Merged PR 1200: Fix Customer Allowed to Create Service Bookings While Having Unpaid Invoices

Changes: - Added verifyAllPaymentsCompleted() helper in MenuHelper.h to check if the authenticated customer has completed all invoices. - Integrated payment verification into CustomerMenu::selectService() to block new service bookings when pending payments exist. - Integrated payment verification into CustomerMenu::selectComboPackage() to block new combo package bookings when invoices are incomplete. - Implemented iteration over customer invoices to ensure only users with all payments marked as COMPLETED can proceed with new bookings. - Added user-facing messages to inform customers when bookings are denied due to outstanding payments. Related work items: #2116
Implement review fixes
2026-06-18 19:55:12 +05:30 · 2026-06-18 19:54:12 +05:30 · 2026-06-18 19:44:35 +05:30 · 2026-06-18 19:43:41 +05:30 · 2026-06-18 19:37:31 +05:30 · 2026-06-18 19:31:18 +05:30
36 changed files with 1376 additions and 365 deletions
@@ -102,7 +102,7 @@
      <SDLCheck>true</SDLCheck>
      <PreprocessorDefinitions>_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <ConformanceMode>true</ConformanceMode>
-      <AdditionalIncludeDirectories>$(ProjectDir)models;$(ProjectDir)controllers;$(ProjectDir)factories;$(ProjectDir)views;$(ProjectDir)services;$(ProjectDir)utilities;$(ProjectDir)core\patterns;$(ProjectDir)datastores;$(ProjectDir)datastores\sharedmemory;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>$(ProjectDir)models;$(ProjectDir)controllers;$(ProjectDir)factories;$(ProjectDir)views;$(ProjectDir)services;$(ProjectDir)utilities;$(ProjectDir)core\patterns;$(ProjectDir)datastores;$(ProjectDir)core\sharedmemory;$(ProjectDir)core\events;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
    </ClCompile>
    <Link>
      <SubSystem>Console</SubSystem>
@@ -117,7 +117,7 @@
      <SDLCheck>true</SDLCheck>
      <PreprocessorDefinitions>NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
      <ConformanceMode>true</ConformanceMode>
-      <AdditionalIncludeDirectories>$(ProjectDir)models;$(ProjectDir)controllers;$(ProjectDir)factories;$(ProjectDir)views;$(ProjectDir)services;$(ProjectDir)utilities;$(ProjectDir)core\patterns;$(ProjectDir)datastores;$(ProjectDir)datastores\sharedmemory;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>$(ProjectDir)models;$(ProjectDir)controllers;$(ProjectDir)factories;$(ProjectDir)views;$(ProjectDir)services;$(ProjectDir)utilities;$(ProjectDir)core\patterns;$(ProjectDir)datastores;$(ProjectDir)core\sharedmemory;$(ProjectDir)core\events;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
    </ClCompile>
    <Link>
      <SubSystem>Console</SubSystem>
@@ -126,10 +126,11 @@
  </ItemDefinitionGroup>
  <ItemGroup>
    <ClCompile Include="controllers\Controller.cpp" />
+    <ClCompile Include="core\events\EventManager.cpp" />
    <ClCompile Include="core\patterns\Observer.cpp" />
    <ClCompile Include="core\patterns\Subject.cpp" />
+    <ClCompile Include="core\sharedmemory\SharedMemory.cpp" />
    <ClCompile Include="datastores\DataStore.cpp" />
-    <ClCompile Include="datastores\sharedmemory\SharedMemory.cpp" />
    <ClCompile Include="models\ComboPackage.cpp" />
    <ClCompile Include="models\InventoryItem.cpp" />
    <ClCompile Include="models\Invoice.cpp" />
@@ -148,21 +149,23 @@
    <ClCompile Include="utilities\Validator.cpp" />
    <ClCompile Include="views\AdminMenu.cpp" />
    <ClCompile Include="views\CustomerMenu.cpp" />
+    <ClCompile Include="views\Menu.cpp" />
    <ClCompile Include="views\TechnicianMenu.cpp" />
    <ClCompile Include="views\UserInterface.cpp" />
  </ItemGroup>
  <ItemGroup>
    <ClInclude Include="controllers\Controller.h" />
+    <ClInclude Include="core\events\EventManager.h" />
    <ClInclude Include="core\patterns\Observer.h" />
    <ClInclude Include="core\patterns\Subject.h" />
+    <ClInclude Include="core\sharedmemory\FileHeader.h" />
+    <ClInclude Include="core\sharedmemory\MappingInfo.h" />
+    <ClInclude Include="core\sharedmemory\RecordState.h" />
+    <ClInclude Include="core\sharedmemory\SerializedRecords.h" />
+    <ClInclude Include="core\sharedmemory\SharedMemory.h" />
+    <ClInclude Include="core\sharedmemory\TrackedRecord.h" />
    <ClInclude Include="datastores\DataStore.h" />
    <ClInclude Include="datastores\DataStoreLockGuard.h" />
-    <ClInclude Include="datastores\sharedmemory\FileHeader.h" />
-    <ClInclude Include="datastores\sharedmemory\MappingInfo.h" />
-    <ClInclude Include="datastores\sharedmemory\RecordState.h" />
-    <ClInclude Include="datastores\sharedmemory\SerializedRecords.h" />
-    <ClInclude Include="datastores\sharedmemory\SharedMemory.h" />
-    <ClInclude Include="datastores\sharedmemory\TrackedRecord.h" />
    <ClInclude Include="factories\Factory.h" />
    <ClInclude Include="models\ComboPackage.h" />
    <ClInclude Include="models\InventoryItem.h" />
@@ -191,6 +194,7 @@
    <ClInclude Include="utilities\Vector.h" />
    <ClInclude Include="views\AdminMenu.h" />
    <ClInclude Include="views\CustomerMenu.h" />
+    <ClInclude Include="views\Menu.h" />
    <ClInclude Include="views\MenuHelper.h" />
    <ClInclude Include="views\TechnicianMenu.h" />
    <ClInclude Include="views\UserInterface.h" />
@@ -64,11 +64,17 @@
    <Filter Include="Source Files\Core\Patterns">
      <UniqueIdentifier>{8057b93d-51a9-42df-b06e-01ce395f6308}</UniqueIdentifier>
    </Filter>
-    <Filter Include="Header Files\DataStores\SharedMemory">
-      <UniqueIdentifier>{ec639004-44c6-4bd6-9963-077adde82b5f}</UniqueIdentifier>
+    <Filter Include="Header Files\Core\SharedMemory">
+      <UniqueIdentifier>{d9da9793-fe6f-4914-bee3-99d5934da228}</UniqueIdentifier>
    </Filter>
-    <Filter Include="Source Files\DataStores\SharedMemory">
-      <UniqueIdentifier>{7aa8722e-adfa-466e-8211-de63f3b7892b}</UniqueIdentifier>
+    <Filter Include="Source Files\Core\SharedMemory">
+      <UniqueIdentifier>{0769afb6-f57d-4ae3-a1cf-ceca6e606af0}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="Header Files\Core\Events">
+      <UniqueIdentifier>{85029bdb-6941-41dc-a3a7-9e5841671d8c}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="Source Files\Core\Events">
+      <UniqueIdentifier>{1050aca7-6f2c-4ccb-a446-db9c898c3599}</UniqueIdentifier>
    </Filter>
  </ItemGroup>
  <ItemGroup>
@@ -144,8 +150,14 @@
    <ClCompile Include="models\ComboPackage.cpp">
      <Filter>Source Files\Models</Filter>
    </ClCompile>
-    <ClCompile Include="datastores\sharedmemory\SharedMemory.cpp">
-      <Filter>Source Files\DataStores\SharedMemory</Filter>
+    <ClCompile Include="core\sharedmemory\SharedMemory.cpp">
+      <Filter>Source Files\Core\SharedMemory</Filter>
+    </ClCompile>
+    <ClCompile Include="core\events\EventManager.cpp">
+      <Filter>Source Files\Core\Events</Filter>
+    </ClCompile>
+    <ClCompile Include="views\Menu.cpp">
+      <Filter>Source Files\Views</Filter>
    </ClCompile>
  </ItemGroup>
  <ItemGroup>
@@ -254,26 +266,32 @@
    <ClInclude Include="views\MenuHelper.h">
      <Filter>Header Files\Views</Filter>
    </ClInclude>
-    <ClInclude Include="datastores\sharedmemory\FileHeader.h">
-      <Filter>Header Files\DataStores\SharedMemory</Filter>
-    </ClInclude>
-    <ClInclude Include="datastores\sharedmemory\MappingInfo.h">
-      <Filter>Header Files\DataStores\SharedMemory</Filter>
-    </ClInclude>
-    <ClInclude Include="datastores\sharedmemory\RecordState.h">
-      <Filter>Header Files\DataStores\SharedMemory</Filter>
-    </ClInclude>
-    <ClInclude Include="datastores\sharedmemory\TrackedRecord.h">
-      <Filter>Header Files\DataStores\SharedMemory</Filter>
-    </ClInclude>
-    <ClInclude Include="datastores\sharedmemory\SerializedRecords.h">
-      <Filter>Header Files\DataStores\SharedMemory</Filter>
-    </ClInclude>
-    <ClInclude Include="datastores\sharedmemory\SharedMemory.h">
-      <Filter>Header Files\DataStores\SharedMemory</Filter>
-    </ClInclude>
    <ClInclude Include="datastores\DataStoreLockGuard.h">
      <Filter>Header Files\DataStores</Filter>
    </ClInclude>
+    <ClInclude Include="core\sharedmemory\FileHeader.h">
+      <Filter>Header Files\Core\SharedMemory</Filter>
+    </ClInclude>
+    <ClInclude Include="core\sharedmemory\MappingInfo.h">
+      <Filter>Header Files\Core\SharedMemory</Filter>
+    </ClInclude>
+    <ClInclude Include="core\sharedmemory\RecordState.h">
+      <Filter>Header Files\Core\SharedMemory</Filter>
+    </ClInclude>
+    <ClInclude Include="core\sharedmemory\SerializedRecords.h">
+      <Filter>Header Files\Core\SharedMemory</Filter>
+    </ClInclude>
+    <ClInclude Include="core\sharedmemory\SharedMemory.h">
+      <Filter>Header Files\Core\SharedMemory</Filter>
+    </ClInclude>
+    <ClInclude Include="core\sharedmemory\TrackedRecord.h">
+      <Filter>Header Files\Core\SharedMemory</Filter>
+    </ClInclude>
+    <ClInclude Include="core\events\EventManager.h">
+      <Filter>Header Files\Core\Events</Filter>
+    </ClInclude>
+    <ClInclude Include="views\Menu.h">
+      <Filter>Header Files\Views</Filter>
+    </ClInclude>
  </ItemGroup>
 </Project>
@@ -234,6 +234,17 @@ void Controller::removeInventoryItem(const std::string& inventoryItemID)
    m_inventoryManagementService.removeInventoryItem(inventoryItemID);
 }

+/*
+Function: removeServiceBooking
+Description: Removes a service booking from the service management system by its booking ID.
+Parameter: const std::string& bookingID - ID of the service booking
+Return type: void
+*/
+void Controller::removeServiceBooking(const std::string& bookingID)
+{
+    m_serviceManagementService.removeServiceBooking(bookingID);
+}
+
 /*
 Function: addInventoryItemStock
 Description: Adds stock to an existing inventory item in the inventory management service.
@@ -265,6 +276,7 @@ util::Map<std::string, const ServiceBooking*> Controller::getServiceBookings()
    return readOnlyServiceBookings;
 }

+
 /*
 Function: getServiceBookingsByUser
 Description: Retrieves all service bookings for a specific user.
@@ -622,3 +634,16 @@ void Controller::shutdown()
    auto& dataStore = DataStore::getInstance();
    dataStore.shutdown();
 }
+
+/*
+Function: registerEvents
+Description: Registers menu event handles with the authentication
+             service.
+Parameter: HANDLE accountDisabledEvent - account disabled event handle
+           HANDLE notificationAvailableEvent - notification event handle
+Return type: void
+*/
+void Controller::registerEvents(HANDLE accountDisabledEvent, HANDLE notificationAvailableEvent)
+{
+    m_authenticationManagementService.registerEvents(accountDisabledEvent, notificationAvailableEvent);
+}
@@ -8,6 +8,7 @@ Date:19-May-2026
 */

 #pragma once
+#include <windows.h>
 #include <string>
 #include "AuthenticationManagementService.h"
 #include "Enums.h"
@@ -57,6 +58,7 @@ public:
    util::Map<std::string, const User*> getUsers(util::UserType userType);
    void createJobCard(const std::string& bookingID, const std::string& technicianID, const std::string& serviceID);
    void createService(const std::string& name, const util::Vector<std::string>& inventoryItemIDs, double laborCost);
+    void removeServiceBooking(const std::string& bookingID);
    void removeService(const std::string& serviceID);
    util::Map<std::string, const JobCard*> getJobCardsByUser();
    void updateJobStatus(const std::string& jobID);
@@ -72,4 +74,5 @@ public:
    void configureNotifications(bool paymentNotifications, bool serviceNotifications);
    bool initialize();
    void shutdown();
+    void registerEvents(HANDLE accountDisabledEvent, HANDLE notificationAvailableEvent);
 };
@@ -0,0 +1,225 @@
+/*
+File: EventManager.cpp
+Description: Implementation file containing the method definitions of the
+             EventManager class, including listener management and
+             interprocess event publishing.
+Author: Trenser
+Date:15-Jun-2026
+*/
+
+#include <iostream>
+#include <stdexcept>
+#include "EventManager.h"
+
+namespace
+{
+    const std::string USER_DISABLED_EVENT = "userDisabled_";
+
+    const std::string NOTIFICATION_AVAILABLE_EVENT = "notificationAvailable_";
+}
+
+/*
+Function: EventManager
+Description: Constructs an EventManager instance with default values.
+Parameter: None
+Return type: None
+*/
+EventManager::EventManager()
+    :
+    m_userDisabledEvent(NULL),
+    m_notificationAvailableEvent(NULL),
+    m_shutdownEvent(NULL),
+    m_running(false) {}
+
+/*
+Function: ~EventManager
+Description: Destroys the EventManager and performs final cleanup.
+Parameter: None
+Return type: None
+*/
+EventManager::~EventManager()
+{
+    shutdown();
+    if (m_listenerThread.joinable())
+    {
+        m_listenerThread.join();
+    }
+}
+
+/*
+Function: initialize
+Description: Creates the user-specific events and starts the listener
+             thread.
+Parameter: const std::string& userId - unique identifier of the user
+           std::function<void()> userDisabledCallback - callback for
+           user disable events
+           std::function<void()> notificationCallback - callback for
+           notification events
+Return type: bool - true if initialization succeeds, false otherwise
+*/
+bool EventManager::initialize(const std::string& userId, std::function<void()> userDisabledCallback, std::function<void()> notificationCallback)
+{
+    if (m_running.load())
+    {
+        return false;
+    }
+    m_userDisabledCallback = userDisabledCallback;
+    m_notificationCallback = notificationCallback;
+    m_userDisabledEvent = CreateEventA(NULL, FALSE, FALSE, (USER_DISABLED_EVENT + userId).c_str());
+    if (!m_userDisabledEvent)
+    {
+        return false;
+    }
+    if (GetLastError() == ERROR_ALREADY_EXISTS)
+    {
+        CloseHandle(m_userDisabledEvent);
+        m_userDisabledEvent = NULL;
+        throw std::runtime_error("Only one session allowed per user.");
+    }
+    m_notificationAvailableEvent = CreateEventA(NULL, FALSE, FALSE, (NOTIFICATION_AVAILABLE_EVENT + userId).c_str());
+    if (!m_notificationAvailableEvent)
+    {
+        CloseHandle(m_userDisabledEvent);
+        m_userDisabledEvent = NULL;
+        return false;
+    }
+    m_shutdownEvent = CreateEventA(NULL, FALSE, FALSE, NULL);
+    if (!m_shutdownEvent)
+    {
+        CloseHandle(m_userDisabledEvent);
+        CloseHandle(m_notificationAvailableEvent);
+        m_userDisabledEvent = NULL;
+        m_notificationAvailableEvent = NULL;
+        return false;
+    }
+    m_running.store(true);
+    m_listenerThread = std::thread(&EventManager::run, this);
+    return true;
+}
+
+/*
+Function: shutdown
+Description: Stops the listener thread and releases event resources.
+Parameter: None
+Return type: None
+*/
+void EventManager::shutdown()
+{
+    if (!m_running.load())
+    {
+        return;
+    }
+    m_running.store(false);
+    if (m_shutdownEvent)
+    {
+        SetEvent(m_shutdownEvent);
+    }
+    if (m_listenerThread.joinable())
+    {
+        if (std::this_thread::get_id() != m_listenerThread.get_id())
+        {
+            m_listenerThread.join();
+        }
+    }
+    if (m_userDisabledEvent)
+    {
+        CloseHandle(m_userDisabledEvent);
+        m_userDisabledEvent = NULL;
+    }
+    if (m_notificationAvailableEvent)
+    {
+        CloseHandle(m_notificationAvailableEvent);
+        m_notificationAvailableEvent = NULL;
+    }
+    if (m_shutdownEvent)
+    {
+        CloseHandle(m_shutdownEvent);
+        m_shutdownEvent = NULL;
+    }
+}
+
+/*
+Function: run
+Description: Waits for and dispatches user-related events.
+Parameter: None
+Return type: void
+*/
+void EventManager::run()
+{
+    HANDLE handles[3];
+    handles[0] = m_userDisabledEvent;
+    handles[1] = m_notificationAvailableEvent;
+    handles[2] = m_shutdownEvent;
+    while (m_running.load())
+    {
+        DWORD result = WaitForMultipleObjects(3, handles, FALSE, INFINITE);
+        switch (result)
+        {
+        case WAIT_OBJECT_0:
+            try
+            {
+                if (m_userDisabledCallback)
+                {
+                    m_userDisabledCallback();
+                }
+            }
+            catch (const std::exception& exception)
+            {
+                std::cout << exception.what() << std::endl;
+            }
+            break;
+        case WAIT_OBJECT_0 + 1:
+            try
+            {
+                if (m_notificationCallback)
+                {
+                    m_notificationCallback();
+                }
+            }
+            catch (const std::exception& exception)
+            {
+                std::cout << exception.what() << std::endl;
+            }
+            break;
+        case WAIT_OBJECT_0 + 2:
+            return;
+        default:
+            break;
+        }
+    }
+}
+
+/*
+Function: sendUserDisabledEvent
+Description: Publishes a user disabled event for a specific user.
+Parameter: const std::string& userId - target user identifier
+Return type: void
+*/
+void EventManager::sendUserDisabledEvent(const std::string& userId)
+{
+    HANDLE eventHandle = CreateEventA(NULL, FALSE, FALSE, (USER_DISABLED_EVENT + userId).c_str());
+    if (!eventHandle)
+    {
+        return;
+    }
+    SetEvent(eventHandle);
+    CloseHandle(eventHandle);
+}
+
+/*
+Function: sendNotificationAvailableEvent
+Description: Publishes a notification available event for a specific
+             user.
+Parameter: const std::string& userId - target user identifier
+Return type: void
+*/
+void EventManager::sendNotificationAvailableEvent(const std::string& userId)
+{
+    HANDLE eventHandle = CreateEventA(NULL, FALSE, FALSE, (NOTIFICATION_AVAILABLE_EVENT + userId).c_str());
+    if (!eventHandle)
+    {
+        return;
+    }
+    SetEvent(eventHandle);
+    CloseHandle(eventHandle);
+}
@@ -0,0 +1,37 @@
+/*
+File: EventManager.h
+Description: Header file declaring the EventManager class, which manages
+             user-specific interprocess events for user disable and
+             notification availability updates.
+Author: Trenser
+Date:15-Jun-2026
+*/
+
+#pragma once
+
+#include <windows.h>
+#include <atomic>
+#include <functional>
+#include <string>
+#include <thread>
+
+class EventManager
+{
+private:
+    HANDLE m_userDisabledEvent;
+    HANDLE m_notificationAvailableEvent;
+    HANDLE m_shutdownEvent;
+    std::atomic<bool> m_running;
+    std::thread m_listenerThread;
+    std::function<void()> m_userDisabledCallback;
+    std::function<void()> m_notificationCallback;
+    void run();
+
+public:
+    EventManager();
+    ~EventManager();
+    bool initialize(const std::string& userId, std::function<void()> userDisabledCallback, std::function<void()> notificationCallback);
+    void shutdown();
+    static void sendUserDisabledEvent(const std::string& userId);
+    static void sendNotificationAvailableEvent(const std::string& userId);
+};
@@ -14,6 +14,7 @@ Date: 19-May-2026
 #include "FileHelper.h"
 #include "ServiceBooking.h"
 #include "JobCard.h"
+#include "Invoice.h"

 /*
 Function: DataStore
@@ -324,6 +325,8 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<InventoryItem>>& DataStore::getInventoryItems()
 {
+    auto inventoryItems = loadRecords<InventoryItem, SerializedInventoryItem>(m_inventoryItems);
+    refreshCache(m_inventoryItemCache, inventoryItems);
    return m_inventoryItemCache;
 }

@@ -355,7 +358,7 @@ util::Map<std::string, TrackedRecord<ServiceBooking>>& DataStore::getServiceBook
            {
                throw std::runtime_error("Invalid service index.");
            }
-            auto currentService = services.getValueAt(serviceIndex);
+            auto& currentService = services.getValueAt(serviceIndex);
            servicesInBooking[currentServiceId] = currentService.data;
        }
        serviceBooking->setServices(servicesInBooking);
@@ -366,7 +369,7 @@ util::Map<std::string, TrackedRecord<ServiceBooking>>& DataStore::getServiceBook
            {
                throw std::runtime_error("Invalid user index.");
            }
-            auto customer = users.getValueAt(userIndex);
+            auto& customer = users.getValueAt(userIndex);
            serviceBooking->setCustomer(customer.data);
        }
        if (!serviceBooking->getAssignedTechnicianId().empty())
@@ -376,7 +379,7 @@ util::Map<std::string, TrackedRecord<ServiceBooking>>& DataStore::getServiceBook
            {
                throw std::runtime_error("Invalid technician index.");
            }
-            auto technician = users.getValueAt(technicianIndex);
+            auto& technician = users.getValueAt(technicianIndex);
            serviceBooking->setAssignedTechnician(technician.data);
        }
    }
@@ -412,7 +415,7 @@ util::Map<std::string, TrackedRecord<JobCard>>& DataStore::getJobCards()
        {
            throw std::runtime_error("Invalid booking ID: " + bookingId);
        }
-        auto trackedBooking = serviceBookings.getValueAt(bookingIndex);
+        auto& trackedBooking = serviceBookings.getValueAt(bookingIndex);
        jobCard->setBooking(trackedBooking.data);
        const std::string& serviceId = jobCard->getServiceId();
        int serviceIndex = services.find(serviceId);
@@ -420,7 +423,7 @@ util::Map<std::string, TrackedRecord<JobCard>>& DataStore::getJobCards()
        {
            throw std::runtime_error("Invalid service ID: " + serviceId);
        }
-        auto trackedService = services.getValueAt(serviceIndex);
+        auto& trackedService = services.getValueAt(serviceIndex);
        jobCard->setService(trackedService.data);
        const std::string& technicianId = jobCard->getTechnicianId();
        if (!technicianId.empty())
@@ -430,7 +433,7 @@ util::Map<std::string, TrackedRecord<JobCard>>& DataStore::getJobCards()
            {
                throw std::runtime_error("Invalid technician ID: " + technicianId);
            }
-            auto trackedTechnician = users.getValueAt(technicianIndex);
+            auto& trackedTechnician = users.getValueAt(technicianIndex);
            jobCard->setTechnician(trackedTechnician.data);
        }
    }
@@ -448,6 +451,45 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<Invoice>>& DataStore::getInvoices()
 {
+    auto& serviceBookings = getServiceBookings();
+    auto& inventoryItems = getInventoryItems();
+    util::Map<std::string, TrackedRecord<Invoice>> invoices = loadRecords<Invoice, SerializedInvoice>(m_invoices);
+    refreshCache(m_invoiceCache, invoices);
+    for (int iterator = 0; iterator < m_invoiceCache.getSize(); iterator++)
+    {
+        auto& trackedInvoice = m_invoiceCache.getValueAt(iterator);
+        Invoice* invoice = trackedInvoice.data;
+        if (!invoice)
+        {
+            continue;
+        }
+        const std::string& currentBookingId = invoice->getBookingId();
+        int currentBookingIndex = serviceBookings.find(currentBookingId);
+        if (currentBookingIndex == -1)
+        {
+            throw std::runtime_error("Invalid Service Booking Index.");
+        }
+        ServiceBooking* currentBooking = serviceBookings.getValueAt(currentBookingIndex).data;
+        auto& currentInventoryItemIds = invoice->getPartIDs();
+        util::Map<std::string, InventoryItem*> currentInventoryItems;
+        for (int iterator = 0; iterator < currentInventoryItemIds.getSize(); iterator++)
+        {
+            const std::string& currentItemId = currentInventoryItemIds[iterator];
+            int currentItemIndex = inventoryItems.find(currentItemId);
+            if (currentItemIndex == -1)
+            {
+                throw std::runtime_error("Invalid Inventory item id.");
+            }
+            InventoryItem* currentItem = inventoryItems.getValueAt(currentItemIndex).data;
+            if (!currentItem)
+            {
+                continue;
+            }
+            currentInventoryItems[currentItemId] = currentItem;
+        }
+        invoice->setBooking(currentBooking);
+        invoice->setParts(currentInventoryItems);
+    }
    return m_invoiceCache;
 }

@@ -583,6 +625,7 @@ Returns:
 */
 void DataStore::saveInventoryItems()
 {
+    saveRecords<InventoryItem, SerializedInventoryItem>(m_inventoryItems, m_inventoryItemCache);
 }

 /*
@@ -621,6 +664,7 @@ Returns:
 */
 void DataStore::saveInvoices()
 {
+    saveRecords<Invoice, SerializedInvoice>(m_invoices, m_invoiceCache);
 }

 /*
@@ -647,7 +691,7 @@ void DataStore::saveObservers(MappingInfo& mapping, util::Map<std::string, User*
    SharedMemory::setRecordCount(mapping, observerCount);
    for (size_t index = 0; index < observerCount; index++)
    {
-        SerializedObserver serializedObserver;
+        SerializedObserver serializedObserver{};
        User* user = observers.getValueAt(static_cast<int>(index));
        strcpy_s(serializedObserver.id, sizeof(serializedObserver.id), user->getId().c_str());
        SerializedObserver* destination = static_cast<SerializedObserver*>(SharedMemory::getRecordAddress(mapping, index));
@@ -737,4 +781,3 @@ bool DataStore::unlockDataStore()
    }
    return ReleaseMutex(m_globalMutex) != 0;
 }
-
@@ -220,6 +220,12 @@ void DataStore::refreshCache(util::Map<std::string, TrackedRecord<TObject>>& cac
        if (oldIndex != -1)
        {
            TrackedRecord<TObject>& oldRecord = oldCache.getValueAt(oldIndex);
+            if (oldRecord.state == RecordState::MODIFIED)
+            {
+                delete refreshedRecord.data;
+                cache.insert(id, oldRecord);
+                continue;
+            }
            *oldRecord.data = *refreshedRecord.data;
            oldRecord.slotIndex = refreshedRecord.slotIndex;
            oldRecord.state = refreshedRecord.state;
@@ -8,6 +8,7 @@ Date: 19-May-2026

 #include <sstream>
 #include <stdexcept>
+#include "SerializedRecords.h"
 #include "Factory.h"
 #include "StringHelper.h"
 #include "InventoryItem.h"
@@ -27,7 +28,8 @@ InventoryItem::InventoryItem()
    : m_id("IIM" + std::to_string(++m_uid)),
    m_quantity(0),
    m_status(util::State::ACTIVE),
-    m_price(0.0) {}
+    m_price(0.0) {
+}

 /*
 Function: InventoryItem
@@ -45,7 +47,8 @@ InventoryItem::InventoryItem(const std::string& partName, int quantity, double p
    m_partName(partName),
    m_quantity(quantity),
    m_status(util::State::ACTIVE),
-    m_price(price) {}
+    m_price(price) {
+}

 /*
 Function: InventoryItem (parameterized constructor with ID)
@@ -206,73 +209,37 @@ void InventoryItem::setState(util::State status)

 /*
 Function: serialize
-Description: Serializes the inventory item into a CSV-formatted string.
+Description: Serializes the InventoryItem object into a SerializedInventoryItem record.
 Parameters:
    - None
 Returns:
-    - std::string: Serialized inventory item record
+    - SerializedInventoryItem: Serialized representation of the inventory item
 */
-std::string InventoryItem::serialize() const
+SerializedInventoryItem InventoryItem::serialize() const
 {
-    std::ostringstream serializedInventoryItem;
-    serializedInventoryItem << m_id << ','
-        << m_partName << ','
-        << m_quantity << ','
-        << m_price << ','
-        << util::getStateString(m_status);
-    return serializedInventoryItem.str();
+    SerializedInventoryItem serialized = {};
+    strcpy_s(serialized.id, sizeof(serialized.id), m_id.c_str());
+    strcpy_s(serialized.partName, sizeof(serialized.partName), m_partName.c_str());
+    serialized.quantity = m_quantity;
+    serialized.price = m_price;
+    serialized.status = m_status;
+    return serialized;
 }

 /*
 Function: deserialize
-Description: Deserializes a CSV-formatted string into an InventoryItem object.
+Description: Deserializes a SerializedInventoryItem record into an InventoryItem object.
 Parameters:
-    - record: const std::string&, serialized inventory item record
+    - serializedInventoryItem: const SerializedInventoryItem&, serialized inventory item record
 Returns:
    - InventoryItem*: Pointer to the deserialized InventoryItem object
-Throws:
-    - std::runtime_error if data is invalid
 */
-InventoryItem* InventoryItem::deserialize(const std::string& record)
+InventoryItem* InventoryItem::deserialize(const SerializedInventoryItem& serializedInventoryItem)
 {
-    std::string id, partName;
-    std::string quantityString, priceString, statusString;
-    int quantity;
-    double price;
-    std::istringstream serializedInventoryItem(record);
-    getline(serializedInventoryItem, id, ',');
-    getline(serializedInventoryItem, partName, ',');
-    getline(serializedInventoryItem, quantityString, ',');
-    getline(serializedInventoryItem, priceString, ',');
-    getline(serializedInventoryItem, statusString, ',');
-    try
-    {
-        quantity = std::stoi(quantityString);
-        price = std::stod(priceString);
-    }
-    catch (...)
-    {
-        throw std::runtime_error("Invalid inventory item data");
-    }
-    util::State status = util::getState(statusString);
    return Factory::getObject<InventoryItem>(
-        id,
-        partName,
-        quantity,
-        price,
-        status
-    );
-}
-
-/*
-Function: getHeaders
-Description: Retrieves the CSV headers for inventory item serialization.
-Parameters:
-    - None
-Returns:
-    - std::string: Header string ("ID,PartName,Quantity,Price,Status")
-*/
-std::string InventoryItem::getHeaders()
-{
-    return "ID,PartName,Quantity,Price,Status";
+        serializedInventoryItem.id,
+        serializedInventoryItem.partName,
+        serializedInventoryItem.quantity,
+        serializedInventoryItem.price,
+        serializedInventoryItem.status);
 }
@@ -6,11 +6,12 @@ Author: Trenser
 Date: 19-May-2026
 */

-
 #pragma once
 #include <string>
 #include "Enums.h"

+struct SerializedInventoryItem;
+
 class InventoryItem
 {
 private:
@@ -34,7 +35,6 @@ 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();
+    SerializedInventoryItem serialize() const;
+    static InventoryItem* deserialize(const SerializedInventoryItem&);
 };
@@ -9,6 +9,7 @@ Date: 19-May-2026

 #include <sstream>
 #include <stdexcept>
+#include "SerializedRecords.h"
 #include "Invoice.h"
 #include "Factory.h"
 #include "InventoryItem.h"
@@ -34,7 +35,8 @@ Invoice::Invoice()
    m_discountPercentage(0.0),
    m_totalAmount(0.0),
    m_paymentMethod(util::PaymentMode()),
-    m_status(util::PaymentStatus()) {}
+    m_status(util::PaymentStatus()) {
+}

 /*
 Function: Invoice
@@ -66,7 +68,7 @@ Invoice::Invoice(
    const util::Timestamp& paymentDate,
    util::PaymentMode paymentMethod,
    util::PaymentStatus status
-    )
+)
    : m_id("INV" + std::to_string(++m_uid)),
    m_bookingId(bookingId),
    m_booking(booking),
@@ -473,100 +475,50 @@ static util::Vector<std::string> getPartIDsAsVector(const std::string& partIDsSt

 /*
 Function: serialize
-Description: Serializes the invoice into a CSV-formatted string.
+Description: Serializes the Invoice object into a SerializedInvoice record.
 Parameters:
    - None
 Returns:
-    - std::string: Serialized invoice record
+    - SerializedInvoice: Serialized representation of the invoice
 */
-std::string Invoice::serialize() const
+SerializedInvoice 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();
+    SerializedInvoice serialized = {};
+    strcpy_s(serialized.id, sizeof(serialized.id), m_id.c_str());
+    strcpy_s(serialized.bookingId, sizeof(serialized.bookingId), m_bookingId.c_str());
+    strcpy_s(serialized.partIDs, sizeof(serialized.partIDs), getPartIDsAsString(m_partIDs).c_str());
+    serialized.invoiceDate = m_invoiceDate;
+    serialized.laborCost = m_laborCost;
+    serialized.partsCost = m_partsCost;
+    serialized.discountPercentage = m_discountPercentage;
+    serialized.totalAmount = m_totalAmount;
+    serialized.paymentDate = m_paymentDate;
+    serialized.paymentMethod = m_paymentMethod;
+    serialized.status = m_status;
+    return serialized;
 }

 /*
 Function: deserialize
-Description: Deserializes a CSV-formatted string into an Invoice object.
+Description: Deserializes a SerializedInvoice record into an Invoice object.
 Parameters:
-    - record: const std::string&, serialized invoice record
+    - serializedInvoice: const SerializedInvoice&, serialized invoice record
 Returns:
    - Invoice*: Pointer to the deserialized Invoice object
-Throws:
-    - std::runtime_error if data is invalid
 */
-Invoice* Invoice::deserialize(const std::string& record)
+Invoice* Invoice::deserialize(const SerializedInvoice& serializedInvoice)
 {
-    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);
+    util::Vector<std::string> partIDs = getPartIDsAsVector(serializedInvoice.partIDs);
    return Factory::getObject<Invoice>(
-        id,
-        bookingId,
-        invoiceDate,
+        serializedInvoice.id,
+        serializedInvoice.bookingId,
+        serializedInvoice.invoiceDate,
        partIDs,
-        laborCost,
-        partsCost,
-        discountPercentage,
-        totalAmount,
-        paymentDate,
-        paymentMethod,
-        status
-    );
-}
-
-/*
-Function: getHeaders
-Description: Retrieves the CSV headers for invoice serialization.
-Parameters:
-    - None
-Returns:
-    - std::string: Header string ("ID,BookingID,InvoiceDate,LaborCost,PartIDs,PartsCost,DiscountPercentage,TotalAmount,PaymentDate,PaymentMethod,Status")
-*/
-std::string Invoice::getHeaders()
-{
-    return "ID,BookingID,InvoiceDate,LaborCost,PartIDs,PartsCost,DiscountPercentage,TotalAmount,PaymentDate,PaymentMethod,Status";
+        serializedInvoice.laborCost,
+        serializedInvoice.partsCost,
+        serializedInvoice.discountPercentage,
+        serializedInvoice.totalAmount,
+        serializedInvoice.paymentDate,
+        serializedInvoice.paymentMethod,
+        serializedInvoice.status);
 }
@@ -6,7 +6,6 @@ Author: Trenser
 Date: 19-May-2026
 */

-
 #pragma once
 #include <string>
 #include "Map.h"
@@ -16,6 +15,7 @@ Date: 19-May-2026

 class ServiceBooking;
 class InventoryItem;
+struct SerializedInvoice;

 class Invoice
 {
@@ -41,7 +41,7 @@ public:
        ServiceBooking* booking,
        const util::Timestamp& invoiceDate,
        double laborCost,
-        const util::Map<std::string,InventoryItem*>& parts,
+        const util::Map<std::string, InventoryItem*>& parts,
        double partsCost,
        double discountPercentage,
        double totalAmount,
@@ -87,7 +87,6 @@ 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();
+    SerializedInvoice serialize() const;
+    static Invoice* deserialize(const SerializedInvoice&);
 };
@@ -14,6 +14,28 @@ Date:19-May-2026
 #include "DataStoreLockGuard.h"

 User* AuthenticationManagementService::m_authenticatedUser = nullptr;
+bool AuthenticationManagementService::m_isAuthorized = false;
+EventManager AuthenticationManagementService::m_eventManager;
+HANDLE AuthenticationManagementService::m_accountDisabledEvent = NULL;
+HANDLE AuthenticationManagementService::m_notificationsAvailableEvent = NULL;
+
+
+/*
+Function: ensureAuthorization
+Description: Verifies that a user is currently authenticated before allowing
+			 access to a protected operation. Throws an exception if no
+			 authorized user session exists.
+Parameter: None
+Return type: void
+Throws: std::runtime_error - if the user is not authorized
+*/
+void AuthenticationManagementService::ensureAuthorization()
+{
+	if (!m_authenticatedUser || !m_isAuthorized)
+	{
+		throw std::runtime_error("You are not authorized to do this operation!");
+	}
+}

 /*
 Function: login
@@ -37,6 +59,24 @@ bool AuthenticationManagementService::login(const std::string& username, const s
 			if (password == user->getPassword())
 			{
 				m_authenticatedUser = user;
+				m_isAuthorized = true;
+				m_eventManager.initialize(
+					user->getId(),
+					[]()
+					{
+						if (m_accountDisabledEvent)
+						{
+							AuthenticationManagementService::m_isAuthorized = false;
+							SetEvent(m_accountDisabledEvent);
+						}
+					},
+					[]()
+					{
+						if (m_notificationsAvailableEvent)
+						{
+							SetEvent(m_notificationsAvailableEvent);
+						}
+					});
 				return true;
 			}
 			return false;
@@ -65,7 +105,11 @@ Return type: void
 */
 void AuthenticationManagementService::logout()
 {
+	m_eventManager.shutdown();
 	m_authenticatedUser = nullptr;
+	m_isAuthorized = false;
+	m_accountDisabledEvent = NULL;
+	m_notificationsAvailableEvent = NULL;
 }

 /*
@@ -77,6 +121,7 @@ Return type: void
 */
 void AuthenticationManagementService::changePassword(const std::string& newPassword)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	DataStoreLockGuard lock(m_dataStore);
 	auto& trackedUsersMap = m_dataStore.getUsers();
 	if (m_authenticatedUser == nullptr)
@@ -92,3 +137,17 @@ void AuthenticationManagementService::changePassword(const std::string& newPassw
 	trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
 	m_dataStore.saveUsers();
 }
+
+/*
+Function: registerEvents
+Description: Registers menu event handles used to notify the active
+			 menu of account disable and notification events.
+Parameter: HANDLE accountDisabledEvent - account disabled event handle
+		   HANDLE notificationAvailableEvent - notification event handle
+Return type: void
+*/
+void AuthenticationManagementService::registerEvents(HANDLE accountDisabledEvent, HANDLE notificationAvailableEvent)
+{
+	m_accountDisabledEvent = accountDisabledEvent;
+	m_notificationsAvailableEvent = notificationAvailableEvent;
+}
@@ -9,6 +9,8 @@ Date:19-May-2026

 #pragma once
 #include <string>
+#include <windows.h>
+#include "EventManager.h"
 #include "DataStore.h"

 class User;
@@ -17,11 +19,17 @@ class AuthenticationManagementService
 {
 private:
    static User* m_authenticatedUser;
+    static bool m_isAuthorized;
+    static EventManager m_eventManager;
+    static HANDLE m_accountDisabledEvent;
+    static HANDLE m_notificationsAvailableEvent;
    DataStore& m_dataStore;
 public:
    AuthenticationManagementService() : m_dataStore(DataStore::getInstance()) {}
+    static void ensureAuthorization();
    bool login(const std::string& username, const std::string& password);
    void logout();
    void changePassword(const std::string& newPassword);
    User* getAuthenticatedUser();
+    void registerEvents(HANDLE accountDisabledEvent, HANDLE notificationAvailableEvent);
 };
@@ -14,11 +14,13 @@ Date: 22-May-2026
 #include "Factory.h"
 #include "InventoryItem.h"
 #include "InventoryManagementService.h"
+#include "AuthenticationManagementService.h"
 #include "Timestamp.h"
 #include "User.h"
 #include "Utility.h"
 #include "Vector.h"
 #include "DataStoreLockGuard.h"
+#include "EventManager.h"

 util::Map<std::string, User*> InventoryManagementService::m_observers{};

@@ -57,18 +59,19 @@ Returns:
 */
 void InventoryManagementService::sendLowStockAlerts()
 {
-	auto& inventoryItems = m_dataStore.getInventoryItems();
-	if (inventoryItems.isEmpty())
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedInventoryItemsMap = m_dataStore.getInventoryItems();
+	auto& trackedUserMap = m_dataStore.getUsers();
+	if (trackedInventoryItemsMap.isEmpty())
 	{
 		return;
 	}
-	int inventoryItemsSize = inventoryItems.getSize();
-	auto& usersMap = m_dataStore.getUsers();
-	int usersMapSize = usersMap.getSize();
+	int inventoryItemsSize = trackedInventoryItemsMap.getSize();
+	int usersMapSize = trackedUserMap.getSize();
 	util::Vector<User*> adminUsers;
 	for (int index = 0; index < usersMapSize; index++)
 	{
-		User* user = usersMap.getValueAt(index);
+		User* user = trackedUserMap.getValueAt(index).data;
 		if (user->getUserType() == util::UserType::ADMIN)
 		{
 			adminUsers.push_back(user);
@@ -81,7 +84,7 @@ void InventoryManagementService::sendLowStockAlerts()
 	}
 	for (int index = 0; index < inventoryItemsSize; index++)
 	{
-		InventoryItem* inventoryItem = inventoryItems.getValueAt(index);
+		InventoryItem* inventoryItem = trackedInventoryItemsMap.getValueAt(index).data;
 		if (inventoryItem && inventoryItem->getQuantity() < config::threshold::INVENTORY_LOW_STOCK_THRESHOLD)
 		{
 			sendLowStockAlertsToAdmins(*this, inventoryItem, adminUsers);
@@ -100,8 +103,12 @@ Return type: void
 */
 void InventoryManagementService::addInventoryItem(const std::string& partName, int quantity, double price)
 {
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedInventoryItemMap = m_dataStore.getInventoryItems();
    InventoryItem* newItem = Factory::getObject<InventoryItem>(partName, quantity, price);
-    m_dataStore.getInventoryItems().insert(newItem->getId(), newItem);
+	trackedInventoryItemMap.insert(newItem->getId(), util::createNewRecord(newItem));
+	m_dataStore.saveInventoryItems();
 }

 /*
@@ -113,16 +120,23 @@ Return type: void
 */
 void InventoryManagementService::addInventoryItemStock(const std::string& selectedItemId, int quantity)
 {
-    int index = m_dataStore.getInventoryItems().find(selectedItemId);
-    if (index != -1)
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedInventoryItemMap = m_dataStore.getInventoryItems();
+	int index = trackedInventoryItemMap.find(selectedItemId);
+	if (index == -1)
 	{
-        InventoryItem* item = m_dataStore.getInventoryItems().getValueAt(index);
-        if (item != nullptr)
+		throw std::runtime_error("Inventory update failed: Item ID '" + selectedItemId + "' not found.");
+	}
+	InventoryItem* item = trackedInventoryItemMap.getValueAt(index).data;
+	if (item == nullptr)
 	{
+		throw std::runtime_error("Inventory update failed. Item does not exist.\n");
+	}
 	int totalQuantity = item->getQuantity() + quantity;
 	item->setQuantity(totalQuantity);
-        }
-    }
+	trackedInventoryItemMap.getValueAt(index).state = RecordState::MODIFIED;
+	m_dataStore.saveInventoryItems();
 }

 /*
@@ -133,7 +147,11 @@ Return type: util::Map<std::string, InventoryItem*>
 */
 util::Map<std::string, InventoryItem*> InventoryManagementService::getInventoryItems()
 {
-	return m_dataStore.getInventoryItems();
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedInventoryItemMap = m_dataStore.getInventoryItems();
+	auto inventoryMap = util::getObjects(trackedInventoryItemMap);
+	return inventoryMap;
 }

 /*
@@ -144,15 +162,22 @@ Return type: void
 */
 void InventoryManagementService::removeInventoryItem(const std::string& inventoryItemID)
 {
-    int index = m_dataStore.getInventoryItems().find(inventoryItemID);
-    if (index != -1)
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedInventoryItemMap = m_dataStore.getInventoryItems();
+	int index = trackedInventoryItemMap.find(inventoryItemID);
+	if (index == -1)
 	{
-        InventoryItem* item = m_dataStore.getInventoryItems().getValueAt(index);
-        if (item != nullptr)
+		throw std::runtime_error("Inventory removal failed: Item ID '" + inventoryItemID + "' not found.");
+	}
+	InventoryItem* item = trackedInventoryItemMap.getValueAt(index).data;
+	if (item == nullptr)
 	{
+		throw std::runtime_error("Inventory removal failed: Item ID does not exist.");
+	}
 	item->setState(util::State::INACTIVE);
-        }
-    }
+	trackedInventoryItemMap.getValueAt(index).state = RecordState::MODIFIED;
+	m_dataStore.saveInventoryItems();
 }

 /*
@@ -163,12 +188,20 @@ Return type: InventoryItem*
 */
 InventoryItem* InventoryManagementService::getInventoryItem(const std::string& inventoryItemID)
 {
-    int index = m_dataStore.getInventoryItems().find(inventoryItemID);
-    if (index != -1)
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedInventoryItemMap = m_dataStore.getInventoryItems();
+    int index = trackedInventoryItemMap.find(inventoryItemID);
+    if (index == -1)
    {
-        return m_dataStore.getInventoryItems().getValueAt(index);
-    }
 		return nullptr;
+    }
+	InventoryItem* inventoryItem = trackedInventoryItemMap.getValueAt(index).data;
+	if (inventoryItem == nullptr)
+	{
+		throw std::runtime_error("Item ID does not exist.");
+	}
+	return inventoryItem;
 }

 /*
@@ -243,6 +276,7 @@ void InventoryManagementService::sendNotification(User* user, const std::string&
 	{
 		return;
 	}
+	auto& trackedNotificationsMap = m_dataStore.getNotifications();
 	Notification* notification = Factory::getObject<Notification>(
 		user->getId(),
 		title,
@@ -252,8 +286,8 @@ void InventoryManagementService::sendNotification(User* user, const std::string&
 	{
 		throw std::runtime_error("Failed to create notification");
 	}
-	auto& trackedNotificationsMap = m_dataStore.getNotifications();
 	trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
 	m_dataStore.saveNotifications();
+	EventManager::sendNotificationAvailableEvent(user->getId());
 }

@@ -15,12 +15,15 @@ Date: 20-May-2026
 #include "Invoice.h"
 #include "JobCard.h"
 #include "PaymentManagementService.h"
+#include "AuthenticationManagementService.h"
+#include "DataStoreLockGuard.h"
 #include "Service.h"
 #include "ServiceBooking.h"
 #include "Timestamp.h"
 #include "User.h"
 #include "Utility.h"
 #include "DataStoreLockGuard.h"
+#include "EventManager.h"

 util::Map<std::string, User*> PaymentManagementService::m_observers{};

@@ -96,6 +99,7 @@ void PaymentManagementService::sendNotification(User* user, const std::string& t
 	{
 		return;
 	}
+	auto& trackedNotificationsMap = m_dataStore.getNotifications();
 	Notification* notification = Factory::getObject<Notification>(
 		user->getId(),
 		title,
@@ -105,9 +109,9 @@ void PaymentManagementService::sendNotification(User* user, const std::string& t
 	{
 		throw std::runtime_error("Failed to create notification");
 	}
-	auto& trackedNotificationsMap = m_dataStore.getNotifications();
 	trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
 	m_dataStore.saveNotifications();
+	EventManager::sendNotificationAvailableEvent(user->getId());
 }

 /*
@@ -121,11 +125,12 @@ Returns:
 */
 void PaymentManagementService::sendPaymentReminders()
 {
-	auto& invoicesMap = m_dataStore.getInvoices();
-	int invoicesMapSize = invoicesMap.getSize();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedInvoicesMap = m_dataStore.getInvoices();
+	int invoicesMapSize = trackedInvoicesMap.getSize();
 	for (int index = 0; index < invoicesMapSize; index++)
 	{
-		const Invoice* invoice = invoicesMap.getValueAt(index);
+		const Invoice* invoice = trackedInvoicesMap.getValueAt(index).data;
 		if (invoice && invoice->getStatus() == util::PaymentStatus::PENDING)
 		{
 			util::Timestamp invoiceCreationTimestamp = invoice->getInvoiceDate();
@@ -181,6 +186,7 @@ Throws:
 */
 void PaymentManagementService::generateInvoice(ServiceBooking* booking)
 {
+	DataStoreLockGuard lock(m_dataStore);
 	if (!booking)
 	{
 		throw std::runtime_error("Invoice generation failed: booking is null.");
@@ -190,10 +196,10 @@ void PaymentManagementService::generateInvoice(ServiceBooking* booking)
 	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++)
+	auto& currentTrackedJobCards = m_dataStore.getJobCards();
+	for (int iterator = 0; iterator < currentTrackedJobCards.getSize(); iterator++)
 	{
-		JobCard* currentJobCard = currentJobCards.getValueAt(iterator);
+		JobCard* currentJobCard = currentTrackedJobCards.getValueAt(iterator).data;
 		util::ServiceJobStatus currentJobCardStatus = currentJobCard->getStatus();
 		if (currentJobCard->getBookingId() == bookingID && currentJobCardStatus != util::ServiceJobStatus::CANCELLED && currentJobCardStatus != util::ServiceJobStatus::COMPLETED)
 		{
@@ -213,8 +219,9 @@ void PaymentManagementService::generateInvoice(ServiceBooking* booking)
 	totalServiceCost = totalLaborCost + totalPartsCost;
 	totalServiceCost -= (totalServiceCost * (discountPercentage / 100));
 	Invoice* invoice = Factory::getObject<Invoice>(bookingID, booking, util::Timestamp(), totalLaborCost, 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);
+	auto& currentTrackedInvoices = m_dataStore.getInvoices();
+	currentTrackedInvoices.insert(invoice->getId(), util::createNewRecord(invoice));
+	m_dataStore.saveInvoices();
 }

 /*
@@ -227,11 +234,13 @@ Returns:
 */
 util::Map<std::string, Invoice*> PaymentManagementService::getInvoices(const std::string& customerID)
 {
-	util::Map<std::string, Invoice*>& currentInvoices = m_dataStore.getInvoices();
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& currentTrackedInvoices = m_dataStore.getInvoices();
 	util::Map<std::string, Invoice*> currentUserInvoices;
-	for (int iterator = 0; iterator < currentInvoices.getSize(); iterator++)
+	for (int iterator = 0; iterator < currentTrackedInvoices.getSize(); iterator++)
 	{
-		Invoice* currentInvoice = currentInvoices.getValueAt(iterator);
+		Invoice* currentInvoice = currentTrackedInvoices.getValueAt(iterator).data;
 		if (currentInvoice->getBooking()->getCustomerId() == customerID)
 		{
 			currentUserInvoices.insert(currentInvoice->getId(), currentInvoice);
@@ -254,11 +263,14 @@ Throws:
 */
 void PaymentManagementService::completePayment(const std::string& invoiceID, util::PaymentMode paymentMode)
 {
-	auto& currentInvoices = m_dataStore.getInvoices();
-	int invoiceIndex = currentInvoices.find(invoiceID);
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& currentTrackedInvoices = m_dataStore.getInvoices();
+	int invoiceIndex = currentTrackedInvoices.find(invoiceID);
 	if (invoiceIndex != -1)
 	{
-		Invoice* invoice = currentInvoices.getValueAt(invoiceIndex);
+		auto& trackedInvoice = currentTrackedInvoices.getValueAt(invoiceIndex);
+		Invoice* invoice = trackedInvoice.data;
 		if (invoice && invoice->getStatus() != util::PaymentStatus::PAID)
 		{
 			User* currentUser = invoice->getBooking()->getCustomer();
@@ -269,25 +281,31 @@ void PaymentManagementService::completePayment(const std::string& invoiceID, uti
 			title = "Payment successful";
 			message = "Payment successful for Invoice ID " + invoiceID;
 			sendNotification(currentUser, title, message);
+			trackedInvoice.state = RecordState::MODIFIED;
 		}
 	}
 	else
 	{
 		throw std::runtime_error("Payment failed: invalid invoice ID.");
 	}
+	m_dataStore.saveInvoices();
 }

 /*
-Function: getAllInvoice
+Function: getAllInvoices
 Description: Provides access to all invoices stored in the data store.
 Parameters:
 	- none
 Returns:
-	- util::Map<std::string, Invoice*>&: Map of invoice IDs to invoice objects
+	- util::Map<std::string, Invoice*>: Map of invoice IDs to invoice objects
 */
-util::Map<std::string, Invoice*>& PaymentManagementService::getAllInvoices()
+util::Map<std::string, Invoice*> PaymentManagementService::getAllInvoices()
 {
-	return m_dataStore.getInvoices();
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	util::Map<std::string, Invoice*> invoices;
+	invoices = util::getObjects(m_dataStore.getInvoices());
+	return invoices;
 }

 /*
@@ -303,20 +321,25 @@ Throws:
 */
 void PaymentManagementService::confirmPayment(const std::string& invoiceID)
 {
-	auto& currentInvoices = m_dataStore.getInvoices();
-	int invoiceIndex = currentInvoices.find(invoiceID);
+    AuthenticationManagementService::ensureAuthorization();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& currentTrackedInvoices = m_dataStore.getInvoices();
+	int invoiceIndex = currentTrackedInvoices.find(invoiceID);
 	if (invoiceIndex == -1)
 	{
 		throw std::runtime_error("Payment confirmation failed: invalid invoice ID.");
 	}
-	Invoice* invoice = currentInvoices.getValueAt(invoiceIndex);
+	auto& trackedInvoice = currentTrackedInvoices.getValueAt(invoiceIndex);
+	Invoice* invoice = trackedInvoice.data;
 	if (!invoice || invoice->getStatus() != util::PaymentStatus::PAID)
 	{
 		throw std::runtime_error("Payment confirmation failed: invoice is not awaiting confirmation.");
 	}
 	User* currentUser = invoice->getBooking()->getCustomer();
 	invoice->setStatus(util::PaymentStatus::COMPLETED);
+	trackedInvoice.state = RecordState::MODIFIED;
 	std::string title = "Payment Confirmed";
 	std::string message = "Payment Confirmed for Invoice ID " + invoiceID;
 	sendNotification(currentUser, title, message);
+	m_dataStore.saveInvoices();
 }
@@ -27,7 +27,7 @@ public:
    void generateInvoice(ServiceBooking* booking);
    util::Map<std::string, Invoice*> getInvoices(const std::string& customerID);
    void completePayment(const std::string& invoiceID, util::PaymentMode paymentMode);
-    util::Map<std::string, Invoice*>& getAllInvoices();
+    util::Map<std::string, Invoice*> getAllInvoices();
    void confirmPayment(const std::string& invoiceID);
    void sendPaymentReminders();
    void sendNotification(User* user, const std::string& title, const std::string& message) override;
@@ -26,7 +26,32 @@ Date:19-May-2026
 #include "UserManagementService.h"
 #include "DataStoreLockGuard.h"
 #include "Utility.h"
-#include "DataStoreLockGuard.h"
+#include "EventManager.h"
+
+/*
+Function: notifyAllAdmins
+Description: Sends a notification to all users with the ADMIN role.
+             Iterates through the provided user collection and delivers
+             the specified notification to each administrator using the
+             ServiceManagementService notification mechanism.
+Parameter: const std::string& title - notification title
+Parameter: const std::string& message - notification message
+Parameter: const util::Map<std::string, TrackedRecord<User>>& users - collection of tracked users
+Parameter: ServiceManagementService* serviceManagementService - service used to dispatch notifications
+Return type: void
+*/
+static void notifyAllAdmins(const std::string& title, const std::string& message, const util::Map<std::string, TrackedRecord<User>>& users, ServiceManagementService* serviceManagementService)
+{
+    int numberOfUsers = users.getSize();
+    for (int index = 0; index < numberOfUsers; index++)
+    {
+        User* user = users.getValueAt(index).data;
+        if (user->getUserType() == util::UserType::ADMIN)
+        {
+            serviceManagementService->sendNotification(user, title, message);
+        }
+    }
+}

 /*
 Function: purchaseService
@@ -41,6 +66,7 @@ Return type: void
 */
 void ServiceManagementService::purchaseService(const util::Vector<std::string>& serviceIDs, const std::string& vehicleNumber, const std::string& vehicleBrand, const std::string& vehicleModel)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	AuthenticationManagementService m_authenticationManagementService;
 	auto authenticatedUser = m_authenticationManagementService.getAuthenticatedUser();
 	if (authenticatedUser == nullptr)
@@ -71,6 +97,8 @@ void ServiceManagementService::purchaseService(const util::Vector<std::string>&
    std::string title = "Service Booking succeeded";
    std::string message = "Your service booking has been successfully placed with ID " + serviceBooking->getId();
    sendNotification(authenticatedUser, title, message);
+    m_dataStore.saveServiceBookings();
+    notifyAllAdmins("New Service Order Available", "A new service order has been placed with Service Booking ID " + serviceBooking->getId(), m_dataStore.getUsers(), this);
 }

 /*
@@ -86,6 +114,7 @@ Return type: void
 */
 void ServiceManagementService::purchaseComboPackage(const std::string& comboPackageID, const std::string& vehicleNumber, const std::string& vehicleBrand, const std::string& vehicleModel)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	AuthenticationManagementService m_authenticationManagementService;
 	auto authenticatedUser = m_authenticationManagementService.getAuthenticatedUser();
 	if (authenticatedUser == nullptr)
@@ -111,6 +140,8 @@ void ServiceManagementService::purchaseComboPackage(const std::string& comboPack
    std::string title = "Combo Package Service Booking succeeded";
    std::string message = "Your service booking for the combo package has been successfully placed with ID " + serviceBooking->getId();
    sendNotification(authenticatedUser, title, message);
+    m_dataStore.saveServiceBookings();
+    notifyAllAdmins("New Combo Package Order Available", "A new combo package order has been placed with Service Booking ID " + serviceBooking->getId(), m_dataStore.getUsers(), this);
 }

 util::Map<std::string, User*> ServiceManagementService::m_observers{};
@@ -187,6 +218,7 @@ void ServiceManagementService::sendNotification(User* user, const std::string& t
    {
        return;
    }
+    auto& trackedNotificationsMap = m_dataStore.getNotifications();
    Notification* notification = Factory::getObject<Notification>(
        user->getId(),
        title,
@@ -196,9 +228,9 @@ void ServiceManagementService::sendNotification(User* user, const std::string& t
    {
        throw std::runtime_error("Failed to create notification");
    }
-    auto& trackedNotificationsMap = m_dataStore.getNotifications();
    trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
    m_dataStore.saveNotifications();
+    EventManager::sendNotificationAvailableEvent(user->getId());
 }

 /*
@@ -431,6 +463,7 @@ Return type: void
 */
 void ServiceManagementService::createComboPackage(const std::string& packageName, const util::Vector<std::string>& serviceIDsInNewCombo, double discountPercentage)
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
    if (packageName.empty())
    {
@@ -500,6 +533,7 @@ Return type: util::Map<std::string, ComboPackage*>
 */
 util::Map<std::string, ComboPackage*> ServiceManagementService::getComboPackages()
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
    util::Map<std::string, ComboPackage*> comboPackages;
    comboPackages = util::getObjects(m_dataStore.getComboPackages());
@@ -514,6 +548,7 @@ Return type: void
 */
 void ServiceManagementService::removeComboPackage(const std::string& comboPackageID)
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
    bool removed = false;
    auto& trackedComboPackages = m_dataStore.getComboPackages();
@@ -546,6 +581,7 @@ Returns:
 */
 util::Map<std::string, ServiceBooking*> ServiceManagementService::getServiceBookings()
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
    util::Map<std::string, ServiceBooking*> serviceBookings;
    serviceBookings = util::getObjects(m_dataStore.getServiceBookings());
@@ -562,6 +598,7 @@ Returns:
 */
 ServiceBooking* ServiceManagementService::getServiceBooking(const std::string& serviceID)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	auto currentServiceBookings = getServiceBookings();
 	for (int iterator = 0; iterator < currentServiceBookings.getSize(); iterator++)
 	{
@@ -588,14 +625,28 @@ Throws:
 */
 void ServiceManagementService::createJobCard(const std::string& bookingID, const std::string& technicianID, const std::string& serviceID)
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
 	UserManagementService m_userManagementService;
 	ServiceBooking* currentBooking = getServiceBooking(bookingID);
-	auto& currentTrackedJobCards = m_dataStore.getJobCards();
+    std::string title, message;
    if (currentBooking == nullptr)
    {
        throw std::runtime_error("Service Booking not available");
    }
+    if (currentBooking->getStatus() == util::ServiceJobStatus::CANCELLED)
+    {
+        throw std::runtime_error("Cannot create job card. Service Booking was cancelled!");
+    }
+	auto& currentTrackedJobCards = m_dataStore.getJobCards();
+    auto& currentTrackedInventoryItems = m_dataStore.getInventoryItems();
+    auto& currentTrackedServiceBookings = m_dataStore.getServiceBookings();
+    int currentTrackedServiceBookingIndex = currentTrackedServiceBookings.find(bookingID);
+    if (currentTrackedServiceBookingIndex == -1)
+    {
+        throw std::runtime_error("Invalid service booking id.");
+    }
+    auto& currentTrackedServiceBooking = currentTrackedServiceBookings.getValueAt(currentTrackedServiceBookingIndex);
 	auto& currentServices = currentBooking->getServices();
 	if (currentServices.find(serviceID) == -1)
 	{
@@ -620,23 +671,44 @@ void ServiceManagementService::createJobCard(const std::string& bookingID, const
 	for (int iterator = 0; iterator < inventoryItems.getSize(); iterator++)
 	{
 		InventoryItem* currentInventoryItem = inventoryItems.getValueAt(iterator);
+        const std::string& currentInventoryItemId = inventoryItems.getKeyAt(iterator);
 		if (currentInventoryItem)
 		{
+            int trackedCurrentInventoryItemIndex = currentTrackedInventoryItems.find(currentInventoryItemId);
+            if (trackedCurrentInventoryItemIndex == -1)
+            {
+                throw std::runtime_error("Invalid inventory item index.");
+            }
+            auto& trackedCurrentInventoryItem = currentTrackedInventoryItems.getValueAt(trackedCurrentInventoryItemIndex);
 			int currentStockQuantity = currentInventoryItem->getQuantity();
 			currentInventoryItem->setQuantity(currentStockQuantity - 1);
+            trackedCurrentInventoryItem.state = RecordState::MODIFIED;
 		}
 	}
+    const User* currentAssignedTechnician = currentBooking->getAssignedTechnician();
+    const std::string& currentAssignedTechnicianId = currentBooking->getAssignedTechnicianId();
+    if (!currentAssignedTechnician && currentAssignedTechnicianId.empty())
+    {
        currentBooking->setAssignedTechnician(selectedTechnician);
        currentBooking->setAssignedTechnicianId(selectedTechnician->getId());
+        title = "Technician assigned";
+        message = "A technician has been assigned to your Service Booking with ID " + bookingID;
+        sendNotification(currentBooking->getCustomer(), title, message);
+    }
+
    if (currentBooking->getStatus() == util::ServiceJobStatus::PENDING)
    {
        currentBooking->setStatus(util::ServiceJobStatus::STARTED);
    }
-	std::string title = "Job card created";
-	std::string message = "Job card created for the service and you are assigned for that.";
+    currentTrackedServiceBooking.state = RecordState::MODIFIED;
 	JobCard* jobCard = Factory::getObject<JobCard>(bookingID, currentBooking, currentService, serviceID, technicianID, selectedTechnician, util::Timestamp(), util::ServiceJobStatus::STARTED, util::Timestamp());
 	if (jobCard)
 	{
+        title = "Job Card Assigned";
+        message = "A new Job Card (ID: " + jobCard->getId() +
+            ") has been created for Service " + serviceID +
+            " in Booking " + bookingID +
+            ". You have been assigned to this job.";
 		currentTrackedJobCards.insert(jobCard->getId(), util::createNewRecord(jobCard));
 		sendNotification(selectedTechnician, title, message);
 	}
@@ -644,10 +716,9 @@ void ServiceManagementService::createJobCard(const std::string& bookingID, const
 	{
 		throw std::runtime_error("Failed to create job card.");
 	}
-    title = "Technician assigned";
-    message = "A technician has been assigned to your Service Booking with ID " + bookingID;
-    sendNotification(currentBooking->getCustomer(), title, message);
    m_dataStore.saveJobCards();
+    m_dataStore.saveServiceBookings();
+    m_dataStore.saveInventoryItems();
 }

 /*
@@ -665,6 +736,7 @@ Throws:
 */
 void ServiceManagementService::createService(const std::string& name, const util::Vector<std::string>& inventoryItemIDs, double laborCost)
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
 	util::Map<std::string, InventoryItem*> currentServiceInventoryItems;
 	auto& trackedInventoryItems = m_dataStore.getInventoryItems();
@@ -711,6 +783,7 @@ Returns:
 */
 util::Map<std::string, Service*> ServiceManagementService::getServices()
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
    util::Map<std::string, Service*> services;
    services = util::getObjects(m_dataStore.getServices());
@@ -729,6 +802,7 @@ Throws:
 */
 void ServiceManagementService::removeService(const std::string& serviceID)
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
 	auto& currentTrackedServices = m_dataStore.getServices();
    auto& currentTrackedComboPackages =  m_dataStore.getComboPackages();
@@ -766,6 +840,61 @@ void ServiceManagementService::removeService(const std::string& serviceID)
    m_dataStore.saveComboPackages();
 }

+/*
+Function: removeServiceBooking
+Description: Removes a pending service booking by its ID.
+             Cancels only if status is PENDING, otherwise throws exceptions
+             for invalid states. Sends notification to the customer and
+             persists changes.
+Parameter: const std::string& bookingID - ID of the service booking
+Return type: void
+*/
+void ServiceManagementService::removeServiceBooking(const std::string& bookingID)
+{
+    DataStoreLockGuard lock(m_dataStore);
+    auto& trackedServiceBookings = m_dataStore.getServiceBookings();
+    bool serviceBookingRemoved = false;
+    for (int iterator = 0; iterator < trackedServiceBookings.getSize(); iterator++)
+    {
+        auto& currentTrackedServiceBooking = trackedServiceBookings.getValueAt(iterator);
+        ServiceBooking* currentServiceBooking = currentTrackedServiceBooking.data;
+        if (currentServiceBooking && currentServiceBooking->getId() == bookingID)
+        {
+            if (currentServiceBooking->getStatus() == util::ServiceJobStatus::PENDING)
+            {
+                const std::string title = "Service Booking Cancelled";
+                const std::string message = "Service Booking (ID: " + bookingID + ") has been successfully cancelled";
+                currentServiceBooking->setStatus(util::ServiceJobStatus::CANCELLED);
+                currentTrackedServiceBooking.state = RecordState::MODIFIED;
+                serviceBookingRemoved = true;
+                sendNotification(currentServiceBooking->getCustomer(), title, message);
+                break;
+            }
+            else if(currentServiceBooking->getStatus() == util::ServiceJobStatus::COMPLETED)
+            {
+                throw std::runtime_error("Unable to cancel completed service booking.");
+            }
+            else if (currentServiceBooking->getStatus() == util::ServiceJobStatus::STARTED)
+            {
+                throw std::runtime_error("Unable to cancel started service booking.");
+            }
+            else if (currentServiceBooking->getStatus() == util::ServiceJobStatus::IN_PROGRESS)
+            {
+                throw std::runtime_error("Unable to cancel currently Inprogress service booking.");
+            }
+            else
+            {
+                throw std::runtime_error("Service Booking already cancelled.");
+            }
+        }
+    }
+    if (!serviceBookingRemoved)
+    {
+        throw std::runtime_error("Unable to cancel service booking.");
+    }
+    m_dataStore.saveServiceBookings();
+}
+
 /*
 Function: getServiceBookings (overloaded)
 Description: Retrieves all service bookings for a specific customer.
@@ -776,6 +905,7 @@ Returns:
 */
 util::Map<std::string, ServiceBooking*> ServiceManagementService::getServiceBookings(const std::string& customerID)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	util::Map<std::string, ServiceBooking*> currentServiceBookings = getServiceBookings();
 	util::Map<std::string, ServiceBooking*> currentUserServiceBookings;
 	if (currentServiceBookings.getSize() != 0)
@@ -802,6 +932,7 @@ Returns:
 */
 util::Map<std::string, JobCard*> ServiceManagementService::getJobCards(const std::string& technicianID)
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
 	auto& trackedJobCards = m_dataStore.getJobCards();
 	util::Map<std::string, JobCard*> technicianJobCards;
@@ -856,11 +987,11 @@ Returns:
 */
 void ServiceManagementService::updateJobStatus(const std::string& jobID)
 {
+    AuthenticationManagementService::ensureAuthorization();
    DataStoreLockGuard lock(m_dataStore);
    AuthenticationManagementService authenticationManagementService;
    PaymentManagementService paymentManagementService;
    bool jobStatusUpdated = false, serviceBookingCompleted;
-	JobCard* currentJob;
    User* currentTechnician = authenticationManagementService.getAuthenticatedUser();
    if (currentTechnician == nullptr)
    {
@@ -880,7 +1011,8 @@ void ServiceManagementService::updateJobStatus(const std::string& jobID)
        {
            throw std::runtime_error("Unable to fetch current job.");
        }
-		currentJob = currentAssignedJobs.getValueAt(currentAssignedJobs.find(jobID));
+        auto& trackedCurrentJob = trackedJobCards.getValueAt(jobIndex);
+        JobCard* currentJob = trackedCurrentJob.data;
        if (currentJob == nullptr)
        {
            throw std::runtime_error("Unable to fetch current job.");
@@ -888,13 +1020,13 @@ void ServiceManagementService::updateJobStatus(const std::string& jobID)
        if (currentJob->getStatus() == util::ServiceJobStatus::STARTED)
        {
            currentJob->setStatus(util::ServiceJobStatus::IN_PROGRESS);
-            trackedJobCards.getValueAt(jobIndex).state = RecordState::MODIFIED;
+            trackedCurrentJob.state = RecordState::MODIFIED;
            jobStatusUpdated = true;
        }
        else if (currentJob->getStatus() == util::ServiceJobStatus::IN_PROGRESS)
        {
            currentJob->setStatus(util::ServiceJobStatus::COMPLETED);
-            trackedJobCards.getValueAt(jobIndex).state = RecordState::MODIFIED;
+            trackedCurrentJob.state = RecordState::MODIFIED;
            jobStatusUpdated = true;
            serviceBookingCompleted = hasCompletedAllJobs(currentJob->getBookingId(), currentAssignedJobs);
            if (serviceBookingCompleted)
@@ -903,8 +1035,8 @@ void ServiceManagementService::updateJobStatus(const std::string& jobID)
                currentJob->getBooking()->setStatus(util::ServiceJobStatus::COMPLETED);
                trackedServiceBookings.getValueAt(trackedServiceBookings.find(bookingId)).state = RecordState::MODIFIED;
                paymentManagementService.generateInvoice(currentJob->getBooking());
-                std::string title = "Service Booking completed. Invoice Generated.";
-                std::string message = "Services completed for the booking and invoice generated.";
+                std::string title = "Service Booking Completed";
+                std::string message = "Service Booking (ID: " + bookingId + ") has been completed successfully. An invoice has been generated.";
                sendNotification(currentJob->getBooking()->getCustomer(), title, message);
            }
        }
@@ -35,6 +35,7 @@ public:
    void createJobCard(const std::string& bookingID, const std::string& technicianID, const std::string& serviceID);
    void createService(const std::string& name, const util::Vector<std::string>& inventoryItemIDs, double laborCost);
    void removeService(const std::string& serviceID);
+    void removeServiceBooking(const std::string& bookingID);
    util::Map<std::string, JobCard*> getJobCards(const std::string& technicianID);
    void updateJobStatus(const std::string& jobID);
    void cancelCustomerServiceBookings(const std::string& customerID);
@@ -15,6 +15,7 @@ Date:19-May-2026
 #include "Notification.h"
 #include "PaymentManagementService.h"
 #include "ServiceManagementService.h"
+#include "AuthenticationManagementService.h"
 #include "User.h"
 #include "UserManagementService.h"
 #include "Vector.h"
@@ -22,6 +23,7 @@ Date:19-May-2026
 #include "Utility.h"
 #include "TrackedRecord.h"
 #include "DataStoreLockGuard.h"
+#include "EventManager.h"

 /*
 Function: ensureAdminExists
@@ -113,6 +115,7 @@ Return type: void
 */
 void UserManagementService::updateUserDetails(const std::string& userID, const std::string& email, const std::string& phone)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	DataStoreLockGuard lock(m_dataStore);
 	auto& trackedUsersMap = m_dataStore.getUsers();
 	auto usersMap = util::getObjects(trackedUsersMap);
@@ -160,6 +163,7 @@ Throws:
 */
 util::Vector<Notification*> UserManagementService::getUserNotifications(const std::string& userID)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	DataStoreLockGuard lock(m_dataStore);
 	auto& trackedUsersMap = m_dataStore.getUsers(); 
 	if (trackedUsersMap.find(userID) == -1)
@@ -203,6 +207,7 @@ Throws:
 */
 void UserManagementService::deleteNotification(const std::string& notificationID, const std::string& userID)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	DataStoreLockGuard lock(m_dataStore);
 	auto& trackedUsersMap = m_dataStore.getUsers();
 	auto& trackedNotificationsMap = m_dataStore.getNotifications();
@@ -264,9 +269,12 @@ Return type: void
 */
 void UserManagementService::removeUser(const std::string& userID)
 {
+    AuthenticationManagementService::ensureAuthorization();
 	InventoryManagementService inventoryManagementService;
 	PaymentManagementService paymentManagementService;
 	ServiceManagementService serviceManagementService;
+	std::string removedUserID;
+	{
 		DataStoreLockGuard lock(m_dataStore);
 		auto& trackedUsersMap = m_dataStore.getUsers();
 		int index = trackedUsersMap.find(userID);
@@ -288,9 +296,15 @@ void UserManagementService::removeUser(const std::string& userID)
 				serviceManagementService.detach(user);
 				user->setState(util::State::INACTIVE);
 				trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
+				removedUserID = user->getId();
 				m_dataStore.saveUsers();
 			}
 		}
+	}
+	if (!removedUserID.empty())
+	{
+		EventManager::sendUserDisabledEvent(removedUserID);
+	}
 }

 /*
@@ -30,10 +30,16 @@ Return type: void
 */
 void AdminMenu::showMenu()
 {
+	startEventListener();
    while (true)
    {
        try
        {
+			if (!m_isMenuActive)
+			{
+				logout();
+				break;
+			}
            int choice;
            util::clear();
            std::cout << "Admin Menu"
@@ -68,6 +74,7 @@ void AdminMenu::showMenu()
            util::pressEnter();
        }
    }
+	stopEventListener();
 }

 /*
@@ -78,6 +85,11 @@ Return type: bool - true if menu continues, false if logout
 */
 bool AdminMenu::handleOperation(int choice)
 {
+	if (!m_isMenuActive)
+	{
+		logout();
+		return false;
+	}
    switch (choice)
    {
    case 1:
@@ -141,6 +153,25 @@ bool AdminMenu::handleOperation(int choice)
    return true;
 }

+/*
+Function: handleNotificationEvent
+Description: Retrieves and displays the latest notification for the
+			 currently logged in admin.
+Parameter: None
+Return type: void
+*/
+void AdminMenu::handleNotificationEvent()
+{
+	auto notifications = m_controller.getNotifications();
+	const User* authenticatedUser = m_controller.getAuthenticatedUser();
+	std::string name;
+	if (authenticatedUser)
+	{
+		name = authenticatedUser->getName();
+	}
+	displayNewNotification(notifications, name);
+}
+
 /*
 Function: logout
 Description: Logs out the currently authenticated admin user.
@@ -307,6 +338,23 @@ void AdminMenu::removeInventoryItem()
            std::string selectedItemId = selectedItem->getId();
            m_controller.removeInventoryItem(selectedItemId);
            std::cout << "Item " << selectedItem->getPartName() << " removed successfully." << std::endl;
+			const util::Map<std::string, const Service*>& listOfService = m_controller.getServices();
+			for (int serviceIndex = 0; serviceIndex < listOfService.getSize(); serviceIndex++)
+			{
+				const Service* service = listOfService.getValueAt(serviceIndex);
+				if (!service)
+				{
+					continue;
+				}
+				const util::Map<std::string, InventoryItem*>& requiredItems = service->getRequiredInventoryItems();
+				if (requiredItems.find(selectedItemId) != -1) 
+				{
+					m_controller.removeService(service->getId()); 
+					std::cout << "Service " << service->getName()
+						<< " removed as the item "
+						<< selectedItem->getPartName() << " required for the service has been removed." << std::endl;
+				}
+			}
        }
    }
    util::pressEnter();
@@ -9,12 +9,13 @@ Date:19-May-2026

 #pragma once
 #include "Controller.h"
+#include "Menu.h"

-class AdminMenu
+class AdminMenu : public Menu
 {
 private:
-    Controller m_controller;
    bool handleOperation(int choice);
+    void handleNotificationEvent() override;
 public:
    void showMenu();
    void logout();
@@ -32,10 +32,17 @@ Return type: void
 */
 void CustomerMenu::showMenu()
 {
+
+    startEventListener();
    while (true)
    {
        try
        {
+            if (!m_isMenuActive)
+            {
+                logout();
+                break;
+            }
            int choice;
            util::clear();
            std::cout << "Customer Menu"
@@ -44,11 +51,12 @@ void CustomerMenu::showMenu()
                << "\n3. Update Profile"
                << "\n4. Change Password"
                << "\n5. View Service History"
-                << "\n6. Complete Payments"
-                << "\n7. View Invoices"
-                << "\n8. View Notifications"
-                << "\n9. Configure Notifications"
-                << "\n10. Logout"
+                << "\n6. Cancel Service Booking"
+                << "\n7. Complete Payments"
+                << "\n8. View Invoices"
+                << "\n9. View Notifications"
+                << "\n10. Configure Notifications"
+                << "\n11. Logout"
                << "\nEnter a choice: ";
            util::read(choice);
            if (!handleOperation(choice))
@@ -62,6 +70,7 @@ void CustomerMenu::showMenu()
            util::pressEnter();
        }
    }
+    stopEventListener();
 }

 /*
@@ -72,6 +81,11 @@ Return type: bool - true if menu continues, false if logout
 */
 bool CustomerMenu::handleOperation(int choice)
 {
+    if (!m_isMenuActive)
+    {
+        logout();
+        return false;
+    }
    switch (choice)
    {
    case 1:
@@ -90,18 +104,21 @@ bool CustomerMenu::handleOperation(int choice)
        viewServiceHistory();
        break;
    case 6:
-        completePayments();
+        cancelServiceBooking();
        break;
    case 7:
-        viewInvoices();
+        completePayments();
        break;
    case 8:
-        viewNotifications();
+        viewInvoices();
        break;
    case 9:
-        configureNotifications();
+        viewNotifications();
        break;
    case 10:
+        configureNotifications();
+        break;
+    case 11:
        logout();
        return false;
    default:
@@ -111,6 +128,25 @@ bool CustomerMenu::handleOperation(int choice)
    return true;
 }

+/*
+Function: handleNotificationEvent
+Description: Retrieves and displays the latest notification for the
+             currently logged in admin.
+Parameter: None
+Return type: void
+*/
+void CustomerMenu::handleNotificationEvent()
+{
+    auto notifications = m_controller.getNotifications();
+    const User* authenticatedUser = m_controller.getAuthenticatedUser();
+    std::string name;
+    if (authenticatedUser)
+    {
+        name = authenticatedUser->getName();
+    }
+    displayNewNotification(notifications, name);
+}
+
 /*
 Function: logout
 Description: Logs out the currently authenticated customer user.
@@ -184,6 +220,13 @@ void CustomerMenu::selectService()
        util::pressEnter();
        return;
    }
+    if (!verifyAllPaymentsCompleted(m_controller))
+    {
+        std::cout << "Your booking cannot be processed because you have pending payments for previous services. Please complete all outstanding invoices before booking a new service."
+             << std::endl;
+        util::pressEnter();
+        return;
+    }
    util::Vector<std::string> selectedServices;
    const Service* selectedService = selectServiceFromServices(services);
    if (selectedService == nullptr)
@@ -226,6 +269,13 @@ void CustomerMenu::selectComboPackage()
        util::pressEnter();
        return;
    }
+    if (!verifyAllPaymentsCompleted(m_controller))
+    {
+        std::cout << "Your booking cannot be processed because you have pending payments for previous services. Please complete all outstanding invoices before booking a new combo package."
+            << std::endl;
+        util::pressEnter();
+        return;
+    }
    const ComboPackage* selectedComboPackage = selectComboPackageFromPackages(activeComboPackages);
    if (selectedComboPackage == nullptr)
    {
@@ -301,6 +351,46 @@ void CustomerMenu::viewServiceHistory()
    util::pressEnter();
 }

+/*
+Function: cancelServiceBooking
+Description: Allows the customer to cancel a pending service booking.
+             Displays the list of active bookings, lets the user select one,
+             and removes it from the system. If no bookings are available,
+             an appropriate message is shown.
+Parameter: None
+Return type: void
+*/
+void CustomerMenu::cancelServiceBooking()
+{
+    util::clear();
+    std::cout << "Cancel Service Booking\n";
+    const User* currentUser = m_controller.getAuthenticatedUser();
+    std::string currentUserID = currentUser->getId();
+    util::Map<std::string, const ServiceBooking*> serviceBookingsByCurrentUser = m_controller.getServiceBookingsByUser(currentUserID);
+    util::Map<int, const ServiceBooking*> serviceBookingsMap;
+    auto currentPendingServiceBookings = filterActiveServiceBookings(serviceBookingsByCurrentUser);
+    int bookingsSize = currentPendingServiceBookings.getSize();
+    if (listServiceBookings(currentPendingServiceBookings, bookingsSize, serviceBookingsMap))
+    {
+        const ServiceBooking* selectedService = selectPendingServiceBookings(serviceBookingsMap);
+        if (selectedService)
+        {
+            m_controller.removeServiceBooking(selectedService->getId());
+            std::cout << "Cancelled Service booking of id " + selectedService->getId() << std::endl << std::endl;
+        }
+        else
+        {
+            std::cout << "Invalid service booking index.\n\n";
+            return;
+        }
+    }
+    else
+    {
+        std::cout << "No pending service bookings available.\n\n";
+    }
+    util::pressEnter();
+}
+
 /*
 Function: completePayments
 Description: Allows the customer to complete pending payments for invoices.
@@ -9,13 +9,14 @@ Date:19-May-2026
 */

 #pragma once
+#include "Menu.h"
 #include "Controller.h"

-class CustomerMenu
+class CustomerMenu : public Menu
 {
 private:
-    Controller m_controller;
    bool handleOperation(int choice);
+    void handleNotificationEvent();
 public:
    void showMenu();
    void logout();
@@ -27,5 +28,6 @@ public:
    void completePayments();
    void viewInvoices();
    void viewNotifications();
+    void cancelServiceBooking();
    void configureNotifications();
 };
@@ -0,0 +1,150 @@
+/*
+File: Menu.cpp
+Description: Implementation file containing common menu event listener
+             functionality, account disable handling, and notification
+             event dispatching for all menu types.
+Author: Trenser
+Date:16-Jun-2026
+*/
+
+#include "Menu.h"
+
+/*
+Function: Menu
+Description: Constructs a Menu object and initializes event handles
+             and menu state.
+Parameter: None
+Return type: None
+*/
+Menu::Menu()
+    :
+    m_isMenuActive(false),
+    m_accountDisabledEvent(NULL),
+    m_notificationAvailableEvent(NULL),
+    m_shutdownEvent(NULL) {}
+
+/*
+Function: ~Menu
+Description: Destroys the Menu object and performs event listener
+             cleanup.
+Parameter: None
+Return type: None
+*/
+Menu::~Menu()
+{
+    stopEventListener();
+}
+
+/*
+Function: startEventListener
+Description: Creates menu event handles, registers them with the
+             authentication service, and starts the event listener
+             thread.
+Parameter: None
+Return type: void
+*/
+void Menu::startEventListener()
+{
+    if (m_isMenuActive.load())
+    {
+        return;
+    }
+    m_isMenuActive.store(true);
+    m_accountDisabledEvent = CreateEventA(NULL, FALSE, FALSE, NULL);
+    m_notificationAvailableEvent = CreateEventA(NULL, FALSE, FALSE, NULL);
+    m_shutdownEvent = CreateEventA(NULL, FALSE, FALSE, NULL);
+    m_controller.registerEvents(m_accountDisabledEvent, m_notificationAvailableEvent);
+    m_eventListenerThread = std::thread(&Menu::eventListenerLoop, this);
+}
+
+/*
+Function: eventListenerLoop
+Description: Waits for account disabled, notification available,
+             and shutdown events and dispatches them to the
+             appropriate handlers.
+Parameter: None
+Return type: void
+*/
+void Menu::eventListenerLoop()
+{
+    HANDLE handles[3] = { NULL, NULL, NULL };
+    handles[0] = m_accountDisabledEvent;
+    handles[1] = m_notificationAvailableEvent;
+    handles[2] = m_shutdownEvent;
+    while (m_isMenuActive.load())
+    {
+        DWORD result = WaitForMultipleObjects(3, handles, FALSE, INFINITE);
+        switch (result)
+        {
+        case WAIT_OBJECT_0:
+            handleAccountDisabledEvent();
+            break;
+        case WAIT_OBJECT_0 + 1:
+            handleNotificationEvent();
+            break;
+        case WAIT_OBJECT_0 + 2:
+            return;
+        }
+    }
+}
+
+/*
+Function: stopEventListener
+Description: Stops the event listener thread and releases all
+             associated event handles.
+Parameter: None
+Return type: void
+*/
+void Menu::stopEventListener()
+{
+    m_isMenuActive.store(false);
+    if (m_shutdownEvent)
+    {
+        SetEvent(m_shutdownEvent);
+    }
+    if (m_eventListenerThread.joinable())
+    {
+        m_eventListenerThread.join();
+    }
+    if (m_accountDisabledEvent)
+    {
+        CloseHandle(m_accountDisabledEvent);
+    }
+    if (m_notificationAvailableEvent)
+    {
+        CloseHandle(m_notificationAvailableEvent);
+    }
+    if (m_shutdownEvent)
+    {
+        CloseHandle(m_shutdownEvent);
+    }
+    m_accountDisabledEvent = NULL;
+    m_notificationAvailableEvent = NULL;
+    m_shutdownEvent = NULL;
+}
+
+/*
+Function: handleAccountDisabledEvent
+Description: Handles an account disabled event by marking the menu
+             inactive and notifying the user.
+Parameter: None
+Return type: void
+*/
+void Menu::handleAccountDisabledEvent()
+{
+    m_isMenuActive.store(false);
+    const User* authenticatedUser = m_controller.getAuthenticatedUser();
+    std::string messageTitle = "Account Disabled";
+    if (authenticatedUser)
+    {
+        messageTitle += " - " + authenticatedUser->getName();
+    }
+    MessageBoxA(
+        GetConsoleWindow(),
+        "Your account has been disabled.",
+        messageTitle.c_str(),
+        MB_OK |
+        MB_ICONWARNING |
+        MB_SETFOREGROUND |
+        MB_TOPMOST);
+}
@@ -0,0 +1,33 @@
+/*
+File: Menu.h
+Description: Base class providing common event listener functionality
+             for all menu implementations.
+Author: Trenser
+Date:16-Jun-2026
+*/
+
+#pragma once
+
+#include <windows.h>
+#include <atomic>
+#include <thread>
+#include "Controller.h"
+
+class Menu
+{
+protected:
+    Controller m_controller;
+    std::atomic<bool> m_isMenuActive;
+    HANDLE m_accountDisabledEvent;
+    HANDLE m_notificationAvailableEvent;
+    HANDLE m_shutdownEvent;
+    std::thread m_eventListenerThread;
+    void startEventListener();
+    void stopEventListener();
+    void eventListenerLoop();
+    void handleAccountDisabledEvent();
+    virtual void handleNotificationEvent() = 0;
+public:
+    Menu();
+    virtual ~Menu();
+};
@@ -28,6 +28,7 @@ Date: 21-May-2026
 #include "Utility.h"
 #include "Validator.h"
 #include "Vector.h"
+#include "StringHelper.h"

 /*
 Function: displayAllServices
@@ -587,7 +588,7 @@ inline void displayInvoices(util::Map<std::string, const Invoice*> currentUserIn
                    << util::getPaymentStatusString(selectedInvoice->getStatus()) << std::endl;
                std::cout << std::left << std::setw(20) << "Payment Mode:"
                    << util::getPaymentModeString(selectedInvoice->getPaymentMethod()) << std::endl;
-                auto inventoryItemsInInvoice = selectedInvoice->getParts();
+                auto& inventoryItemsInInvoice = selectedInvoice->getParts();
                if (inventoryItemsInInvoice.isEmpty())
                {
                    std::cout << "No inventory items used.\n\n";
@@ -596,7 +597,6 @@ inline void displayInvoices(util::Map<std::string, const Invoice*> currentUserIn
                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;
@@ -605,7 +605,6 @@ inline void displayInvoices(util::Map<std::string, const Invoice*> currentUserIn
                    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;
                }
@@ -1056,6 +1055,21 @@ inline const Service* selectServiceFromServices(const util::Map<std::string, con
        {
            continue;
        }
+        bool hasDepletedItem = false;
+        const util::Map<std::string, InventoryItem*>& requiredItems = currentService->getRequiredInventoryItems();
+        for (int itemIndex = 0; itemIndex < requiredItems.getSize(); itemIndex++)
+        {
+            const InventoryItem* item = requiredItems.getValueAt(itemIndex);
+            if (!item || item->getQuantity() < 1)
+            {
+                hasDepletedItem = true;
+                break;
+            }
+        }
+        if (hasDepletedItem)
+        {
+            continue; 
+        }
        activeServicesMap.insert(currentIndex, currentService);
        double partsCost = util::calculatePartsCost(currentService);
        std::cout << std::left
@@ -1130,7 +1144,9 @@ inline void displayAllComboPackages(util::Map<std::string, const ComboPackage*>
    for (int index = 0; index < comboPackages.getSize(); index++)
    {
        const ComboPackage* currentComboPackage = comboPackages.getValueAt(index);
-        if (currentComboPackage && currentComboPackage->getState() != util::State::ACTIVE)
+        if (currentComboPackage) 
+        {
+            if (currentComboPackage->getState() != util::State::ACTIVE)
            {
                continue;
            }
@@ -1140,6 +1156,7 @@ inline void displayAllComboPackages(util::Map<std::string, const ComboPackage*>
                << std::setw(15) << util::calculateComboServiceEstimatedCost(currentComboPackage)
                << std::endl;
        }
+    }
 }


@@ -1164,7 +1181,9 @@ inline const ComboPackage* selectComboPackageFromPackages(const util::Map<std::s
    for (int index = 0; index < comboPackages.getSize(); index++)
    {
        const ComboPackage* currentComboPackage = comboPackages.getValueAt(index);
-        if (currentComboPackage && currentComboPackage->getState() != util::State::ACTIVE)
+        if (currentComboPackage)
+        {
+            if (currentComboPackage->getState() != util::State::ACTIVE)
            {
                continue;
            }
@@ -1177,6 +1196,7 @@ inline const ComboPackage* selectComboPackageFromPackages(const util::Map<std::s
                << std::endl;
            currentIndex++;
        }
+    }
    if (activeComboPackages.getSize() == 0)
    {
        std::cout << "No active combo packages available." << std::endl;
@@ -1408,3 +1428,88 @@ inline std::string selectComboPackage(util::Map<std::string, const ComboPackage*
        return "";
    }
 }
+
+/*
+Function: displayNewNotification
+Description: Displays the most recent notification from the supplied
+             notification collection.
+Parameter: util::Vector<const Notification*> notifications -
+           collection of notifications
+           const std::string& - The name of the user currently authenticated with the system
+Return type: void
+*/
+inline void displayNewNotification(util::Vector<const Notification*> notifications, const std::string& name)
+{
+    const Notification* notification = nullptr;
+	size_t numberOfNotifications = notifications.getSize();
+	for (int index = 0; index < numberOfNotifications; index++)
+	{
+		if (!notification)
+		{
+			notification = notifications[index];
+		}
+		else
+		{
+            if (util::extractNumber(notification->getId()) < util::extractNumber(notifications[index]->getId()))
+			{
+				notification = notifications[index];
+			}
+		}
+	}
+    if (notification)
+    {
+        std::string messageTitle = notification->getTitle();
+        if (!name.empty())
+        {
+            messageTitle += " - " + name;
+        }
+        MessageBoxA(
+            GetConsoleWindow(),
+            notification->getMessage().c_str(),
+            messageTitle.c_str(),
+            MB_OK |
+            MB_ICONINFORMATION);
+    }
+}
+
+/*
+Function: verifyAllPaymentsCompleted
+Description: Checks whether the authenticated customer has completed
+             all payments for their invoices. Iterates through all
+             invoices belonging to the customer and verifies that
+             each invoice has a payment status of COMPLETED.
+Parameters: Controller& m_controller -
+            reference to the Controller object used to access
+            authenticated user and invoice data
+Return type: bool
+             true if all invoices for the authenticated customer
+             are completed, false if any invoice is pending or not completed
+Throws: std::runtime_error if no authenticated user is found
+*/
+inline bool verifyAllPaymentsCompleted(Controller& m_controller)
+{
+    const User* authenticatedUser = m_controller.getAuthenticatedUser();
+    if (!authenticatedUser)
+    {
+        throw std::runtime_error("No authenticated user found.");
+    }
+    const std::string& authenticatedUserId = authenticatedUser->getId();
+    util::Map<std::string, const Invoice*> listOfInvoices = m_controller.getAllInvoices();
+    for (int invoiceIndex = 0; invoiceIndex < listOfInvoices.getSize(); ++invoiceIndex)
+    {
+        const Invoice* invoice = listOfInvoices.getValueAt(invoiceIndex);
+        if (!invoice)
+        {
+            continue;
+        }
+        const std::string& customerId = invoice->getBooking()->getCustomerId();
+        if (customerId == authenticatedUserId)
+        {
+            if (invoice->getStatus() != util::PaymentStatus::COMPLETED)
+            {
+                return false;
+            }
+        }
+    }
+    return true;
+}
@@ -27,10 +27,16 @@ Returns:
 */
 void TechnicianMenu::showMenu()
 {
+    startEventListener();
    while (true)
    {
        try
        {
+            if (!m_isMenuActive)
+            {
+                logout();
+                break;
+            }
            int choice;
            util::clear();
            std::cout << "Technician Menu"
@@ -52,6 +58,7 @@ void TechnicianMenu::showMenu()
            util::pressEnter();
        }
    }
+    stopEventListener();
 }

 /*
@@ -62,6 +69,11 @@ Return type: bool - true if menu continues, false if logout
 */
 bool TechnicianMenu::handleOperation(int choice)
 {
+    if (!m_isMenuActive)
+    {
+        logout();
+        return false;
+    }
    switch (choice)
    {
    case 1:
@@ -86,6 +98,25 @@ bool TechnicianMenu::handleOperation(int choice)
    return true;
 }

+/*
+Function: handleNotificationEvent
+Description: Retrieves and displays the latest notification for the
+             currently logged in admin.
+Parameter: None
+Return type: void
+*/
+void TechnicianMenu::handleNotificationEvent()
+{
+    auto notifications = m_controller.getNotifications();
+    const User* authenticatedUser = m_controller.getAuthenticatedUser();
+    std::string name;
+    if (authenticatedUser)
+    {
+        name = authenticatedUser->getName();
+    }
+    displayNewNotification(notifications, name);
+}
+
 /*
 Function: displayJobs
 Description: Displays all Jobs assigned to a Technician
@@ -9,12 +9,13 @@ Date:19-May-2026

 #pragma once
 #include "Controller.h"
+#include "Menu.h"

-class TechnicianMenu
+class TechnicianMenu : public Menu
 {
 private:
-    Controller m_controller;
    bool handleOperation(int choice);
+    void handleNotificationEvent();
 public:
    void showMenu();
    void displayJobs();