() const;
@@ -61,4 +70,7 @@ public:
     void setAssignedDate(const util::Timestamp& assignedDate);
     void setStatus(util::ServiceJobStatus status);
     void setCompletionDate(const util::Timestamp& completionDate);
+    std::string serialize() const;
+    static JobCard* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/Notification.cpp

@@ -1,11 +1,42 @@
+/*
+File: Notification.cpp
+Description: Implements the Notification class which represents system notifications in the Vehicle Service Management System.
+             Provides constructors, accessors, and mutators for notification details such as ID, recipient, title, message, and timestamp.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+#include <sstream>
 #include "Notification.h"
+#include "StringHelper.h"
+#include "Factory.h"
 
 int Notification::m_uid = 0;
 
+/*
+Function: Notification
+Description: Default constructor that initializes a new notification with a unique ID and null recipient.
+Parameters:
+    - None
+Returns:
+    - A new Notification object.
+*/
 Notification::Notification()
     : m_id("NOT" + std::to_string(++m_uid)),
     m_recipient(nullptr) {}
 
+/*
+Function: Notification
+Description: Parameterized constructor that initializes a new notification with a unique ID and specified details.
+Parameters:
+    - recipientUserId: ID of the recipient user.
+    - recipient: Pointer to the User object representing the recipient.
+    - title: Title of the notification.
+    - message: Message content of the notification.
+    - createdAt: Timestamp of when the notification was created.
+Returns:
+    - A new Notification object.
+*/
 Notification::Notification(const std::string& recipientUserId, User* recipient, const std::string& title, const std::string& message, const util::Timestamp& createdAt)
     : m_id("NOT" + std::to_string(++m_uid)),
     m_recipientUserId(recipientUserId),
@@ -14,62 +45,243 @@ Notification::Notification(const std::string& recipientUserId, User* recipient,
     m_message(message),
     m_createdAt(createdAt) {}
 
+/*
+Function: Notification (parameterized constructor with ID)
+Description: Initializes a notification with an existing ID, recipient details,
+             title, message, and creation timestamp. Updates UID tracking based on ID.
+Parameters:
+    - id: const std::string&, unique notification ID
+    - recipientUserId: const std::string&, ID of the recipient user
+    - title: const std::string&, notification title
+    - message: const std::string&, notification message
+    - createdAt: const util::Timestamp&, timestamp of creation
+Returns:
+    - A new Notification object
+*/
+Notification::Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt)
+    : m_id(id),
+    m_recipientUserId(recipientUserId),
+    m_recipient(nullptr),
+    m_title(title),
+    m_message(message),
+    m_createdAt(createdAt) 
+{
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
+    {
+        m_uid = idNumber;
+    }
+}
+
+/*
+Function: getId
+Description: Retrieves the unique ID of the notification.
+Returns:
+    - const std::string& representing the notification ID.
+*/
 const std::string& Notification::getId() const 
 {
     return m_id;
 }
 
+/*
+Function: getRecipientUserId
+Description: Retrieves the recipient user ID associated with the notification.
+Returns:
+    - const std::string& representing the recipient user ID.
+*/
 const std::string& Notification::getRecipientUserId() const
 {
     return m_recipientUserId;
 }
 
+/*
+Function: getRecipient
+Description: Retrieves the pointer to the recipient user.
+Returns:
+    - User* representing the recipient.
+*/
 User* Notification::getRecipient() const
 {
     return m_recipient;
 }
 
+/*
+Function: getTitle
+Description: Retrieves the title of the notification.
+Returns:
+    - const std::string& representing the notification title.
+*/
 const std::string& Notification::getTitle() const
 {
     return m_title;
 }
 
+/*
+Function: getMessage
+Description: Retrieves the message content of the notification.
+Returns:
+    - const std::string& representing the notification message.
+*/
 const std::string& Notification::getMessage() const
 {
     return m_message;
 }
 
+/*
+Function: getCreatedAt
+Description: Retrieves the timestamp of when the notification was created.
+Returns:
+    - const util::Timestamp& representing the creation timestamp.
+*/
 const util::Timestamp& Notification::getCreatedAt() const
 {
     return m_createdAt;
 }
 
+/*
+Function: setId
+Description: Sets the unique ID of the notification.
+Parameters:
+    - id: New notification ID string.
+Returns:
+    - void
+*/
 void Notification::setId(const std::string& id)
 {
     m_id = id;
 }
 
+/*
+Function: setRecipientUserId
+Description: Sets the recipient user ID for the notification.
+Parameters:
+    - recipientUserId: New recipient user ID string.
+Returns:
+    - void
+*/
 void Notification::setRecipientUserId(const std::string& recipientUserId)
 {
     m_recipientUserId = recipientUserId;
 }
 
+/*
+Function: setRecipient
+Description: Sets the recipient user pointer for the notification.
+Parameters:
+    - recipient: Pointer to the User object.
+Returns:
+    - void
+*/
 void Notification::setRecipient(User* recipient)
 {
     m_recipient = recipient;
 }
 
+/*
+Function: setTitle
+Description: Sets the title of the notification.
+Parameters:
+    - title: New notification title string.
+Returns:
+    - void
+*/
 void Notification::setTitle(const std::string& title)
 {
     m_title = title;
 }
 
+/*
+Function: setMessage
+Description: Sets the message content of the notification.
+Parameters:
+    - message: New notification message string.
+Returns:
+    - void
+*/
 void Notification::setMessage(const std::string& message)
 {
     m_message = message;
 }
 
+/*
+Function: setCreatedAt
+Description: Sets the timestamp of when the notification was created.
+Parameters:
+    - createdAt: New timestamp value.
+Returns:
+    - void
+*/
 void Notification::setCreatedAt(const util::Timestamp& createdAt)
 {
     m_createdAt = createdAt;
+}
+
+/*
+Function: serialize
+Description: Serializes the notification into a CSV-formatted string.
+Parameters:
+    - None
+Returns:
+    - std::string: Serialized notification record
+*/
+std::string Notification::serialize() const
+{
+    std::ostringstream serializedNotification;
+    serializedNotification << m_id << ','
+        << m_recipientUserId << ','
+        << m_title << ','
+        << m_message << ','
+        << m_createdAt.toString();
+    return serializedNotification.str();
+}
+
+/*
+Function: deserialize
+Description: Deserializes a CSV-formatted string into a Notification object.
+Parameters:
+    - record: const std::string&, serialized notification record
+Returns:
+    - Notification*: Pointer to the deserialized Notification object
+Throws:
+    - std::runtime_error if timestamp parsing fails
+*/
+Notification* Notification::deserialize(const std::string& record)
+{
+    std::string id, recipientUserId, title, message, createdAtTimestampString;
+    std::istringstream serializedNotification(record);
+    getline(serializedNotification, id, ',');
+    getline(serializedNotification, recipientUserId, ',');
+    getline(serializedNotification, title, ',');
+    getline(serializedNotification, message, ',');
+    getline(serializedNotification, createdAtTimestampString, ',');
+    util::Timestamp createdAtTimestamp;
+    try
+    {
+        createdAtTimestamp = util::Timestamp::fromString(createdAtTimestampString);
+    }
+    catch (...)
+    {
+        throw std::runtime_error("Invalid createdAt timestamp");
+    }
+    return Factory::getObject<Notification>(
+        id,
+        recipientUserId,
+        title,
+        message,
+        createdAtTimestamp
+    );
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for notification serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,RecipientID,Title,Message,Timestamp")
+*/
+std::string Notification::getHeaders()
+{
+    return "ID,RecipientID,Title,Message,Timestamp";
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/Notification.h

@@ -1,3 +1,11 @@
+/*
+File: Notification.h
+Description: Declares the Notification class which represents system messages sent to users in the Vehicle Service Management System.
+             Each notification includes a unique ID, recipient details, title, message content, and timestamp of creation.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #pragma once
 #include <string>
 #include "Timestamp.h"
@@ -17,6 +25,7 @@ private:
 public:
     Notification();
     Notification(const std::string& recipientUserId, User* recipient, const std::string& title, const std::string& message, const util::Timestamp& createdAt);
+    Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt);
     const std::string& getId() const;
     const std::string& getRecipientUserId() const;
     User* getRecipient() const;
@@ -29,4 +38,7 @@ public:
     void setTitle(const std::string& title);
     void setMessage(const std::string& message);
     void setCreatedAt(const util::Timestamp& createdAt);
+    std::string serialize() const;
+    static Notification* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/Service.cpp

@@ -1,65 +1,337 @@
+/*
+File: Service.cpp
+Description: Implements the Service class which represents a vehicle service in the Vehicle Service Management System.
+             Provides constructors, accessors, and mutators for service details such as ID, name, required inventory items,
+             labor cost, and state.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+#include <sstream>
 #include "Service.h"
+#include "InventoryItem.h"
+#include "StringHelper.h"
+#include "Factory.h"
 
 int Service::m_uid = 0;
 
+/*
+Function: Service
+Description: Default constructor that initializes a new service with a unique ID,
+             active state, and zero labor cost.
+Parameters:
+    - None
+Returns:
+    - A new Service object.
+*/
 Service::Service()
     : m_id("SRV" + std::to_string(++m_uid)),
     m_status(util::State::ACTIVE),
     m_laborCost(0.0) {}
 
+/*
+Function: Service
+Description: Parameterized constructor that initializes a new service with a unique ID and specified details.
+Parameters:
+    - name: Name of the service.
+    - requiredInventoryItems: Map of inventory items required for the service.
+    - laborCost: Labor cost associated with the service.
+Returns:
+    - A new Service object.
+*/
 Service::Service(const std::string& name, const util::Map<std::string, InventoryItem*>& requiredInventoryItems, double laborCost)
     : m_id("SRV" + std::to_string(++m_uid)),
     m_name(name),
     m_requiredInventoryItems(requiredInventoryItems),
     m_status(util::State::ACTIVE),
-    m_laborCost(laborCost) {}
+    m_laborCost(laborCost) 
+{
+    int numberOfInventoryItems = m_requiredInventoryItems.getSize();
+    auto inventoryItemPointers = m_requiredInventoryItems.getValues();
+    for (int index = 0; index < numberOfInventoryItems; index++)
+    {
+        m_requiredInventoryItemIDs.push_back(inventoryItemPointers[index]->getId());
+    }
+}
 
+/*
+Function: Service (parameterized constructor with ID)
+Description: Initializes a service with an existing ID, name, inventory item IDs,
+             labor cost, and state. Updates UID tracking based on ID.
+Parameters:
+    - id: const std::string&, unique service ID
+    - name: const std::string&, name of the service
+    - requiredInventoryItemIDs: const util::Vector<std::string>&, IDs of required inventory items
+    - laborCost: double, labor cost of the service
+    - status: util::State, state of the service (ACTIVE/INACTIVE)
+Returns:
+    - A new Service object
+*/
+Service::Service(const std::string& id, const std::string& name, const util::Vector<std::string>& requiredInventoryItemIDs, double laborCost, util::State status)
+    : m_id(id),
+    m_name(name),
+    m_requiredInventoryItemIDs(requiredInventoryItemIDs),
+    m_status(status),
+    m_laborCost(laborCost)
+{
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
+    {
+        m_uid = idNumber;
+    }
+}
+
+/*
+Function: getId
+Description: Retrieves the unique ID of the service.
+Returns:
+    - const std::string& representing the service ID.
+*/
 const std::string& Service::getId() const
 {
     return m_id;
 }
 
+/*
+Function: getName
+Description: Retrieves the name of the service.
+Returns:
+    - const std::string& representing the service name.
+*/
 const std::string& Service::getName() const
 {
     return m_name;
 }
 
+/*
+Function: getRequiredInventoryItemIDs
+Description: Retrieves the IDs of required inventory items for the service.
+Parameters:
+    - None
+Returns:
+    - const util::Vector<std::string>&: Inventory item IDs
+*/
+const util::Vector<std::string>& Service::getRequiredInventoryItemIDs() const
+{
+    return m_requiredInventoryItemIDs;
+}
+
+/*
+Function: getRequiredInventoryItems
+Description: Retrieves the map of inventory items required for the service.
+Returns:
+    - const util::Map<std::string, InventoryItem*>& representing the required inventory items.
+*/
 const util::Map<std::string, InventoryItem*>& Service::getRequiredInventoryItems() const
 {
     return m_requiredInventoryItems;
 }
 
+/*
+Function: getLaborCost
+Description: Retrieves the labor cost associated with the service.
+Returns:
+    - double representing the labor cost.
+*/
 double Service::getLaborCost() const
 {
     return m_laborCost;
 }
 
+/*
+Function: getState
+Description: Retrieves the current state (ACTIVE/INACTIVE) of the service.
+Returns:
+    - util::State representing the service state.
+*/
 util::State Service::getState() const
 {
     return m_status;
 }
 
+/*
+Function: setId
+Description: Sets the unique ID of the service.
+Parameters:
+    - id: New service ID string.
+Returns:
+    - void
+*/
 void Service::setId(const std::string& id)
 {
     m_id = id;
 }
 
+/*
+Function: setName
+Description: Sets the name of the service.
+Parameters:
+    - name: New service name string.
+Returns:
+    - void
+*/
 void Service::setName(const std::string& name)
 {
     m_name = name;
 }
 
+/*
+Function: setRequiredInventoryItems
+Description: Sets the inventory items required for the service.
+Parameters:
+    - requiredInventoryItems: Map of inventory items.
+Returns:
+    - void
+*/
 void Service::setRequiredInventoryItems(const util::Map<std::string, InventoryItem*>& requiredInventoryItems)
 {
     m_requiredInventoryItems = requiredInventoryItems;
+    m_requiredInventoryItemIDs.clear();
+    int numberOfRequiredInventoryItems = m_requiredInventoryItems.getSize();
+    auto inventoryItemPointers = m_requiredInventoryItems.getValues();
+    for (int index = 0; index < numberOfRequiredInventoryItems; index++)
+    {
+        m_requiredInventoryItemIDs.push_back(inventoryItemPointers[index]->getId());
+    }
 }
 
+/*
+Function: setLaborCost
+Description: Sets the labor cost for the service.
+Parameters:
+    - laborCost: New labor cost value.
+Returns:
+    - void
+*/
 void Service::setLaborCost(double laborCost)
 {
     m_laborCost = laborCost;
 }
 
+/*
+Function: setState
+Description: Sets the state (ACTIVE/INACTIVE) of the service.
+Parameters:
+    - status: New state value.
+Returns:
+    - void
+*/
 void Service::setState(util::State status)
 {
     m_status = status;
+}
+
+/*
+Function: getInventoryItemIDsAsString (static helper)
+Description: Converts a vector of inventory item IDs into a single string separated by '|'.
+Parameters:
+    - inventoryItemIds: const util::Vector<std::string>&, vector of inventory item IDs
+Returns:
+    - std::string: Concatenated inventory item IDs string
+*/
+static std::string getInventoryItemIDsAsString(const util::Vector<std::string>& inventoryItemIds)
+{
+    int numberOfInventoryItems = inventoryItemIds.getSize();
+    std::string inventoryItemIDs;
+    for (int index = 0; index < numberOfInventoryItems; index++)
+    {
+        inventoryItemIDs += inventoryItemIds[index];
+        if (index < numberOfInventoryItems - 1)
+        {
+            inventoryItemIDs += '|';
+        }
+    }
+    return inventoryItemIDs;
+}
+
+/*
+Function: getInventoryItemIDsAsVector (static helper)
+Description: Converts a string of inventory item IDs separated by '|' into a vector.
+Parameters:
+    - inventoryItemIDsString: const std::string&, concatenated inventory item IDs string
+Returns:
+    - util::Vector<std::string>: Vector of inventory item IDs
+*/
+static util::Vector<std::string> getInventoryItemIDsAsVector(const std::string& inventoryItemIDsString)
+{
+    util::Vector<std::string> inventoryItemIDs;
+    std::string inventoryItemID;
+    std::istringstream serializedInventoryItemIDs(inventoryItemIDsString);
+    while (getline(serializedInventoryItemIDs, inventoryItemID, '|'))
+    {
+        inventoryItemIDs.push_back(inventoryItemID);
+    }
+    return inventoryItemIDs;
+}
+
+/*
+Function: serialize
+Description: Serializes the service into a CSV-formatted string.
+Parameters:
+    - None
+Returns:
+    - std::string: Serialized service record
+*/
+std::string Service::serialize() const
+{
+    std::ostringstream serializedService;
+    serializedService << m_id << ','
+        << m_name << ','
+        << getInventoryItemIDsAsString(m_requiredInventoryItemIDs) << ','
+        << m_laborCost << ','
+        << util::getStateString(m_status);
+    return serializedService.str();
+}
+
+/*
+Function: deserialize
+Description: Deserializes a CSV-formatted string into a Service object.
+Parameters:
+    - record: const std::string&, serialized service record
+Returns:
+    - Service*: Pointer to the deserialized Service object
+Throws:
+    - std::runtime_error if labor cost parsing fails
+*/
+Service* Service::deserialize(const std::string& record)
+{
+    std::string id, name;
+    std::string inventoryItemIDsString, laborCostString, statusString;
+    double laborCost;
+    std::istringstream serializedService(record);
+    getline(serializedService, id, ',');
+    getline(serializedService, name, ',');
+    getline(serializedService, inventoryItemIDsString, ',');
+    getline(serializedService, laborCostString, ',');
+    getline(serializedService, statusString, ',');
+    util::Vector<std::string> inventoryItemIDs = getInventoryItemIDsAsVector(inventoryItemIDsString);
+    try
+    {
+        laborCost = std::stod(laborCostString);
+    }
+    catch (...)
+    {
+        throw std::runtime_error("Invalid labor cost");
+    }
+    util::State status = util::getState(statusString);
+    return Factory::getObject<Service>(
+        id,
+        name,
+        inventoryItemIDs,
+        laborCost,
+        status
+    );
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for service serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,Name,InventoryIDs,LaborCost,Status")
+*/
+std::string Service::getHeaders()
+{
+    return "ID,Name,InventoryIDs,LaborCost,Status";
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/Service.h

@@ -1,6 +1,16 @@
+/*
+File: Service.h
+Description: Declares the Service class which represents a vehicle service in the Vehicle Service Management System.
+             Each service includes a unique ID, name, required inventory items, labor cost, and status.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "Enums.h"
 
 class InventoryItem;
@@ -11,14 +21,17 @@ private:
     static int m_uid;
     std::string m_id;
     std::string m_name;
+    util::Vector<std::string> m_requiredInventoryItemIDs;
     util::Map<std::string, InventoryItem*> m_requiredInventoryItems;
     double m_laborCost;
     util::State m_status;
 public:
     Service();
     Service(const std::string& name, const util::Map<std::string, InventoryItem*>& requiredInventoryItems, double laborCost);
+    Service(const std::string& id, const std::string& name, const util::Vector<std::string>& requiredInventoryItemIDs, double laborCost, util::State state);
     const std::string& getId() const;
     const std::string& getName() const;
+    const util::Vector<std::string>& getRequiredInventoryItemIDs() const;
     const util::Map<std::string, InventoryItem*>& getRequiredInventoryItems() const;
     double getLaborCost() const;
     util::State getState() const;
@@ -27,4 +40,7 @@ public:
     void setRequiredInventoryItems(const util::Map<std::string, InventoryItem*>& requiredInventoryItems);
     void setLaborCost(double laborCost);
     void setState(util::State status);
+    std::string serialize() const;
+    static Service* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/ServiceBooking.cpp

@@ -6,41 +6,46 @@ Description: Implementation file containing the method definitions of the
 Author: Trenser
 Date:19-May-2026
 */
+#include <stdexcept>
+#include <sstream>
 #include "ServiceBooking.h"
+#include "Service.h"
+#include "Enums.h"
+#include "Factory.h"
+#include "StringHelper.h"
 
 int ServiceBooking::m_uid = 0;
 
 /*
 Function: ServiceBooking
-Description: Default constructor that initializes a new service booking
-             with a unique ID, no customer, and zero discount.
-Parameter: None
-Return type: Constructor
+Description: Default constructor that initializes a new service booking with a unique ID,
+             null customer, and zero discount percentage.
+Parameters: None
+Returns: A new ServiceBooking object.
 */
 ServiceBooking::ServiceBooking()
     : m_id("SRV" + std::to_string(++m_uid)),
     m_customer(nullptr),
+    m_assignedTechnician(nullptr),
     m_discountPercentage(0.0) {}
 
 /*
 Function: ServiceBooking
-Description: Parameterized constructor that initializes a service booking
-             with customer, vehicle, technician, and discount details.
-Parameter: const std::string& id - booking ID
-           util::ServiceJobStatus status - current booking status
-           const util::Map<std::string, Service*>& services - map of services
-           const std::string& customerId - ID of the customer
-           User* customer - pointer to the customer object
-           const std::string& vehicleNumber - vehicle registration number
-           const std::string& vehicleBrand - brand of the vehicle
-           const std::string& vehicleModel - model of the vehicle
-           const std::string& assignedTechnicianId - ID of the assigned technician
-           User* assignedTechnician - pointer to the technician object
-           double discountPercentage - discount applied to the booking
-Return type: Constructor
+Description: Parameterized constructor that initializes a new service booking with a unique ID and specified details.
+Parameters:
+    - id: Booking ID string.
+    - status: Current status of the booking (e.g., PENDING, COMPLETED).
+    - services: Map of services included in the booking.
+    - customerId: ID of the customer.
+    - customer: Pointer to the User object representing the customer.
+    - vehicleNumber: Vehicle registration number.
+    - vehicleBrand: Brand of the vehicle.
+    - vehicleModel: Model of the vehicle.
+    - discountPercentage: Discount applied to the booking.
+Returns:
+    - A new ServiceBooking object.
 */
 ServiceBooking::ServiceBooking(
-    const std::string& id,
     util::ServiceJobStatus status,
     const util::Map<std::string,
     Service*>& services,
@@ -49,8 +54,6 @@ ServiceBooking::ServiceBooking(
     const std::string& vehicleNumber,
     const std::string& vehicleBrand,
     const std::string& vehicleModel,
-    const std::string& assignedTechnicianId,
-    User* assignedTechnician,
     double discountPercentage
 )
     : m_id("SRV" + std::to_string(++m_uid)),
@@ -61,10 +64,64 @@ ServiceBooking::ServiceBooking(
     m_vehicleNumber(vehicleNumber),
     m_vehicleBrand(vehicleBrand),
     m_vehicleModel(vehicleModel),
-    m_assignedTechnicianId(assignedTechnicianId),
-    m_assignedTechnician(assignedTechnician),
+    m_assignedTechnicianId(""),
+    m_assignedTechnician(nullptr),
     m_discountPercentage(discountPercentage)
 {
+    int numberOfServices = m_services.getSize();
+    auto servicePointers = m_services.getValues();
+    for (int index = 0; index < numberOfServices; index++)
+    {
+        m_serviceIDs.push_back(servicePointers[index]->getId());
+    }
+}
+
+/*
+Function: ServiceBooking (parameterized constructor with ID)
+Description: Initializes a service booking with an existing ID, status, service IDs,
+             customer details, vehicle details, technician ID, and discount percentage.
+             Updates UID tracking based on ID.
+Parameters:
+    - id: const std::string&, unique booking ID
+    - status: util::ServiceJobStatus, job status of the booking
+    - serviceIDs: const util::Vector<std::string>&, IDs of booked services
+    - customerId: const std::string&, ID of the customer
+    - vehicleNumber: const std::string&, vehicle number
+    - vehicleBrand: const std::string&, vehicle brand
+    - vehicleModel: const std::string&, vehicle model
+    - assignedTechnicianId: const std::string&, ID of the assigned technician
+    - discountPercentage: double, discount applied
+Returns:
+    - A new ServiceBooking object
+*/
+ServiceBooking::ServiceBooking(
+    const std::string& id,
+    util::ServiceJobStatus status,
+    const util::Vector<std::string>& serviceIDs,
+    const std::string& customerId,
+    const std::string& vehicleNumber,
+    const std::string& vehicleBrand,
+    const std::string& vehicleModel,
+    const std::string& assignedTechnicianId,
+    double discountPercentage
+)
+    : m_id(id),
+    m_status(status),
+    m_serviceIDs(serviceIDs),
+    m_customerId(customerId),
+    m_customer(nullptr),
+    m_vehicleNumber(vehicleNumber),
+    m_vehicleBrand(vehicleBrand),
+    m_vehicleModel(vehicleModel),
+    m_assignedTechnicianId(assignedTechnicianId),
+    m_assignedTechnician(nullptr),
+    m_discountPercentage(discountPercentage)
+{
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
+    {
+        m_uid = idNumber;
+    }
 }
 
 /*
@@ -89,6 +146,25 @@ util::ServiceJobStatus ServiceBooking::getStatus() const
     return m_status;
 }
 
+/*
+Function: getServiceIDs
+Description: Retrieves the IDs of services booked.
+Parameters:
+    - None
+Returns:
+    - const util::Vector<std::string>&: Service IDs
+*/
+const util::Vector<std::string>& ServiceBooking::getServiceIDs() const
+{
+    return m_serviceIDs;
+}
+
+/*
+Function: getServices
+Description: Retrieves the services associated with the booking.
+Parameter: None
+Return type: const util::Map<std::string, Service*>&
+*/
 /*
 Function: getServices
 Description: Retrieves the services associated with the booking.
@@ -176,7 +252,6 @@ User* ServiceBooking::getAssignedTechnician() const
 {
     return m_assignedTechnician;
 }
-
 /*
 Function: getDiscountPercentage
 Description: Retrieves the discount percentage applied to the booking.
@@ -219,6 +294,13 @@ Return type: void
 void ServiceBooking::setServices(const util::Map<std::string, Service*>& services)
 {
     m_services = services;
+    m_serviceIDs.clear();
+    int numberOfServices = m_services.getSize();
+    auto servicePointers = m_services.getValues();
+    for (int index = 0; index < numberOfServices; index++)
+    {
+        m_serviceIDs.push_back(servicePointers[index]->getId());
+    }
 }
 
 /*
@@ -307,4 +389,131 @@ Return type: void
 void ServiceBooking::setDiscountPercentage(double discountPercentage)
 {
     m_discountPercentage = discountPercentage;
+}
+
+/*
+Function: getServiceIDsAsString (static helper)
+Description: Converts a vector of service IDs into a single string separated by '|'.
+Parameters:
+    - serviceIDs: const util::Vector<std::string>&, vector of service IDs
+Returns:
+    - std::string: Concatenated service IDs string
+*/
+static std::string getServiceIDsAsString(const util::Vector<std::string>& serviceIDs)
+{
+    int numberOfServices = serviceIDs.getSize();
+    std::string serviceIDsString;
+    for (int index = 0; index < numberOfServices; index++)
+    {
+        serviceIDsString += serviceIDs[index];
+        if (index < numberOfServices - 1)
+        {
+            serviceIDsString += '|';
+        }
+    }
+    return serviceIDsString;
+}
+
+/*
+Function: getServiceIDsAsVector (static helper)
+Description: Converts a string of service IDs separated by '|' into a vector.
+Parameters:
+    - serviceIDsString: const std::string&, concatenated service IDs string
+Returns:
+    - util::Vector<std::string>: Vector of service IDs
+*/
+static util::Vector<std::string> getServiceIDsAsVector(const std::string& serviceIDsString)
+{
+    util::Vector<std::string> serviceIDs;
+    std::string serviceID;
+    std::istringstream serializedServiceIDs(serviceIDsString);
+    while (getline(serializedServiceIDs, serviceID, '|'))
+    {
+        serviceIDs.push_back(serviceID);
+    }
+    return serviceIDs;
+}
+
+/*
+Function: serialize
+Description: Serializes the service booking into a CSV-formatted string.
+Parameters:
+    - None
+Returns:
+    - std::string: Serialized booking record
+*/
+std::string ServiceBooking::serialize() const
+{
+    std::ostringstream serializedBooking;
+    serializedBooking << m_id << ','
+        << util::getServiceJobStatusString(m_status) << ','
+        << getServiceIDsAsString(m_serviceIDs) << ','
+        << m_customerId << ','
+        << m_vehicleNumber << ','
+        << m_vehicleBrand << ','
+        << m_vehicleModel << ','
+        << m_assignedTechnicianId << ','
+        << m_discountPercentage << ',';
+    return serializedBooking.str();
+}
+
+/*
+Function: deserialize
+Description: Deserializes a CSV-formatted string into a ServiceBooking object.
+Parameters:
+    - record: const std::string&, serialized booking record
+Returns:
+    - ServiceBooking*: Pointer to the deserialized ServiceBooking object
+Throws:
+    - std::runtime_error if discount percentage parsing fails
+*/
+ServiceBooking* ServiceBooking::deserialize(const std::string& record)
+{
+    std::string id, customerId, vehicleNumber, vehicleBrand, vehicleModel, assignedTechnicianId;
+    std::string serviceJobStatusString, serviceIDsString, discountPercentageString;
+    double discountPercentage;
+    std::istringstream serializedBooking(record);
+    getline(serializedBooking, id, ',');
+    getline(serializedBooking, serviceJobStatusString, ',');
+    getline(serializedBooking, serviceIDsString, ',');
+    getline(serializedBooking, customerId, ',');
+    getline(serializedBooking, vehicleNumber, ',');
+    getline(serializedBooking, vehicleBrand, ',');
+    getline(serializedBooking, vehicleModel, ',');
+    getline(serializedBooking, assignedTechnicianId, ',');
+    getline(serializedBooking, discountPercentageString, ',');
+    util::Vector<std::string> serviceIDs = getServiceIDsAsVector(serviceIDsString);
+    try
+    {
+        discountPercentage = std::stod(discountPercentageString);
+    }
+    catch (...)
+    {
+        throw std::runtime_error("Invalid discount percentage");
+    }
+    util::ServiceJobStatus status = util::getServiceJobStatus(serviceJobStatusString);
+    return Factory::getObject<ServiceBooking>(
+        id,
+        status,
+        serviceIDs,
+        customerId,
+        vehicleNumber,
+        vehicleBrand,
+        vehicleModel,
+        assignedTechnicianId,
+        discountPercentage
+    );
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for service booking serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,Status,ServiceIDs,CustomerID,VehicleNumber,VehicleBrand,VehicleModel,AssignedTechnicianID,DiscountPercentage")
+*/
+std::string ServiceBooking::getHeaders()
+{
+    return "ID,Status,ServiceIDs,CustomerID,VehicleNumber,VehicleBrand,VehicleModel,AssignedTechnicianID,DiscountPercentage";
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/ServiceBooking.h

@@ -9,6 +9,7 @@ Date:19-May-2026
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "Enums.h"
 
 class Service;
@@ -20,6 +21,7 @@ private:
     static int m_uid;
     std::string m_id;
     util::ServiceJobStatus m_status;
+    util::Vector<std::string> m_serviceIDs;
     util::Map<std::string, Service*> m_services;
     std::string m_customerId;
     User* m_customer;
@@ -32,7 +34,6 @@ private:
 public:
     ServiceBooking();
     ServiceBooking(
-        const std::string& id,
         util::ServiceJobStatus status,
         const util::Map<std::string,
         Service*>& services,
@@ -41,12 +42,22 @@ public:
         const std::string& vehicleNumber,
         const std::string& vehicleBrand,
         const std::string& vehicleModel,
+        double discountPercentage
+    );
+    ServiceBooking(
+        const std::string& id,
+        util::ServiceJobStatus status,
+        const util::Vector<std::string>& serviceIDs,
+        const std::string& customerId,
+        const std::string& vehicleNumber,
+        const std::string& vehicleBrand,
+        const std::string& vehicleModel,
         const std::string& assignedTechnicianId,
-        User* assignedTechnician,
         double discountPercentage
     );
     const std::string& getId() const;
     util::ServiceJobStatus getStatus() const;
+    const util::Vector<std::string>& getServiceIDs() const;
     const util::Map<std::string, Service*>& getServices() const;
     const std::string& getCustomerId() const;
     User* getCustomer() const;
@@ -67,4 +78,7 @@ public:
     void setAssignedTechnicianId(const std::string& assignedTechnicianId);
     void setAssignedTechnician(User* assignedTechnician);
     void setDiscountPercentage(double discountPercentage);
+    std::string serialize() const;
+    static ServiceBooking* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/User.cpp

@@ -1,14 +1,48 @@
+/*
+File: User.cpp
+Description: Implements the User class which represents system users in the Vehicle Service Management System.
+             Provides constructors, destructor, accessors, and mutators for user details such as ID, username,
+             password, name, phone, email, role, state, and notifications.
+Author: Trenser
+Date: 19-May-2026
+*/
+
+#include <sstream>
 #include "User.h"
 #include "Notification.h"
 #include "Enums.h"
+#include "Factory.h"
+#include "StringHelper.h"
 
 int User::m_uid = 0;
 
+/*
+Function: User
+Description: Default constructor that initializes a new user with a unique ID,
+             default role as CUSTOMER, and active state.
+Parameters:
+    - None
+Returns:
+    - A new User object.
+*/
 User::User()
     : m_id("USR" + std::to_string(++m_uid)),
     m_type(util::UserType::CUSTOMER),
     m_status(util::State::ACTIVE) {}
 
+/*
+Function: User
+Description: Parameterized constructor that initializes a new user with a unique ID and specified details.
+Parameters:
+    - userName: Username for login.
+    - password: Password for authentication.
+    - name: Full name of the user.
+    - phone: Phone number of the user.
+    - email: Email address of the user.
+    - role: Role of the user (CUSTOMER, ADMIN, TECHNICIAN, etc.).
+Returns:
+    - A new User object.
+*/
 User::User(const std::string& userName, const std::string& password, const std::string& name, const std::string& phone, const std::string& email, util::UserType role)
     : m_id("USR" + std::to_string(++m_uid)),
     m_userName(userName),
@@ -19,104 +53,339 @@ User::User(const std::string& userName, const std::string& password, const std::
     m_type(role),
     m_status(util::State::ACTIVE) {}
 
-User::~User()
+/*
+Function: User (parameterized constructor with ID)
+Description: Initializes a user with an existing ID, credentials, personal details,
+             role, and state. Updates UID tracking based on ID.
+Parameters:
+    - userId: const std::string&, unique user ID
+    - userName: const std::string&, username
+    - password: const std::string&, password
+    - name: const std::string&, full name
+    - phone: const std::string&, phone number
+    - email: const std::string&, email address
+    - role: util::UserType, role of the user
+    - status: util::State, state of the user (ACTIVE/INACTIVE)
+Returns:
+    - A new User object
+*/
+User::User(const std::string& userId, const std::string& userName, const std::string& password, const std::string& name, const std::string& phone, const std::string& email, util::UserType role, util::State status)
+    : m_id(userId),
+    m_userName(userName),
+    m_password(password),
+    m_name(name),
+    m_phone(phone),
+    m_email(email),
+    m_type(role),
+    m_status(status)
 {
-    for (int index = 0; index < m_notifications.getSize(); index++)
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
     {
-        delete m_notifications.getValues()[index];
+        m_uid = idNumber;
     }
 }
 
+/*
+Function: ~User
+Description: Destructor that cleans up dynamically allocated notifications associated with the user.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+User::~User()
+{
+    auto values = m_notifications.getValues();
+    for (int index = 0; index < values.getSize(); index++)
+    {
+        delete values[index];
+    }
+}
+
+/*
+Function: getId
+Description: Retrieves the unique ID of the user.
+Returns:
+    - const std::string& representing the user ID.
+*/
 const std::string& User::getId() const
 {
     return m_id;
 }
 
+/*
+Function: getUserName
+Description: Retrieves the username of the user.
+Returns:
+    - const std::string& representing the username.
+*/
 const std::string& User::getUserName() const
 {
     return m_userName;
 }
 
+/*
+Function: getPassword
+Description: Retrieves the password of the user.
+Returns:
+    - const std::string& representing the password.
+*/
 const std::string& User::getPassword() const
 {
     return m_password;
 }
 
+/*
+Function: getName
+Description: Retrieves the full name of the user.
+Returns:
+    - const std::string& representing the name.
+*/
 const std::string& User::getName() const
 {
     return m_name;
 }
 
+/*
+Function: getPhone
+Description: Retrieves the phone number of the user.
+Returns:
+    - const std::string& representing the phone number.
+*/
 const std::string& User::getPhone() const
 {
     return m_phone;
 }
 
+/*
+Function: getEmail
+Description: Retrieves the email address of the user.
+Returns:
+    - const std::string& representing the email.
+*/
 const std::string& User::getEmail() const
 {
     return m_email;
 }
 
+/*
+Function: getNotifications
+Description: Retrieves the map of notifications associated with the user.
+Returns:
+    - util::Map<std::string, Notification*>& representing the notifications.
+*/
 util::Map<std::string, Notification*>& User::getNotifications()
 {
     return m_notifications;
 }
 
+/*
+Function: getUserType
+Description: Retrieves the role of the user.
+Returns:
+    - util::UserType representing the user role.
+*/
 util::UserType User::getUserType() const
 {
     return m_type;
 }
 
+/*
+Function: getState
+Description: Retrieves the current state (ACTIVE/INACTIVE) of the user.
+Returns:
+    - util::State representing the user state.
+*/
 util::State User::getState() const
 {
     return m_status;
 }
 
+/*
+Function: setId
+Description: Sets the unique ID of the user.
+Parameters:
+    - id: New user ID string.
+Returns:
+    - void
+*/
 void User::setId(const std::string& id)
 {
     m_id = id;
 }
 
+/*
+Function: setUserName
+Description: Sets the username of the user.
+Parameters:
+    - userName: New username string.
+Returns:
+    - void
+*/
 void User::setUserName(const std::string& userName)
 {
     m_userName = userName;
 }
 
+/*
+Function: setPassword
+Description: Sets the password of the user.
+Parameters:
+    - password: New password string.
+Returns:
+    - void
+*/
 void User::setPassword(const std::string& password)
 {
     m_password = password;
 }
 
+/*
+Function: setName
+Description: Sets the full name of the user.
+Parameters:
+    - name: New name string.
+Returns:
+    - void
+*/
 void User::setName(const std::string& name)
 {
     m_name = name;
 }
 
+/*
+Function: setPhone
+Description: Sets the phone number of the user.
+Parameters:
+    - phone: New phone number string.
+Returns:
+    - void
+*/
 void User::setPhone(const std::string& phone)
 {
     m_phone = phone;
 }
 
+/*
+Function: setEmail
+Description: Sets the email address of the user.
+Parameters:
+    - email: New email string.
+Returns:
+    - void
+*/
 void User::setEmail(const std::string& email)
 {
     m_email = email;
 }
 
+/*
+Function: addNotification
+Description: Adds a new notification to the user’s notification map.
+Parameters:
+    - notification: Pointer to the Notification object.
+Returns:
+    - void
+*/
 void User::addNotification(Notification* notification)
 {
-    m_notifications.insert(notification->getId(), notification);
+    if (notification)
+    {
+        m_notifications.insert(notification->getId(), notification);
+    }
 }
 
+/*
+Function: setRole
+Description: Sets the role of the user.
+Parameters:
+    - role: New user role value.
+Returns:
+    - void
+*/
 void User::setRole(util::UserType role)
 {
     m_type = role;
 }
 
+/*
+Function: setState
+Description: Sets the state (ACTIVE/INACTIVE) of the user.
+Parameters:
+    - status: New state value.
+Returns:
+    - void
+*/
 void User::setState(util::State status)
 {
     m_status = status;
 }
 
-void User::update(Notification* notification)
+/*
+Function: serialize
+Description: Serializes the user into a CSV-formatted string.
+Parameters:
+    - None
+Returns:
+    - std::string: Serialized user record
+*/
+std::string User::serialize() const
 {
+    std::ostringstream serializedUser;
+    serializedUser << m_id << ','
+        << m_userName << ','
+        << m_password << ','
+        << m_name << ','
+        << m_phone << ','
+        << m_email << ','
+        << util::getUserTypeString(m_type) << ','
+        << util::getStateString(m_status);
+    return serializedUser.str();
 }
+
+/*
+Function: deserialize
+Description: Deserializes a CSV-formatted string into a User object.
+Parameters:
+    - record: const std::string&, serialized user record
+Returns:
+    - User*: Pointer to the deserialized User object
+*/
+User* User::deserialize(const std::string& record)
+{
+    std::string id, name, username, phone, password, email;
+    std::string userTypeString, stateString;
+    std::istringstream serializedUser(record);
+    getline(serializedUser, id, ',');
+    getline(serializedUser, username, ',');
+    getline(serializedUser, password, ',');
+    getline(serializedUser, name, ',');
+    getline(serializedUser, phone, ',');
+    getline(serializedUser, email, ',');
+    getline(serializedUser, userTypeString, ',');
+    getline(serializedUser, stateString);
+    util::UserType userType = util::getUserType(userTypeString);
+    util::State status = util::getState(stateString);
+    return Factory::getObject<User>(id,
+        username,
+        password,
+        name,
+        phone,
+        email,
+        userType,
+        status);
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for user serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,Username,Password,Name,Phone,Email,UserType,UserStatus")
+*/
+std::string User::getHeaders()
+{
+    return "ID,Username,Password,Name,Phone,Email,UserType,UserStatus";
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/User.h

@@ -1,3 +1,12 @@
+/*
+File: User.h
+Description: Declares the User class which represents system users in the Vehicle Service Management System.
+             Each user has a unique ID, credentials, personal details, notifications, role type, and status.
+             The User class also implements the Observer interface to handle notifications.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #pragma once
 #include <string>
 #include "Map.h"
@@ -22,6 +31,7 @@ private:
 public:
     User();
     User(const std::string& userName, const std::string& password, const std::string& name, const std::string& phone, const std::string& email, util::UserType role);
+    User(const std::string& userId, const std::string& userName, const std::string& password, const std::string& name, const std::string& phone, const std::string& email, util::UserType role, util::State status);
     ~User();
     const std::string& getId() const;
     const std::string& getUserName() const;
@@ -38,8 +48,10 @@ public:
     void setName(const std::string& name);
     void setPhone(const std::string& phone);
     void setEmail(const std::string& email);
-    void addNotification(Notification* notification);
+    void addNotification(Notification* notification) override;
     void setRole(util::UserType role);
     void setState(util::State status);
-    void update(Notification* notification) override;
+    std::string serialize() const;
+    static User* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/AuthenticationManagementService.cpp

@@ -6,11 +6,53 @@ Description: Implementation file containing the method definitions of the
 Author: Trenser
 Date:19-May-2026
 */
+
+#include <stdexcept>
 #include "AuthenticationManagementService.h"
 #include "User.h"
 
 User* AuthenticationManagementService::m_authenticatedUser = nullptr;
 
+/*
+Function: login
+Description: Authenticates a user by checking the provided username and password
+			 against the stored users in the DataStore. If successful, sets the
+			 authenticated user.
+Parameter: const std::string& username - user’s username
+		   const std::string& password - user’s password
+Return type: bool - true if login successful, false otherwise
+*/
+bool AuthenticationManagementService::login(const std::string& username, const std::string& password)
+{
+	util::Map<std::string, User*> users = m_dataStore.getUsers();
+	int usersMapSize = users.getSize();
+	for (int index = 0; index < usersMapSize; index++)
+	{
+		User* user = users.getValueAt(index);
+		if (username == user->getUserName())
+		{
+			if (password == user->getPassword())
+			{
+				m_authenticatedUser = user;
+				return true;
+			}
+			return false;
+		}
+	}
+	return false;
+}
+
+/*
+Function: getAuthenticatedUser
+Description: Retrieves the currently authenticated user.
+Parameter: None
+Return type: User* - pointer to the authenticated user
+*/
+User* AuthenticationManagementService::getAuthenticatedUser()
+{
+	return m_authenticatedUser;
+}
+
 /*
 Function: logout
 Description: Logs out the currently authenticated user by clearing the

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/AuthenticationManagementService.h

@@ -6,6 +6,7 @@ Description: Header file declaring the AuthenticationManagementService class, wh
 Author: Trenser
 Date:19-May-2026
 */
+
 #pragma once
 #include <string>
 #include "DataStore.h"

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/InventoryManagementService.cpp

@@ -1 +1,341 @@
+/*
+File: InventoryManagementService.cpp
+Description: Implements the InventoryManagementService class, which manages inventory
+			 items and observer relationships within the system. Provides methods
+			 for loading and saving inventory items from persistent storage, as well
+			 as attaching and persisting observers for notification handling.
+Author: Trenser
+Date: 22-May-2026
+*/
+
+#include <stdexcept>
+#include "Config.h"
+#include "Enums.h"
+#include "Factory.h"
+#include "FileManager.h"
+#include "InventoryItem.h"
 #include "InventoryManagementService.h"
+#include "Timestamp.h"
+#include "User.h"
+#include "Utility.h"
+#include "Vector.h"
+
+
+util::Map<std::string, User*> InventoryManagementService::m_observers{};
+
+/*
+Function: sendLowStockAlertsToAdmins (static helper)
+Description: Sends low stock alert notifications to all admin users for a given inventory item.
+Parameters:
+	- inventoryManagementService: InventoryManagementService&, service used to send notifications
+	- inventoryItem: const InventoryItem*, pointer to the low-stock inventory item
+	- adminUsers: const util::Vector<User*>&, list of admin users to notify
+Returns:
+	- None
+*/
+static void sendLowStockAlertsToAdmins(InventoryManagementService& inventoryManagementService, const InventoryItem* inventoryItem, const util::Vector<User*>& adminUsers)
+{
+	int adminUsersSize = adminUsers.getSize();
+	for (int index = 0; index < adminUsersSize; index++)
+	{
+		std::string title = "Low Stock Alert";
+		std::string message = "The inventory item with ID " + inventoryItem->getId() + " has very low quantity in the inventory";
+		inventoryManagementService.sendNotification(
+			adminUsers[index],
+			title,
+			message
+		);
+	}
+}
+
+/*
+Function: sendLowStockAlerts
+Description: Sends alerts to user for inventory items with low stock
+Parameters:
+	- None
+Returns:
+	- None
+*/
+void InventoryManagementService::sendLowStockAlerts()
+{
+	auto& inventoryItems = m_dataStore.getInventoryItems();
+	if (inventoryItems.isEmpty())
+	{
+		return;
+	}
+	int inventoryItemsSize = inventoryItems.getSize();
+	auto& usersMap = m_dataStore.getUsers();
+	int usersMapSize = usersMap.getSize();
+	util::Vector<User*> adminUsers;
+	for (int index = 0; index < usersMapSize; index++)
+	{
+		User* user = usersMap.getValueAt(index);
+		if (user->getUserType() == util::UserType::ADMIN)
+		{
+			adminUsers.push_back(user);
+		}
+	}
+	int adminUsersSize = adminUsers.getSize();
+	if (adminUsersSize < 1)
+	{
+		throw std::runtime_error("The system has no admins present!");
+	}
+	for (int index = 0; index <= inventoryItemsSize; index++)
+	{
+		InventoryItem* inventoryItem = inventoryItems.getValueAt(index);
+		if (inventoryItem && inventoryItem->getQuantity() < config::threshold::INVENTORY_LOW_STOCK_THRESHOLD)
+		{
+			sendLowStockAlertsToAdmins(*this, inventoryItem, adminUsers);
+		}
+	}
+}
+
+/*
+Function: getObserverIDs
+Description: Retrieves the IDs of all observers currently attached to the
+			 InventoryManagementService.
+Parameters:
+	- None
+Returns:
+	- util::Vector<std::string>: Vector of observer user IDs
+*/
+util::Vector<std::string> InventoryManagementService::getObserverIDs()
+{
+	util::Vector<std::string> observerIDs;
+	int numberOfObservers = m_observers.getSize();
+	for (int index = 0; index < numberOfObservers; index++)
+	{
+		User* observer = m_observers.getValueAt(index);
+		if (observer)
+		{
+			observerIDs.push_back(observer->getId());
+		}
+	}
+	return observerIDs;
+}
+
+/*
+Function: loadInventoryItems
+Description: Loads inventory items from persistent storage into the datastore.
+			 Uses FileManager to deserialize inventory items from the configured file.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void InventoryManagementService::loadInventoryItems()
+{
+	util::FileManager<InventoryItem> inventoryItemFileManager(config::file::INVENTORYITEM_FILE);
+	auto& inventoryItems = m_dataStore.getInventoryItems();
+	auto inventoryItemsMap = inventoryItemFileManager.load();
+	int numberOfInventoryItems = inventoryItemsMap.getSize();
+	for (int index = 0; index < numberOfInventoryItems; index++)
+	{
+		inventoryItems[inventoryItemsMap.getKeyAt(index)] = inventoryItemsMap.getValueAt(index);
+	}
+}
+
+/*
+Function: saveInventoryItems
+Description: Saves inventory items from the datastore to persistent storage.
+			 Uses FileManager to serialize inventory items into the configured file.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void InventoryManagementService::saveInventoryItems()
+{
+	util::FileManager<InventoryItem> inventoryItemFileManager(config::file::INVENTORYITEM_FILE);
+	auto& inventoryItems = m_dataStore.getInventoryItems();
+	inventoryItemFileManager.save(inventoryItems);
+}
+
+/*
+Function: loadObservers
+Description: Loads observer IDs from persistent storage and attaches corresponding
+			 users as observers to the InventoryManagementService.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void InventoryManagementService::loadObservers()
+{
+	util::loadObservers(config::file::INVENTORYMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+/*
+Function: saveObservers
+Description: Saves the current observer IDs of the InventoryManagementService
+			 to persistent storage for future retrieval.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void InventoryManagementService::saveObservers()
+{
+	util::saveObservers(config::file::INVENTORYMANAGEMENTOBSERVERS, this);
+}
+
+/*
+Function: addInventoryItem
+Description: Creates a new inventory item using the Factory and inserts it
+             into the DataStore.
+Parameter: const std::string& partName - name of the part
+           int quantity - initial quantity of the part
+           double price - price of the part
+Return type: void
+*/
+void InventoryManagementService::addInventoryItem(const std::string& partName, int quantity, double price)
+{
+    InventoryItem* newItem = Factory::getObject<InventoryItem>(partName, quantity, price);
+    m_dataStore.getInventoryItems().insert(newItem->getId(), newItem);
+}
+
+/*
+Function: addInventoryItemStock
+Description: Increases the stock quantity of an existing inventory item.
+Parameter: const std::string& selectedItemId - ID of the inventory item
+           int quantity - quantity to add
+Return type: void
+*/
+void InventoryManagementService::addInventoryItemStock(const std::string& selectedItemId, int quantity)
+{
+    int index = m_dataStore.getInventoryItems().find(selectedItemId);
+    if (index != -1)
+    {
+        InventoryItem* item = m_dataStore.getInventoryItems().getValueAt(index);
+        if (item != nullptr)
+        {
+            int totalQuantity = item->getQuantity() + quantity;
+            item->setQuantity(totalQuantity);
+        }
+    }
+}
+
+/*
+Function: getInventoryItems
+Description: Retrieves all inventory items stored in the DataStore.
+Parameter: None
+Return type: util::Map<std::string, InventoryItem*>
+*/
+util::Map<std::string, InventoryItem*> InventoryManagementService::getInventoryItems()
+{
+	return m_dataStore.getInventoryItems();
+}
+
+/*
+Function: removeInventoryItem
+Description: Marks an inventory item as inactive instead of deleting it.
+Parameter: const std::string& inventoryItemID - ID of the inventory item
+Return type: void
+*/
+void InventoryManagementService::removeInventoryItem(const std::string& inventoryItemID)
+{
+    int index = m_dataStore.getInventoryItems().find(inventoryItemID);
+    if (index != -1)
+    {
+        InventoryItem* item = m_dataStore.getInventoryItems().getValueAt(index);
+        if (item != nullptr)
+        {
+            item->setState(util::State::INACTIVE);
+        }
+    }
+}
+
+/*
+Function: getInventoryItem
+Description: Retrieves a specific inventory item by its ID from the DataStore.
+Parameter: const std::string& inventoryItemID - ID of the inventory item
+Return type: InventoryItem*
+*/
+InventoryItem* InventoryManagementService::getInventoryItem(const std::string& inventoryItemID)
+{
+    int index = m_dataStore.getInventoryItems().find(inventoryItemID);
+    if (index != -1)
+    {
+        return m_dataStore.getInventoryItems().getValueAt(index);
+    }
+    return nullptr;
+}
+
+/*
+Function: attach
+Description: Adds a user to the observer list for receiving inventory notifications.
+Parameters:
+	- user: User*, pointer to the user to be attached as an observer
+Returns:
+	- None
+*/
+void InventoryManagementService::attach(User* user)
+{
+	if (user)
+	{
+		const std::string& userID = user->getId();
+		if (m_observers.find(userID) == -1)
+		{
+			m_observers[userID] = user;
+		}
+	}
+}
+
+/*
+Function: detach
+Description: Removes a user from the observer list so they no longer receive inventory notifications.
+Parameters:
+	- user: User*, pointer to the user to be detached from the observer list
+Returns:
+	- None
+*/
+void InventoryManagementService::detach(User* user)
+{
+	if (user)
+	{
+		const std::string& userID = user->getId();
+		if (m_observers.find(userID) != -1)
+		{
+			m_observers.remove(userID);
+		}
+	}
+}
+
+/*
+Function: sendNotification
+Description: Sends a notification to a user if they are subscribed as an observer.
+Parameters:
+	- user: User*, pointer to the user receiving the notification
+	- title: std::string, title of the notification
+	- message: std::string, body/content of the notification
+Returns:
+	- None
+Throws:
+	- std::runtime_error if notification creation fails
+*/
+void InventoryManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
+{
+	if (user)
+	{
+		if (m_observers.find(user->getId()) != -1)
+		{
+			Notification* notification =
+				Factory::getObject<Notification>(
+					user->getId(),
+					user,
+					"InventoryManagementService: " + title,
+					message,
+					util::Timestamp()
+				);
+			if (notification)
+			{
+				user->addNotification(notification);
+			}
+			else
+			{
+				throw std::runtime_error("Failed to create notification");
+			}
+		}
+	}
+}
+

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/InventoryManagementService.h

@@ -1,6 +1,16 @@
+/*
+File: InventoryManagementService.h
+Description: Header file declaring the InventoryManagementService class,
+             which manages inventory items, stock updates, and notifications
+             related to low stock alerts. Inherits from NotificationManagementService.
+Author: Trenser
+Date:19-May-2026
+*/
+
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "NotificationManagementService.h"
 #include "DataStore.h"
 
@@ -11,14 +21,20 @@ class InventoryManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
+    util::Vector<std::string> getObserverIDs() override;
 public:
     InventoryManagementService() : m_dataStore(DataStore::getInstance()) {}
     util::Map<std::string, InventoryItem*> getInventoryItems();
     InventoryItem* getInventoryItem(const std::string& inventoryItemID);
     void addInventoryItem(const std::string& partName, int quantity, double price);
     void removeInventoryItem(const std::string& inventoryItemID);
+    void addInventoryItemStock(const std::string& selectedItemId, int quantity);
     void sendLowStockAlerts();
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
+    void loadInventoryItems();
+    void saveInventoryItems();
+    void loadObservers();
+    void saveObservers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/NotificationManagementService.h

@@ -1,6 +1,15 @@
+/*
+File: NotificationManagementService.h
+Description: Declares the NotificationManagementService abstract class which defines the contract for managing notifications in the Vehicle Service Management System.
+			 Implements the Subject interface and provides pure virtual methods for sending notifications and managing user subscriptions (attach/detach).
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #pragma once
 #include <string>
 #include "Subject.h"
+#include "Notification.h"
 #include "User.h"
 
 class NotificationManagementService : public Subject
@@ -10,4 +19,5 @@ public:
 	virtual void sendNotification(User* recipient, const std::string& title, const std::string& message) = 0;
 	virtual void attach(User* user) = 0;
 	virtual void detach(User* user) = 0;
+	virtual util::Vector<std::string> getObserverIDs() = 0;
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/PaymentManagementService.cpp

@@ -1 +1,386 @@
+/*
+File: PaymentManagementService.cpp
+Description: Implements the PaymentManagementService class which manages payment-related operations
+			 in the Vehicle Service Management System. Provides functionality for attaching/detaching observers,
+			 sending notifications, and issuing payment reminders based on invoice status and thresholds.
+Author: Trenser
+Date: 20-May-2026
+*/
+
+#include <stdexcept>
+#include "Config.h"
+#include "Enums.h"
+#include "Factory.h"
+#include "FileManager.h"
+#include "InventoryItem.h"
+#include "Invoice.h"
+#include "JobCard.h"
 #include "PaymentManagementService.h"
+#include "Service.h"
+#include "ServiceBooking.h"
+#include "Timestamp.h"
+#include "User.h"
+#include "Utility.h"
+
+util::Map<std::string, User*> PaymentManagementService::m_observers{};
+
+/*
+Function: attach
+Description: Attaches a user as an observer to the PaymentManagementService for receiving notifications.
+Parameters:
+	- user: Pointer to the User object to be attached.
+Returns:
+	- void
+*/
+void PaymentManagementService::attach(User* user)
+{
+	if (user)
+	{
+		const std::string& userID = user->getId();
+		if (m_observers.find(userID) == -1)
+		{
+			m_observers[userID] = user;
+		}
+	}
+}
+
+/*
+Function: detach
+Description: Detaches a user from the observer list of the PaymentManagementService.
+Parameters:
+	- user: Pointer to the User object to be detached.
+Returns:
+	- void
+*/
+void PaymentManagementService::detach(User* user)
+{
+	if (user)
+	{
+		const std::string& userID = user->getId();
+		if (m_observers.find(userID) != -1)
+		{
+			m_observers.remove(userID);
+		}
+	}
+}
+
+/*
+Function: sendNotification
+Description: Sends a notification to a user if they are registered as an observer.
+Parameters:
+	- user: Pointer to the User object to receive the notification.
+	- title: Title of the notification.
+	- message: Message content of the notification.
+Returns:
+	- void
+Throws:
+	- std::runtime_error if notification creation fails.
+*/
+void PaymentManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
+{
+	if (user)
+	{
+		if (m_observers.find(user->getId()) != -1)
+		{
+			Notification* notification =
+				Factory::getObject<Notification>(
+					user->getId(),
+					user,
+					"PaymentManagementService: " + title,
+					message,
+					util::Timestamp()
+				);
+			if (notification)
+			{
+				user->addNotification(notification);
+			}
+			else
+			{
+				throw std::runtime_error("Failed to create notification");
+			}
+		}
+	}
+}
+
+/*
+Function: sendPaymentReminders
+Description: Iterates through all invoices in the datastore and sends payment reminders to customers
+			 whose invoices are pending beyond the configured threshold duration.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void PaymentManagementService::sendPaymentReminders()
+{
+	auto& invoicesMap = m_dataStore.getInvoices();
+	int invoicesMapSize = invoicesMap.getSize();
+	for (int index = 0; index < invoicesMapSize; index++)
+	{
+		const Invoice* invoice = invoicesMap.getValueAt(index);
+		if (invoice && invoice->getStatus() == util::PaymentStatus::PENDING)
+		{
+			util::Timestamp invoiceCreationTimestamp = invoice->getInvoiceDate();
+			util::Timestamp currentTimestamp;
+			if (util::Timestamp::getDurationInHours(invoiceCreationTimestamp, currentTimestamp) >= config::threshold::PAYMENT_REMINDER_THRESHOLD_HOURS)
+			{
+				const ServiceBooking* serviceBooking = invoice->getBooking();
+				if (serviceBooking)
+				{
+					User* customer = serviceBooking->getCustomer();
+					if (customer)
+					{
+						std::string title = "Payment Reminder";
+						std::string message = "Your payment for Invoice ID " + invoice->getId() + " is still pending. Please complete the payment.";
+						sendNotification(customer, title, message);
+					}
+				}
+			}
+		}
+	}
+}
+
+/*
+Function: getObserverIDs
+Description: Retrieves the IDs of all observers currently attached to the
+             PaymentManagementService.
+Parameters:
+    - None
+Returns:
+    - util::Vector<std::string>: Vector of observer user IDs
+*/
+util::Vector<std::string> PaymentManagementService::getObserverIDs()
+{
+	util::Vector<std::string> observerIDs;
+	int numberOfObservers = m_observers.getSize();
+	for (int index = 0; index < numberOfObservers; index++)
+	{
+		User* observer = m_observers.getValueAt(index);
+		if (observer)
+		{
+			observerIDs.push_back(observer->getId());
+		}
+	}
+	return observerIDs;
+}
+
+/*
+Function: loadInvoices
+Description: Loads invoices from persistent storage into the datastore.
+             Validates associated service bookings and inventory parts before
+             attaching them to each invoice. Throws exceptions if invalid IDs
+             are encountered.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a booking ID or part ID is invalid
+*/
+void PaymentManagementService::loadInvoices()
+{
+    util::FileManager<Invoice> invoiceFileManager(config::file::INVOICE_FILE);
+    auto& invoices = m_dataStore.getInvoices();
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    auto& inventoryItems = m_dataStore.getInventoryItems();
+    auto invoicesMap = invoiceFileManager.load();
+    for (int invoiceIndex = 0; invoiceIndex < invoicesMap.getSize(); invoiceIndex++)
+    {
+        Invoice* invoice = invoicesMap.getValueAt(invoiceIndex);
+        int bookingIndex = serviceBookings.find(invoice->getBookingId());
+        if (bookingIndex == -1)
+        {
+            throw std::runtime_error("Invalid Booking ID");
+        }
+        ServiceBooking* booking = serviceBookings.getValueAt(bookingIndex);
+        invoice->setBooking(booking);
+        util::Map<std::string, InventoryItem*> invoiceParts;
+        auto& partIDs = invoice->getPartIDs();
+        for (int partIndex = 0; partIndex < partIDs.getSize(); partIndex++)
+        {
+            const std::string& partID = partIDs[partIndex];
+            int inventoryIndex = inventoryItems.find(partID);
+            if (inventoryIndex == -1)
+            {
+                throw std::runtime_error("Invalid Part ID");
+            }
+            invoiceParts[partID] = inventoryItems.getValueAt(inventoryIndex);
+        }
+        invoice->setParts(invoiceParts);
+        invoices[invoice->getId()] = invoice;
+    }
+}
+
+/*
+Function: saveInvoices
+Description: Saves invoices from the datastore to persistent storage.
+             Uses FileManager to serialize invoices into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void PaymentManagementService::saveInvoices()
+{
+    util::FileManager<Invoice> invoiceFileManager(config::file::INVOICE_FILE);
+    auto& invoices = m_dataStore.getInvoices();
+    invoiceFileManager.save(invoices);
+}
+
+/*
+Function: loadObservers
+Description: Loads observer IDs from persistent storage and attaches corresponding
+             users as observers to the PaymentManagementService.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if an observer ID is invalid (not found in datastore)
+*/
+void PaymentManagementService::loadObservers()
+{
+    util::loadObservers(config::file::PAYMENTMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+/*
+Function: saveObservers
+Description: Saves the current observer IDs of the PaymentManagementService
+             to persistent storage for future retrieval.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void PaymentManagementService::saveObservers()
+{
+    util::saveObservers(config::file::PAYMENTMANAGEMENTOBSERVERS, this);
+}
+
+/*
+Function: createInventoryItemsMap (static helper)
+Description: Builds a map of inventory items required for a given service and adds them to the booking’s inventory map.
+Parameters:
+	- completeInventoryItemMapOfBooking: util::Map<std::string, InventoryItem*>&, map to store inventory items for the booking
+	- currentService: const Service*, pointer to the current service
+Returns:
+	- void
+*/
+static void createInventoryItemsMap(util::Map<std::string, InventoryItem*>& completeInventoryItemMapOfBooking, const Service* currentService)
+{
+	auto& currentRequiredInventoryItems = currentService->getRequiredInventoryItems();
+	for (int iterator = 0; iterator < currentRequiredInventoryItems.getSize(); iterator++)
+	{
+		auto& currentRequiredInventoryItem = currentRequiredInventoryItems.getValueAt(iterator);
+		completeInventoryItemMapOfBooking.insert(currentRequiredInventoryItem->getId(), currentRequiredInventoryItem);
+	}
+}
+
+/*
+Function: generateInvoice
+Description: Generates an invoice for a completed service booking.
+			 Validates that all job cards are completed, calculates labor and parts cost, applies discount,
+			 and stores the invoice in the datastore.
+Parameters:
+	- booking: ServiceBooking*, pointer to the service booking
+Returns:
+	- void
+Throws:
+	- std::runtime_error if booking is null or job cards are incomplete
+*/
+void PaymentManagementService::generateInvoice(ServiceBooking* booking)
+{
+	if (!booking)
+	{
+		throw std::runtime_error("Invoice generation failed: booking is null.");
+	}
+	double totalLabourCost = 0, totalPartsCost = 0, totalServiceCost = 0;
+	double discountPercentage = booking->getDiscountPercentage();
+	std::string bookingID = booking->getId();
+	util::Map<std::string, Service*> servicesInTheBookedService = booking->getServices();
+	util::Map<std::string, InventoryItem*> completeInventoryItemMapOfBooking;
+	util::Map<std::string, JobCard*> currentJobCards = m_dataStore.getJobCards();
+	for (int iterator = 0; iterator < currentJobCards.getSize(); iterator++)
+	{
+		JobCard* currentJobCard = currentJobCards.getValueAt(iterator);
+		if (currentJobCard->getBookingId() == bookingID && currentJobCard->getStatus() != util::ServiceJobStatus::COMPLETED)
+		{
+			throw std::runtime_error("Invoice generation failed: not all job cards are completed for booking '" + bookingID + "'.");
+		}
+	}
+	for (int iterator = 0; iterator < servicesInTheBookedService.getSize(); iterator++)
+	{
+		Service* currentService = servicesInTheBookedService.getValueAt(iterator);
+		if (currentService)
+		{
+			createInventoryItemsMap(completeInventoryItemMapOfBooking, currentService);
+			totalLabourCost += currentService->getLaborCost();
+			totalPartsCost += util::calculatePartsCost(currentService);
+		}
+	}
+	totalServiceCost = totalLabourCost + totalPartsCost;
+	totalServiceCost -= (totalServiceCost * (discountPercentage / 100));
+	Invoice* invoice = Factory::getObject<Invoice>(bookingID, booking, util::Timestamp(), totalLabourCost, completeInventoryItemMapOfBooking, totalPartsCost, discountPercentage, totalServiceCost, util::Timestamp(), util::PaymentMode::NOTSET, util::PaymentStatus::PENDING);
+	util::Map<std::string, Invoice*>& currentInvoices = m_dataStore.getInvoices();
+	currentInvoices.insert(invoice->getId(), invoice);
+}
+
+/*
+Function: getInvoices
+Description: Retrieves all invoices associated with a specific customer.
+Parameters:
+	- customerID: std::string, ID of the customer
+Returns:
+	- util::Map<std::string, Invoice*> containing the customer’s invoices
+*/
+util::Map<std::string, Invoice*> PaymentManagementService::getInvoices(const std::string& customerID)
+{
+	util::Map<std::string, Invoice*>& currentInvoices = m_dataStore.getInvoices();
+	util::Map<std::string, Invoice*> currentUserInvoices;
+	for (int iterator = 0; iterator < currentInvoices.getSize(); iterator++)
+	{
+		Invoice* currentInvoice = currentInvoices.getValueAt(iterator);
+		if (currentInvoice->getBooking()->getCustomerId() == customerID)
+		{
+			currentUserInvoices.insert(currentInvoice->getId(), currentInvoice);
+		}
+	}
+	return currentUserInvoices;
+}
+
+/*
+Function: completePayment
+Description: Completes payment for a specific invoice. Updates payment method, date, and status,
+			 then sends a notification to the customer.
+Parameters:
+	- invoiceID: std::string, ID of the invoice
+	- paymentMode: util::PaymentMode, mode of payment (e.g., ONLINE, OFFLINE)
+Returns:
+	- void
+Throws:
+	- std::runtime_error if the invoice ID is invalid
+*/
+void PaymentManagementService::completePayment(const std::string& invoiceID, util::PaymentMode paymentMode)
+{
+	auto& currentInvoices = m_dataStore.getInvoices();
+	int invoiceIndex = currentInvoices.find(invoiceID);
+	if (invoiceIndex != -1)
+	{
+		Invoice* invoice = currentInvoices.getValueAt(invoiceIndex);
+		if (invoice && invoice->getStatus() != util::PaymentStatus::COMPLETED)
+		{
+			User* currentUser = invoice->getBooking()->getCustomer();
+			invoice->setPaymentMethod(paymentMode);
+			invoice->setPaymentDate(util::Timestamp());
+			invoice->setStatus(util::PaymentStatus::COMPLETED);
+			std::string title, message;
+			title = "Payment successful";
+			message = "Payment successful for invoice ID " + invoiceID;
+			sendNotification(currentUser, title, message);
+		}
+	}
+	else
+	{
+		throw std::runtime_error("Payment failed: invalid invoice ID.");
+	}
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/PaymentManagementService.h

@@ -1,3 +1,12 @@
+/*
+File: PaymentManagementService.h
+Description: Declares the PaymentManagementService class which manages payment operations in the Vehicle Service Management System.
+             Provides functionality to generate invoices, retrieve customer invoices, complete payments, send payment reminders,
+             and handle notifications using the Observer pattern.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #pragma once
 #include <string>
 #include "Map.h"
@@ -13,6 +22,7 @@ class PaymentManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
+    util::Vector<std::string> getObserverIDs() override;
 public:
     PaymentManagementService() : m_dataStore(DataStore::getInstance()) {}
     void generateInvoice(ServiceBooking* booking);
@@ -22,4 +32,8 @@ public:
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
+    void loadInvoices();
+    void saveInvoices();
+    void loadObservers();
+    void saveObservers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/ServiceManagementService.cpp

@@ -1,19 +1,512 @@
 /*
 File: ServiceManagementService.cpp
 Description: Implementation file containing the method definitions of the
-             ServiceManagementService class, including service booking cancellation,
-             job card management, combo package creation, and removal logic.
+			 ServiceManagementService class, including service and combo package
+			 purchasing logic, booking creation, and notification handling.
 Author: Trenser
 Date:19-May-2026
 */
-#include "ServiceManagementService.h"
-#include "DataStore.h"
-#include "ServiceBooking.h"
-#include "JobCard.h"
-#include "Service.h"
-#include "InventoryItem.h"
-#include "Factory.h"
+
+#include <stdexcept>
+#include "AuthenticationManagementService.h"
 #include "ComboPackage.h"
+#include "Config.h"
+#include "DataStore.h"
+#include "Enums.h"
+#include "Factory.h"
+#include "FileManager.h"
+#include "InventoryItem.h"
+#include "JobCard.h"
+#include "NotificationManagementService.h"
+#include "PaymentManagementService.h"
+#include "Service.h"
+#include "ServiceBooking.h"
+#include "ServiceManagementService.h"
+#include "Timestamp.h"
+#include "Timestamp.h"
+#include "User.h"
+#include "UserManagementService.h"
+#include "Utility.h"
+
+/*
+Function: purchaseService
+Description: Creates a new service booking for the authenticated user. Validates
+			 service IDs, retrieves services from the DataStore, and generates a
+			 booking. Sends a notification upon successful booking.
+Parameter: const util::Vector<std::string>& serviceIDs - IDs of services to purchase
+		   const std::string& vehicleNumber - vehicle registration number
+		   const std::string& vehicleBrand - brand of the vehicle
+		   const std::string& vehicleModel - model of the vehicle
+Return type: void
+*/
+void ServiceManagementService::purchaseService(const util::Vector<std::string>& serviceIDs, const std::string& vehicleNumber, const std::string& vehicleBrand, const std::string& vehicleModel)
+{
+	AuthenticationManagementService m_authenticationManagementService;
+	auto authenticatedUser = m_authenticationManagementService.getAuthenticatedUser();
+	if (authenticatedUser == nullptr)
+	{
+		throw std::runtime_error("No user is currently logged in!");
+	}
+	auto& servicesMap = m_dataStore.getServices();
+	auto& serviceBookingMap = m_dataStore.getServiceBookings();
+	util::Map<std::string, Service*> selectedServices;
+	int selectedServicesCount = serviceIDs.getSize();
+	for (int index = 0; index < selectedServicesCount; index++)
+	{
+		int serviceIndex = servicesMap.find(serviceIDs[index]);
+		if (serviceIndex == -1)
+		{
+			throw std::runtime_error("Service not found!");
+		}
+		Service* service = servicesMap.getValueAt(serviceIndex);
+		selectedServices[service->getId()] = service;
+	}
+	ServiceBooking* serviceBooking = Factory::getObject<ServiceBooking>(util::ServiceJobStatus::STARTED, selectedServices, authenticatedUser->getId(), authenticatedUser, vehicleNumber, vehicleBrand, vehicleModel, 0);
+	if (serviceBooking == nullptr)
+	{
+		throw std::runtime_error("Failed to create service booking");
+	}
+	serviceBookingMap[serviceBooking->getId()] = serviceBooking;
+    std::string title = "Service Booking succeeded";
+    std::string message = "Your service booking has been successfully placed with ID " + serviceBooking->getId();
+    sendNotification(authenticatedUser, title, message);
+}
+
+/*
+Function: purchaseComboPackage
+Description: Creates a new service booking for a combo package. Validates the combo
+			 package ID, retrieves services from the package, and generates a booking
+			 with the applicable discount. Sends a notification upon successful booking.
+Parameter: const std::string& comboPackageID - ID of the combo package
+		   const std::string& vehicleNumber - vehicle registration number
+		   const std::string& vehicleBrand - brand of the vehicle
+		   const std::string& vehicleModel - model of the vehicle
+Return type: void
+*/
+void ServiceManagementService::purchaseComboPackage(const std::string& comboPackageID, const std::string& vehicleNumber, const std::string& vehicleBrand, const std::string& vehicleModel)
+{
+	AuthenticationManagementService m_authenticationManagementService;
+	auto authenticatedUser = m_authenticationManagementService.getAuthenticatedUser();
+	if (authenticatedUser == nullptr)
+	{
+		throw std::runtime_error("No user is currently logged in!");
+	}
+	auto& comboPackagesMap = m_dataStore.getComboPackages();
+	auto& serviceBookingMap = m_dataStore.getServiceBookings();
+	int comboPackageIndex = comboPackagesMap.find(comboPackageID);
+	if (comboPackageIndex == -1)
+	{
+		throw std::runtime_error("Combo Package not found!");
+	}
+	const ComboPackage* comboPackage = comboPackagesMap[comboPackageID];
+	util::Map<std::string, Service*> selectedServices = comboPackage->getServices();
+	ServiceBooking* serviceBooking = Factory::getObject<ServiceBooking>(util::ServiceJobStatus::STARTED, selectedServices, authenticatedUser->getId(), authenticatedUser, vehicleNumber, vehicleBrand, vehicleModel, comboPackage->getDiscountPercentage());
+	if (serviceBooking == nullptr)
+	{
+		throw std::runtime_error("Failed to create combo package service booking");
+	}
+	serviceBookingMap[serviceBooking->getId()] = serviceBooking;
+    std::string title = "Combo Package Service Booking succeeded";
+    std::string message = "Your service booking for the combo package has been successfully placed with ID " + serviceBooking->getId();
+    sendNotification(authenticatedUser, title, message);
+}
+
+util::Map<std::string, User*> ServiceManagementService::m_observers{};
+
+/*
+Function: attach
+Description: Attaches a user as an observer to the ServiceManagementService for receiving notifications.
+Parameters:
+	- user: Pointer to the User object to be attached.
+Returns:
+	- void
+*/
+void ServiceManagementService::attach(User* user)
+{
+	if (user)
+	{
+		const std::string& userID = user->getId();
+		if (m_observers.find(userID) == -1)
+		{
+			m_observers[userID] = user;
+		}
+	}
+}
+
+/*
+Function: detach
+Description: Detaches a user from the observer list of the ServiceManagementService.
+Parameters:
+	- user: Pointer to the User object to be detached.
+Returns:
+	- void
+*/
+void ServiceManagementService::detach(User* user)
+{
+	if (user)
+	{
+		const std::string& userID = user->getId();
+		if (m_observers.find(userID) != -1)
+		{
+			m_observers.remove(userID);
+		}
+	}
+}
+
+/*
+Function: sendNotification
+Description: Sends a notification to a user if they are registered as an observer.
+Parameters:
+	- user: Pointer to the User object to receive the notification.
+	- title: Title of the notification.
+	- message: Message content of the notification.
+Returns:
+	- void
+Throws:
+	- std::runtime_error if notification creation fails.
+*/
+void ServiceManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
+{
+	if (user)
+	{
+		if (m_observers.find(user->getId()) != -1)
+		{
+			Notification* notification =
+				Factory::getObject<Notification>(
+					user->getId(),
+					user,
+					"ServiceManagementService: " + title,
+					message,
+					util::Timestamp()
+				);
+			if (notification)
+			{
+				user->addNotification(notification);
+			}
+			else
+			{
+				throw std::runtime_error("Failed to create notification");
+			}
+		}
+	}
+}
+
+/*
+Function: getObserverIDs
+Description: Retrieves the IDs of all observers currently attached to the
+             ServiceManagementService.
+Parameters:
+    - None
+Returns:
+    - util::Vector<std::string>: Vector of observer user IDs
+*/
+util::Vector<std::string> ServiceManagementService::getObserverIDs()
+{
+	util::Vector<std::string> observerIDs;
+	int numberOfObservers = m_observers.getSize();
+	for (int index = 0; index < numberOfObservers; index++)
+	{
+		User* observer = m_observers.getValueAt(index);
+		if (observer)
+		{
+			observerIDs.push_back(observer->getId());
+		}
+	}
+	return observerIDs;
+}
+
+/*
+Function: loadServices
+Description: Loads services from persistent storage into the datastore.
+             Validates required inventory items and attaches them to each service.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if an inventory item ID is invalid
+*/
+void ServiceManagementService::loadServices()
+{
+    util::FileManager<Service> serviceFileManager(config::file::SERVICE_FILE);
+    auto& services = m_dataStore.getServices();
+    auto& inventoryItems = m_dataStore.getInventoryItems();
+    auto servicesMap = serviceFileManager.load();
+    for (int serviceIndex = 0; serviceIndex < servicesMap.getSize(); serviceIndex++)
+    {
+        Service* service = servicesMap.getValueAt(serviceIndex);
+        services[service->getId()] = service;
+        util::Map<std::string, InventoryItem*> inventoryItemsMap;
+        auto& inventoryItemIDs = service->getRequiredInventoryItemIDs();
+        for (int inventoryItemIndex = 0; inventoryItemIndex < inventoryItemIDs.getSize(); inventoryItemIndex++)
+        {
+            const std::string& inventoryItemID = inventoryItemIDs[inventoryItemIndex];
+            int index = inventoryItems.find(inventoryItemID);
+            if (index == -1)
+            {
+                throw std::runtime_error("Invalid Inventory Item ID");
+            }
+            inventoryItemsMap[inventoryItemID] = inventoryItems.getValueAt(index);
+        }
+        service->setRequiredInventoryItems(inventoryItemsMap);
+    }
+}
+
+/*
+Function: saveServices
+Description: Saves services from the datastore to persistent storage.
+             Uses FileManager to serialize services into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveServices()
+{
+	util::FileManager<Service> serviceFileManager(config::file::SERVICE_FILE);
+	auto& services = m_dataStore.getServices();
+	serviceFileManager.save(services);
+}
+
+/*
+Function: loadComboPackages
+Description: Loads combo packages from persistent storage into the datastore.
+             Validates associated services and attaches them to each package.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a service ID is invalid
+*/
+void ServiceManagementService::loadComboPackages()
+{
+    util::FileManager<ComboPackage> comboPackageFileManager(config::file::COMBOPACKAGE_FILE);
+    auto& comboPackages = m_dataStore.getComboPackages();
+    auto& services = m_dataStore.getServices();
+    auto comboPackagesMap = comboPackageFileManager.load();
+    for (int packageIndex = 0; packageIndex < comboPackagesMap.getSize(); packageIndex++)
+    {
+        ComboPackage* comboPackage = comboPackagesMap.getValueAt(packageIndex);
+        util::Map<std::string, Service*> packageServices;
+        auto& serviceIDs = comboPackage->getServiceIDs();
+        for (int serviceIndex = 0; serviceIndex < serviceIDs.getSize(); serviceIndex++)
+        {
+            const std::string& serviceID = serviceIDs[serviceIndex];
+            int serviceMapIndex = services.find(serviceID);
+            if (serviceMapIndex == -1)
+            {
+                throw std::runtime_error("Invalid Service ID");
+            }
+            packageServices[serviceID] = services.getValueAt(serviceMapIndex);
+        }
+        comboPackage->setServices(packageServices);
+        comboPackages[comboPackage->getId()] = comboPackage;
+    }
+}
+
+/*
+Function: saveComboPackages
+Description: Saves combo packages from the datastore to persistent storage.
+             Uses FileManager to serialize combo packages into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveComboPackages()
+{
+    util::FileManager<ComboPackage> comboPackageFileManager(config::file::COMBOPACKAGE_FILE);
+    auto& comboPackages = m_dataStore.getComboPackages();
+    comboPackageFileManager.save(comboPackages);
+}
+
+/*
+Function: loadServiceBookings
+Description: Loads service bookings from persistent storage into the datastore.
+             Validates associated services, customers, and technicians before
+             attaching them to each booking.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a service ID, customer ID, or technician ID is invalid
+    - std::runtime_error if a user is not of the expected type (customer/technician)
+*/
+void ServiceManagementService::loadServiceBookings()
+{
+    util::FileManager<ServiceBooking> bookingFileManager(config::file::SERVICEBOOKING_FILE);
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    auto& services = m_dataStore.getServices();
+    auto& users = m_dataStore.getUsers();
+    auto bookingsMap = bookingFileManager.load();
+    for (int bookingIndex = 0; bookingIndex < bookingsMap.getSize(); bookingIndex++)
+    {
+        ServiceBooking* booking = bookingsMap.getValueAt(bookingIndex);
+        util::Map<std::string, Service*> bookingServices;
+        auto& serviceIDs = booking->getServiceIDs();
+        for (int serviceIndex = 0; serviceIndex < serviceIDs.getSize(); serviceIndex++)
+        {
+            const std::string& serviceID = serviceIDs[serviceIndex];
+            int serviceMapIndex = services.find(serviceID);
+            if (serviceMapIndex == -1)
+            {
+                throw std::runtime_error("Invalid Service ID");
+            }
+
+            bookingServices[serviceID] = services.getValueAt(serviceMapIndex);
+        }
+        booking->setServices(bookingServices);
+        int customerIndex = users.find(booking->getCustomerId());
+        if (customerIndex == -1)
+        {
+            throw std::runtime_error("Invalid Customer ID");
+        }
+        User* customer = users.getValueAt(customerIndex);
+        if (customer->getUserType() != util::UserType::CUSTOMER)
+        {
+            throw std::runtime_error("User is not a customer");
+        }
+        booking->setCustomer(customer);
+        const std::string& technicianId = booking->getAssignedTechnicianId();
+        if (!technicianId.empty())
+        {
+            int technicianIndex = users.find(technicianId);
+            if (technicianIndex == -1)
+            {
+                throw std::runtime_error("Invalid Technician ID");
+            }
+            User* technician = users.getValueAt(technicianIndex);
+            if (technician->getUserType() != util::UserType::TECHNICIAN)
+            {
+                throw std::runtime_error("User is not a technician");
+            }
+            booking->setAssignedTechnician(technician);
+        }
+        serviceBookings[booking->getId()] = booking;
+    }
+}
+
+/*
+Function: saveServiceBookings
+Description: Saves service bookings from the datastore to persistent storage.
+             Uses FileManager to serialize bookings into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveServiceBookings()
+{
+    util::FileManager<ServiceBooking> bookingFileManager(config::file::SERVICEBOOKING_FILE);
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    bookingFileManager.save(serviceBookings);
+}
+
+/*
+Function: loadJobCards
+Description: Loads job cards from persistent storage into the datastore.
+             Validates associated bookings, services, and technicians before
+             attaching them to each job card.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a booking ID, service ID, or technician ID is invalid
+    - std::runtime_error if a service does not belong to the booking
+    - std::runtime_error if a user is not a technician
+*/
+void ServiceManagementService::loadJobCards()
+{
+    util::FileManager<JobCard> jobCardFileManager(config::file::JOBCARD_FILE);
+    auto& jobCards = m_dataStore.getJobCards();
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    auto& services = m_dataStore.getServices();
+    auto& users = m_dataStore.getUsers();
+    auto jobCardsMap = jobCardFileManager.load();
+    for (int jobCardIndex = 0; jobCardIndex < jobCardsMap.getSize(); jobCardIndex++)
+    {
+        JobCard* jobCard = jobCardsMap.getValueAt(jobCardIndex);
+        int bookingIndex = serviceBookings.find(jobCard->getBookingId());
+        if (bookingIndex == -1)
+        {
+            throw std::runtime_error("Invalid Booking ID");
+        }
+        ServiceBooking* booking = serviceBookings.getValueAt(bookingIndex);
+        jobCard->setBooking(booking);
+        int serviceIndex = services.find(jobCard->getServiceId());
+        if (serviceIndex == -1)
+        {
+            throw std::runtime_error("Invalid Service ID");
+        }
+        Service* service = services.getValueAt(serviceIndex);
+        if (booking->getServices().find(jobCard->getServiceId()) == -1)
+        {
+            throw std::runtime_error("Service does not belong to booking");
+        }
+        jobCard->setService(service);
+        int technicianIndex = users.find(jobCard->getTechnicianId());
+        if (technicianIndex == -1)
+        {
+            throw std::runtime_error("Invalid Technician ID");
+        }
+        User* technician = users.getValueAt(technicianIndex);
+        if (technician->getUserType() != util::UserType::TECHNICIAN)
+        {
+            throw std::runtime_error("User is not a technician");
+        }
+        jobCard->setTechnician(technician);
+        jobCards[jobCard->getId()] = jobCard;
+    }
+}
+
+/*
+Function: saveJobCards
+Description: Saves job cards from the datastore to persistent storage.
+             Uses FileManager to serialize job cards into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveJobCards()
+{
+    util::FileManager<JobCard> jobCardFileManager(config::file::JOBCARD_FILE);
+    auto& jobCards = m_dataStore.getJobCards();
+    jobCardFileManager.save(jobCards);
+}
+
+/*
+Function: loadObservers
+Description: Loads observer IDs from persistent storage and attaches corresponding
+             users as observers to the ServiceManagementService.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if an observer ID is invalid (not found in datastore)
+*/
+void ServiceManagementService::loadObservers()
+{
+    util::loadObservers(config::file::SERVICEMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+/*
+Function: saveObservers
+Description: Saves the current observer IDs of the ServiceManagementService
+             to persistent storage for future retrieval.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveObservers()
+{
+    util::saveObservers(config::file::SERVICEMANAGEMENTOBSERVERS, this);
+}
 
 /*
 Function: cancelCustomerServiceBookings
@@ -54,12 +547,16 @@ void ServiceManagementService::cancelCustomerServiceBookings(const std::string&
                     booking->setCustomer(nullptr);
                     booking->setCustomerId("");
                     User* assignedTechnician = booking->getAssignedTechnician();
-                    sendNotification(assignedTechnician, "Customer Service Cancelled", "Uh?Oh. The customer has cancelled their service booking. Your assigned job card has been cancelled and the inventory has been restocked.");
+                    std::string title = "Customer Service Cancelled";
+                    std::string message = "The customer has cancelled their service booking. Your assigned job card has been cancelled and the inventory has been restocked.";
+                    sendNotification(assignedTechnician, title, message);
                 }
                 else if (type == util::UserType::TECHNICIAN)
                 {
                     booking->setStatus(util::ServiceJobStatus::PENDING);
-                    sendNotification(booking->getCustomer(), "Technician Unavailable", "Your assigned technician is no longer available. Your booking has been reset to pending, and we will reassign a new technician shortly.");
+                    std::string title = "Technician Unavailable";
+                    std::string message = "Your assigned technician is no longer available. Your booking has been reset to pending, and we will reassign a new technician shortly.";
+                    sendNotification(booking->getCustomer(), title, message); 
                 }
                 booking->setAssignedTechnician(nullptr);
                 booking->setAssignedTechnicianId("");
@@ -104,7 +601,9 @@ void ServiceManagementService::cancelTechnicianJobs(const std::string& technicia
             if (job->getStatus() == util::ServiceJobStatus::PENDING || job->getStatus() == util::ServiceJobStatus::STARTED)
             {
                 job->setStatus(util::ServiceJobStatus::CANCELLED);
-                sendNotification(job->getTechnician(), "Job Cancelled", "The Job has cancelled. Your job card has been cancelled and the inventory has been restocked.");
+                std::string title = "Job Cancelled";
+                std::string message = "The Job has cancelled. Your job card has been cancelled and the inventory has been restocked.";
+                sendNotification(job->getTechnician(), title, message);
                 Service* service = job->getService();
                 if (service != nullptr)
                 {
@@ -229,3 +728,325 @@ void ServiceManagementService::removeComboPackage(const std::string& comboPackag
         throw std::runtime_error("Combo package with ID '" + comboPackageID + "' not found.");
     }
 }
+
+/*
+Function: getServiceBookings
+Description: Retrieves all service bookings from the datastore.
+Parameters:
+	- None
+Returns:
+	- util::Map<std::string, ServiceBooking*> containing all service bookings
+*/
+util::Map<std::string, ServiceBooking*> ServiceManagementService::getServiceBookings()
+{
+	return m_dataStore.getServiceBookings();
+}
+
+/*
+Function: getServiceBooking
+Description: Retrieves a specific service booking by its ID.
+Parameters:
+	- serviceID: std::string, ID of the service booking
+Returns:
+	- ServiceBooking*: Pointer to the service booking, or nullptr if not found
+*/
+ServiceBooking* ServiceManagementService::getServiceBooking(const std::string& serviceID)
+{
+	auto currentServiceBookings = getServiceBookings();
+	for (int iterator = 0; iterator < currentServiceBookings.getSize(); iterator++)
+	{
+		if (currentServiceBookings.getValueAt(iterator)->getId() == serviceID)
+		{
+			return currentServiceBookings.getValueAt(iterator);
+		}
+	}
+	return nullptr;
+}
+
+/*
+Function: createJobCard
+Description: Creates a job card for a given service booking, service, and technician.
+			 Validates booking, service, technician, and inventory availability before creation.
+Parameters:
+	- bookingID: std::string, ID of the service booking
+	- technicianID: std::string, ID of the technician
+	- serviceID: std::string, ID of the service
+Returns:
+	- void
+Throws:
+	- std::runtime_error if booking, service, technician, or inventory validation fails
+*/
+void ServiceManagementService::createJobCard(const std::string& bookingID, const std::string& technicianID, const std::string& serviceID)
+{
+	UserManagementService m_userManagementService;
+	ServiceBooking* currentBooking = getServiceBooking(bookingID);
+	auto& currentJobCards = m_dataStore.getJobCards();
+	if (currentBooking == nullptr)
+	{
+		throw std::runtime_error("Service Booking not available");
+	}
+	auto& currentServices = currentBooking->getServices();
+	if (currentServices.find(serviceID) == -1)
+	{
+		throw std::runtime_error("Invalid service Id");
+	}
+	Service* currentService = currentServices.getValueAt(currentServices.find(serviceID));
+	User* selectedTechnician = m_userManagementService.getUser(technicianID);
+	if (selectedTechnician == nullptr)
+	{
+		throw std::runtime_error("Technician not available");
+	}
+	auto& inventoryItems = currentService->getRequiredInventoryItems();
+	for (int iterator = 0; iterator < inventoryItems.getSize(); iterator++)
+	{
+		InventoryItem* currentInventoryItem = inventoryItems.getValueAt(iterator);
+		if (currentInventoryItem && currentInventoryItem->getQuantity() == 0)
+		{
+			std::string errorMessage = "Failed to create job card, " + currentInventoryItem->getPartName() + " is out of stock.";
+			throw std::runtime_error(errorMessage);
+		}
+	}
+	for (int iterator = 0; iterator < inventoryItems.getSize(); iterator++)
+	{
+		InventoryItem* currentInventoryItem = inventoryItems.getValueAt(iterator);
+		if (currentInventoryItem)
+		{
+			int currentStockQuantity = currentInventoryItem->getQuantity();
+			currentInventoryItem->setQuantity(currentStockQuantity - 1);
+		}
+	}
+	currentBooking->setAssignedTechnician(selectedTechnician);
+	currentBooking->setAssignedTechnicianId(selectedTechnician->getId());
+	std::string title = "Job card created";
+	std::string message = "Job card created for the service and you are assigned for that.";
+	JobCard* jobCard = Factory::getObject<JobCard>(bookingID, currentBooking, currentService, serviceID, technicianID, selectedTechnician, util::Timestamp(), util::ServiceJobStatus::STARTED, util::Timestamp());
+	if (jobCard)
+	{
+		currentJobCards.insert(jobCard->getId(), jobCard);
+		sendNotification(selectedTechnician, title, message);
+	}
+	else
+	{
+		throw std::runtime_error("Failed to create job card.");
+	}
+}
+
+/*
+Function: createService
+Description: Creates a new service with associated inventory items and labor cost.
+			 Validates inventory items before creation.
+Parameters:
+	- name: std::string, name of the service
+	- inventoryItemIDs: util::Vector<std::string>, IDs of required inventory items
+	- laborCost: double, labor cost for the service
+Returns:
+	- void
+Throws:
+	- std::runtime_error if inventory items are not found or service creation fails
+*/
+void ServiceManagementService::createService(const std::string& name, const util::Vector<std::string>& inventoryItemIDs, double laborCost)
+{
+	util::Map<std::string, InventoryItem*> currentServiceInventoryItems;
+	auto inventoryItems = m_dataStore.getInventoryItems();
+	for (int iteratorOne =0; iteratorOne < inventoryItemIDs.getSize(); iteratorOne++)
+	{
+		std::string currentItemID = inventoryItemIDs[iteratorOne];
+		bool itemFound = false;
+		for (int iteratorTwo = 0; iteratorTwo < inventoryItems.getSize(); iteratorTwo++)
+		{
+			InventoryItem* currentInventoryItem = inventoryItems.getValueAt(iteratorTwo);
+			if (currentInventoryItem && currentInventoryItem->getId() == currentItemID)
+			{
+				itemFound = true;
+				currentServiceInventoryItems.insert(currentInventoryItem->getId(), currentInventoryItem);
+				break;
+			}
+		}
+		if (!itemFound)
+		{
+			throw std::runtime_error("Inventory item with ID '" + currentItemID + "' not found.");
+		}
+	}
+	Service* newService = Factory::getObject<Service>(name, currentServiceInventoryItems, laborCost);
+	if (newService == nullptr)
+	{
+		throw std::runtime_error("Unable to create new service.");
+	}
+	util::Map<std::string, Service*>& currentServices = m_dataStore.getServices();
+	if (currentServices.find(newService->getId()) != -1)
+	{
+		throw std::runtime_error("Service with this ID Already exists.");
+	}
+	currentServices.insert(newService->getId(), newService);
+}
+
+/*
+Function: getServices
+Description: Retrieves all services from the datastore.
+Parameters:
+	- None
+Returns:
+	- util::Map<std::string, Service*> containing all services
+*/
+util::Map<std::string, Service*> ServiceManagementService::getServices()
+{
+	return m_dataStore.getServices();
+}
+
+/*
+Function: removeService
+Description: Marks a service as inactive by its ID.
+Parameters:
+	- serviceID: std::string, ID of the service
+Returns:
+	- void
+Throws:
+	- std::runtime_error if the service is not found
+*/
+void ServiceManagementService::removeService(const std::string& serviceID)
+{
+	util::Map<std::string, Service*>& currentServices = m_dataStore.getServices();
+	if (currentServices.find(serviceID) != -1)
+	{
+		currentServices.getValueAt(currentServices.find(serviceID))->setState(util::State::INACTIVE);
+	}
+	else
+	{
+		throw std::runtime_error("Service not found.");
+	}
+}
+
+/*
+Function: getServiceBookings (overloaded)
+Description: Retrieves all service bookings for a specific customer.
+Parameters:
+	- customerID: std::string, ID of the customer
+Returns:
+	- util::Map<std::string, ServiceBooking*> containing bookings for the customer
+*/
+util::Map<std::string, ServiceBooking*> ServiceManagementService::getServiceBookings(const std::string& customerID)
+{
+	util::Map<std::string, ServiceBooking*> currentServiceBookings = getServiceBookings();
+	util::Map<std::string, ServiceBooking*> currentUserServiceBookings;
+	if (currentServiceBookings.getSize() != 0)
+	{
+		for (int iterator = 0; iterator < currentServiceBookings.getSize(); iterator++)
+		{
+			auto currentServiceBooking = currentServiceBookings.getValueAt(iterator);
+			if (currentServiceBooking->getCustomerId() == customerID)
+			{
+				currentUserServiceBookings.insert(currentServiceBooking->getId(), currentServiceBooking);
+			}
+		}
+	}
+	return currentUserServiceBookings;
+}
+
+/*
+Function: getJobCards
+Description: Retrieves all job cards assigned to a specific technician.
+Parameters:
+	- technicianID: std::string, ID of the technician
+Returns:
+	- util::Map<std::string, JobCard*> containing job cards assigned to the technician
+*/
+util::Map<std::string, JobCard*> ServiceManagementService::getJobCards(const std::string& technicianID)
+{
+	util::Map<std::string, JobCard*> jobCards = m_dataStore.getJobCards();
+	util::Map<std::string, JobCard*> technicianJobCards;
+	for (int iterator = 0; iterator < jobCards.getSize(); iterator++)
+	{
+		JobCard* currentJobCard = jobCards.getValueAt(iterator);
+		if (currentJobCard->getTechnicianId() == technicianID)
+		{
+			technicianJobCards.insert(currentJobCard->getId(), currentJobCard);
+		}
+	}
+	return technicianJobCards;
+}
+
+/*
+Function: hasCompletedAllJobs (static helper)
+Description: Checks if all job cards for a given service booking are completed.
+Parameters:
+	- bookingId: std::string, ID of the service booking
+	- currentAssignedJobs: util::Map<std::string, JobCard*>&, map of assigned job cards
+Returns:
+	- bool: True if all job cards are completed, False otherwise
+*/
+static bool hasCompletedAllJobs(std::string bookingId, util::Map<std::string, JobCard*>& currentAssignedJobs)
+{
+	for (int iterator = 0; iterator < currentAssignedJobs.getSize(); iterator++)
+	{
+		JobCard* currentJob = currentAssignedJobs.getValueAt(iterator);
+		if (currentJob->getBookingId() == bookingId)
+		{
+			if (currentJob->getStatus() == util::ServiceJobStatus::STARTED)
+			{
+				return false;
+			}
+		}
+	}
+	return true;
+}
+
+/*
+Function: completeJob
+Description: Marks a job card as completed for the authenticated technician.
+			 If all job cards in the booking are completed, marks the booking as completed
+			 and generates an invoice.
+Parameters:
+	- jobID: std::string, ID of the job card
+Returns:
+	- void
+Throws:
+	- std::runtime_error if technician is not authenticated, job card not found, or job already completed
+*/
+void ServiceManagementService::completeJob(const std::string& jobID)
+{
+	AuthenticationManagementService authenticationManagementService;
+	PaymentManagementService paymentManagementService;
+	bool jobStatusUpdated = false, serviceBookingCompleted;
+	JobCard* currentJob;
+	User* currentTechnician = authenticationManagementService.getAuthenticatedUser();
+	if (currentTechnician == nullptr)
+	{
+		throw std::runtime_error("Unable to fetch current technician.");
+	}
+	util::Map<std::string, JobCard*> currentAssignedJobs = getJobCards(currentTechnician->getId());
+	if (currentAssignedJobs.getSize() == 0)
+	{
+		throw std::runtime_error("No job cards assigned to the technician.");
+	}
+	if (currentAssignedJobs.find(jobID) != -1)
+	{
+		currentJob = currentAssignedJobs.getValueAt(currentAssignedJobs.find(jobID));
+		if (currentJob == nullptr)
+		{
+			throw std::runtime_error("Unable to fetch current job.");
+		}
+		if (currentJob->getStatus() == util::ServiceJobStatus::STARTED)
+		{
+			currentJob->setStatus(util::ServiceJobStatus::COMPLETED);
+			jobStatusUpdated = true;
+		}
+	}
+	else
+	{
+		throw std::runtime_error("Failed to complete the job, some error occured or job already completed.");
+	}
+	if (!jobStatusUpdated)
+	{
+		throw std::runtime_error("Failed to complete the job, some error occured or job already completed.");
+	}
+
+	serviceBookingCompleted = hasCompletedAllJobs(currentJob->getBookingId(), currentAssignedJobs);
+	if (serviceBookingCompleted)
+	{
+		currentJob->getBooking()->setStatus(util::ServiceJobStatus::COMPLETED);
+		paymentManagementService.generateInvoice(currentJob->getBooking());
+		std::string title = "Service Booking completed,Invoice Generated.\n";
+		std::string message = "Services completed for the booking and invoice generated.\n";
+		sendNotification(currentJob->getBooking()->getCustomer(), title, message);
+	}
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/ServiceManagementService.h

@@ -6,6 +6,7 @@ Description: Header file declaring the ServiceManagementService class, which man
 Author: Trenser
 Date:19-May-2026
 */
+
 #pragma once
 #include <string>
 #include "Map.h"
@@ -22,6 +23,7 @@ class ServiceManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
+    util::Vector<std::string> getObserverIDs() override;
 public:
     ServiceManagementService() : m_dataStore(DataStore::getInstance()) {}
     util::Map<std::string, Service*> getServices();
@@ -30,6 +32,7 @@ public:
     void purchaseComboPackage(const std::string& comboPackageID, const std::string& vehicleNumber, const std::string& vehicleBrand, const std::string& vehicleModel);
     util::Map<std::string, ServiceBooking*> getServiceBookings();
     util::Map<std::string, ServiceBooking*> getServiceBookings(const std::string& customerID);
+    ServiceBooking* getServiceBooking(const std::string& serviceID);
     void createJobCard(const std::string& bookingID, const std::string& technicianID, const std::string& serviceID);
     void createService(const std::string& name, const util::Vector<std::string>& inventoryItemIDs, double laborCost);
     void removeService(const std::string& serviceID);
@@ -42,4 +45,14 @@ public:
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
+    void loadServices();
+    void saveServices();
+    void loadComboPackages();
+    void saveComboPackages();
+    void loadServiceBookings();
+    void saveServiceBookings();
+    void loadJobCards();
+    void saveJobCards();
+    void loadObservers();
+    void saveObservers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/UserManagementService.cpp

@@ -1,12 +1,250 @@
 /*
 File: UserManagementService.cpp
 Description: Implementation file containing the method definitions of the
-			 UserManagementService class, including user retrieval and removal logic.
+			 UserManagementService class, including user creation, updates,
+			 and ensuring an admin account exists.
 Author: Trenser
 Date:19-May-2026
 */
-#include "UserManagementService.h"
+
+#include <stdexcept>
+#include "Config.h"
+#include "Enums.h"
+#include "Factory.h"
+#include "FileManager.h"
+#include "InventoryManagementService.h"
+#include "Notification.h"
+#include "PaymentManagementService.h"
+#include "ServiceManagementService.h"
 #include "User.h"
+#include "UserManagementService.h"
+#include "Vector.h"
+
+
+/*
+Function: ensureAdminExists
+Description: Ensures that at least one admin user exists in the system.
+			 If no admin is found, creates a default admin user using
+			 configuration constants.
+Parameter: None
+Return type: void
+*/
+void UserManagementService::ensureAdminExists()
+{
+	auto& usersMap = m_dataStore.getUsers();
+	int usersMapSize = usersMap.getSize();
+	bool isAdminFound = false;
+	for (int index = 0; index < usersMapSize; index++)
+	{
+		User* user = usersMap.getValueAt(index);
+		if (user && user->getUserType() == util::UserType::ADMIN)
+		{
+			isAdminFound = true;
+			break;
+		}
+	}
+	if (!isAdminFound)
+	{
+		createUser(
+			config::admin::DEFAULT_ADMIN_USERNAME,
+			config::admin::DEFAULT_ADMIN_NAME,
+			config::admin::DEFAULT_ADMIN_PASSWORD,
+			config::admin::DEFAULT_ADMIN_EMAIL,
+			config::admin::DEFAULT_ADMIN_PHONE, 
+			util::UserType::ADMIN);
+	}
+}
+
+/*
+Function: createUser
+Description: Creates a new user with the provided details. Validates that
+			 the username is unique, then attaches the user to relevant
+			 management services (payment, service, inventory).
+Parameter: const std::string& username - user’s username
+		   const std::string& name - user’s name
+		   const std::string& password - user’s password
+		   const std::string& email - user’s email address
+		   const std::string& phone - user’s phone number
+		   util::UserType type - type of user (ADMIN, CUSTOMER, TECHNICIAN)
+Return type: void
+*/
+void UserManagementService::createUser(const std::string& username, const std::string& name, const std::string& password, const std::string& email, const std::string& phone, util::UserType type)
+{
+	InventoryManagementService inventoryManagementService;
+	PaymentManagementService paymentManagementService;
+	ServiceManagementService serviceManagementService;
+	auto& usersMap = m_dataStore.getUsers();
+	int index = usersMap.findIf(
+		[&](const std::string&, User* user)
+		{
+			return user->getUserName() == username;
+		}
+	);
+	if (index != -1)
+	{
+		throw std::runtime_error("Username already exists");
+	}
+	User* newUser = Factory::getObject<User>(username, password, name, phone, email, type);
+	usersMap.insert(newUser->getId(), newUser);
+	paymentManagementService.attach(newUser);
+	serviceManagementService.attach(newUser);
+	if (newUser->getUserType() == util::UserType::ADMIN)
+	{
+		inventoryManagementService.attach(newUser);
+	}
+}
+
+/*
+Function: updateUserDetails
+Description: Updates the email and phone details of an existing user.
+			 Throws an exception if the user does not exist.
+Parameter: const std::string& userID - ID of the user to update
+		   const std::string& email - new email address
+		   const std::string& phone - new phone number
+Return type: void
+*/
+void UserManagementService::updateUserDetails(const std::string& userID, const std::string& email, const std::string& phone)
+{
+	auto& usersMap = m_dataStore.getUsers();
+	int index = usersMap.find(userID);
+	if (index == -1)
+	{
+		throw std::runtime_error("User does not exist!");
+	}
+	User* user = usersMap.getValueAt(index);
+	user->setEmail(email);
+	user->setPhone(phone);
+}
+
+/*
+Function: getUserNotifications
+Description: Retrieves all notifications associated with a given user ID.
+Parameters:
+	- userID: The unique ID of the user whose notifications are to be retrieved.
+Returns:
+	- util::Vector<Notification*> containing all notifications for the user.
+Throws:
+	- std::runtime_error if no user is found with the given UserID or if the User object is invalid.
+*/
+util::Vector<Notification*> UserManagementService::getUserNotifications(const std::string& userID)
+{
+	auto& usersMap = m_dataStore.getUsers();
+	if (usersMap.find(userID) == -1)
+	{
+		throw std::runtime_error("No user found with given UserID");
+	}
+	User* user = usersMap[userID];
+	if (user)
+	{
+		auto& notifications = user->getNotifications();
+		int numberOfNotifications = notifications.getSize();
+		util::Vector<Notification*> notificationsVector;
+		for (int index = 0; index < numberOfNotifications; index++)
+		{
+		    notificationsVector.push_back(notifications.getValueAt(index));
+		}
+		return notificationsVector;
+	}
+	else
+	{
+		throw std::runtime_error("Invalid User object");
+	}
+}
+
+/*
+Function: deleteNotification
+Description: Deletes a specific notification associated with a given user ID.
+Parameters:
+	- notificationID: The unique ID of the notification to be deleted.
+	- userID: The unique ID of the user whose notification is to be deleted.
+Returns:
+	- void
+Throws:
+	- std::runtime_error if no user is found with the given UserID or if no notification is found with the given NotificationID.
+*/
+void UserManagementService::deleteNotification(const std::string& notificationID, const std::string& userID)
+{
+	auto& usersMap = m_dataStore.getUsers();
+	if (usersMap.find(userID) == -1)
+	{
+		throw std::runtime_error("No user found with given UserID");
+	}
+	User* user = usersMap[userID];
+	auto& notifications = user->getNotifications();
+	if (notifications.find(notificationID) == -1)
+	{
+		throw std::runtime_error("No notification found with given NotificationID");
+	}
+	notifications.remove(notificationID);
+}
+
+/*
+Function: loadUsers
+Description: Loads users and notifications from persistent storage into the datastore.
+             Validates that each notification’s recipient exists and attaches the
+             notification to the corresponding user.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a notification recipient user ID is invalid
+*/
+void UserManagementService::loadUsers()
+{
+    util::FileManager<User> userFileManager(config::file::USER_FILE);
+    util::FileManager<Notification> notificationFileManager(config::file::NOTIFICATION_FILE);
+    auto& users = m_dataStore.getUsers();
+    auto usersMap = userFileManager.load();
+    auto notificationsMap = notificationFileManager.load();
+    int numberOfUsers = usersMap.getSize();
+    int numberOfNotifications = notificationsMap.getSize();
+    for (int index = 0; index < numberOfUsers; index++)
+    {
+        users[usersMap.getKeyAt(index)] = usersMap.getValueAt(index);
+    }
+    for (int index = 0; index < numberOfNotifications; index++)
+    {
+        Notification* notification = notificationsMap.getValueAt(index);
+        const std::string& recipientUserId = notification->getRecipientUserId();
+        int userIndex = users.find(recipientUserId);
+        if (userIndex == -1)
+        {
+            throw std::runtime_error("Invalid recipient user ID");
+        }
+        User* user = users.getValueAt(userIndex);
+        user->addNotification(notification);
+    }
+}
+
+/*
+Function: saveUsers
+Description: Saves users and their notifications from the datastore to persistent storage.
+             Collects notifications from all users into a single map before saving.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void UserManagementService::saveUsers()
+{
+    util::FileManager<User> userFileManager(config::file::USER_FILE);
+    util::FileManager<Notification> notificationFileManager(config::file::NOTIFICATION_FILE);
+    auto& users = m_dataStore.getUsers();
+    util::Map<std::string, Notification*> notifications;
+    for (int userIndex = 0; userIndex < users.getSize(); userIndex++)
+    {
+        User* user = users.getValueAt(userIndex);
+        auto& userNotifications = user->getNotifications();
+        for (int notificationIndex = 0; notificationIndex < userNotifications.getSize(); notificationIndex++)
+        {
+            notifications[userNotifications.getKeyAt(notificationIndex)] =
+                userNotifications.getValueAt(notificationIndex);
+        }
+    }
+    userFileManager.save(users);
+    notificationFileManager.save(notifications);
+}
 
 /*
 Function: getUsers
@@ -52,4 +290,19 @@ void UserManagementService::removeUser(const std::string& userID)
 			user->setState(util::State::INACTIVE);
 		}
 	}
+}
+
+util::Map<std::string, User*> UserManagementService::getUsers(util::UserType type)
+{
+	util::Map<std::string, User*>& currentUsers = m_dataStore.getUsers();
+	util::Map<std::string, User*> filteredUsersMap;
+	for (int iterator = 0; iterator < currentUsers.getSize(); iterator++)
+	{
+		User* currentUser = currentUsers.getValueAt(iterator);
+		if (currentUser->getUserType() == type)
+		{
+			filteredUsersMap.insert(currentUser->getId(), currentUser);
+		}
+	}
+	return filteredUsersMap;
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/UserManagementService.h

@@ -1,7 +1,8 @@
 /*
 File: UserManagementService.h
 Description: Header file declaring the UserManagementService class, which manages
-             user creation, updates, retrieval, removal, and notification handling.
+             user creation, updates, retrieval, removal, notifications, and ensures
+             the existence of an admin account.
 Author: Trenser
 Date:19-May-2026
 */
@@ -24,8 +25,11 @@ public:
     void updateUserDetails(const std::string& userID, const std::string& email, const std::string& phone);
     util::Map<std::string, User*> getUsers();
     util::Map<std::string, User*> getUsers(util::UserType type);
-    User* getUser(const std::string& userID);
+    User* getUser (const std::string& userID);
     void removeUser(const std::string& userID);
     util::Vector<Notification*> getUserNotifications(const std::string& userID);
     void deleteNotification(const std::string& notificationID, const std::string& userID);
+    void ensureAdminExists();
+    void loadUsers();
+    void saveUsers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/Config.h

@@ -0,0 +1,43 @@
+/*
+File: Config.h
+Description: Header file declaring configuration constants for the Vehicle Service System.
+			 Includes default admin account details such as username, name, password,
+			 email, and phone number.
+Author: Trenser
+Date: 21-May-2026
+*/
+
+#pragma once
+
+namespace config
+{
+	namespace admin
+	{
+		constexpr const char* DEFAULT_ADMIN_USERNAME = "admin";
+		constexpr const char* DEFAULT_ADMIN_NAME = "admin";
+		constexpr const char* DEFAULT_ADMIN_PASSWORD = "admin";
+		constexpr const char* DEFAULT_ADMIN_EMAIL = "admin@vss";
+		constexpr const char* DEFAULT_ADMIN_PHONE = "0000000000";
+	}
+
+	namespace threshold
+	{
+		constexpr int INVENTORY_LOW_STOCK_THRESHOLD = 5;
+		constexpr int PAYMENT_REMINDER_THRESHOLD_HOURS = 168;
+	}
+
+	namespace file
+	{
+		constexpr const char* INVENTORYITEM_FILE = "files/InventoryItem.csv";
+		constexpr const char* USER_FILE = "files/User.csv";
+		constexpr const char* NOTIFICATION_FILE = "files/Notification.csv";
+		constexpr const char* SERVICE_FILE = "files/Service.csv";
+		constexpr const char* COMBOPACKAGE_FILE = "files/ComboPackage.csv";
+		constexpr const char* SERVICEBOOKING_FILE = "files/ServiceBooking.csv";
+		constexpr const char* JOBCARD_FILE = "files/JobCard.csv";
+		constexpr const char* INVOICE_FILE = "files/Invoice.csv";
+		constexpr const char* SERVICEMANAGEMENTOBSERVERS = "files/ServiceManagementObservers.csv";
+		constexpr const char* PAYMENTMANAGEMENTOBSERVERS = "files/PaymentManagementObservers.csv";
+		constexpr const char* INVENTORYMANAGEMENTOBSERVERS = "files/InventoryManagementObservers.csv";
+	}
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/Enums.h

@@ -1,3 +1,12 @@
+/*
+File: Enums.h
+Description: Declares enumerations and utility functions for user types, payment modes, payment status,
+             service job status, and state management in the Vehicle Service Management System.
+             Provides string conversion and parsing functions for each enum type.
+Author: Trenser
+Date: 19-May-2026
+*/
+
 #pragma once
 #include <stdexcept>
 
@@ -13,7 +22,8 @@ namespace util
 	enum class PaymentMode
 	{
 		ONLINE,
-		OFFLINE
+		OFFLINE,
+        NOTSET
 	};
 
 	enum class PaymentStatus
@@ -36,6 +46,14 @@ namespace util
         INACTIVE
     };
 
+    /*
+    Function: getUserTypeString
+    Description: Converts a UserType enum value to its corresponding string representation.
+    Parameters:
+        - type: UserType enum value.
+    Returns:
+        - std::string representing the UserType.
+    */
     inline std::string getUserTypeString(UserType type)
     {
         switch (type)
@@ -50,6 +68,16 @@ namespace util
         throw std::invalid_argument("Invalid UserType");
     }
 
+    /*
+    Function: getUserType
+    Description: Converts a string value to its corresponding UserType enum.
+    Parameters:
+        - value: std::string representing the UserType.
+    Returns:
+        - UserType enum value.
+    Throws:
+        - std::invalid_argument if the string does not match a valid UserType.
+    */
     inline UserType getUserType(const std::string& value)
     {
         if (value == "ADMIN")
@@ -67,6 +95,14 @@ namespace util
         throw std::invalid_argument("Invalid UserType string");
     }
 
+    /*
+    Function: getPaymentModeString
+    Description: Converts a PaymentMode enum value to its corresponding string representation.
+    Parameters:
+        - mode: PaymentMode enum value.
+    Returns:
+        - std::string representing the PaymentMode.
+    */
     inline std::string getPaymentModeString(PaymentMode mode)
     {
         switch (mode)
@@ -75,10 +111,22 @@ namespace util
             return "ONLINE";
         case PaymentMode::OFFLINE:
             return "OFFLINE";
+        case PaymentMode::NOTSET:
+            return "NOTSET";
         }
         throw std::invalid_argument("Invalid PaymentMode");
     }
 
+    /*
+    Function: getPaymentMode
+    Description: Converts a string value to its corresponding PaymentMode enum.
+    Parameters:
+        - value: std::string representing the PaymentMode.
+    Returns:
+        - PaymentMode enum value.
+    Throws:
+        - std::invalid_argument if the string does not match a valid PaymentMode.
+    */
     inline PaymentMode getPaymentMode(const std::string& value)
     {
         if (value == "ONLINE")
@@ -92,6 +140,14 @@ namespace util
         throw std::invalid_argument("Invalid PaymentMode string");
     }
 
+    /*
+    Function: getPaymentStatusString
+    Description: Converts a PaymentStatus enum value to its corresponding string representation.
+    Parameters:
+        - status: PaymentStatus enum value.
+    Returns:
+        - std::string representing the PaymentStatus.
+    */
     inline std::string getPaymentStatusString(PaymentStatus status)
     {
         switch (status)
@@ -104,6 +160,16 @@ namespace util
         throw std::invalid_argument("Invalid PaymentStatus");
     }
 
+    /*
+    Function: getPaymentStatus
+    Description: Converts a string value to its corresponding PaymentStatus enum.
+    Parameters:
+        - value: std::string representing the PaymentStatus.
+    Returns:
+        - PaymentStatus enum value.
+    Throws:
+        - std::invalid_argument if the string does not match a valid PaymentStatus.
+    */
     inline PaymentStatus getPaymentStatus(const std::string& value)
     {
         if (value == "PENDING")
@@ -119,6 +185,14 @@ namespace util
         throw std::invalid_argument("Invalid PaymentStatus string");
     }
 
+    /*
+    Function: getServiceJobStatusString
+    Description: Converts a ServiceJobStatus enum value to its corresponding string representation.
+    Parameters:
+        - status: ServiceJobStatus enum value.
+    Returns:
+        - std::string representing the ServiceJobStatus.
+    */
     inline std::string getServiceJobStatusString(ServiceJobStatus status)
     {
         switch (status)
@@ -135,6 +209,16 @@ namespace util
         throw std::invalid_argument("Invalid ServiceJobStatus");
     }
 
+    /*
+    Function: getServiceJobStatus
+    Description: Converts a string value to its corresponding ServiceJobStatus enum.
+    Parameters:
+        - value: std::string representing the ServiceJobStatus.
+    Returns:
+        - ServiceJobStatus enum value.
+    Throws:
+        - std::invalid_argument if the string does not match a valid ServiceJobStatus.
+    */
     inline ServiceJobStatus getServiceJobStatus(const std::string& value)
     {
         if (value == "STARTED")
@@ -156,28 +240,46 @@ namespace util
         throw std::invalid_argument("Invalid ServiceJobStatus string");
     }
 
+    /*
+    Function: getStateString
+    Description: Converts a State enum value to its corresponding string representation.
+    Parameters:
+        - status: State enum value.
+    Returns:
+        - std::string representing the State.
+    */
     inline std::string getStateString(State status)
     {
         switch (status)
         {
         case State::ACTIVE:
-            return "STARTED";
+            return "ACTIVE";
         case State::INACTIVE:
-            return "COMPLETED";
+            return "INACTIVE";
         }
         throw std::invalid_argument("Invalid State");
     }
 
+    /*
+    Function: getState
+    Description: Converts a string value to its corresponding State enum.
+    Parameters:
+        - value: std::string representing the State.
+    Returns:
+        - State enum value.
+    Throws:
+        - std::invalid_argument if the string does not match a valid State.
+    */
     inline State getState(const std::string& value)
     {
         if (value == "ACTIVE")
         {
             return State::ACTIVE;
         }
-        if (value == "COMPLETED")
+        if (value == "INACTIVE")
         {
             return State::INACTIVE;
         }
         throw std::invalid_argument("Invalid State string");
     }
-}
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/FileHelper.h

@@ -0,0 +1,79 @@
+/*
+File: FileHelper.h
+Description: Provides utility functions for loading and saving records
+             from and to CSV-like text files. Ensures files are created
+             if missing and supports simple record persistence.
+Author: Trenser
+Date: 22-May-2026
+*/
+
+#pragma once
+#include <fstream>
+#include <string>
+#include <stdexcept>
+#include "Vector.h"
+
+namespace util
+{
+    /*
+    Function: loadRecords
+    Description: Loads records from a given file path into a vector of strings.
+                 Skips the header line if present. Creates the file if it does not exist.
+    Parameters:
+        - filePath: const std::string&, path to the file
+    Returns:
+        - util::Vector<std::string>: Vector containing all records (excluding header)
+    Throws:
+        - None (creates file if missing)
+    */
+    inline util::Vector<std::string> loadRecords(const std::string& filePath)
+    {
+        util::Vector<std::string> records;
+        std::ifstream file(filePath);
+        if (!file.is_open())
+        {
+            std::ofstream newFile(filePath);
+            newFile.close();
+            file.open(filePath);
+        }
+        std::string line;
+        bool isHeader = true;
+        while (std::getline(file, line))
+        {
+            if (isHeader)
+            {
+                isHeader = false;
+                continue;
+            }
+            records.push_back(line);
+        }
+        return records;
+    }
+
+    /*
+    Function: saveRecords
+    Description: Saves records to a given file path. Overwrites existing content
+                 and writes a header line followed by all records.
+    Parameters:
+        - filePath: const std::string&, path to the file
+        - records: const util::Vector<std::string>&, vector of records to save
+    Returns:
+        - void
+    Throws:
+        - std::runtime_error if the file cannot be opened for writing
+    */
+    inline void saveRecords(const std::string& filePath, const util::Vector<std::string>& records)
+    {
+        std::ofstream file(filePath, std::ios::trunc);
+        if (!file.is_open())
+        {
+            throw std::runtime_error("Failed to open file " + filePath);
+        }
+        file << "Values" << '\n';
+        int numberOfRecords = records.getSize();
+        for (int index = 0; index < numberOfRecords; index++)
+        {
+            file << records[index] << '\n';
+        }
+    }
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/FileManager.h

@@ -0,0 +1,117 @@
+/*
+File: FileManager.h
+Description: Declares and implements a generic FileManager template class for
+			 loading and saving objects to and from files. Uses serialization
+			 and deserialization methods defined in the object type T.
+			 Provides persistence support for system entities such as Users,
+			 Services, InventoryItems, etc.
+Author: Trenser
+Date: 22-May-2026
+*/
+
+#pragma once
+#include <stdexcept>
+#include <string>
+#include <fstream>
+#include "Vector.h"
+#include "Map.h"
+
+namespace util
+{
+	template <typename T> using objects = util::Map<std::string, T*>;
+
+	template <typename T>
+	class FileManager
+	{
+	private:
+		std::string m_filePath;
+	public:
+		FileManager() : m_filePath("") {}
+		FileManager(const std::string& filePath) : m_filePath(filePath) {}
+		objects<T> load();
+		void save(const objects<T>&);
+	};
+
+	/*
+	Function: load
+	Description: Loads records from the file into a map of objects.
+				 Skips the header line, deserializes each record into an object of type T,
+				 and stores them in a map keyed by object ID.
+	Parameters:
+		- None
+	Returns:
+		- util::Map<std::string, T*> containing deserialized objects
+	Throws:
+		- std::runtime_error if deserialization fails for any record
+	*/
+	template <typename T>
+	objects<T> FileManager<T>::load()
+	{
+		objects<T> records;
+		std::ifstream file(m_filePath);
+		if (!file.is_open())
+		{
+			std::ofstream newFile(m_filePath);
+			newFile.close();
+			file.open(m_filePath);
+		}
+		util::Vector<std::string> lines;
+		std::string line;
+		while (std::getline(file, line))
+		{
+			lines.push_back(line);
+		}
+		int numberOfLines = lines.getSize();
+		bool isHeader = true;
+		for (int lineIndex = 0; lineIndex < numberOfLines; lineIndex++)
+		{
+			const auto& record = lines[lineIndex];
+			if (isHeader)
+			{
+				isHeader = false;
+				continue;
+			}
+			auto object = T::deserialize(record);
+			if (!object)
+			{
+				throw std::runtime_error("Failed to deserialize record");
+			}
+			records[object->getId()] = object;
+		}
+		return records;
+	}
+
+	/*
+	Function: save
+	Description: Saves records to the file. Serializes each object of type T into a string,
+				 writes a header line, and then writes all serialized records to the file.
+	Parameters:
+		- records: const util::Map<std::string, T*>&, map of objects to save
+	Returns:
+		- void
+	Throws:
+		- std::runtime_error if the file cannot be opened for writing
+	*/
+	template <typename T>
+	void FileManager<T>::save(const objects<T>& records)
+	{
+		util::Vector<std::string> lines;
+		lines.push_back(T::getHeaders());
+		int numberOfRecords = records.getSize();
+		for (int recordIndex = 0; recordIndex < numberOfRecords; recordIndex++)
+		{
+			const auto& record = records.getValueAt(recordIndex);
+			lines.push_back(record->serialize());
+		}
+		std::ofstream file(m_filePath, std::ios::trunc);
+		if (!file.is_open())
+		{
+			throw std::runtime_error("Failed to open file " + m_filePath);
+		}
+		int numberOfLines = lines.getSize();
+		for (int lineIndex = 0; lineIndex < numberOfLines; lineIndex++)
+		{
+			file << lines[lineIndex] << '\n';
+		}
+	}
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/InputHelper.h

@@ -34,7 +34,7 @@ namespace util
 
     /*
      * Function: read
-     * Description: Reads a line of text input from console into a string.
+     * Description: Reads a line of text input from console into a string and cleans it up.
      * Parameters:
      *     value - reference to a string where the input will be stored
      * Returns:
@@ -43,6 +43,15 @@ namespace util
     inline void read(std::string& value)
     {
         std::getline(std::cin >> std::ws, value);
+        std::string cleanedValue;
+        for (int index = 0; index < value.length(); index++)
+        {
+            if (value[index] != ',')
+            {
+                cleanedValue += value[index];
+            }
+        }
+        value = cleanedValue;
     }
 
     /*

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/StringHelper.h

@@ -0,0 +1,36 @@
+/*
+File: StringHelper.h
+Description: Provides utility functions for extracting numeric values from strings.
+             Useful for parsing IDs, codes, or mixed alphanumeric inputs where
+             digits need to be isolated and converted into integers.
+Author: Trenser
+Date: 22-May-2026
+*/
+
+#include <cctype>
+#include <string>
+
+namespace util
+{
+    /*
+    Function: extractNumber
+    Description: Extracts all digits from the given string and converts them into an integer.
+                 Ignores non-digit characters. For example, "abc123xyz" returns 123.
+    Parameters:
+        - input: const std::string&, the input string containing digits and/or other characters
+    Returns:
+        - int: The integer value formed by concatenating all digits in the string
+    */
+    inline int extractNumber(const std::string& input)
+    {
+        int result = 0;
+        for (char character : input)
+        {
+            if (std::isdigit(static_cast<unsigned char>(character)))
+            {
+                result = result * 10 + (character - '0');
+            }
+        }
+        return result;
+    }
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/Utility.h

@@ -1,29 +1,102 @@
 /*
 File: Utility.h
-Description: Header file declaring utility functions used across the system,
-             including cost calculation for services based on required inventory items.
+Description: Header file declaring utility functions used across the system
 Author: Trenser
 Date:19-May-2026
 */
-#pragma once
-#include "Service.h"
-#include "InventoryItem.h"
 
-/*
-Function: calculatePartsCost
-Description: Calculates the total cost of parts required for a given service
-             by summing the prices of all associated inventory items.
-Parameter: const Service* service - pointer to the service object
-Return type: double - total cost of required parts
-*/
-inline double calculatePartsCost(const Service* service)
+#pragma once
+#include "ComboPackage.h"
+#include "DataStore.h"
+#include "FileHelper.h"
+#include "InventoryItem.h"
+#include "NotificationManagementService.h"
+#include "Service.h"
+
+namespace util
 {
-    double cost = 0;
-    auto& requiredInventoryItems = service->getRequiredInventoryItems();
-    int requiredInventoryItemsSize = requiredInventoryItems.getSize();
-    for (int index = 0; index < requiredInventoryItemsSize; index++)
+    /*
+    Function: calculatePartsCost
+    Description: Calculates the total cost of parts required for a given service
+                 by summing the prices of all associated inventory items.
+    Parameter: const Service* service - pointer to the service object
+    Return type: double - total cost of required parts
+    */
+    inline double calculatePartsCost(const Service* service)
     {
-        cost += requiredInventoryItems.getValueAt(index)->getPrice();
+        double cost = 0;
+        auto& requiredInventoryItems = service->getRequiredInventoryItems();
+        int requiredInventoryItemsSize = requiredInventoryItems.getSize();
+        for (int index = 0; index < requiredInventoryItemsSize; index++)
+        {
+            cost += requiredInventoryItems.getValueAt(index)->getPrice();
+        }
+        return cost;
     }
-    return cost;
-}
+
+    /*
+    Function: calculateComboServiceEstimatedCost
+    Description: Calculates the estimated total cost of a combo package by summing
+                  the labor and parts costs of all services included in the package.
+    Parameter: const ComboPackage* comboPackage - pointer to the combo package object
+    Return type: double - estimated total cost of the combo package
+    */
+    inline double calculateComboServiceEstimatedCost(const ComboPackage* comboPackage)
+    {
+        double cost = 0;
+        auto& services = comboPackage->getServices();
+        int servicesSize = services.getSize();
+        for (int index = 0; index < servicesSize; index++)
+        {
+            const Service* service = services.getValueAt(index);
+            cost += calculatePartsCost(service) + service->getLaborCost();
+        }
+        return cost;
+    }
+
+    /*
+    Function: loadObservers
+    Description: Loads observer IDs from a file and attaches the corresponding users
+                 to the notification management service. Validates that each observer ID
+                 exists in the datastore before attaching.
+    Parameters:
+        - filePath: const std::string&, path to the file containing observer IDs
+        - service: NotificationManagementService*, pointer to the notification service
+        - dataStore: DataStore&, reference to the datastore containing users
+    Returns:
+        - void
+    Throws:
+        - std::runtime_error if an observer ID is invalid (not found in datastore)
+    */
+    inline void loadObservers(const std::string& filePath, NotificationManagementService* service, DataStore& dataStore)
+    {
+        auto observerIDs = util::loadRecords(filePath);
+        auto& users = dataStore.getUsers();
+        for (int index = 0; index < observerIDs.getSize(); index++)
+        {
+            const std::string& observerID = observerIDs[index];
+            int userIndex = users.find(observerID);
+            if (userIndex == -1)
+            {
+                throw std::runtime_error("Invalid Observer ID");
+            }
+            service->attach(users.getValueAt(userIndex));
+        }
+    }
+
+    /*
+    Function: saveObservers
+    Description: Saves the current observer IDs from the notification management service
+                 to a file for persistence.
+    Parameters:
+        - filePath: const std::string&, path to the file where observer IDs will be saved
+        - service: NotificationManagementService*, pointer to the notification service
+    Returns:
+        - void
+    */
+    inline void saveObservers(const std::string& filePath, NotificationManagementService* service)
+    {
+        auto observerIDs = service->getObserverIDs();
+        util::saveRecords(filePath, observerIDs);
+    }
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/AdminMenu.cpp

@@ -1,22 +1,26 @@
 /*
 File: AdminMenu.cpp
-Description: Implementation file containing the method definitions of the
-			 AdminMenu class, including menu handling, inventory operations,
-			 user management, and combo package management functions.
+Description: Implements the AdminMenu class which provides the administrator’s console interface
+			 in the Vehicle Service Management System. Handles menu display, user input, and
+			 admin-specific operations such as inventory management, technician management,
+			 service creation, combo package management, job assignment, and notifications.
 Author: Trenser
-Date:19-May-2026
+Date: 19-May-2026
 */
-#include <iostream>
+
 #include <iomanip>
+#include <iostream>
 #include "AdminMenu.h"
-#include "InputHelper.h"
-#include "OutputHelper.h"
-#include "User.h"
-#include "Validator.h"
-#include "Service.h"
-#include "Utility.h"
-#include "ComboPackage.h"
 #include "Enums.h"
+#include "InputHelper.h"
+#include "InventoryItem.h"
+#include "MenuHelper.h"
+#include "OutputHelper.h"
+#include "Service.h"
+#include "ServiceBooking.h"
+#include "User.h"
+#include "Utility.h"
+#include "Validator.h"
 
 /*
 Function: showMenu
@@ -131,6 +135,7 @@ void AdminMenu::logout()
 {
 	m_controller.logout();
 }
+
 /*
 Function: changePassword
 Description: Allows the admin to change their password after validation.
@@ -139,51 +144,247 @@ Return type: void
 */
 void AdminMenu::changePassword()
 {
-	std::string newPassword;
-	while (true)
+	changePasswordHelper(m_controller);
+}
+
+/*
+Function: viewStockLevels
+Description: Displays all active inventory items with their details
+             including ID, part name, quantity, and price.
+Parameter: None
+Return type: void
+*/
+void AdminMenu::viewStockLevels()
+{
+    util::clear();
+	auto inventoryItems = m_controller.getInventoryItems();
+	std::cout << std::left << std::setw(15) << "Item ID"
+		<< std::setw(25) << "Part Name"
+		<< std::setw(10) << "Quantity"
+		<< std::setw(10) << "Price"
+		<< std::endl;
+	for (int iterator = 0; iterator < inventoryItems.getSize(); ++iterator)
 	{
-		util::clear();
-		std::cout << "Enter new password: ";
-		util::read(newPassword);
-		if (!util::isPasswordValid(newPassword))
+		const InventoryItem* item = inventoryItems.getValueAt(iterator);
+		if (item != nullptr)
 		{
-			std::cout << "Error: Password is not strong enough!\n";
-			util::pressEnter();
-			continue;
+			if (item->getState() != util::State::INACTIVE)
+			{
+				std::cout << std::left << std::setw(15) << item->getId()
+					<< std::setw(25) << item->getPartName()
+					<< std::setw(10) << item->getQuantity()
+					<< std::setw(10) << item->getPrice()
+					<< std::endl;
+			}
 		}
-		m_controller.changePassword(newPassword);
-		std::cout << "Password changed successfully\n";
-		util::pressEnter();
-		break;
 	}
 }
 
-void AdminMenu::viewStockLevels()
-{
-}
-
+/*
+Function: addInventoryItem
+Description: Allows the admin to either add a new inventory item
+             or increase the quantity of an existing item.
+Parameter: None
+Return type: void
+*/
 void AdminMenu::addInventoryItem()
 {
+	util::clear();
+	int choice, quantity;
+	double price;
+	std::string partName;
+	std::cout << "1. Add new item \n2. Add Quantity\nEnter your choice : ";
+	util::read(choice);
+	switch (choice)
+	{
+	case 1: 
+	{
+		std::cout << "--------Enter Item Details----------\n";
+		std::cout << "Part Name : ";
+		util::read(partName);
+		std::cout << "Quantity : ";
+		util::read(quantity);
+		std::cout << "Price : ";
+		util::read(price);
+		m_controller.addInventoryItem(partName, quantity, price);
+		std::cout << "New Item " << partName << " added to the Inventory.\n";
+		break;
+	}
+	case 2:
+	{
+		auto inventoryItems = m_controller.getInventoryItems();
+		addQuantityToItem(inventoryItems, m_controller);
+		break;
+	}
+	}
+	util::pressEnter();
 }
 
+/*
+Function: removeInventoryItem
+Description: Removes an active inventory item by marking it inactive
+             after user selection.
+Parameter: None
+Return type: void
+*/
 void AdminMenu::removeInventoryItem()
 {
+    util::clear();
+    auto inventoryItems = m_controller.getInventoryItems();
+    auto activeItems = filterActiveItems(inventoryItems);
+    int activeItemsSize = activeItems.getSize();
+    if (activeItemsSize == 0)
+    {
+        std::cout << "No items available in Inventory." << std::endl;
+        util::pressEnter();
+        return;
+    }
+    displayInventoryWithItems(activeItems);
+    int itemIndex;
+    std::cout << "Enter the index of the item to remove: ";
+    util::read(itemIndex);
+    if (itemIndex < 1 || itemIndex > activeItemsSize)
+    {
+        std::cout << "Invalid index selected." << std::endl;
+        util::pressEnter();
+        return;
+    }
+    const InventoryItem* selectedItem = activeItems.getValueAt(itemIndex - 1);
+    if (selectedItem != nullptr)
+    {
+        if(selectedItem->getState() != util::State::INACTIVE)
+        {
+            std::string selectedItemId = selectedItem->getId();
+            m_controller.removeInventoryItem(selectedItemId);
+            std::cout << "Item " << selectedItem->getPartName() << " removed successfully." << std::endl;
+        }
+    }
+    util::pressEnter();
 }
 
+/*
+Function: checkStockAvailability
+Description: Checks if a specific inventory item is available
+             and displays its details if active.
+Parameter: None
+Return type: void
+*/
 void AdminMenu::checkStockAvailability()
 {
+	util::clear();
+	std::string itemId;
+	std::cout << "Enter the Item Id : ";
+	util::read(itemId);
+	const InventoryItem* selectedItem = m_controller.getInventoryItem(itemId);
+	if (selectedItem != nullptr)
+	{
+		if (selectedItem->getState() != util::State::INACTIVE)
+		{
+			std::cout << "Item Details\n";
+			std::cout << "---------------------------------------------\n";
+			std::cout << "Item ID      : " << selectedItem->getId() << "\n";
+			std::cout << "Part Name    : " << selectedItem->getPartName() << "\n";
+			std::cout << "Quantity     : " << selectedItem->getQuantity() << "\n";
+		}
+	}
+	util::pressEnter();
 }
 
+/*
+Function: assignJob
+Description: Allows the admin to assign pending service bookings to available technicians.
+			 Creates job cards for selected services.
+Parameters:
+	- None
+Returns:
+	- void
+*/
 void AdminMenu::assignJob()
 {
+	util::clear();
+	std::string selectedService;
+	bool hasPendingService = false;
+	auto currentBookings = m_controller.getServiceBookings();
+	auto availableTechnicians = m_controller.getUsers(util::UserType::TECHNICIAN);
+	int bookingsSize = currentBookings.getSize();
+	util::Map<int, const ServiceBooking*> serviceBookingsMap;
+	util::Map<int, const User*> currentAvailableTechniciansMap;
+	if (listServiceBookings(currentBookings, bookingsSize, serviceBookingsMap))
+	{
+		const ServiceBooking* selectedService = selectPendingServiceBookings(serviceBookingsMap);
+		if (selectedService)
+		{
+			if (availableTechnicians.getSize() != 0)
+			{
+				listAvailableTechnicians(availableTechnicians, availableTechnicians.getSize(), currentAvailableTechniciansMap);
+				const User* selectedTechnician = selectTechnician(currentAvailableTechniciansMap);
+				if (selectedTechnician)
+				{
+					auto& servicesInBooking = selectedService->getServices();
+					for (int iterator = 0; iterator < servicesInBooking.getSize(); iterator++)
+					{
+						m_controller.createJobCard(selectedService->getId(), selectedTechnician->getId(), servicesInBooking.getValueAt(iterator)->getId());
+					}
+				}
+			}
+			else
+			{
+				std::cout << "No technicians are currently available.";
+			}
+		}
+	}
+	util::pressEnter();
 }
 
+/*
+Function: createService
+Description: Allows the admin to create a new service by selecting inventory items and specifying labor cost.
+Parameters:
+	- None
+Returns:
+	- void
+*/
 void AdminMenu::createService()
 {
+	util::clear();
+	std::string serviceName;
+	double labourCost;
+	std::cout << "Enter the service name: ";
+	util::read(serviceName);
+	util::Map<std::string, const InventoryItem*> currentInventoryItems = m_controller.getInventoryItems();
+	util::Vector<std::string> selectedInventoryItems;
+	selectInventoryItems(currentInventoryItems,selectedInventoryItems);
+	std::cout << "Enter the labour cost: ";
+	util::read(labourCost);
+    m_controller.createService(serviceName, selectedInventoryItems, labourCost);
+    std::cout << "Service created sucessfully.\n";
+	util::pressEnter();
 }
 
+/*
+Function: removeService
+Description: Allows the admin to remove an existing service by selecting from available services.
+Parameters:
+	- None
+Returns:
+	- void
+*/
 void AdminMenu::removeService()
 {
+	util::clear();
+	std::string selectedServiceID;
+	util::Map<std::string, const Service*> currentServices = m_controller.getServices();
+	selectedServiceID = selectServicesToRemove(currentServices);
+	if (selectedServiceID != "")
+	{
+		m_controller.removeService(selectedServiceID);
+		std::cout << "Service removed sucessfully.";
+	}
+	else
+	{
+		std::cout << "Failed  to remove service.";
+	}
+	util::pressEnter();
 }
 
 /*
@@ -229,62 +430,6 @@ void AdminMenu::addTechnician()
 	util::pressEnter();
 }
 
-/*
-Function: filterActiveUsers
-Description: Filters out inactive users and returns a map of active users.
-Parameter: const util::Map<std::string, const User*>& listOfUsers - all users
-Return type: util::Map<std::string, const User*>
-*/
-static util::Map<std::string, const User*>
-filterActiveUsers(const util::Map<std::string, const User*>& listOfUsers)
-{
-	util::Map<std::string, const User*> activeUsers;
-	int inventorySize = listOfUsers.getSize();
-	for (int index = 0; index < inventorySize; index++)
-	{
-		const User* user = listOfUsers.getValueAt(index);
-		if (user != nullptr && user->getState() != util::State::INACTIVE)
-		{
-			activeUsers.insert(user->getId(), user);
-		}
-	}
-	return activeUsers;
-}
-
-/*
-Function: displayAllActiveUsers
-Description: Displays all active users in a tabular format with index, ID, username, and type.
-Parameter: util::Map<std::string, const User*>& activeUsers - active users list
-		   int activeUserCount - number of active users
-Return type: void
-*/
-static void displayAllActiveUsers(util::Map<std::string, const User*>& activeUsers, int activeUserCount)
-{
-	std::cout << std::left << std::setw(10) << "Index"
-		<< std::setw(15) << "User ID"
-		<< std::setw(25) << "Username"
-		<< std::setw(25) << "User Type"
-		<< std::endl;
-	for (int iterator = 0; iterator < activeUserCount; iterator++)
-	{
-		const User* user = activeUsers.getValueAt(iterator);
-		if (user != nullptr)
-		{
-			std::cout << std::left << std::setw(10) << (iterator + 1)
-				<< std::setw(15) << user->getId()
-				<< std::setw(25) << user->getUserName()
-				<< std::setw(25) << util::getUserTypeString(user->getUserType())
-				<< std::endl;
-		}
-		else
-		{
-			std::cout << "No users found.\n";
-			util::pressEnter();
-			return;
-		}
-	}
-}
-
 /*
 Function: removeUser
 Description: Removes a selected active user (customer or technician) from the system.
@@ -323,55 +468,6 @@ void AdminMenu::removeUser()
 	util::pressEnter();
 }
 
-/*
-Function: selectServiceFromServices
-Description: Displays active services and allows the admin to select one by index.
-Parameter: const util::Map<std::string, const Service*>& services - list of services
-Return type: const Service* - selected service
-*/
-static const Service* selectServiceFromServices(const util::Map<std::string, const Service*>& services)
-{
-    util::Map<int, const Service*> activeServicesMap;
-    int currentIndex = 1;
-    int userInputIndex;
-    std::cout << std::left
-        << std::setw(10) << "Index"
-        << std::setw(15) << "Service ID"
-        << std::setw(25) << "Service Name"
-        << std::setw(15) << "Estimated Cost"
-        << std::endl;
-    for (int index = 0; index < services.getSize(); index++)
-    {
-        const Service* currentService = services.getValueAt(index);
-        if (currentService->getState() != util::State::ACTIVE)
-        {
-            continue;
-        }
-        activeServicesMap.insert(currentIndex, currentService);
-        double partsCost = calculatePartsCost(currentService);
-        std::cout << std::left
-            << std::setw(10) << currentIndex
-            << std::setw(15) << currentService->getId()
-            << std::setw(25) << currentService->getName()
-            << std::setw(15) << (currentService->getLaborCost() + partsCost)
-            << std::endl;
-        currentIndex++;
-    }
-    if (activeServicesMap.getSize() == 0)
-    {
-        std::cout << "No active services available." << std::endl;
-        return nullptr;
-    }
-    std::cout << "Enter service index: ";
-    util::read(userInputIndex);
-    if (activeServicesMap.find(userInputIndex) == -1)
-    {
-        std::cout << "Invalid service index." << std::endl;
-        return nullptr;
-    }
-    return activeServicesMap[userInputIndex];
-}
-
 /*
 Function: createComboPackages
 Description: Creates a new combo package by selecting two active services and applying a discount.
@@ -382,19 +478,38 @@ void AdminMenu::createComboPackages()
 {
 	util::clear();
 	auto serviceList = m_controller.getServices();
-    const int numberOfServicesInPackage = 2;
+    const int NUMBER_OF_SERVICE_PER_PACKAGE = 2;
 	util::Vector<std::string> selectedServiceID;
-    for (int iterator = 0; iterator < numberOfServicesInPackage; iterator++)
+    for (int iterator = 0; iterator < NUMBER_OF_SERVICE_PER_PACKAGE; iterator++)
     {
-        const Service* chosenService = selectServiceFromServices(serviceList);
-        if (chosenService == nullptr)
+        const Service* chosenService = nullptr;
+        while (true)
         {
-            std::cout << "Failed to create combo package!";
-            util::pressEnter();
-            return;
+            chosenService = selectServiceFromServices(serviceList);
+            if (chosenService == nullptr)
+            {
+                std::cout << "Failed to create combo package!";
+                util::pressEnter();
+                return;
+            }
+            bool alreadyChosen = false;
+            for (int iteratorOne = 0; iteratorOne < selectedServiceID.getSize(); iteratorOne++)
+            {
+                if (selectedServiceID[iteratorOne] == chosenService->getId())
+                {
+                    alreadyChosen = true;
+                    break;
+                }
+            }
+            if (alreadyChosen)
+            {
+                std::cout << "Service already selected. Please choose a different one." << std::endl;
+                continue; 
+            }
+            selectedServiceID.push_back(chosenService->getId());
+            util::clear();
+            break;
         }
-        selectedServiceID.push_back(chosenService->getId());
-        util::clear();
     }
     std::string packageName;
     double discountPercentage;
@@ -413,81 +528,6 @@ void AdminMenu::createComboPackages()
     util::pressEnter();
 }
 
-/*
-Function: displayComboPackagesWithIndex
-Description: Displays combo packages with index, ID, name, and discount percentage.
-Parameter: util::Map<int, const ComboPackage*>& currentComboPackageIndexMap - combo packages map
-Return type: void
-*/
-static void displayComboPackagesWithIndex(util::Map<int, const ComboPackage*>& currentComboPackageIndexMap)
-{
-	for (int iterator = 0; iterator < currentComboPackageIndexMap.getSize(); iterator++)
-	{
-		const ComboPackage* currentComboPackage = currentComboPackageIndexMap.getValueAt(iterator);
-		if (currentComboPackage == nullptr)
-		{
-			throw std::runtime_error("Error accessing the combopackage.\n");
-		}
-		if (iterator == 0)
-		{
-			std::cout << std::left
-				<< std::setw(8) << "Index"
-				<< std::setw(10) << "ID"
-				<< std::setw(20) << "Package Name"
-				<< std::setw(15) << "Discount (%)"
-				<< "\n";
-		}
-		std::cout << std::left
-			<< std::setw(8) << currentComboPackageIndexMap.getKeyAt(iterator)
-			<< std::setw(10) << currentComboPackage->getId()
-			<< std::setw(20) << currentComboPackage->getPackageName()
-			<< std::setw(15) << currentComboPackage->getDiscountPercentage()
-			<< "\n";
-	}
-}
-
-/*
-Function: selectComboPackage
-Description: Allows the admin to select an active combo package by index.
-Parameter: util::Map<std::string, const ComboPackage*>& currentComboPackages - combo packages list
-Return type: std::string - ID of the selected combo package
-*/
-static std::string selectComboPackage(util::Map<std::string, const ComboPackage*>& currentComboPackages)
-{
-	util::Map<int, const ComboPackage*> currentComboPackageIndexMap;
-	if (currentComboPackages.getSize() == 0)
-	{
-		throw std::runtime_error("No combo packages are available.\n");
-	}
-	int currentIndex = 1, choice, selectedIndex;
-	for (int iterator = 0; iterator < currentComboPackages.getSize(); iterator++)
-	{
-		if (currentComboPackages.getValueAt(iterator)->getState() == util::State::INACTIVE)
-		{
-			continue;
-		}
-		currentComboPackageIndexMap.insert(currentIndex++, currentComboPackages.getValueAt(iterator));
-	}
-	if (currentComboPackageIndexMap.getSize() == 0)
-	{
-		throw std::runtime_error("No combo packages currently active.");
-	}
-	displayComboPackagesWithIndex(currentComboPackageIndexMap);
-	std::cout << "Enter your choice(Index): ";
-	util::read(choice);
-	selectedIndex = currentComboPackageIndexMap.find(choice);
-	if (selectedIndex != -1)
-	{
-		std::string selectedComboPackageID = currentComboPackageIndexMap.getValueAt(selectedIndex)->getId();
-		return selectedComboPackageID;
-	}
-	else
-	{
-		std::cout << "Enter a valid choice.\n";
-		return "";
-	}
-}
-
 /*
 Function: removeComboPackage
 Description: Removes a selected combo package from the system.
@@ -511,6 +551,15 @@ void AdminMenu::removeComboPackage()
 	util::pressEnter();
 }
 
+/*
+Function: viewNotifications
+Description: Displays notifications for the admin and allows deletion of notifications.
+Parameters:
+	- None
+Returns:
+	- void
+*/
 void AdminMenu::viewNotifications()
 {
+	viewAndDeleteNotification(m_controller);
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/AdminMenu.h

@@ -6,6 +6,7 @@ Description: Header file declaring the AdminMenu class, which provides
 Author: Trenser
 Date:19-May-2026
 */
+
 #pragma once
 #include "Controller.h"
 

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/CustomerMenu.cpp

@@ -1,72 +1,355 @@
+/*
+File: CustomerMenu.cpp
+Description: Implementation file containing the method definitions of the
+             CustomerMenu class, including menu handling, service selection,
+             combo package booking, profile updates, and password management.
+Author: Trenser
+Date:19-May-2026
+*/
+
+#include <iomanip>
+#include "ComboPackage.h"
 #include "CustomerMenu.h"
+#include "MenuHelper.h"
+#include "Enums.h"
 #include "InputHelper.h"
 #include "OutputHelper.h"
+#include "InventoryItem.h"
+#include "Invoice.h"
+#include "Map.h"
+#include "Service.h"
+#include "ServiceBooking.h"
+#include "Timestamp.h"
+#include "User.h"
+#include "Validator.h"
+#include "Vector.h"
+
+/*
+Function: showMenu
+Description: Displays the customer menu and handles user input until logout is selected.
+Parameter: None
+Return type: void
+*/
 
 void CustomerMenu::showMenu()
 {
-	bool isMenuActive = true;
-	while (isMenuActive)
-	{
-		try
-		{
-			int choice;
-			util::clear();
-			std::cout << "" << std::endl;
-			util::read(choice);
-			if (!handleOperation(choice))
-			{
-				isMenuActive = false;
-			}
-		}
-		catch (const std::exception& e)
-		{
-			std::cout << "Exception: " << e.what() << std::endl;
-			util::pressEnter();
-		}
-	}
+    while (true)
+    {
+        try
+        {
+            int choice;
+            util::clear();
+            std::cout << "Customer Menu"
+                << "\n1. Select a service"
+                << "\n2. Select a combo package"
+                << "\n3. Update Profile"
+                << "\n4. Change Password"
+                << "\n5. View Service History"
+                << "\n6. Complete Payments"
+                << "\n7. View Invoices"
+                << "\n8. View Notifications"
+                << "\n9. Configure Notifications"
+                << "\n10. Logout"
+                << "\nEnter a choice: ";
+            util::read(choice);
+            if (!handleOperation(choice))
+            {
+                break;
+            }
+        }
+        catch (const std::exception& e)
+        {
+            std::cout << "Exception: " << e.what() << std::endl;
+            util::pressEnter();
+        }
+    }
 }
 
+/*
+Function: handleOperation
+Description: Executes the corresponding customer operation based on the selected menu choice.
+Parameter: int choice - selected menu option
+Return type: bool - true if menu continues, false if logout
+*/
 bool CustomerMenu::handleOperation(int choice)
 {
-	return false;
+    switch (choice)
+    {
+    case 1:
+        selectService();
+        break;
+    case 2:
+        selectComboPackage();
+        break;
+    case 3:
+        updateDetails();
+        break;
+    case 4:
+        changePassword();
+        break;
+    case 5:
+        viewServiceHistory();
+        break;
+    case 6:
+        completePayments();
+        break;
+    case 7:
+        viewInvoices();
+        break;
+    case 8:
+        viewNotifications();
+        break;
+    case 9:
+        configureNotifications();
+        break;
+    case 10:
+        logout();
+        return false;
+    default:
+        std::cout << "Enter a valid choice!" << std::endl;
+        util::pressEnter();
+    }
+    return true;
 }
 
+/*
+Function: logout
+Description: Logs out the currently authenticated customer user.
+Parameter: None
+Return type: void
+*/
 void CustomerMenu::logout()
 {
+	m_controller.logout();
 }
 
+/*
+Function: changePassword
+Description: Allows the customer to change their password after validation.
+Parameter: None
+Return type: void
+*/
 void CustomerMenu::changePassword()
 {
+    changePasswordHelper(m_controller);
 }
 
+/*
+Function: updateDetails
+Description: Allows the customer to update their email and phone number after validation.
+Parameter: None
+Return type: void
+*/
 void CustomerMenu::updateDetails()
 {
+	std::string email, phone;
+	util::clear();
+	std::cout << "Enter new email: ";
+	util::read(email);
+	if (!util::isEmailValid(email))
+	{
+		std::cout << "Error: Email is invalid!";
+		util::pressEnter();
+		return;
+	}
+	std::cout << "Enter new phone: ";
+	util::read(phone);
+	if (!util::isPhoneNumberValid(phone))
+	{
+		std::cout << "Error: Phone number is invalid!";
+		util::pressEnter();
+		return;
+	}
+	m_controller.updateUserDetails(email, phone);
+	std::cout << "Profile details updated successfully";
+	util::pressEnter();
 }
 
+/*
+Function: selectService
+Description: Allows the customer to select a service, provide vehicle details,
+             and book the service through the controller.
+Parameter: None
+Return type: void
+*/
 void CustomerMenu::selectService()
 {
+    std::string vehicleNumber, vehicleBrand, vehicleModel;
+	auto services = m_controller.getServices();
+    util::Vector<std::string> selectedServices;
+    util::clear();
+    const Service* selectedService = selectServiceFromServices(services);
+    if (selectedService == nullptr)
+    {
+        std::cout << "Failed to book service!";
+        util::pressEnter();
+        return;
+    }
+    selectedServices.push_back(selectedService->getId());
+    util::clear();
+    std::cout << "Enter vehicle number: ";
+    util::read(vehicleNumber);
+    std::cout << "Enter vehicle brand: ";
+    util::read(vehicleBrand);
+    std::cout << "Enter vehicle model: ";
+    util::read(vehicleModel);
+    m_controller.purchaseService(selectedServices, vehicleNumber, vehicleBrand, vehicleModel);
+    std::cout << "Service has been booked successfully";
+    util::pressEnter();
 }
 
+/*
+Function: selectComboPackage
+Description: Allows the customer to select a combo package, provide vehicle details,
+             and book the package through the controller.
+Parameter: None
+Return type: void
+*/
 void CustomerMenu::selectComboPackage()
 {
+    std::string vehicleNumber, vehicleBrand, vehicleModel;
+    auto comboPackages = m_controller.getComboPackages();
+    util::clear();
+    const ComboPackage* selectedComboPackage = selectComboPackageFromPackages(comboPackages);
+    if (selectedComboPackage == nullptr)
+    {
+        std::cout << "Failed to book combo package!";
+        util::pressEnter();
+        return;
+    }
+    util::clear();
+    std::cout << "Enter vehicle number: ";
+    util::read(vehicleNumber);
+    std::cout << "Enter vehicle brand: ";
+    util::read(vehicleBrand);
+    std::cout << "Enter vehicle model: ";
+    util::read(vehicleModel);
+    m_controller.purchaseComboPackage(selectedComboPackage->getId(), vehicleNumber, vehicleBrand, vehicleModel);
+    std::cout << "Combo Package has been booked successfully";
+    util::pressEnter();
 }
 
+/*
+Function: viewServiceHistory
+Description: Displays the customer’s past service bookings in tabular format,
+             including booking ID, technician, vehicle details, discount percentage, and status.
+Parameters:
+    - None
+Returns:
+    - void
+*/
 void CustomerMenu::viewServiceHistory()
 {
+	util::clear();
+	bool hasServiceHistory = false;
+	const User* currentUser = m_controller.getAuthenticatedUser();
+	std::string currentUserID = currentUser->getId();
+	util::Map<std::string, const ServiceBooking*> serviceBookingsByCurrentUser = m_controller.getServiceBookingsByUser(currentUserID);
+    if (serviceBookingsByCurrentUser.getSize() != 0)
+    {
+        std::cout << std::left
+            << std::setw(12) << "Booking ID"
+            << std::setw(20) << "Technician"
+            << std::setw(15) << "Vehicle Brand"
+            << std::setw(15) << "Vehicle Number"
+            << std::setw(15) << "Vehicle Model"
+            << std::setw(10) << "Discount %"
+            << std::setw(12) << "Status"
+            << std::endl;
+        for (int iterator = 0; iterator < serviceBookingsByCurrentUser.getSize(); iterator++)
+        {
+            const ServiceBooking* currentBooking = serviceBookingsByCurrentUser.getValueAt(iterator);
+            std::string technicianName = currentBooking->getAssignedTechnician() == nullptr
+                ? "Not Assigned"
+                : currentBooking->getAssignedTechnician()->getName();
+            std::cout << std::left
+                << std::setw(12) << currentBooking->getId()
+                << std::setw(20) << technicianName
+                << std::setw(15) << currentBooking->getVehicleBrand()
+                << std::setw(15) << currentBooking->getVehicleNumber()
+                << std::setw(15) << currentBooking->getVehicleModel()
+                << std::setw(10) << currentBooking->getDiscountPercentage()
+                << std::setw(12) << util::getServiceJobStatusString(currentBooking->getStatus())
+                << std::endl;
+            hasServiceHistory = true;
+        }
+    }
+    if (!hasServiceHistory)
+    {
+        std::cout << "No history available." << std::endl;
+    }
+    util::pressEnter();
 }
 
+/*
+Function: completePayments
+Description: Allows the customer to complete pending payments for invoices.
+             Validates invoice selection and payment mode before completing payment.
+Parameters:
+    - None
+Returns:
+    - void
+*/
 void CustomerMenu::completePayments()
 {
+	util::clear();
+	util::Map<std::string, const Invoice*> currentInvoices = m_controller.getInvoicesByUser();
+	std::string selectedID = selectInvoiceFromUserForPayment(currentInvoices);
+    if (selectedID == "")
+    {
+        std::cout << "Payment failed.\n";
+        return;
+    }
+    util::PaymentMode paymentMode = selectPaymentMode();
+    m_controller.completePayment(selectedID, paymentMode);
+    std::cout << "Payment completed successfully.\n";
+    util::pressEnter();
 }
 
+/*
+Function: viewInvoices
+Description: Displays invoices associated with the customer by calling displayInvoices.
+Parameters:
+    - None
+Returns:
+    - void
+*/
 void CustomerMenu::viewInvoices()
 {
+	util::clear();
+	util::Map<std::string, const Invoice*> currentUserInvoices = m_controller.getInvoicesByUser();
+	displayInvoices(currentUserInvoices);
+    util::pressEnter();
 }
 
+/*
+Function: viewNotifications
+Description: Displays notifications for the customer and allows deletion of notifications.
+Parameters:
+    - None
+Returns:
+    - void
+*/
 void CustomerMenu::viewNotifications()
 {
+	viewAndDeleteNotification(m_controller);
 }
 
+
+/*
+Function: configureNotifications
+Description: Allows the customer to configure notification preferences for payment and service management.
+Parameters:
+    - None
+Returns:
+    - void
+*/
 void CustomerMenu::configureNotifications()
 {
+    bool paymentServiceNotifications = getNotificationPreference("Payment Management Service");
+    bool serviceManagementNotifications = getNotificationPreference("Service Management Service");
+    m_controller.configureNotifications(paymentServiceNotifications, serviceManagementNotifications);
+    util::clear();
+    std::cout << "Notification preferences updated successfully.\n";
+    util::pressEnter();
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/CustomerMenu.h

@@ -1,3 +1,13 @@
+/*
+File: CustomerMenu.h
+Description: Header file declaring the CustomerMenu class, which provides
+             customer operations such as selecting services, booking combo
+             packages, updating profile details, managing payments, viewing
+             invoices, and configuring notifications.
+Author: Trenser
+Date:19-May-2026
+*/
+
 #pragma once
 #include "Controller.h"
 

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/TechnicianMenu.cpp

@@ -6,16 +6,23 @@ Description: Implementation file containing the method definitions of the
 Author: Trenser
 Date:19-May-2026
 */
-#include "TechnicianMenu.h"
+#include "Enums.h"
 #include "InputHelper.h"
+#include "JobCard.h"
+#include "MenuHelper.h"
 #include "OutputHelper.h"
+#include "Service.h"
+#include "TechnicianMenu.h"
 #include "Validator.h"
 
 /*
 Function: showMenu
-Description: Displays the technician menu and handles user input until logout is selected.
-Parameter: None
-Return type: void
+Description: Displays the technician menu in a loop until the user chooses to logout.
+			 Handles exceptions and ensures smooth user interaction.
+Parameters:
+	- None
+Returns:
+	- void
 */
 void TechnicianMenu::showMenu()
 {
@@ -74,13 +81,44 @@ bool TechnicianMenu::handleOperation(int choice)
     return true;
 }
 
-
+/*
+Function: completeJob
+Description: Allows the technician to mark a selected job card as completed.
+             Validates selection and updates job status through the controller.
+Parameters:
+    - None
+Returns:
+    - void
+*/
 void TechnicianMenu::completeJob()
 {
+	util::Map<std::string, const JobCard*> assignedJobCards = m_controller.getJobCardsByUser();
+	util::Map<int, const JobCard*> incompleteJobCards;
+	std::cout << "Jobs to be completed.\n";
+	std::string selectedJobID = selectJobCardToComplete(assignedJobCards, incompleteJobCards);
+	if (selectedJobID == "")
+	{
+		std::cout << "Failed to complete the job.\n";
+	}
+	else
+	{
+		m_controller.completeJob(selectedJobID);
+		std::cout << "Job marked as completed.\n";
+	}
+    util::pressEnter();
 }
 
+/*
+Function: viewNotifications
+Description: Displays notifications for the technician and allows deletion of notifications.
+Parameters:
+	- None
+Returns:
+	- void
+*/
 void TechnicianMenu::viewNotifications()
 {
+	viewAndDeleteNotification(m_controller);
 }
 
 /*
@@ -100,23 +138,8 @@ Description: Allows the technician to change their password after validation.
 Parameter: None
 Return type: void
 */
+
 void TechnicianMenu::changePassword()
 {
-	std::string newPassword;
-	while (true)
-	{
-		util::clear();
-		std::cout << "Enter new password: ";
-		util::read(newPassword);
-		if (!util::isPasswordValid(newPassword))
-		{
-			std::cout << "Error: Password is not strong enough!\n";
-			util::pressEnter();
-			continue;
-		}
-		m_controller.changePassword(newPassword);
-		std::cout << "Password changed successfully\n";
-		util::pressEnter();
-		break;
-	}
+    changePasswordHelper(m_controller);
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/TechnicianMenu.h

@@ -6,6 +6,7 @@ Description: Header file declaring the TechnicianMenu class, which provides
 Author: Trenser
 Date:19-May-2026
 */
+
 #pragma once
 #include "Controller.h"
 

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/UserInterface.cpp

@@ -6,10 +6,13 @@ Description: Implementation file containing the method definitions of the
 Author: Trenser
 Date:19-May-2026
 */
-#include "UserInterface.h"
+
+#include "Enums.h"
 #include "InputHelper.h"
 #include "OutputHelper.h"
 #include "User.h"
+#include "UserInterface.h"
+#include "Validator.h"
 
 /*
 Function: run
@@ -20,6 +23,8 @@ Return type: void
 */
 void UserInterface::run()
 {
+	m_controller.loadSystemData();
+	m_controller.runSystemChecks();
 	bool isMenuActive = true;
 	while (isMenuActive)
 	{
@@ -40,6 +45,7 @@ void UserInterface::run()
 			util::pressEnter();
 		}
 	}
+	m_controller.saveSystemData();
 }
 
 /*
@@ -111,7 +117,47 @@ void UserInterface::login()
 	}
 }
 
+/*
+Function: registerCustomer
+Description: Registers a new customer by collecting and validating details such as
+			 username, name, email, password, and phone number. Delegates creation
+			 to the controller.
+Parameter: None
+Return type: void
+*/
 void UserInterface::registerCustomer()
 {
-
+	std::string username, name, email, phone, password;
+	util::clear();
+	std::cout << "Enter username: ";
+	util::read(username);
+	std::cout << "Enter name: ";
+	util::read(name);
+	std::cout << "Enter email: ";
+	util::read(email);
+	if (!util::isEmailValid(email))
+	{
+		std::cout << "Error: Email is invalid!";
+		util::pressEnter();
+		return;
+	}
+	std::cout << "Enter password: ";
+	util::read(password);
+	if (!util::isPasswordValid(password))
+	{
+		std::cout << "Error: Password is invalid!";
+		util::pressEnter();
+		return;
+	}
+	std::cout << "Enter phone: ";
+	util::read(phone);
+	if (!util::isPhoneNumberValid(phone))
+	{
+		std::cout << "Error: Phone number is invalid!";
+		util::pressEnter();
+		return;
+	}
+	m_controller.createCustomer(username, name, password, email, phone);
+	std::cout << "Registration is successful";
+	util::pressEnter();
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/UserInterface.h

@@ -7,6 +7,7 @@ Description: Header file declaring the UserInterface class, which provides
 Author: Trenser
 Date:19-May-2026
 */
+
 #pragma once
 #include "Controller.h"
 #include "AdminMenu.h"