Merge branch 'feature-file-management' into feature

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

@@ -173,9 +173,12 @@
     <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" />

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

@@ -242,5 +242,14 @@
     <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>
   </ItemGroup>
 </Project>

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

@@ -423,6 +423,34 @@ void Controller::configureNotifications(bool paymentNotifications, bool serviceN
     }
 }
 
+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();
+}
+
+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: Executes system checks including sending low stock alerts

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

@@ -67,5 +67,7 @@ public:
     util::Vector<const Notification*> getNotifications();
     void deleteNotification(const std::string& notificationID);
     void configureNotifications(bool paymentNotifications, bool serviceNotifications);
+    void loadSystemData();
+    void saveSystemData();
     void runSystemChecks();
 };

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

@@ -8,6 +8,7 @@ Date: 19-May-2026
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 
 class User;
 class Notification;

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

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

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

@@ -7,7 +7,12 @@ 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;
 
@@ -41,7 +46,29 @@ ComboPackage::ComboPackage(const std::string& packageName, double discountPercen
     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());
+    }
+}
+
+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
@@ -95,6 +122,11 @@ 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.
@@ -158,6 +190,13 @@ Returns:
 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());
+    }
 }
 
 /*
@@ -172,3 +211,76 @@ void ComboPackage::setState(util::State status)
 {
     m_status = status;
 }
+
+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;
+}
+
+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;
+}
+
+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();
+}
+
+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
+    );
+}
+
+std::string ComboPackage::getHeaders()
+{
+    return "ID,PackageName,DiscountPercentage,ServiceIDs,Status";
+}

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

@@ -8,6 +8,7 @@ Date: 19-May-2026
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "Enums.h"
 
 class Service;
@@ -19,14 +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);
@@ -34,4 +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

@@ -6,7 +6,11 @@ Author: Trenser
 Date: 19-May-2026
 */
 
+#include <sstream>
+#include <stdexcept>
 #include "InventoryItem.h"
+#include "Factory.h"
+#include "StringHelper.h"
 
 int InventoryItem::m_uid = 0;
 
@@ -43,6 +47,20 @@ InventoryItem::InventoryItem(const std::string& partName, int quantity, double p
     m_status(util::State::ACTIVE),
     m_price(price) {}
 
+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.
@@ -172,3 +190,50 @@ void InventoryItem::setState(util::State status)
 {
     m_status = status;
 }
+
+std::string InventoryItem::serialize() const
+{
+    std::ostringstream serializedInventoryItem;
+    serializedInventoryItem << m_id << ','
+        << m_partName << ','
+        << m_quantity << ','
+        << m_price << ','
+        << util::getStateString(m_status);
+    return serializedInventoryItem.str();
+}
+
+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
+    );
+}
+
+std::string InventoryItem::getHeaders()
+{
+    return "ID,PartName,Quantity,Price,Status";
+}

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

@@ -23,6 +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;
@@ -33,4 +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

@@ -7,7 +7,12 @@ 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;
 
@@ -74,14 +79,49 @@ 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;
@@ -131,6 +171,11 @@ double Invoice::getLaborCost() const
     return m_laborCost;
 }
 
+const util::Vector<std::string>& Invoice::getPartIDs() const
+{
+    return m_partIDs;
+}
+
 /*
 Function: getParts
 Description: Retrieves the map of inventory items used in the service.
@@ -284,6 +329,13 @@ Returns:
 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());
+    }
 }
 
 /*
@@ -363,3 +415,104 @@ void Invoice::setStatus(util::PaymentStatus status)
 {
     m_status = status;
 }
+
+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;
+}
+
+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;
+}
+
+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();
+}
+
+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
+    );
+}
+
+std::string Invoice::getHeaders()
+{
+    return "ID,BookingID,InvoiceDate,LaborCost,PartIDs,PartsCost,DiscountPercentage,TotalAmount,PaymentDate,PaymentMethod,Status";
+}

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

@@ -10,6 +10,7 @@ Date: 19-May-2026
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "Timestamp.h"
 #include "Enums.h"
 
@@ -25,6 +26,7 @@ private:
     ServiceBooking* m_booking;
     util::Timestamp m_invoiceDate;
     double m_laborCost;
+    util::Vector<std::string> m_partIDs;
     util::Map<std::string, InventoryItem*> m_parts;
     double m_partsCost;
     double m_discountPercentage;
@@ -32,7 +34,6 @@ private:
     util::Timestamp m_paymentDate;
     util::PaymentMode m_paymentMethod;
     util::PaymentStatus m_status;
-
 public:
     Invoice();
     Invoice(
@@ -48,11 +49,25 @@ 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::Vector<std::string>& getPartIDs() const;
     const util::Map<std::string, InventoryItem*>& getParts() const;
     double getPartsCost() const;
     double getDiscountPercentage() const;
@@ -72,4 +87,7 @@ public:
     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 +6,12 @@ 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;
 
@@ -62,6 +67,32 @@ JobCard::JobCard(const std::string& bookingId,
     m_status(status),
     m_completionDate(completionDate) {}
 
+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 ID of the job card.
@@ -299,3 +330,56 @@ void JobCard::setCompletionDate(const util::Timestamp& completionDate)
 {
     m_completionDate = completionDate;
 }
+
+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();
+}
+
+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
+    );
+}
+
+std::string JobCard::getHeaders()
+{
+    return "ID,BookingID,ServiceID,TechnicianID,AssignedDate,Status,CompletionDate";
+}

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

@@ -42,6 +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;
@@ -62,4 +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

@@ -6,7 +6,10 @@ Author: Trenser
 Date: 19-May-2026
 */
 
+#include <sstream>
 #include "Notification.h"
+#include "StringHelper.h"
+#include "Factory.h"
 
 int Notification::m_uid = 0;
 
@@ -42,6 +45,21 @@ Notification::Notification(const std::string& recipientUserId, User* recipient,
     m_message(message),
     m_createdAt(createdAt) {}
 
+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.
@@ -185,3 +203,46 @@ void Notification::setCreatedAt(const util::Timestamp& createdAt)
 {
     m_createdAt = createdAt;
 }
+
+std::string Notification::serialize() const
+{
+    std::ostringstream serializedNotification;
+    serializedNotification << m_id << ','
+        << m_recipientUserId << ','
+        << m_title << ','
+        << m_message << ','
+        << m_createdAt.toString();
+    return serializedNotification.str();
+}
+
+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
+    );
+}
+
+std::string Notification::getHeaders()
+{
+    return "ID,RecipientID,Title,Message,Timestamp";
+}

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

@@ -25,6 +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;
@@ -37,4 +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

@@ -7,7 +7,11 @@ 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;
 
@@ -40,7 +44,29 @@ Service::Service(const std::string& name, const util::Map<std::string, Inventory
     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());
+    }
+}
+
+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
@@ -64,6 +90,11 @@ const std::string& Service::getName() const
     return m_name;
 }
 
+const util::Vector<std::string>& Service::getRequiredInventoryItemIDs() const
+{
+    return m_requiredInventoryItemIDs;
+}
+
 /*
 Function: getRequiredInventoryItems
 Description: Retrieves the map of inventory items required for the service.
@@ -134,6 +165,13 @@ Returns:
 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());
+    }
 }
 
 /*
@@ -161,3 +199,76 @@ void Service::setState(util::State status)
 {
     m_status = status;
 }
+
+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;
+}
+
+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;
+}
+
+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();
+}
+
+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
+    );
+}
+
+std::string Service::getHeaders()
+{
+    return "ID,Name,InventoryIDs,LaborCost,Status";
+}

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

@@ -10,6 +10,7 @@ Date: 19-May-2026
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "Enums.h"
 
 class InventoryItem;
@@ -20,14 +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;
@@ -36,4 +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

@@ -6,7 +6,13 @@ 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;
 
@@ -37,8 +43,6 @@ Parameter: const std::string& id - booking ID
            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
 */
@@ -65,14 +69,44 @@ ServiceBooking::ServiceBooking(
     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());
+    }
+}
+
+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;
+    }
 }
 
-/*
-Function: getId
-Description: Retrieves the unique ID of the service booking.
-Returns:
-    - const std::string& representing the booking ID.
-*/
 const std::string& ServiceBooking::getId() const
 {
     return m_id;
@@ -89,6 +123,11 @@ util::ServiceJobStatus ServiceBooking::getStatus() const
     return m_status;
 }
 
+const util::Vector<std::string>& ServiceBooking::getServiceIDs() const
+{
+    return m_serviceIDs;
+}
+
 /*
 Function: getServices
 Description: Retrieves the map of services included in the booking.
@@ -225,6 +264,13 @@ Returns:
 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());
+    }
 }
 
 /*
@@ -328,3 +374,88 @@ void ServiceBooking::setDiscountPercentage(double discountPercentage)
 {
     m_discountPercentage = discountPercentage;
 }
+
+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;
+}
+
+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;
+}
+
+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();
+}
+
+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
+    );
+}
+
+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;
@@ -42,8 +44,20 @@ public:
         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,
+        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;
@@ -64,4 +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

@@ -7,9 +7,12 @@ 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;
 
@@ -50,6 +53,23 @@ User::User(const std::string& userName, const std::string& password, const std::
     m_type(role),
     m_status(util::State::ACTIVE) {}
 
+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)
+{
+    int idNumber = util::extractNumber(m_id);
+    if (idNumber > m_uid)
+    {
+        m_uid = idNumber;
+    }
+}
+
 /*
 Function: ~User
 Description: Destructor that cleans up dynamically allocated notifications associated with the user.
@@ -60,9 +80,10 @@ Returns:
 */
 User::~User()
 {
-    for (int index = 0; index < m_notifications.getSize(); index++)
+    auto values = m_notifications.getValues();
+    for (int index = 0; index < values.getSize(); index++)
     {
-        delete m_notifications.getValues()[index];
+        delete values[index];
     }
 }
 
@@ -284,3 +305,48 @@ void User::setState(util::State status)
 {
     m_status = status;
 }
+
+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();
+}
+
+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);
+}
+
+std::string User::getHeaders()
+{
+    return "ID,Username,Password,Name,Phone,Email,UserType,UserStatus";
+}
+

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

@@ -31,6 +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;
@@ -50,4 +51,7 @@ public:
     void addNotification(Notification* notification) override;
     void setRole(util::UserType role);
     void setState(util::State status);
+    std::string serialize() const;
+    static User* deserialize(const std::string&);
+    static std::string getHeaders();
 };

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

@@ -7,6 +7,7 @@ Author: Trenser
 Date:19-May-2026
 */
 #include "InventoryManagementService.h"
+#include "Config.h"
 #include "Vector.h"
 #include "Enums.h"
 #include "InventoryItem.h"
@@ -14,6 +15,8 @@ Date:19-May-2026
 #include "User.h"
 #include "Factory.h"
 #include "Timestamp.h"
+#include "FileManager.h"
+#include "Utility.h"
 
 util::Map<std::string, User*> InventoryManagementService::m_observers{};
 
@@ -196,3 +199,47 @@ void InventoryManagementService::sendLowStockAlerts()
 		}
 	}
 }
+
+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;
+}
+
+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);
+	}
+}
+
+void InventoryManagementService::saveInventoryItems()
+{
+	util::FileManager<InventoryItem> inventoryItemFileManager(config::file::INVENTORYITEM_FILE);
+	auto& inventoryItems = m_dataStore.getInventoryItems();
+	inventoryItemFileManager.save(inventoryItems);
+}
+
+void InventoryManagementService::loadObservers()
+{
+	util::loadObservers(config::file::INVENTORYMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+void InventoryManagementService::saveObservers()
+{
+	util::saveObservers(config::file::INVENTORYMANAGEMENTOBSERVERS, this);
+}

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

@@ -9,6 +9,7 @@ Date:19-May-2026
 #pragma once
 #include <string>
 #include "Map.h"
+#include "Vector.h"
 #include "NotificationManagementService.h"
 #include "DataStore.h"
 
@@ -19,6 +20,7 @@ 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();
@@ -30,4 +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 loadInventoryItems();
+    void saveInventoryItems();
+    void loadObservers();
+    void saveObservers();
 };

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

@@ -19,4 +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

@@ -7,15 +7,15 @@ Author: Trenser
 Date: 20-May-2026
 */
 
+#include <stdexcept>
+#include "PaymentManagementService.h"
 #include "Config.h"
 #include "Enums.h"
-#include <stdexcept>
-#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"
@@ -61,7 +61,7 @@ void PaymentManagementService::generateInvoice(ServiceBooking* booking)
 		{
 			createInventoryItemsMap(completeInventoryItemMapOfBooking, currentService);
 			totalLabourCost += currentService->getLaborCost();
-			totalPartsCost += calculatePartsCost(currentService);
+			totalPartsCost += util::calculatePartsCost(currentService);
 		}
 	}
 	totalServiceCost = totalLabourCost + totalPartsCost;
@@ -223,3 +223,68 @@ void PaymentManagementService::sendPaymentReminders()
 		}
 	}
 }
+
+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;
+}
+
+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;
+    }
+}
+void PaymentManagementService::saveInvoices()
+{
+    util::FileManager<Invoice> invoiceFileManager(config::file::INVOICE_FILE);
+    auto& invoices = m_dataStore.getInvoices();
+    invoiceFileManager.save(invoices);
+}
+
+void PaymentManagementService::loadObservers()
+{
+    util::loadObservers(config::file::PAYMENTMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+void PaymentManagementService::saveObservers()
+{
+    util::saveObservers(config::file::PAYMENTMANAGEMENTOBSERVERS, this);
+}

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

@@ -22,6 +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);
@@ -31,4 +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

@@ -6,12 +6,16 @@ Description: Implementation file containing the method definitions of the
 Author: Trenser
 Date:19-May-2026
 */
+
 #include <stdexcept>
 #include "AuthenticationManagementService.h"
 #include "ComboPackage.h"
+#include "Config.h"
 #include "Enums.h"
 #include "Factory.h"
+#include "FileManager.h"
 #include "InventoryItem.h"
+#include "Invoice.h"
 #include "JobCard.h"
 #include "NotificationManagementService.h"
 #include "PaymentManagementService.h"
@@ -21,6 +25,7 @@ Date:19-May-2026
 #include "Timestamp.h"
 #include "User.h"
 #include "UserManagementService.h"
+#include "Utility.h"
 
 util::Map<std::string, User*> ServiceManagementService::m_observers{};
 
@@ -590,3 +595,205 @@ void ServiceManagementService::sendNotification(User* user, const std::string& t
 		}
 	}
 }
+
+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;
+}
+
+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);
+    }
+}
+
+void ServiceManagementService::saveServices()
+{
+	util::FileManager<Service> serviceFileManager(config::file::SERVICE_FILE);
+	auto& services = m_dataStore.getServices();
+	serviceFileManager.save(services);
+}
+
+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;
+    }
+}
+
+void ServiceManagementService::saveComboPackages()
+{
+    util::FileManager<ComboPackage> comboPackageFileManager(config::file::COMBOPACKAGE_FILE);
+    auto& comboPackages = m_dataStore.getComboPackages();
+    comboPackageFileManager.save(comboPackages);
+}
+
+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;
+    }
+}
+
+void ServiceManagementService::saveServiceBookings()
+{
+    util::FileManager<ServiceBooking> bookingFileManager(config::file::SERVICEBOOKING_FILE);
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    bookingFileManager.save(serviceBookings);
+}
+
+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;
+    }
+}
+void ServiceManagementService::saveJobCards()
+{
+    util::FileManager<JobCard> jobCardFileManager(config::file::JOBCARD_FILE);
+    auto& jobCards = m_dataStore.getJobCards();
+    jobCardFileManager.save(jobCards);
+}
+
+void ServiceManagementService::loadObservers()
+{
+    util::loadObservers(config::file::SERVICEMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+void ServiceManagementService::saveObservers()
+{
+    util::saveObservers(config::file::SERVICEMANAGEMENTOBSERVERS, this);
+}

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

@@ -22,6 +22,7 @@ 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();
@@ -43,4 +44,14 @@ 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

@@ -5,16 +5,20 @@ Description: Implementation file containing the method definitions of the
 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 "Invoice.h"
 #include "PaymentManagementService.h"
 #include "ServiceManagementService.h"
 #include "User.h"
+#include "UserManagementService.h"
+#include "Utility.h"
 #include "Vector.h"
-#include <stdexcept>
 
 void UserManagementService::ensureAdminExists()
 {
@@ -203,3 +207,50 @@ void UserManagementService::deleteNotification(const std::string& notificationID
 	}
 	notifications.remove(notificationID);
 }
+
+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);
+    }
+}
+
+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);
+}

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

@@ -29,4 +29,6 @@ public:
     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

@@ -24,4 +24,19 @@ namespace config
 		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

@@ -253,9 +253,9 @@ namespace util
         switch (status)
         {
         case State::ACTIVE:
-            return "STARTED";
+            return "ACTIVE";
         case State::INACTIVE:
-            return "COMPLETED";
+            return "INACTIVE";
         }
         throw std::invalid_argument("Invalid State");
     }
@@ -276,7 +276,7 @@ namespace util
         {
             return State::ACTIVE;
         }
-        if (value == "COMPLETED")
+        if (value == "INACTIVE")
         {
             return State::INACTIVE;
         }

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

@@ -0,0 +1,47 @@
+#pragma once
+#include <fstream>
+#include <string>
+#include <stdexcept>
+#include "Vector.h"
+
+namespace util
+{
+    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;
+    }
+
+    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 +1,83 @@
+#pragma once
+#include <string>
+#include <stdexcept>
+#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>&);
+	};
+
+	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;
+	}
+
+	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 +1,18 @@
+#include <cctype>
+#include <string>
+
+namespace util
+{
+    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

@@ -9,7 +9,12 @@ Date:19-May-2026
 #include "Service.h"
 #include "ComboPackage.h"
 #include "InventoryItem.h"
+#include "NotificationManagementService.h"
+#include "FileHelper.h"
+#include "DataStore.h"
 
+namespace util
+{
     /*
     Function: calculatePartsCost
     Description: Calculates the total cost of parts required for a given service
@@ -50,3 +55,26 @@ inline double calculateComboServiceEstimatedCost(const ComboPackage* comboPackag
         }
         return cost;
     }
+
+    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));
+        }
+    }
+
+    inline void saveObservers(const std::string& filePath, NotificationManagementService* service)
+    {
+        auto observerIDs = service->getObserverIDs();
+        util::saveRecords(filePath, observerIDs);
+    }
+}

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

@@ -858,7 +858,7 @@ static const Service* selectServiceFromServices(const util::Map<std::string, con
             continue;
         }
         activeServicesMap.insert(currentIndex, currentService);
-        double partsCost = calculatePartsCost(currentService);
+        double partsCost = util::calculatePartsCost(currentService);
         std::cout << std::left
             << std::setw(10) << currentIndex
             << std::setw(15) << currentService->getId()

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

@@ -177,7 +177,7 @@ static const Service* selectServiceFromServices(const util::Map<std::string, con
             continue;
         }
         activeServicesMap.insert(currentIndex, currentService);
-        double partsCost = calculatePartsCost(currentService);
+        double partsCost = util::calculatePartsCost(currentService);
         std::cout << std::left
             << std::setw(10) << currentIndex
             << std::setw(15) << currentService->getId()
@@ -250,7 +250,7 @@ static const ComboPackage* selectComboPackageFromPackages(const util::Map<std::s
             << std::setw(10) << currentIndex
             << std::setw(15) << currentComboPackage->getId()
             << std::setw(25) << currentComboPackage->getPackageName()
-            << std::setw(15) << calculateComboServiceEstimatedCost(currentComboPackage)
+            << std::setw(15) << util::calculateComboServiceEstimatedCost(currentComboPackage)
             << std::endl;
         currentIndex++;
     }

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

@@ -22,6 +22,7 @@ Return type: void
 */
 void UserInterface::run()
 {
+	m_controller.loadSystemData();
 	m_controller.runSystemChecks();
 	bool isMenuActive = true;
 	while (isMenuActive)
@@ -43,6 +44,7 @@ void UserInterface::run()
 			util::pressEnter();
 		}
 	}
+	m_controller.saveSystemData();
 }
 
 /*