Add documentation headers across system modules

<UserStory> PAY001: Generate Invoice </UserStory>

<Changes>
    1. Added Utility.h to project configuration for supporting invoice generation utilities.
    2. Updated Invoice model to use string-based keys for parts mapping instead of integer keys.
    3. Implemented PaymentManagementService::generateInvoice to aggregate labour cost, parts cost, and apply discounts.
    4. Integrated invoice creation with Factory to instantiate Invoice objects and persist them into datastore.
    5. Enhanced Enums with PaymentMode::NOTSET to handle default invoice state.
</Changes>

<Test>

 Acceptance Criteria:
 1. Invoice auto-generates for each service booking once jobs are completed.
 2. Invoice shows a clear breakdown of charges including labour cost, parts cost, discount, and total amount.

 Precondition:
  1. Service booking exists with at least one service and required inventory items.
  2. Datastore is available for storing invoices.
  3. Payment mode and status enums are properly configured.

 Steps:
  1. Complete all jobs in a service booking.
    - Verify that PaymentManagementService::generateInvoice is triggered.
  2. Check datastore for newly created invoice.
    - Verify that invoice contains booking ID, labour cost, parts cost, discount, and total amount.
  3. Inspect invoice details.
    - Verify that breakdown of charges is accurate and discount is applied correctly.
  4. Confirm invoice status.
    - Verify that invoice is created with PaymentMode::NOTSET and PaymentStatus::PENDING.
</Test>

<Review>
Sreeja Reghukumar, please review
</Review>

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

@@ -176,6 +176,7 @@
     <ClInclude Include="utilities\Map.h" />
     <ClInclude Include="utilities\OutputHelper.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" />

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

@@ -233,5 +233,8 @@
     <ClInclude Include="models\ComboPackage.h">
       <Filter>Header Files\Models</Filter>
     </ClInclude>
+    <ClInclude Include="utilities\Utility.h">
+      <Filter>Header Files\Utilities</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>

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

@@ -1,4 +1,6 @@
 #include "Controller.h"
+#include "User.h"
+#include "Invoice.h"
 
 bool Controller::login(const std::string& username, const std::string& password)
 {
@@ -119,13 +121,40 @@ void Controller::removeComboPackage(const std::string& 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);
 }
 
 util::Vector<const Notification*> Controller::getNotifications()
@@ -143,5 +172,4 @@ void Controller::configureNotifications(const std::string& userID, bool paymentN
 
 void Controller::runSystemChecks()
 {
-}
-
+}

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

@@ -2,6 +2,8 @@
 #include "Map.h"
 #include <string>
 #include "Enums.h"
+#include "PaymentManagementService.h"
+#include "AuthenticationManagementService.h"
 
 class Service;
 class ComboPackage;
@@ -14,6 +16,9 @@ class Notification;
 
 class Controller
 {
+private:
+    AuthenticationManagementService m_authenticationManagementService;
+    PaymentManagementService m_paymentManagementService;
 public:
     bool login(const std::string& username, const std::string& password);
     void logout();

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

@@ -16,7 +16,8 @@ Invoice::Invoice(
     const std::string& bookingId,
     ServiceBooking* booking,
     const util::Timestamp& invoiceDate, 
-    double laborCost, const util::Map<int,
+    double laborCost, 
+    const util::Map<std::string,
     InventoryItem*>& parts,
     double partsCost,
     double discountPercentage, 
@@ -63,7 +64,7 @@ double Invoice::getLaborCost() const
     return m_laborCost;
 }
 
-const util::Map<int, InventoryItem*>& Invoice::getParts() const
+const util::Map<std::string, InventoryItem*>& Invoice::getParts() const
 {
     return m_parts;
 }
@@ -123,7 +124,7 @@ void Invoice::setLaborCost(double laborCost)
     m_laborCost = laborCost;
 }
 
-void Invoice::setParts(const util::Map<int, InventoryItem*>& parts)
+void Invoice::setParts(const util::Map<std::string, InventoryItem*>& parts)
 {
     m_parts = parts;
 }

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

@@ -16,7 +16,7 @@ private:
     ServiceBooking* m_booking;
     util::Timestamp m_invoiceDate;
     double m_laborCost;
-    util::Map<int, InventoryItem*> m_parts;
+    util::Map<std::string, InventoryItem*> m_parts;
     double m_partsCost;
     double m_discountPercentage;
     double m_totalAmount;
@@ -30,8 +30,8 @@ public:
         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, 
@@ -44,7 +44,7 @@ public:
     ServiceBooking* getBooking() const;
     const util::Timestamp& getInvoiceDate() const;
     double getLaborCost() const;
-    const util::Map<int, InventoryItem*>& getParts() const;
+    const util::Map<std::string, InventoryItem*>& getParts() const;
     double getPartsCost() const;
     double getDiscountPercentage() const;
     double getTotalAmount() const;
@@ -56,7 +56,7 @@ 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);

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

@@ -7,7 +7,7 @@ JobCard::JobCard()
     m_booking(nullptr),
     m_service(nullptr),
     m_technician(nullptr),
-    m_status(ServiceJobStatus()) {}
+    m_status(util::ServiceJobStatus()) {}
 
 JobCard::JobCard(const std::string& bookingId,
     ServiceBooking* booking,
@@ -16,7 +16,7 @@ JobCard::JobCard(const std::string& bookingId,
     const std::string& technicianId,
     User* technician,
     const util::Timestamp& assignedDate,
-    ServiceJobStatus status,
+    util::ServiceJobStatus status,
     const util::Timestamp& completionDate
 )
     : m_id("JC" + std::to_string(++m_uid)),
@@ -70,7 +70,7 @@ const util::Timestamp& JobCard::getAssignedDate() const
     return m_assignedDate;
 }
 
-ServiceJobStatus JobCard::getStatus() const
+util::ServiceJobStatus JobCard::getStatus() const
 {
     return m_status;
 }
@@ -120,7 +120,7 @@ void JobCard::setAssignedDate(const util::Timestamp& assignedDate)
     m_assignedDate = assignedDate;
 }
 
-void JobCard::setStatus(ServiceJobStatus status)
+void JobCard::setStatus(util::ServiceJobStatus status)
 {
     m_status = status;
 }

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

@@ -1,12 +1,12 @@
 #pragma once
 #include <string>
+#include "Enums.h"
 #include "Timestamp.h"
 
 class ServiceBooking;
 class Service;
 class User;
 
-enum class ServiceJobStatus : int;
 
 class JobCard
 {
@@ -20,7 +20,7 @@ private:
     std::string m_technicianId;
     User* m_technician;
     util::Timestamp m_assignedDate;
-    ServiceJobStatus m_status;
+    util::ServiceJobStatus m_status;
     util::Timestamp m_completionDate;
 
 public:
@@ -32,7 +32,7 @@ public:
         const std::string& technicianId, 
         User* technician, 
         const util::Timestamp& assignedDate, 
-        ServiceJobStatus status,
+        util::ServiceJobStatus status,
         const util::Timestamp& completionDate
     );
     const std::string& getId() const;
@@ -43,7 +43,7 @@ public:
     const std::string& getTechnicianId() const;
     User* getTechnician() const;
     const util::Timestamp& getAssignedDate() const;
-    ServiceJobStatus getStatus() const;
+    util::ServiceJobStatus getStatus() const;
     const util::Timestamp& getCompletionDate() const;
     void setId(const std::string& id);
     void setBookingId(const std::string& bookingId);
@@ -53,6 +53,6 @@ public:
     void setTechnicianId(const std::string& technicianId);
     void setTechnician(User* technician);
     void setAssignedDate(const util::Timestamp& assignedDate);
-    void setStatus(ServiceJobStatus status);
+    void setStatus(util::ServiceJobStatus status);
     void setCompletionDate(const util::Timestamp& completionDate);
 };

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

@@ -18,7 +18,7 @@ ServiceBooking::ServiceBooking(
     const std::string& vehicleBrand,
     const std::string& vehicleModel,
     const std::string& assignedTechnicianId,
-    const std::string& assignedTechnician,
+    const User* assignedTechnician,
     double discountPercentage
 )
     : m_id("SRV" + std::to_string(++m_uid)),
@@ -80,7 +80,7 @@ const std::string& ServiceBooking::getAssignedTechnicianId() const
     return m_assignedTechnicianId;
 }
 
-const std::string& ServiceBooking::getAssignedTechnician() const
+const User* ServiceBooking::getAssignedTechnician() const
 {
     return m_assignedTechnician;
 }
@@ -135,7 +135,7 @@ void ServiceBooking::setAssignedTechnicianId(const std::string& assignedTechnici
     m_assignedTechnicianId = assignedTechnicianId;
 }
 
-void ServiceBooking::setAssignedTechnician(const std::string& assignedTechnician)
+void ServiceBooking::setAssignedTechnician(const User* assignedTechnician)
 {
     m_assignedTechnician = assignedTechnician;
 }

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

@@ -19,7 +19,7 @@ private:
     std::string m_vehicleBrand;
     std::string m_vehicleModel;
     std::string m_assignedTechnicianId;
-    std::string m_assignedTechnician;
+    const User* m_assignedTechnician;
     double m_discountPercentage;
 public:
     ServiceBooking();
@@ -34,7 +34,7 @@ public:
         const std::string& vehicleBrand,
         const std::string& vehicleModel,
         const std::string& assignedTechnicianId,
-        const std::string& assignedTechnician,
+        const User* assignedTechnician,
         double discountPercentage
     );
     const std::string& getId() const;
@@ -46,7 +46,7 @@ public:
     const std::string& getVehicleBrand() const;
     const std::string& getVehicleModel() const;
     const std::string& getAssignedTechnicianId() const;
-    const std::string& getAssignedTechnician() const;
+    const User* getAssignedTechnician() const;
     double getDiscountPercentage() const;
     void setId(const std::string& id);
     void setStatus(const util::ServiceJobStatus& status);
@@ -57,6 +57,6 @@ public:
     void setVehicleBrand(const std::string& vehicleBrand);
     void setVehicleModel(const std::string& vehicleModel);
     void setAssignedTechnicianId(const std::string& assignedTechnicianId);
-    void setAssignedTechnician(const std::string& assignedTechnician);
+    void setAssignedTechnician(const User* assignedTechnician);
     void setDiscountPercentage(double discountPercentage);
 };

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

@@ -1 +1,135 @@
 #include "PaymentManagementService.h"
+#include "ServiceBooking.h"
+#include "Service.h"
+#include "InventoryItem.h"
+#include "Utility.h"
+#include "Factory.h"
+#include "Timestamp.h"
+#include "Invoice.h"
+#include "JobCard.h"
+#include "Enums.h"
+
+/*
+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 += 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);
+		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/utilities/Enums.h

@@ -13,7 +13,8 @@ namespace util
 	enum class PaymentMode
 	{
 		ONLINE,
-		OFFLINE
+		OFFLINE,
+        NOTSET
 	};
 
 	enum class PaymentStatus
@@ -73,6 +74,8 @@ namespace util
             return "ONLINE";
         case PaymentMode::OFFLINE:
             return "OFFLINE";
+        case PaymentMode::NOTSET:
+            return "NOTSET";
         }
         throw std::invalid_argument("Invalid PaymentMode");
     }

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

@@ -0,0 +1,15 @@
+#pragma once
+#include "Service.h"
+#include "InventoryItem.h"
+
+inline double calculatePartsCost(const Service* service)
+{
+    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;
+}

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

@@ -1,6 +1,15 @@
+#include <iomanip>
+#include <iostream>
 #include "CustomerMenu.h"
 #include "InputHelper.h"
 #include "OutputHelper.h"
+#include "Invoice.h"
+#include "Enums.h"
+#include "ServiceBooking.h"
+#include "User.h"
+#include "Timestamp.h"
+#include "Service.h"
+#include "InventoryItem.h"
 
 void CustomerMenu::showMenu()
 {
@@ -55,12 +64,197 @@ void CustomerMenu::viewServiceHistory()
 {
 }
 
-void CustomerMenu::completePayments()
+/*
+Function: selectInvoiceFromUserForPayment (static helper)
+Description: Lists all pending invoices for the customer and allows selection by index.
+Parameters:
+    - currentInvoices: util::Map<std::string, const Invoice*>&, map of customer invoices
+Returns:
+    - std::string: ID of the selected invoice, or empty string if none selected
+*/
+static std::string selectInvoiceFromUserForPayment(const util::Map<std::string, const Invoice*>& currentInvoices)
 {
+    int currentIndex = 1, choice;
+    util::Map<int, const Invoice*> pendingInvoicesForPayment;
+    std::cout << std::left
+        << std::setw(6) << "Index"
+        << std::setw(12) << "BookingID"
+        << std::setw(15) << "VehicleBrand"
+        << std::setw(15) << "VehicleNumber"
+        << std::setw(12) << "TechID"
+        << std::setw(20) << "TechnicianName"
+        << std::setw(10) << "Discount(%)"
+        << std::setw(12) << "TotalAmount"
+        << std::setw(20) << "InvoiceDate"
+        << std::endl;
+    for (int iterator = 0; iterator < currentInvoices.getSize(); iterator++)
+    {
+        const Invoice* currentInvoice = currentInvoices.getValueAt(iterator);
+        if (currentInvoice && currentInvoice->getStatus() == util::PaymentStatus::PENDING)
+        {
+            std::cout << std::left
+                << std::setw(6) << currentIndex
+                << std::setw(12) << currentInvoice->getBookingId()
+                << std::setw(15) << currentInvoice->getBooking()->getVehicleBrand()
+                << std::setw(15) << currentInvoice->getBooking()->getVehicleNumber()
+                << std::setw(12) << currentInvoice->getBooking()->getAssignedTechnician()->getId()
+                << std::setw(20) << currentInvoice->getBooking()->getAssignedTechnician()->getName()
+                << std::setw(10) << currentInvoice->getDiscountPercentage()
+                << std::setw(12) << currentInvoice->getTotalAmount()
+                << std::setw(20) << currentInvoice->getInvoiceDate().toString()
+                << std::endl;
+            pendingInvoicesForPayment.insert(currentIndex++, currentInvoice);
+        }
+    }
+    if (pendingInvoicesForPayment.getSize() == 0)
+    {
+        std::cout << "No pending invoices available for payment.\n";
+        return "";
+    }
+    std::cout << "Select the Invoice to pay (Index): ";
+    util::read(choice);
+    int selectedIndex = pendingInvoicesForPayment.find(choice);
+    if (selectedIndex != -1)
+    {
+        const Invoice* selectedInvoice = pendingInvoicesForPayment.getValueAt(selectedIndex);
+        return selectedInvoice->getId();
+    }
+    else
+    {
+        std::cout << "Invalid choice.\n";
+        return "";
+    }
 }
 
+/*
+Function: selectPaymentMode (static helper)
+Description: Allows the customer to select a payment mode (ONLINE or OFFLINE).
+Parameters:
+    - None
+Returns:
+    - util::PaymentMode: Selected payment mode
+*/
+static util::PaymentMode selectPaymentMode()
+{
+    int choice;
+    std::cout << "Enter the payment Mode\n1.OFFLINE\n2.ONLINE\nChoice: ";
+    util::read(choice);
+    if (choice == 1)
+    {
+        std::cout << "Offline mode selected.\n";
+        return util::PaymentMode::OFFLINE;
+    }
+    else if (choice == 2)
+    {
+        std::cout << "Online mode selected.\n";
+        return util::PaymentMode::ONLINE;
+    }
+    else
+    {
+        std::cout << "Invalid choice, Offline mode selected.\n";
+        return util::PaymentMode::OFFLINE;
+    }
+}
+
+/*
+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";
+}
+
+/*
+Function: displayInvoices (static helper)
+Description: Displays detailed information for all invoices associated with the customer,
+             including booking details, technician, discount, total amount, payment status, and items used.
+Parameters:
+    - currentUserInvoices: util::Map<std::string, const Invoice*>, customer’s invoices
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a null invoice is encountered
+*/
+static void displayInvoices(util::Map<std::string, const Invoice*> currentUserInvoices)
+{
+	if (currentUserInvoices.getSize() == 0)
+	{
+		std::cout << "No invoices found for this account." << std::endl;
+		util::pressEnter();
+		return;
+	}
+	else
+	{
+        for (int index = 0; index < currentUserInvoices.getSize(); index++)
+        {
+            const Invoice* currentInvoice = currentUserInvoices.getValueAt(index);
+            if (currentInvoice)
+            {
+                std::cout << "\nInvoice Details\n";
+                std::cout << "Booking ID: " << currentInvoice->getBookingId() << std::endl;
+                std::cout << "Vehicle Brand: " << currentInvoice->getBooking()->getVehicleBrand() << std::endl;
+                std::cout << "Vehicle Number: " << currentInvoice->getBooking()->getVehicleNumber() << std::endl;
+                std::cout << "Technician ID: " << currentInvoice->getBooking()->getAssignedTechnician()->getId() << std::endl;
+                std::cout << "Technician Name: " << currentInvoice->getBooking()->getAssignedTechnician()->getName() << std::endl;
+                std::cout << "Discount(%): " << currentInvoice->getDiscountPercentage() << std::endl;
+                std::cout << "Total Amount: " << currentInvoice->getTotalAmount() << std::endl;
+                std::cout << "Invoice Date: " << currentInvoice->getInvoiceDate().toString() << std::endl;
+                std::cout << "Payment Status: " << util::getPaymentStatusString(currentInvoice->getStatus()) << std::endl;
+                auto inventoryItemsInInvoice = currentInvoice->getParts();
+                std::cout << "\nItems Used:\n";
+                std::cout << std::left
+                    << std::setw(20) << "ItemName"
+                    << std::setw(10) << "Quantity"
+                    << std::setw(10) << "Price"
+                    << std::endl;
+                std::cout << std::string(40, '-') << std::endl;
+                for (int iterator = 0; iterator < inventoryItemsInInvoice.getSize(); iterator++)
+                {
+                    InventoryItem* currentItem = inventoryItemsInInvoice.getValueAt(iterator);
+                    std::cout << std::left
+                        << std::setw(20) << currentItem->getPartName()
+                        << std::setw(10) << currentItem->getQuantity()
+                        << std::setw(10) << currentItem->getPrice()
+                        << std::endl;
+                }
+            }
+            else
+            {
+                throw std::runtime_error("Null invoice encountered while displaying invoices.");
+            }
+        }
+	}
+}
+
+/*
+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);
 }
 
 void CustomerMenu::viewNotifications()