Merge branch 'develop' into develop-sm-authentication-management

User Story #1953
User Story #1954

**Changes**
- Refactored Notification model to use SerializedNotification for shared memory persistence.
- Removed notification ownership from the User model and stored notifications separately in the DataStore.
- Added notification state tracking to support soft deletion.
- Updated notification creation, retrieval, and deletion flows to use DataStore-managed notifications.
- Refactored observer persistence for Service, Payment, and Inventory Management services to use shared memory mappings.
- Removed file-based observer loading and saving logic.
- Updated notification services to persist notifications directly through the DataStore.
- Added observer load/save support in DataStore.
- Removed legacy FileManager and file-based notification persistence utilities.
- Simplified observer interfaces and removed unused observer ID persistence methods.
- Updated application startup and shutdown flow to use DataStore initialization and cleanup.

Related work items: #1953, #1954

.gitignore

@@ -427,5 +427,5 @@ FodyWeavers.xsd
 *.msm
 *.msp
 
-# CSV Files
-*.csv
+# DAT Files
+*.dat

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

@@ -140,7 +140,6 @@
     <ClCompile Include="models\User.cpp" />
     <ClCompile Include="services\AuthenticationManagementService.cpp" />
     <ClCompile Include="services\InventoryManagementService.cpp" />
-    <ClCompile Include="services\NotificationManagementService.cpp" />
     <ClCompile Include="services\PaymentManagementService.cpp" />
     <ClCompile Include="services\ServiceManagementService.cpp" />
     <ClCompile Include="services\UserManagementService.cpp" />
@@ -157,6 +156,7 @@
     <ClInclude Include="core\patterns\Observer.h" />
     <ClInclude Include="core\patterns\Subject.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" />
@@ -181,7 +181,6 @@
     <ClInclude Include="utilities\Config.h" />
     <ClInclude Include="utilities\Enums.h" />
     <ClInclude Include="utilities\FileHelper.h" />
-    <ClInclude Include="utilities\FileManager.h" />
     <ClInclude Include="utilities\InputHelper.h" />
     <ClInclude Include="utilities\Map.h" />
     <ClInclude Include="utilities\OutputHelper.h" />

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

@@ -114,9 +114,6 @@
     <ClCompile Include="datastores\DataStore.cpp">
       <Filter>Source Files\DataStores</Filter>
     </ClCompile>
-    <ClCompile Include="services\NotificationManagementService.cpp">
-      <Filter>Source Files\Services</Filter>
-    </ClCompile>
     <ClCompile Include="core\patterns\Observer.cpp">
       <Filter>Source Files\Core\Patterns</Filter>
     </ClCompile>
@@ -245,9 +242,6 @@
     <ClInclude Include="utilities\Config.h">
       <Filter>Header Files\Utilities</Filter>
     </ClInclude>
-    <ClInclude Include="utilities\FileManager.h">
-      <Filter>Header Files\Utilities</Filter>
-    </ClInclude>
     <ClInclude Include="utilities\StringHelper.h">
       <Filter>Header Files\Utilities</Filter>
     </ClInclude>
@@ -278,5 +272,8 @@
     <ClInclude Include="datastores\sharedmemory\SharedMemory.h">
       <Filter>Header Files\DataStores\SharedMemory</Filter>
     </ClInclude>
+    <ClInclude Include="datastores\DataStoreLockGuard.h">
+      <Filter>Header Files\DataStores</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>

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

@@ -588,63 +588,37 @@ void Controller::configureNotifications(bool paymentNotifications, bool serviceN
 }
 
 /*
-Function: loadSystemData
-Description: Loads all system data from persistent storage into memory.
-             Invokes the respective management services to load users, inventory items, services,
-             combo packages, service bookings, job cards, invoices, and observers.
+Function: initialize
+Description: Initializes the system and run system checks to ensure critical configurations, such as verifying admin existence.
 Parameters:
     - None
 Returns:
-    - void
+    - bool
 */
-void Controller::loadSystemData()
+bool Controller::initialize()
 {
-    m_userManagementService.loadUsers();
-    m_inventoryManagementService.loadInventoryItems();
-    m_serviceManagementService.loadServices();
-    m_serviceManagementService.loadComboPackages();
-    m_serviceManagementService.loadServiceBookings();
-    m_serviceManagementService.loadJobCards();
-    m_paymentManagementService.loadInvoices();
-    m_serviceManagementService.loadObservers();
-    m_paymentManagementService.loadObservers();
-    m_inventoryManagementService.loadObservers();
-}
+    auto& dataStore = DataStore::getInstance();
 
-/*
-Function: saveSystemData
-Description: Saves all system data from memory back to persistent storage.
-             Invokes the respective management services to save users, inventory items, services,
-             combo packages, service bookings, job cards, invoices, and observers.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void Controller::saveSystemData()
-{
-    m_userManagementService.saveUsers();
-    m_inventoryManagementService.saveInventoryItems();
-    m_serviceManagementService.saveServices();
-    m_serviceManagementService.saveComboPackages();
-    m_serviceManagementService.saveServiceBookings();
-    m_serviceManagementService.saveJobCards();
-    m_paymentManagementService.saveInvoices();
-    m_serviceManagementService.saveObservers();
-    m_paymentManagementService.saveObservers();
-    m_inventoryManagementService.saveObservers();
-}
-
-/*
-Function: runSystemChecks
-Description: Runs system checks to ensure critical configurations, such as verifying admin existence.
-Parameter: None
-Return type: void
-*/
-void Controller::runSystemChecks()
-{
+    if (!dataStore.initialize())
+    {
+        return false;
+    }
     m_userManagementService.ensureAdminExists();
     m_inventoryManagementService.sendLowStockAlerts();
     m_paymentManagementService.sendPaymentReminders();
+    return true;
 }
 
+/*
+Function: shutdown
+Description: Shutdown the system, and do necessary cleanups
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void Controller::shutdown()
+{
+    auto& dataStore = DataStore::getInstance();
+    dataStore.shutdown();
+}

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

@@ -70,7 +70,6 @@ public:
     util::Vector<const Notification*> getNotifications();
     void deleteNotification(const std::string& notificationID);
     void configureNotifications(bool paymentNotifications, bool serviceNotifications);
-    void loadSystemData();
-    void saveSystemData();
-    void runSystemChecks();
+    bool initialize();
+    void shutdown();
 };

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

@@ -7,11 +7,8 @@ Date: 19-May-2026
 
 #pragma once
 
-class Notification;
-
 class Observer
 {
 public:
     virtual ~Observer() = default;
-    virtual void addNotification(Notification* notification) = 0;
 };

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

@@ -144,11 +144,6 @@ bool DataStore::initialize()
             success = false;
             break;
         }
-        if (!SharedMemory::createOrOpenMapping(m_payments))
-        {
-            success = false;
-            break;
-        }
         if (!SharedMemory::createOrOpenMapping(m_serviceManagementObservers))
         {
             success = false;
@@ -193,7 +188,6 @@ void DataStore::shutdown()
     SharedMemory::closeMapping(m_serviceBookings);
     SharedMemory::closeMapping(m_jobCards);
     SharedMemory::closeMapping(m_invoices);
-    SharedMemory::closeMapping(m_payments);
     SharedMemory::closeMapping(m_serviceManagementObservers);
     SharedMemory::closeMapping(m_paymentManagementObservers);
     SharedMemory::closeMapping(m_inventoryManagementObservers);
@@ -228,6 +222,8 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<User>>& DataStore::getUsers()
 {
+    auto users = loadRecords<User, SerializedUser>(m_users);
+    refreshCache(m_userCache, users);
     return m_userCache;
 }
 
@@ -241,6 +237,8 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<Notification>>& DataStore::getNotifications()
 {
+    auto notifications = loadRecords<Notification, SerializedNotification>(m_notifications);
+    refreshCache(m_notificationCache, notifications);
     return m_notificationCache;
 }
 
@@ -322,6 +320,37 @@ util::Map<std::string, TrackedRecord<Invoice>>& DataStore::getInvoices()
     return m_invoiceCache;
 }
 
+/*
+Function: getObservers
+Description: Retrieves observer records from the specified observer mapping
+             and resolves them to User objects.
+Parameters:
+    - mapping: Observer mapping to read from
+Returns:
+    - util::Map<std::string, User*>: Collection of observer records
+Throws:
+    - std::runtime_error if an observer references an invalid user ID
+*/
+util::Map<std::string, User*> DataStore::getObservers(MappingInfo& mapping)
+{
+    auto& users = getUsers();
+    util::Map<std::string, User*> observers;
+    SharedMemory::ensureLatestMapping(mapping);
+    size_t recordCount = SharedMemory::getRecordCount(mapping);
+    for (size_t index = 0; index < recordCount; index++)
+    {
+        const SerializedObserver* observer = static_cast<SerializedObserver*>(SharedMemory::getRecordAddress(mapping, index));
+        int userIndex = users.find(observer->id);
+        if (userIndex == -1)
+        {
+            throw std::runtime_error("Invalid observer user ID");
+        }
+        User* user = users.getValueAt(userIndex).data;
+        observers.insert(user->getId(), user);
+    }
+    return observers;
+}
+
 /*
 Function: getServiceManagementObservers
 Description: Retrieves all service management observer records from the datastore.
@@ -332,7 +361,7 @@ Returns:
 */
 util::Map<std::string, User*> DataStore::getServiceManagementObservers()
 {
-    return util::Map<std::string, User*>();
+    return getObservers(m_serviceManagementObservers);
 }
 
 /*
@@ -345,7 +374,7 @@ Returns:
 */
 util::Map<std::string, User*> DataStore::getPaymentManagementObservers()
 {
-    return util::Map<std::string, User*>();
+    return getObservers(m_paymentManagementObservers);
 }
 
 /*
@@ -358,7 +387,7 @@ Returns:
 */
 util::Map<std::string, User*> DataStore::getInventoryManagementObservers()
 {
-    return util::Map<std::string, User*>();
+    return getObservers(m_inventoryManagementObservers);
 }
 
 /*
@@ -371,6 +400,7 @@ Returns:
 */
 void DataStore::saveUsers()
 {
+    saveRecords<User, SerializedUser>(m_users, m_userCache);
 }
 
 /*
@@ -383,6 +413,7 @@ Returns:
 */
 void DataStore::saveNotifications()
 {
+    saveRecords<Notification, SerializedNotification>(m_notifications, m_notificationCache);
 }
 
 /*
@@ -457,16 +488,49 @@ void DataStore::saveInvoices()
 {
 }
 
+/*
+Function: saveObservers
+Description: Persists observer records to the specified observer mapping.
+Parameters:
+    - mapping: MappingInfo&, observer mapping to save to
+    - observers: util::Map<std::string, User*>&, collection of observer records
+Returns:
+    - None
+*/
+void DataStore::saveObservers(MappingInfo& mapping, util::Map<std::string, User*>& observers)
+{
+    size_t observerCount = static_cast<size_t>(observers.getSize());
+    size_t capacity = config::file::INITIAL_CAPACITY;
+    while (capacity < observerCount)
+    {
+        capacity *= config::file::GROWTH_FACTOR;
+    }
+    if (!SharedMemory::resizeMapping(mapping, capacity))
+    {
+        throw std::runtime_error("Failed to resize observer mapping");
+    }
+    SharedMemory::setRecordCount(mapping, observerCount);
+    for (size_t index = 0; index < observerCount; index++)
+    {
+        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));
+        *destination = serializedObserver;
+    }
+}
+
 /*
 Function: saveServiceManagementObservers
 Description: Persists all service management observer records to the datastore.
 Parameters:
-    - observers: util::Map<std::string, TrackedRecord<std::string>>&, collection of observer records
+    - observers: util::Map<std::string, User*>&, collection of observer records
 Returns:
     - None
 */
 void DataStore::saveServiceManagementObservers(util::Map<std::string, User*>& observers)
 {
+    saveObservers(m_serviceManagementObservers, observers);
 }
 
 /*
@@ -479,6 +543,7 @@ Returns:
 */
 void DataStore::savePaymentManagementObservers(util::Map<std::string, User*>& observers)
 {
+    saveObservers(m_paymentManagementObservers, observers);
 }
 
 /*
@@ -491,32 +556,7 @@ Returns:
 */
 void DataStore::saveInventoryManagementObservers(util::Map<std::string, User*>& observers)
 {
-}
-
-/*
-Function: lockDataStore
-Description: Acquires exclusive access to the datastore.
-Parameters:
-    - None
-Returns:
-    - bool: True if the datastore was successfully locked, otherwise false
-*/
-bool DataStore::lockDataStore()
-{
-    return false;
-}
-
-/*
-Function: unlockDataStore
-Description: Releases exclusive access to the datastore.
-Parameters:
-    - None
-Returns:
-    - bool: True if the datastore was successfully unlocked, otherwise false
-*/
-bool DataStore::unlockDataStore()
-{
-    return false;
+    saveObservers(m_inventoryManagementObservers, observers);
 }
 
 /*

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

@@ -12,14 +12,14 @@ Date: 19-May-2026
 #include "MappingInfo.h"
 #include "TrackedRecord.h"
 #include "SharedMemory.h"
-class User;
-class Notification;
-class Service;
-class ComboPackage;
-class InventoryItem;
-class ServiceBooking;
-class JobCard;
-class Invoice;
+#include "User.h"
+#include "Notification.h"
+#include "Service.h"
+#include "ComboPackage.h"
+#include "InventoryItem.h"
+#include "ServiceBooking.h"
+#include "JobCard.h"
+#include "Invoice.h"
 
 class DataStore
 {
@@ -39,7 +39,6 @@ private:
     MappingInfo m_serviceBookings;
     MappingInfo m_jobCards;
     MappingInfo m_invoices;
-    MappingInfo m_payments;
     MappingInfo m_serviceManagementObservers;
     MappingInfo m_paymentManagementObservers;
     MappingInfo m_inventoryManagementObservers;
@@ -86,6 +85,8 @@ private:
     void saveRecords(MappingInfo& mapping, util::Map<std::string, TrackedRecord<TObject>>& records);
     template<typename TObject> void clearCache(util::Map<std::string, TrackedRecord<TObject>>&cache);
     template<typename TObject> void refreshCache(util::Map<std::string, TrackedRecord<TObject>>&cache, util::Map<std::string, TrackedRecord<TObject>>&refreshedCache);
+    util::Map<std::string, User*> getObservers(MappingInfo& mapping);
+    void saveObservers(MappingInfo& mapping, util::Map<std::string, User*>& observers);
 };
 
 /*
@@ -229,9 +230,17 @@ void DataStore::refreshCache(util::Map<std::string, TrackedRecord<TObject>>& cac
     for (int index = 0; index < oldCache.getSize(); ++index)
     {
         const std::string& id = oldCache.getKeyAt(index);
+        const TrackedRecord<TObject>& localTrackedRecord = oldCache.getValueAt(index);
         if (cache.find(id) == -1)
         {
-            delete oldCache.getValueAt(index).data;
+            if (localTrackedRecord.state == RecordState::NEW_RECORD)
+            {
+                cache.insert(id, localTrackedRecord);
+            }
+            else
+            {
+                delete localTrackedRecord.data;
+            }
         }
     }
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStoreLockGuard.h

@@ -0,0 +1,28 @@
+/*
+File: DataStoreLockGuard.h
+Description: Defines the DataStoreLockGuard class used to manage DataStore
+             locking and unlocking automatically within a scope.
+Author: Trenser
+Date: 12-June-2026
+*/
+
+#pragma once
+#include "DataStore.h"
+
+class DataStoreLockGuard
+{
+public:
+    explicit DataStoreLockGuard(DataStore& dataStore)
+        : m_dataStore(dataStore)
+    {
+        m_dataStore.lockDataStore();
+    }
+    ~DataStoreLockGuard()
+    {
+        m_dataStore.unlockDataStore();
+    }
+    DataStoreLockGuard(const DataStoreLockGuard&) = delete;
+    DataStoreLockGuard& operator=(const DataStoreLockGuard&) = delete;
+private:
+    DataStore& m_dataStore;
+};

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/sharedmemory/SharedMemory.cpp

@@ -10,6 +10,7 @@ Created: 11-June-2026
 */
 
 #include "SharedMemory.h"
+#include "Windows.h"
 #include "Config.h"
 
 /*
@@ -319,7 +320,7 @@ bool SharedMemory::ensureCapacityForInsert(MappingInfo& mapping)
     {
         return true;
     }
-    return resizeMapping(mapping, capacity * 2);
+    return resizeMapping(mapping, capacity * config::file::GROWTH_FACTOR);
 }
 
 /*

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

@@ -12,6 +12,7 @@ Date: 19-May-2026
 #include "Enums.h"
 
 class Service;
+struct SerializedComboPackage;
 
 class ComboPackage
 {

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

@@ -1,12 +1,13 @@
 /*
 File: Notification.cpp
 Description: Implements the Notification class which represents system notifications in the Vehicle Service Management System.
-             Provides constructors, accessors, and mutators for notification details such as ID, recipient, title, message, and timestamp.
+             Provides constructors, accessors, and mutators for notification details such as ID, recipientID, title, message, and timestamp.
 Author: Trenser
 Date: 19-May-2026
 */
 
 #include <sstream>
+#include "SerializedRecords.h"
 #include "Notification.h"
 #include "StringHelper.h"
 #include "Factory.h"
@@ -22,8 +23,8 @@ Returns:
     - A new Notification object.
 */
 Notification::Notification()
-    : m_id("NOT" + std::to_string(++m_uid)),
-    m_recipient(nullptr) {}
+    : m_id("NOT" + std::to_string(++m_uid)), 
+    m_state(util::State::ACTIVE) {}
 
 /*
 Function: Notification
@@ -37,13 +38,14 @@ Parameters:
 Returns:
     - A new Notification object.
 */
-Notification::Notification(const std::string& recipientUserId, User* recipient, const std::string& title, const std::string& message, const util::Timestamp& createdAt)
+Notification::Notification(const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt)
     : m_id("NOT" + std::to_string(++m_uid)),
     m_recipientUserId(recipientUserId),
-    m_recipient(recipient),
     m_title(title),
     m_message(message),
-    m_createdAt(createdAt) {}
+    m_state(util::State::ACTIVE),
+    m_createdAt(createdAt) {
+}
 
 /*
 Function: Notification (parameterized constructor with ID)
@@ -58,13 +60,13 @@ Parameters:
 Returns:
     - A new Notification object
 */
-Notification::Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt)
+Notification::Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt, const util::State& state)
     : m_id(id),
     m_recipientUserId(recipientUserId),
-    m_recipient(nullptr),
     m_title(title),
     m_message(message),
-    m_createdAt(createdAt) 
+    m_createdAt(createdAt),
+    m_state(state)
 {
     int idNumber = util::extractNumber(m_id);
     if (idNumber > m_uid)
@@ -79,7 +81,7 @@ Description: Retrieves the unique ID of the notification.
 Returns:
     - const std::string& representing the notification ID.
 */
-const std::string& Notification::getId() const 
+const std::string& Notification::getId() const
 {
     return m_id;
 }
@@ -95,17 +97,6 @@ const std::string& Notification::getRecipientUserId() const
     return m_recipientUserId;
 }
 
-/*
-Function: getRecipient
-Description: Retrieves the pointer to the recipient user.
-Returns:
-    - User* representing the recipient.
-*/
-User* Notification::getRecipient() const
-{
-    return m_recipient;
-}
-
 /*
 Function: getTitle
 Description: Retrieves the title of the notification.
@@ -139,6 +130,17 @@ const util::Timestamp& Notification::getCreatedAt() const
     return m_createdAt;
 }
 
+/*
+Function: getState
+Description: Retrieves the Notification state
+Returns:
+    - const util::Timestamp& representing the creation timestamp.
+*/
+util::State Notification::getState() const
+{
+    return m_state;
+}
+
 /*
 Function: setId
 Description: Sets the unique ID of the notification.
@@ -165,19 +167,6 @@ void Notification::setRecipientUserId(const std::string& recipientUserId)
     m_recipientUserId = recipientUserId;
 }
 
-/*
-Function: setRecipient
-Description: Sets the recipient user pointer for the notification.
-Parameters:
-    - recipient: Pointer to the User object.
-Returns:
-    - void
-*/
-void Notification::setRecipient(User* recipient)
-{
-    m_recipient = recipient;
-}
-
 /*
 Function: setTitle
 Description: Sets the title of the notification.
@@ -217,71 +206,54 @@ void Notification::setCreatedAt(const util::Timestamp& createdAt)
     m_createdAt = createdAt;
 }
 
+/*
+Function: setState
+Description: Sets the Notification state.
+Parameters:
+    - state: Notification state value.
+Returns:
+    - void
+*/
+void Notification::setState(util::State state)
+{
+    m_state = state;
+}
+
 /*
 Function: serialize
-Description: Serializes the notification into a CSV-formatted string.
+Description: Serializes the Notification object into a SerializedNotification record.
 Parameters:
     - None
 Returns:
-    - std::string: Serialized notification record
+    - SerializedNotification: Serialized representation of the notification
 */
-std::string Notification::serialize() const
+SerializedNotification Notification::serialize() const
 {
-    std::ostringstream serializedNotification;
-    serializedNotification << m_id << ','
-        << m_recipientUserId << ','
-        << m_title << ','
-        << m_message << ','
-        << m_createdAt.toString();
-    return serializedNotification.str();
+    SerializedNotification serialized = {};
+    strcpy_s(serialized.id, sizeof(serialized.id), m_id.c_str());
+    strcpy_s(serialized.recipientUserId, sizeof(serialized.recipientUserId), m_recipientUserId.c_str());
+    strcpy_s(serialized.title, sizeof(serialized.title), m_title.c_str());
+    strcpy_s(serialized.message, sizeof(serialized.message), m_message.c_str());
+    serialized.createdAt = m_createdAt;
+    serialized.state = m_state;
+    return serialized;
 }
 
 /*
 Function: deserialize
-Description: Deserializes a CSV-formatted string into a Notification object.
+Description: Deserializes a SerializedNotification record into a Notification object.
 Parameters:
-    - record: const std::string&, serialized notification record
+    - serializedNotification: const SerializedNotification&, serialized notification record
 Returns:
     - Notification*: Pointer to the deserialized Notification object
-Throws:
-    - std::runtime_error if timestamp parsing fails
 */
-Notification* Notification::deserialize(const std::string& record)
+Notification* Notification::deserialize(const SerializedNotification& serializedNotification)
 {
-    std::string id, recipientUserId, title, message, createdAtTimestampString;
-    std::istringstream serializedNotification(record);
-    getline(serializedNotification, id, ',');
-    getline(serializedNotification, recipientUserId, ',');
-    getline(serializedNotification, title, ',');
-    getline(serializedNotification, message, ',');
-    getline(serializedNotification, createdAtTimestampString, ',');
-    util::Timestamp createdAtTimestamp;
-    try
-    {
-        createdAtTimestamp = util::Timestamp::fromString(createdAtTimestampString);
-    }
-    catch (...)
-    {
-        throw std::runtime_error("Invalid createdAt timestamp");
-    }
     return Factory::getObject<Notification>(
-        id,
-        recipientUserId,
-        title,
-        message,
-        createdAtTimestamp
-    );
-}
-
-/*
-Function: getHeaders
-Description: Retrieves the CSV headers for notification serialization.
-Parameters:
-    - None
-Returns:
-    - std::string: Header string ("ID,RecipientID,Title,Message,Timestamp")
-*/
-std::string Notification::getHeaders()
-{
-    return "ID,RecipientID,Title,Message,Timestamp";
+        serializedNotification.id,
+        serializedNotification.recipientUserId,
+        serializedNotification.title,
+        serializedNotification.message,
+        serializedNotification.createdAt,
+        serializedNotification.state);
 }

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

@@ -9,8 +9,10 @@ Date: 19-May-2026
 #pragma once
 #include <string>
 #include "Timestamp.h"
+#include "Enums.h"
 
 class User;
+struct SerializedNotification;
 
 class Notification
 {
@@ -18,27 +20,26 @@ private:
     static int m_uid;
     std::string m_id;
     std::string m_recipientUserId;
-    User* m_recipient;
     std::string m_title;
     std::string m_message;
     util::Timestamp m_createdAt;
+    util::State m_state;
 public:
     Notification();
-    Notification(const std::string& recipientUserId, User* recipient, const std::string& title, const std::string& message, const util::Timestamp& createdAt);
-    Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt);
+    Notification(const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt);
+    Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt, const util::State& state);
     const std::string& getId() const;
     const std::string& getRecipientUserId() const;
-    User* getRecipient() const;
     const std::string& getTitle() const;
     const std::string& getMessage() const;
     const util::Timestamp& getCreatedAt() const;
     void setId(const std::string& id);
     void setRecipientUserId(const std::string& recipientUserId);
-    void setRecipient(User* recipient);
     void setTitle(const std::string& title);
     void setMessage(const std::string& message);
     void setCreatedAt(const util::Timestamp& createdAt);
-    std::string serialize() const;
-    static Notification* deserialize(const std::string&);
-    static std::string getHeaders();
+    util::State getState() const;
+    void setState(util::State state);
+    SerializedNotification serialize() const;
+    static Notification* deserialize(const SerializedNotification&);
 };

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

@@ -8,6 +8,7 @@ Date: 19-May-2026
 */
 
 #include <sstream>
+#include "SerializedRecords.h"
 #include "User.h"
 #include "Notification.h"
 #include "Enums.h"
@@ -28,7 +29,8 @@ Returns:
 User::User()
     : m_id("USR" + std::to_string(++m_uid)),
     m_type(util::UserType::CUSTOMER),
-    m_status(util::State::ACTIVE) {}
+    m_status(util::State::ACTIVE) {
+}
 
 /*
 Function: User
@@ -51,7 +53,8 @@ User::User(const std::string& userName, const std::string& password, const std::
     m_phone(phone),
     m_email(email),
     m_type(role),
-    m_status(util::State::ACTIVE) {}
+    m_status(util::State::ACTIVE) {
+}
 
 /*
 Function: User (parameterized constructor with ID)
@@ -86,23 +89,6 @@ User::User(const std::string& userId, const std::string& userName, const std::st
     }
 }
 
-/*
-Function: ~User
-Description: Destructor that cleans up dynamically allocated notifications associated with the user.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-User::~User()
-{
-    auto values = m_notifications.getValues();
-    for (int index = 0; index < values.getSize(); index++)
-    {
-        delete values[index];
-    }
-}
-
 /*
 Function: getId
 Description: Retrieves the unique ID of the user.
@@ -169,17 +155,6 @@ const std::string& User::getEmail() const
     return m_email;
 }
 
-/*
-Function: getNotifications
-Description: Retrieves the map of notifications associated with the user.
-Returns:
-    - util::Map<std::string, Notification*>& representing the notifications.
-*/
-util::Map<std::string, Notification*>& User::getNotifications()
-{
-    return m_notifications;
-}
-
 /*
 Function: getUserType
 Description: Retrieves the role of the user.
@@ -280,22 +255,6 @@ void User::setEmail(const std::string& email)
     m_email = email;
 }
 
-/*
-Function: addNotification
-Description: Adds a new notification to the user’s notification map.
-Parameters:
-    - notification: Pointer to the Notification object.
-Returns:
-    - void
-*/
-void User::addNotification(Notification* notification)
-{
-    if (notification)
-    {
-        m_notifications.insert(notification->getId(), notification);
-    }
-}
-
 /*
 Function: setRole
 Description: Sets the role of the user.
@@ -324,68 +283,43 @@ void User::setState(util::State status)
 
 /*
 Function: serialize
-Description: Serializes the user into a CSV-formatted string.
+Description: Serializes the User object into a SerializedUser record.
 Parameters:
     - None
 Returns:
-    - std::string: Serialized user record
+    - SerializedUser: Serialized representation of the user
 */
-std::string User::serialize() const
+SerializedUser User::serialize() const
 {
-    std::ostringstream serializedUser;
-    serializedUser << m_id << ','
-        << m_userName << ','
-        << m_password << ','
-        << m_name << ','
-        << m_phone << ','
-        << m_email << ','
-        << util::getUserTypeString(m_type) << ','
-        << util::getStateString(m_status);
-    return serializedUser.str();
+    SerializedUser serialized = {};
+    strcpy_s(serialized.id, sizeof(serialized.id), m_id.c_str());
+    strcpy_s(serialized.username, sizeof(serialized.username), m_userName.c_str());
+    strcpy_s(serialized.password, sizeof(serialized.password), m_password.c_str());
+    strcpy_s(serialized.name, sizeof(serialized.name), m_name.c_str());
+    strcpy_s(serialized.phone, sizeof(serialized.phone), m_phone.c_str());
+    strcpy_s(serialized.email, sizeof(serialized.email), m_email.c_str());
+    serialized.userType = m_type;
+    serialized.status = m_status;
+    return serialized;
 }
 
 /*
 Function: deserialize
-Description: Deserializes a CSV-formatted string into a User object.
+Description: Deserializes a SerializedUser record into a User object.
 Parameters:
-    - record: const std::string&, serialized user record
+    - serializedUser: const SerializedUser&, serialized user record
 Returns:
     - User*: Pointer to the deserialized User object
 */
-User* User::deserialize(const std::string& record)
+User* User::deserialize(const SerializedUser& serializedUser)
 {
-    std::string id, name, username, phone, password, email;
-    std::string userTypeString, stateString;
-    std::istringstream serializedUser(record);
-    getline(serializedUser, id, ',');
-    getline(serializedUser, username, ',');
-    getline(serializedUser, password, ',');
-    getline(serializedUser, name, ',');
-    getline(serializedUser, phone, ',');
-    getline(serializedUser, email, ',');
-    getline(serializedUser, userTypeString, ',');
-    getline(serializedUser, stateString);
-    util::UserType userType = util::getUserType(userTypeString);
-    util::State status = util::getState(stateString);
-    return Factory::getObject<User>(id,
-        username,
-        password,
-        name,
-        phone,
-        email,
-        userType,
-        status);
-}
-
-/*
-Function: getHeaders
-Description: Retrieves the CSV headers for user serialization.
-Parameters:
-    - None
-Returns:
-    - std::string: Header string ("ID,Username,Password,Name,Phone,Email,UserType,UserStatus")
-*/
-std::string User::getHeaders()
-{
-    return "ID,Username,Password,Name,Phone,Email,UserType,UserStatus";
+    return Factory::getObject<User>(
+        serializedUser.id,
+        serializedUser.username,
+        serializedUser.password,
+        serializedUser.name,
+        serializedUser.phone,
+        serializedUser.email,
+        serializedUser.userType,
+        serializedUser.status);
 }

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

@@ -14,6 +14,7 @@ Date: 19-May-2026
 #include "Enums.h"
 
 class Notification;
+struct SerializedUser;
 
 class User : public Observer
 {
@@ -25,21 +26,19 @@ private:
     std::string m_name;
     std::string m_phone;
     std::string m_email;
-    util::Map<std::string, Notification*> m_notifications;
     util::UserType m_type;
     util::State m_status;
 public:
     User();
     User(const std::string& userName, const std::string& password, const std::string& name, const std::string& phone, const std::string& email, util::UserType role);
     User(const std::string& userId, const std::string& userName, const std::string& password, const std::string& name, const std::string& phone, const std::string& email, util::UserType role, util::State status);
-    ~User();
+    ~User() = default;
     const std::string& getId() const;
     const std::string& getUserName() const;
     const std::string& getPassword() const;
     const std::string& getName() const;
     const std::string& getPhone() const;
     const std::string& getEmail() const;
-    util::Map<std::string, Notification*>& getNotifications();
     util::UserType getUserType() const;
     util::State getState() const;
     void setId(const std::string& id);
@@ -48,10 +47,8 @@ public:
     void setName(const std::string& name);
     void setPhone(const std::string& phone);
     void setEmail(const std::string& email);
-    void addNotification(Notification* notification) override;
     void setRole(util::UserType role);
     void setState(util::State status);
-    std::string serialize() const;
-    static User* deserialize(const std::string&);
-    static std::string getHeaders();
+    SerializedUser serialize() const;
+    static User* deserialize(const SerializedUser& serializedUser);
 };

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

@@ -10,6 +10,8 @@ Date:19-May-2026
 #include <stdexcept>
 #include "AuthenticationManagementService.h"
 #include "User.h"
+#include "Utility.h"
+#include "DataStoreLockGuard.h"
 
 User* AuthenticationManagementService::m_authenticatedUser = nullptr;
 
@@ -24,11 +26,12 @@ Return type: bool - true if login successful, false otherwise
 */
 bool AuthenticationManagementService::login(const std::string& username, const std::string& password)
 {
-	util::Map<std::string, User*> users = m_dataStore.getUsers();
-	int usersMapSize = users.getSize();
-	for (int index = 0; index < usersMapSize; index++)
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUserMap = m_dataStore.getUsers();
+	int trackedUserMapSize = trackedUserMap.getSize();
+	for (int index = 0; index < trackedUserMapSize; index++)
 	{
-		User* user = users.getValueAt(index);
+		User* user = trackedUserMap.getValueAt(index).data;
 		if (username == user->getUserName())
 		{
 			if (password == user->getPassword())
@@ -74,9 +77,18 @@ Return type: void
 */
 void AuthenticationManagementService::changePassword(const std::string& newPassword)
 {
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
 	if (m_authenticatedUser == nullptr)
 	{
 		throw std::runtime_error("There is no user currently logged in!");
 	}
+	int index = trackedUsersMap.find(m_authenticatedUser->getId());
+	if (index == -1)
+	{
+		throw std::runtime_error("User does not exist!\n");
+	}
 	m_authenticatedUser->setPassword(newPassword);
+	trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
+	m_dataStore.saveUsers();
 }

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

@@ -12,14 +12,13 @@ Date: 22-May-2026
 #include "Config.h"
 #include "Enums.h"
 #include "Factory.h"
-#include "FileManager.h"
 #include "InventoryItem.h"
 #include "InventoryManagementService.h"
 #include "Timestamp.h"
 #include "User.h"
 #include "Utility.h"
 #include "Vector.h"
-
+#include "DataStoreLockGuard.h"
 
 util::Map<std::string, User*> InventoryManagementService::m_observers{};
 
@@ -90,95 +89,6 @@ void InventoryManagementService::sendLowStockAlerts()
 	}
 }
 
-/*
-Function: getObserverIDs
-Description: Retrieves the IDs of all observers currently attached to the
-			 InventoryManagementService.
-Parameters:
-	- None
-Returns:
-	- util::Vector<std::string>: Vector of observer user IDs
-*/
-util::Vector<std::string> InventoryManagementService::getObserverIDs()
-{
-	util::Vector<std::string> observerIDs;
-	int numberOfObservers = m_observers.getSize();
-	for (int index = 0; index < numberOfObservers; index++)
-	{
-		User* observer = m_observers.getValueAt(index);
-		if (observer)
-		{
-			observerIDs.push_back(observer->getId());
-		}
-	}
-	return observerIDs;
-}
-
-/*
-Function: loadInventoryItems
-Description: Loads inventory items from persistent storage into the datastore.
-			 Uses FileManager to deserialize inventory items from the configured file.
-Parameters:
-	- None
-Returns:
-	- void
-*/
-void InventoryManagementService::loadInventoryItems()
-{
-	util::FileManager<InventoryItem> inventoryItemFileManager(config::file::INVENTORYITEM_FILE);
-	auto& inventoryItems = m_dataStore.getInventoryItems();
-	auto inventoryItemsMap = inventoryItemFileManager.load();
-	int numberOfInventoryItems = inventoryItemsMap.getSize();
-	for (int index = 0; index < numberOfInventoryItems; index++)
-	{
-		inventoryItems[inventoryItemsMap.getKeyAt(index)] = inventoryItemsMap.getValueAt(index);
-	}
-}
-
-/*
-Function: saveInventoryItems
-Description: Saves inventory items from the datastore to persistent storage.
-			 Uses FileManager to serialize inventory items into the configured file.
-Parameters:
-	- None
-Returns:
-	- void
-*/
-void InventoryManagementService::saveInventoryItems()
-{
-	util::FileManager<InventoryItem> inventoryItemFileManager(config::file::INVENTORYITEM_FILE);
-	auto& inventoryItems = m_dataStore.getInventoryItems();
-	inventoryItemFileManager.save(inventoryItems);
-}
-
-/*
-Function: loadObservers
-Description: Loads observer IDs from persistent storage and attaches corresponding
-			 users as observers to the InventoryManagementService.
-Parameters:
-	- None
-Returns:
-	- void
-*/
-void InventoryManagementService::loadObservers()
-{
-	util::loadObservers(config::file::INVENTORYMANAGEMENTOBSERVERS, this, m_dataStore);
-}
-
-/*
-Function: saveObservers
-Description: Saves the current observer IDs of the InventoryManagementService
-			 to persistent storage for future retrieval.
-Parameters:
-	- None
-Returns:
-	- void
-*/
-void InventoryManagementService::saveObservers()
-{
-	util::saveObservers(config::file::INVENTORYMANAGEMENTOBSERVERS, this);
-}
-
 /*
 Function: addInventoryItem
 Description: Creates a new inventory item using the Factory and inserts it
@@ -271,6 +181,9 @@ Returns:
 */
 void InventoryManagementService::attach(User* user)
 {
+	DataStoreLockGuard lock(m_dataStore);
+	m_observers.clear();
+	m_observers = m_dataStore.getInventoryManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -279,6 +192,7 @@ void InventoryManagementService::attach(User* user)
 			m_observers[userID] = user;
 		}
 	}
+	m_dataStore.saveInventoryManagementObservers(m_observers);
 }
 
 /*
@@ -291,6 +205,9 @@ Returns:
 */
 void InventoryManagementService::detach(User* user)
 {
+	DataStoreLockGuard lock(m_dataStore);
+	m_observers.clear();
+	m_observers = m_dataStore.getInventoryManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -299,6 +216,7 @@ void InventoryManagementService::detach(User* user)
 			m_observers.remove(userID);
 		}
 	}
+	m_dataStore.saveInventoryManagementObservers(m_observers);
 }
 
 /*
@@ -315,27 +233,27 @@ Throws:
 */
 void InventoryManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
 {
-	if (user)
+	if (!user)
 	{
-		if (m_observers.find(user->getId()) != -1)
-		{
-			Notification* notification =
-				Factory::getObject<Notification>(
-					user->getId(),
-					user,
-					title,
-					message,
-					util::Timestamp()
-				);
-			if (notification)
-			{
-				user->addNotification(notification);
-			}
-			else
-			{
-				throw std::runtime_error("Failed to create notification");
-			}
-		}
+		return;
 	}
+	DataStoreLockGuard lock(m_dataStore);
+	m_observers = m_dataStore.getInventoryManagementObservers();
+	if (m_observers.find(user->getId()) == -1)
+	{
+		return;
+	}
+	Notification* notification = Factory::getObject<Notification>(
+		user->getId(),
+		title,
+		message,
+		util::Timestamp());
+	if (!notification)
+	{
+		throw std::runtime_error("Failed to create notification");
+	}
+	auto& trackedNotificationsMap = m_dataStore.getNotifications();
+	trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
+	m_dataStore.saveNotifications();
 }
 

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

@@ -21,7 +21,6 @@ class InventoryManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
-    util::Vector<std::string> getObserverIDs() override;
 public:
     InventoryManagementService() : m_dataStore(DataStore::getInstance()) {}
     util::Map<std::string, InventoryItem*> getInventoryItems();
@@ -33,8 +32,4 @@ public:
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
-    void loadInventoryItems();
-    void saveInventoryItems();
-    void loadObservers();
-    void saveObservers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/NotificationManagementService.cpp

@@ -1 +0,0 @@
-#include "NotificationManagementService.h"

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

@@ -19,5 +19,4 @@ public:
 	virtual void sendNotification(User* recipient, const std::string& title, const std::string& message) = 0;
 	virtual void attach(User* user) = 0;
 	virtual void detach(User* user) = 0;
-	virtual util::Vector<std::string> getObserverIDs() = 0;
 };

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

@@ -11,7 +11,6 @@ Date: 20-May-2026
 #include "Config.h"
 #include "Enums.h"
 #include "Factory.h"
-#include "FileManager.h"
 #include "InventoryItem.h"
 #include "Invoice.h"
 #include "JobCard.h"
@@ -21,6 +20,7 @@ Date: 20-May-2026
 #include "Timestamp.h"
 #include "User.h"
 #include "Utility.h"
+#include "DataStoreLockGuard.h"
 
 util::Map<std::string, User*> PaymentManagementService::m_observers{};
 
@@ -34,6 +34,9 @@ Returns:
 */
 void PaymentManagementService::attach(User* user)
 {
+	DataStoreLockGuard lock(m_dataStore);
+	m_observers.clear();
+	m_observers = m_dataStore.getPaymentManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -42,6 +45,7 @@ void PaymentManagementService::attach(User* user)
 			m_observers[userID] = user;
 		}
 	}
+	m_dataStore.savePaymentManagementObservers(m_observers);
 }
 
 /*
@@ -54,6 +58,9 @@ Returns:
 */
 void PaymentManagementService::detach(User* user)
 {
+	DataStoreLockGuard lock(m_dataStore);
+	m_observers.clear();
+	m_observers = m_dataStore.getPaymentManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -62,6 +69,7 @@ void PaymentManagementService::detach(User* user)
 			m_observers.remove(userID);
 		}
 	}
+	m_dataStore.savePaymentManagementObservers(m_observers);
 }
 
 /*
@@ -78,28 +86,28 @@ Throws:
 */
 void PaymentManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
 {
-	if (user)
+	if (!user)
 	{
-		if (m_observers.find(user->getId()) != -1)
-		{
-			Notification* notification =
-				Factory::getObject<Notification>(
-					user->getId(),
-					user,
-					title,
-					message,
-					util::Timestamp()
-				);
-			if (notification)
-			{
-				user->addNotification(notification);
-			}
-			else
-			{
-				throw std::runtime_error("Failed to create notification");
-			}
-		}
+		return;
 	}
+	DataStoreLockGuard lock(m_dataStore);
+	m_observers = m_dataStore.getPaymentManagementObservers();
+	if (m_observers.find(user->getId()) == -1)
+	{
+		return;
+	}
+	Notification* notification = Factory::getObject<Notification>(
+		user->getId(),
+		title,
+		message,
+		util::Timestamp());
+	if (!notification)
+	{
+		throw std::runtime_error("Failed to create notification");
+	}
+	auto& trackedNotificationsMap = m_dataStore.getNotifications();
+	trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
+	m_dataStore.saveNotifications();
 }
 
 /*
@@ -140,123 +148,6 @@ void PaymentManagementService::sendPaymentReminders()
 	}
 }
 
-/*
-Function: getObserverIDs
-Description: Retrieves the IDs of all observers currently attached to the
-             PaymentManagementService.
-Parameters:
-    - None
-Returns:
-    - util::Vector<std::string>: Vector of observer user IDs
-*/
-util::Vector<std::string> PaymentManagementService::getObserverIDs()
-{
-	util::Vector<std::string> observerIDs;
-	int numberOfObservers = m_observers.getSize();
-	for (int index = 0; index < numberOfObservers; index++)
-	{
-		User* observer = m_observers.getValueAt(index);
-		if (observer)
-		{
-			observerIDs.push_back(observer->getId());
-		}
-	}
-	return observerIDs;
-}
-
-/*
-Function: loadInvoices
-Description: Loads invoices from persistent storage into the datastore.
-             Validates associated service bookings and inventory parts before
-             attaching them to each invoice. Throws exceptions if invalid IDs
-             are encountered.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if a booking ID or part ID is invalid
-*/
-void PaymentManagementService::loadInvoices()
-{
-    util::FileManager<Invoice> invoiceFileManager(config::file::INVOICE_FILE);
-    auto& invoices = m_dataStore.getInvoices();
-    auto& serviceBookings = m_dataStore.getServiceBookings();
-    auto& inventoryItems = m_dataStore.getInventoryItems();
-    auto invoicesMap = invoiceFileManager.load();
-    for (int invoiceIndex = 0; invoiceIndex < invoicesMap.getSize(); invoiceIndex++)
-    {
-        Invoice* invoice = invoicesMap.getValueAt(invoiceIndex);
-        int bookingIndex = serviceBookings.find(invoice->getBookingId());
-        if (bookingIndex == -1)
-        {
-            throw std::runtime_error("Invalid Booking ID");
-        }
-        ServiceBooking* booking = serviceBookings.getValueAt(bookingIndex);
-        invoice->setBooking(booking);
-        util::Map<std::string, InventoryItem*> invoiceParts;
-        auto& partIDs = invoice->getPartIDs();
-        for (int partIndex = 0; partIndex < partIDs.getSize(); partIndex++)
-        {
-            const std::string& partID = partIDs[partIndex];
-            int inventoryIndex = inventoryItems.find(partID);
-            if (inventoryIndex == -1)
-            {
-                throw std::runtime_error("Invalid Part ID");
-            }
-            invoiceParts[partID] = inventoryItems.getValueAt(inventoryIndex);
-        }
-        invoice->setParts(invoiceParts);
-        invoices[invoice->getId()] = invoice;
-    }
-}
-
-/*
-Function: saveInvoices
-Description: Saves invoices from the datastore to persistent storage.
-             Uses FileManager to serialize invoices into the configured file.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void PaymentManagementService::saveInvoices()
-{
-    util::FileManager<Invoice> invoiceFileManager(config::file::INVOICE_FILE);
-    auto& invoices = m_dataStore.getInvoices();
-    invoiceFileManager.save(invoices);
-}
-
-/*
-Function: loadObservers
-Description: Loads observer IDs from persistent storage and attaches corresponding
-             users as observers to the PaymentManagementService.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if an observer ID is invalid (not found in datastore)
-*/
-void PaymentManagementService::loadObservers()
-{
-    util::loadObservers(config::file::PAYMENTMANAGEMENTOBSERVERS, this, m_dataStore);
-}
-
-/*
-Function: saveObservers
-Description: Saves the current observer IDs of the PaymentManagementService
-             to persistent storage for future retrieval.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void PaymentManagementService::saveObservers()
-{
-    util::saveObservers(config::file::PAYMENTMANAGEMENTOBSERVERS, this);
-}
-
 /*
 Function: createInventoryItemsMap (static helper)
 Description: Builds a map of inventory items required for a given service and adds them to the booking’s inventory map.

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

@@ -22,7 +22,6 @@ class PaymentManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
-    util::Vector<std::string> getObserverIDs() override;
 public:
     PaymentManagementService() : m_dataStore(DataStore::getInstance()) {}
     void generateInvoice(ServiceBooking* booking);
@@ -34,8 +33,4 @@ public:
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
-    void loadInvoices();
-    void saveInvoices();
-    void loadObservers();
-    void saveObservers();
 };

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

@@ -14,7 +14,6 @@ Date:19-May-2026
 #include "DataStore.h"
 #include "Enums.h"
 #include "Factory.h"
-#include "FileManager.h"
 #include "InventoryItem.h"
 #include "JobCard.h"
 #include "NotificationManagementService.h"
@@ -26,6 +25,7 @@ Date:19-May-2026
 #include "User.h"
 #include "UserManagementService.h"
 #include "Utility.h"
+#include "DataStoreLockGuard.h"
 
 /*
 Function: purchaseService
@@ -122,6 +122,9 @@ Returns:
 */
 void ServiceManagementService::attach(User* user)
 {
+    DataStoreLockGuard lock(m_dataStore);
+    m_observers.clear();
+    m_observers = m_dataStore.getServiceManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -130,6 +133,7 @@ void ServiceManagementService::attach(User* user)
 			m_observers[userID] = user;
 		}
 	}
+    m_dataStore.saveServiceManagementObservers(m_observers);
 }
 
 /*
@@ -142,6 +146,9 @@ Returns:
 */
 void ServiceManagementService::detach(User* user)
 {
+    DataStoreLockGuard lock(m_dataStore);
+    m_observers.clear();
+    m_observers = m_dataStore.getServiceManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -150,6 +157,7 @@ void ServiceManagementService::detach(User* user)
 			m_observers.remove(userID);
 		}
 	}
+    m_dataStore.saveServiceManagementObservers(m_observers);
 }
 
 /*
@@ -166,345 +174,28 @@ Throws:
 */
 void ServiceManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
 {
-	if (user)
-	{
-		if (m_observers.find(user->getId()) != -1)
-		{
-			Notification* notification =
-				Factory::getObject<Notification>(
-					user->getId(),
-					user,
-					title,
-					message,
-					util::Timestamp()
-				);
-			if (notification)
-			{
-				user->addNotification(notification);
-			}
-			else
-			{
-				throw std::runtime_error("Failed to create notification");
-			}
-		}
-	}
-}
-
-/*
-Function: getObserverIDs
-Description: Retrieves the IDs of all observers currently attached to the
-             ServiceManagementService.
-Parameters:
-    - None
-Returns:
-    - util::Vector<std::string>: Vector of observer user IDs
-*/
-util::Vector<std::string> ServiceManagementService::getObserverIDs()
-{
-	util::Vector<std::string> observerIDs;
-	int numberOfObservers = m_observers.getSize();
-	for (int index = 0; index < numberOfObservers; index++)
-	{
-		User* observer = m_observers.getValueAt(index);
-		if (observer)
-		{
-			observerIDs.push_back(observer->getId());
-		}
-	}
-	return observerIDs;
-}
-
-/*
-Function: loadServices
-Description: Loads services from persistent storage into the datastore.
-             Validates required inventory items and attaches them to each service.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if an inventory item ID is invalid
-*/
-void ServiceManagementService::loadServices()
-{
-    util::FileManager<Service> serviceFileManager(config::file::SERVICE_FILE);
-    auto& services = m_dataStore.getServices();
-    auto& inventoryItems = m_dataStore.getInventoryItems();
-    auto servicesMap = serviceFileManager.load();
-    for (int serviceIndex = 0; serviceIndex < servicesMap.getSize(); serviceIndex++)
+    if (!user)
     {
-        Service* service = servicesMap.getValueAt(serviceIndex);
-        services[service->getId()] = service;
-        util::Map<std::string, InventoryItem*> inventoryItemsMap;
-        auto& inventoryItemIDs = service->getRequiredInventoryItemIDs();
-        for (int inventoryItemIndex = 0; inventoryItemIndex < inventoryItemIDs.getSize(); inventoryItemIndex++)
-        {
-            const std::string& inventoryItemID = inventoryItemIDs[inventoryItemIndex];
-            int index = inventoryItems.find(inventoryItemID);
-            if (index == -1)
-            {
-                throw std::runtime_error("Invalid Inventory Item ID");
-            }
-            inventoryItemsMap[inventoryItemID] = inventoryItems.getValueAt(index);
-        }
-        service->setRequiredInventoryItems(inventoryItemsMap);
+        return;
     }
-}
-
-/*
-Function: saveServices
-Description: Saves services from the datastore to persistent storage.
-             Uses FileManager to serialize services into the configured file.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void ServiceManagementService::saveServices()
-{
-	util::FileManager<Service> serviceFileManager(config::file::SERVICE_FILE);
-	auto& services = m_dataStore.getServices();
-	serviceFileManager.save(services);
-}
-
-/*
-Function: loadComboPackages
-Description: Loads combo packages from persistent storage into the datastore.
-             Validates associated services and attaches them to each package.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if a service ID is invalid
-*/
-void ServiceManagementService::loadComboPackages()
-{
-    util::FileManager<ComboPackage> comboPackageFileManager(config::file::COMBOPACKAGE_FILE);
-    auto& comboPackages = m_dataStore.getComboPackages();
-    auto& services = m_dataStore.getServices();
-    auto comboPackagesMap = comboPackageFileManager.load();
-    for (int packageIndex = 0; packageIndex < comboPackagesMap.getSize(); packageIndex++)
+    DataStoreLockGuard lock(m_dataStore);
+    m_observers = m_dataStore.getServiceManagementObservers();
+    if (m_observers.find(user->getId()) == -1)
     {
-        ComboPackage* comboPackage = comboPackagesMap.getValueAt(packageIndex);
-        util::Map<std::string, Service*> packageServices;
-        auto& serviceIDs = comboPackage->getServiceIDs();
-        for (int serviceIndex = 0; serviceIndex < serviceIDs.getSize(); serviceIndex++)
-        {
-            const std::string& serviceID = serviceIDs[serviceIndex];
-            int serviceMapIndex = services.find(serviceID);
-            if (serviceMapIndex == -1)
-            {
-                throw std::runtime_error("Invalid Service ID");
-            }
-            packageServices[serviceID] = services.getValueAt(serviceMapIndex);
-        }
-        comboPackage->setServices(packageServices);
-        comboPackages[comboPackage->getId()] = comboPackage;
+        return;
     }
-}
-
-/*
-Function: saveComboPackages
-Description: Saves combo packages from the datastore to persistent storage.
-             Uses FileManager to serialize combo packages into the configured file.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void ServiceManagementService::saveComboPackages()
-{
-    util::FileManager<ComboPackage> comboPackageFileManager(config::file::COMBOPACKAGE_FILE);
-    auto& comboPackages = m_dataStore.getComboPackages();
-    comboPackageFileManager.save(comboPackages);
-}
-
-/*
-Function: loadServiceBookings
-Description: Loads service bookings from persistent storage into the datastore.
-             Validates associated services, customers, and technicians before
-             attaching them to each booking.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if a service ID, customer ID, or technician ID is invalid
-    - std::runtime_error if a user is not of the expected type (customer/technician)
-*/
-void ServiceManagementService::loadServiceBookings()
-{
-    util::FileManager<ServiceBooking> bookingFileManager(config::file::SERVICEBOOKING_FILE);
-    auto& serviceBookings = m_dataStore.getServiceBookings();
-    auto& services = m_dataStore.getServices();
-    auto& users = m_dataStore.getUsers();
-    auto bookingsMap = bookingFileManager.load();
-    for (int bookingIndex = 0; bookingIndex < bookingsMap.getSize(); bookingIndex++)
+    Notification* notification = Factory::getObject<Notification>(
+        user->getId(),
+        title,
+        message,
+        util::Timestamp());
+    if (!notification)
     {
-        ServiceBooking* booking = bookingsMap.getValueAt(bookingIndex);
-        util::Map<std::string, Service*> bookingServices;
-        auto& serviceIDs = booking->getServiceIDs();
-        for (int serviceIndex = 0; serviceIndex < serviceIDs.getSize(); serviceIndex++)
-        {
-            const std::string& serviceID = serviceIDs[serviceIndex];
-            int serviceMapIndex = services.find(serviceID);
-            if (serviceMapIndex == -1)
-            {
-                throw std::runtime_error("Invalid Service ID");
-            }
-
-            bookingServices[serviceID] = services.getValueAt(serviceMapIndex);
-        }
-        booking->setServices(bookingServices);
-        int customerIndex = users.find(booking->getCustomerId());
-        if (customerIndex == -1)
-        {
-            throw std::runtime_error("Invalid Customer ID");
-        }
-        User* customer = users.getValueAt(customerIndex);
-        if (customer->getUserType() != util::UserType::CUSTOMER)
-        {
-            throw std::runtime_error("User is not a customer");
-        }
-        booking->setCustomer(customer);
-        const std::string& technicianId = booking->getAssignedTechnicianId();
-        if (!technicianId.empty())
-        {
-            int technicianIndex = users.find(technicianId);
-            if (technicianIndex == -1)
-            {
-                throw std::runtime_error("Invalid Technician ID");
-            }
-            User* technician = users.getValueAt(technicianIndex);
-            if (technician->getUserType() != util::UserType::TECHNICIAN)
-            {
-                throw std::runtime_error("User is not a technician");
-            }
-            booking->setAssignedTechnician(technician);
-        }
-        serviceBookings[booking->getId()] = booking;
+        throw std::runtime_error("Failed to create notification");
     }
-}
-
-/*
-Function: saveServiceBookings
-Description: Saves service bookings from the datastore to persistent storage.
-             Uses FileManager to serialize bookings into the configured file.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void ServiceManagementService::saveServiceBookings()
-{
-    util::FileManager<ServiceBooking> bookingFileManager(config::file::SERVICEBOOKING_FILE);
-    auto& serviceBookings = m_dataStore.getServiceBookings();
-    bookingFileManager.save(serviceBookings);
-}
-
-/*
-Function: loadJobCards
-Description: Loads job cards from persistent storage into the datastore.
-             Validates associated bookings, services, and technicians before
-             attaching them to each job card.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if a booking ID, service ID, or technician ID is invalid
-    - std::runtime_error if a service does not belong to the booking
-    - std::runtime_error if a user is not a technician
-*/
-void ServiceManagementService::loadJobCards()
-{
-    util::FileManager<JobCard> jobCardFileManager(config::file::JOBCARD_FILE);
-    auto& jobCards = m_dataStore.getJobCards();
-    auto& serviceBookings = m_dataStore.getServiceBookings();
-    auto& services = m_dataStore.getServices();
-    auto& users = m_dataStore.getUsers();
-    auto jobCardsMap = jobCardFileManager.load();
-    for (int jobCardIndex = 0; jobCardIndex < jobCardsMap.getSize(); jobCardIndex++)
-    {
-        JobCard* jobCard = jobCardsMap.getValueAt(jobCardIndex);
-        int bookingIndex = serviceBookings.find(jobCard->getBookingId());
-        if (bookingIndex == -1)
-        {
-            throw std::runtime_error("Invalid Booking ID");
-        }
-        ServiceBooking* booking = serviceBookings.getValueAt(bookingIndex);
-        jobCard->setBooking(booking);
-        int serviceIndex = services.find(jobCard->getServiceId());
-        if (serviceIndex == -1)
-        {
-            throw std::runtime_error("Invalid Service ID");
-        }
-        Service* service = services.getValueAt(serviceIndex);
-        if (booking->getServices().find(jobCard->getServiceId()) == -1)
-        {
-            throw std::runtime_error("Service does not belong to booking");
-        }
-        jobCard->setService(service);
-        int technicianIndex = users.find(jobCard->getTechnicianId());
-        if (technicianIndex == -1)
-        {
-            throw std::runtime_error("Invalid Technician ID");
-        }
-        User* technician = users.getValueAt(technicianIndex);
-        if (technician->getUserType() != util::UserType::TECHNICIAN)
-        {
-            throw std::runtime_error("User is not a technician");
-        }
-        jobCard->setTechnician(technician);
-        jobCards[jobCard->getId()] = jobCard;
-    }
-}
-
-/*
-Function: saveJobCards
-Description: Saves job cards from the datastore to persistent storage.
-             Uses FileManager to serialize job cards into the configured file.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void ServiceManagementService::saveJobCards()
-{
-    util::FileManager<JobCard> jobCardFileManager(config::file::JOBCARD_FILE);
-    auto& jobCards = m_dataStore.getJobCards();
-    jobCardFileManager.save(jobCards);
-}
-
-/*
-Function: loadObservers
-Description: Loads observer IDs from persistent storage and attaches corresponding
-             users as observers to the ServiceManagementService.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if an observer ID is invalid (not found in datastore)
-*/
-void ServiceManagementService::loadObservers()
-{
-    util::loadObservers(config::file::SERVICEMANAGEMENTOBSERVERS, this, m_dataStore);
-}
-
-/*
-Function: saveObservers
-Description: Saves the current observer IDs of the ServiceManagementService
-             to persistent storage for future retrieval.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void ServiceManagementService::saveObservers()
-{
-    util::saveObservers(config::file::SERVICEMANAGEMENTOBSERVERS, this);
+    auto& trackedNotificationsMap = m_dataStore.getNotifications();
+    trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
+    m_dataStore.saveNotifications();
 }
 
 /*

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

@@ -23,7 +23,6 @@ class ServiceManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
-    util::Vector<std::string> getObserverIDs() override;
 public:
     ServiceManagementService() : m_dataStore(DataStore::getInstance()) {}
     util::Map<std::string, Service*> getServices();
@@ -45,14 +44,4 @@ public:
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
-    void loadServices();
-    void saveServices();
-    void loadComboPackages();
-    void saveComboPackages();
-    void loadServiceBookings();
-    void saveServiceBookings();
-    void loadJobCards();
-    void saveJobCards();
-    void loadObservers();
-    void saveObservers();
 };

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

@@ -11,7 +11,6 @@ Date:19-May-2026
 #include "Config.h"
 #include "Enums.h"
 #include "Factory.h"
-#include "FileManager.h"
 #include "InventoryManagementService.h"
 #include "Notification.h"
 #include "PaymentManagementService.h"
@@ -20,6 +19,9 @@ Date:19-May-2026
 #include "UserManagementService.h"
 #include "Vector.h"
 #include "Validator.h"
+#include "Utility.h"
+#include "TrackedRecord.h"
+#include "DataStoreLockGuard.h"
 
 /*
 Function: ensureAdminExists
@@ -31,12 +33,13 @@ Return type: void
 */
 void UserManagementService::ensureAdminExists()
 {
+	DataStoreLockGuard lock(m_dataStore);
 	auto& usersMap = m_dataStore.getUsers();
 	int usersMapSize = usersMap.getSize();
 	bool isAdminFound = false;
 	for (int index = 0; index < usersMapSize; index++)
 	{
-		User* user = usersMap.getValueAt(index);
+		User* user = usersMap.getValueAt(index).data;
 		if (user && user->getUserType() == util::UserType::ADMIN)
 		{
 			isAdminFound = true;
@@ -73,7 +76,9 @@ void UserManagementService::createUser(const std::string& username, const std::s
 	InventoryManagementService inventoryManagementService;
 	PaymentManagementService paymentManagementService;
 	ServiceManagementService serviceManagementService;
-	auto& usersMap = m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	auto usersMap = util::getObjects(trackedUsersMap);
 	if (util::isUsernameDuplicate(username, usersMap))
 	{
 		throw std::runtime_error("Username already exists");
@@ -87,13 +92,14 @@ void UserManagementService::createUser(const std::string& username, const std::s
 		throw std::runtime_error("Phone already exists");
 	}
 	User* newUser = Factory::getObject<User>(username, password, name, phone, email, type);
-	usersMap.insert(newUser->getId(), newUser);
+	trackedUsersMap.insert(newUser->getId(), util::createNewRecord(newUser));
 	paymentManagementService.attach(newUser);
 	serviceManagementService.attach(newUser);
 	if (newUser->getUserType() == util::UserType::ADMIN)
 	{
 		inventoryManagementService.attach(newUser);
 	}
+	m_dataStore.saveUsers();
 }
 
 /*
@@ -107,19 +113,24 @@ Return type: void
 */
 void UserManagementService::updateUserDetails(const std::string& userID, const std::string& email, const std::string& phone)
 {
-	auto& usersMap = m_dataStore.getUsers();
-	int index = usersMap.find(userID);
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	auto usersMap = util::getObjects(trackedUsersMap);
+	int index = trackedUsersMap.find(userID);
 	if (index == -1)
 	{
 		throw std::runtime_error("User does not exist!\n");
 	}
-	User* user = usersMap.getValueAt(index);
+	User* user = trackedUsersMap.getValueAt(index).data;
+	bool isModified = false;
 	if (email != user->getEmail())
 	{
 		if (util::isEmailDuplicate(email, usersMap))
 		{
 			throw std::runtime_error("Email already exists!\n");
 		}
+		user->setEmail(email);
+		isModified = true;
 	}
 	if (phone != user->getPhone())
 	{
@@ -127,9 +138,14 @@ void UserManagementService::updateUserDetails(const std::string& userID, const s
 		{
 			throw std::runtime_error("Phone number already exists!\n");
 		}
+		user->setPhone(phone);
+		isModified = true;
+	}
+	if (isModified)
+	{
+		trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
+		m_dataStore.saveUsers();
 	}
-	user->setEmail(email);
-	user->setPhone(phone);
 }
 
 /*
@@ -144,20 +160,25 @@ Throws:
 */
 util::Vector<Notification*> UserManagementService::getUserNotifications(const std::string& userID)
 {
-	auto& usersMap = m_dataStore.getUsers();
-	if (usersMap.find(userID) == -1)
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers(); 
+	if (trackedUsersMap.find(userID) == -1)
 	{
 		throw std::runtime_error("No user found with given UserID");
 	}
-	User* user = usersMap[userID];
+	User* user = trackedUsersMap[userID].data;
 	if (user)
 	{
-		auto& notifications = user->getNotifications();
-		int numberOfNotifications = notifications.getSize();
+		auto& trackedNotificationMap = m_dataStore.getNotifications();
+		int numberOfNotifications = trackedNotificationMap.getSize();
 		util::Vector<Notification*> notificationsVector;
 		for (int index = 0; index < numberOfNotifications; index++)
 		{
-		    notificationsVector.push_back(notifications.getValueAt(index));
+			Notification* notification = trackedNotificationMap.getValueAt(index).data;
+			if (notification->getRecipientUserId() == userID && notification->getState() == util::State::ACTIVE)
+			{
+				notificationsVector.push_back(notification);
+			}
 		}
 		return notificationsVector;
 	}
@@ -169,97 +190,39 @@ util::Vector<Notification*> UserManagementService::getUserNotifications(const st
 
 /*
 Function: deleteNotification
-Description: Deletes a specific notification associated with a given user ID.
+Description: Marks a specific notification associated with a given user
+			 as inactive.
 Parameters:
 	- notificationID: The unique ID of the notification to be deleted.
 	- userID: The unique ID of the user whose notification is to be deleted.
 Returns:
 	- void
 Throws:
-	- std::runtime_error if no user is found with the given UserID or if no notification is found with the given NotificationID.
+	- std::runtime_error if no user is found with the given UserID or
+	  if no notification is found with the given NotificationID.
 */
 void UserManagementService::deleteNotification(const std::string& notificationID, const std::string& userID)
 {
-	auto& usersMap = m_dataStore.getUsers();
-	if (usersMap.find(userID) == -1)
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	auto& trackedNotificationsMap = m_dataStore.getNotifications();
+	int userIndex = trackedUsersMap.find(userID);
+	if (userIndex == -1)
 	{
 		throw std::runtime_error("No user found with given UserID");
 	}
-	User* user = usersMap[userID];
-	auto& notifications = user->getNotifications();
-	if (notifications.find(notificationID) == -1)
+	int notificationIndex = trackedNotificationsMap.find(notificationID);
+	if (notificationIndex == -1)
 	{
 		throw std::runtime_error("No notification found with given NotificationID");
 	}
-	notifications.remove(notificationID);
-}
-
-/*
-Function: loadUsers
-Description: Loads users and notifications from persistent storage into the datastore.
-             Validates that each notification’s recipient exists and attaches the
-             notification to the corresponding user.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if a notification recipient user ID is invalid
-*/
-void UserManagementService::loadUsers()
-{
-    util::FileManager<User> userFileManager(config::file::USER_FILE);
-    util::FileManager<Notification> notificationFileManager(config::file::NOTIFICATION_FILE);
-    auto& users = m_dataStore.getUsers();
-    auto usersMap = userFileManager.load();
-    auto notificationsMap = notificationFileManager.load();
-    int numberOfUsers = usersMap.getSize();
-    int numberOfNotifications = notificationsMap.getSize();
-    for (int index = 0; index < numberOfUsers; index++)
-    {
-        users[usersMap.getKeyAt(index)] = usersMap.getValueAt(index);
-    }
-    for (int index = 0; index < numberOfNotifications; index++)
-    {
-        Notification* notification = notificationsMap.getValueAt(index);
-        const std::string& recipientUserId = notification->getRecipientUserId();
-        int userIndex = users.find(recipientUserId);
-        if (userIndex == -1)
-        {
-            throw std::runtime_error("Invalid recipient user ID");
-        }
-        User* user = users.getValueAt(userIndex);
-        user->addNotification(notification);
-    }
-}
-
-/*
-Function: saveUsers
-Description: Saves users and their notifications from the datastore to persistent storage.
-             Collects notifications from all users into a single map before saving.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void UserManagementService::saveUsers()
-{
-    util::FileManager<User> userFileManager(config::file::USER_FILE);
-    util::FileManager<Notification> notificationFileManager(config::file::NOTIFICATION_FILE);
-    auto& users = m_dataStore.getUsers();
-    util::Map<std::string, Notification*> notifications;
-    for (int userIndex = 0; userIndex < users.getSize(); userIndex++)
-    {
-        User* user = users.getValueAt(userIndex);
-        auto& userNotifications = user->getNotifications();
-        for (int notificationIndex = 0; notificationIndex < userNotifications.getSize(); notificationIndex++)
-        {
-            notifications[userNotifications.getKeyAt(notificationIndex)] =
-                userNotifications.getValueAt(notificationIndex);
-        }
-    }
-    userFileManager.save(users);
-    notificationFileManager.save(notifications);
+	Notification* notification = trackedNotificationsMap.getValueAt(notificationIndex).data;
+	if (notification->getRecipientUserId() == userID)
+	{
+		notification->setState(util::State::INACTIVE);
+		trackedNotificationsMap.getValueAt(notificationIndex).state = RecordState::MODIFIED;
+		m_dataStore.saveNotifications();
+	}
 }
 
 /*
@@ -270,7 +233,9 @@ Return type: util::Map<std::string, User*>
 */
 util::Map<std::string, User*> UserManagementService::getUsers()
 {
-	return m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
+	auto users = util::getObjects(m_dataStore.getUsers());
+	return users;
 }
 
 /*
@@ -281,10 +246,12 @@ Return type: User*
 */
 User* UserManagementService::getUser(const std::string& userID)
 {
-	int index = m_dataStore.getUsers().find(userID);
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	int index = trackedUsersMap.find(userID);
 	if (index != -1)
 	{
-		return m_dataStore.getUsers().getValueAt(index);
+		return trackedUsersMap.getValueAt(index).data;
 	}
 	return nullptr;
 }
@@ -300,35 +267,53 @@ void UserManagementService::removeUser(const std::string& userID)
 	InventoryManagementService inventoryManagementService;
 	PaymentManagementService paymentManagementService;
 	ServiceManagementService serviceManagementService;
-	int index = m_dataStore.getUsers().find(userID);
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	int index = trackedUsersMap.find(userID);
 	if (index != -1)
 	{
-		User* user = m_dataStore.getUsers().getValueAt(index);
+		User* user = trackedUsersMap.getValueAt(index).data;
 		if (user != nullptr)
 		{
 			if (user->getUserType() == util::UserType::CUSTOMER)
 			{
-				serviceManagementService.cancelCustomerServiceBookings(userID);	
+				serviceManagementService.cancelCustomerServiceBookings(userID);
 			}
 			if (user->getUserType() == util::UserType::TECHNICIAN)
 			{
 				serviceManagementService.cancelTechnicianJobs(userID);
 			}
-			user->setState(util::State::INACTIVE);
 			inventoryManagementService.detach(user);
 			paymentManagementService.detach(user);
 			serviceManagementService.detach(user);
+			user->setState(util::State::INACTIVE);
+			trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
+			m_dataStore.saveUsers();
 		}
 	}
 }
 
-util::Map<std::string, User*> UserManagementService::getUsers(util::UserType type)
+/*
+Function: getUsers
+Description: Retrieves all active users of the specified type from
+			 the DataStore.
+Parameters:
+	- type: The user type to filter by
+			(ADMIN, CUSTOMER, or TECHNICIAN).
+Returns:
+	- util::Map<std::string, User*>:
+	  Collection of active users matching the specified type,
+	  keyed by user ID.
+*/
+util::Map<std::string, User*> UserManagementService::getUsers(util::UserType type) 
 {
-	util::Map<std::string, User*>& currentUsers = m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	util::Map<std::string, User*> currentUsers = util::getObjects(trackedUsersMap);
 	util::Map<std::string, User*> filteredUsersMap;
-	for (int iterator = 0; iterator < currentUsers.getSize(); iterator++)
+	for (int index = 0; index < currentUsers.getSize(); index++)
 	{
-		User* currentUser = currentUsers.getValueAt(iterator);
+		User* currentUser = currentUsers.getValueAt(index);
 		if (currentUser && currentUser->getState() == util::State::ACTIVE && currentUser->getUserType() == type)
 		{
 			filteredUsersMap.insert(currentUser->getId(), currentUser);

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

@@ -31,6 +31,4 @@ public:
     util::Vector<Notification*> getUserNotifications(const std::string& userID);
     void deleteNotification(const std::string& notificationID, const std::string& userID);
     void ensureAdminExists();
-    void loadUsers();
-    void saveUsers();
 };

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

@@ -29,6 +29,7 @@ namespace config
 	namespace file
 	{
 		const size_t INITIAL_CAPACITY = 100;
+		const size_t GROWTH_FACTOR = 2;
 		constexpr const char* DIRECTORY = "files/";
 		constexpr const char* INVENTORYITEM_FILE = "files/InventoryItem.dat";
 		constexpr const char* USER_FILE = "files/User.dat";

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

@@ -43,67 +43,4 @@ namespace util
             position++;
         }
     }
-
-    /*
-    Function: loadRecords
-    Description: Loads records from a given file path into a vector of strings.
-                 Skips the header line if present. Creates the file if it does not exist.
-    Parameters:
-        - filePath: const std::string&, path to the file
-    Returns:
-        - util::Vector<std::string>: Vector containing all records (excluding header)
-    Throws:
-        - None (creates file if missing)
-    */
-    inline util::Vector<std::string> loadRecords(const std::string& filePath)
-    {
-        util::Vector<std::string> records;
-        std::ifstream file(filePath);
-        if (!file.is_open())
-        {
-            ensureDirectoryExists(filePath);
-            std::ofstream newFile(filePath);
-            newFile.close();
-            file.open(filePath);
-        }
-        std::string line;
-        bool isHeader = true;
-        while (std::getline(file, line))
-        {
-            if (isHeader)
-            {
-                isHeader = false;
-                continue;
-            }
-            records.push_back(line);
-        }
-        return records;
-    }
-
-    /*
-    Function: saveRecords
-    Description: Saves records to a given file path. Overwrites existing content
-                 and writes a header line followed by all records.
-    Parameters:
-        - filePath: const std::string&, path to the file
-        - records: const util::Vector<std::string>&, vector of records to save
-    Returns:
-        - void
-    Throws:
-        - std::runtime_error if the file cannot be opened for writing
-    */
-    inline void saveRecords(const std::string& filePath, const util::Vector<std::string>& records)
-    {
-        std::ofstream file(filePath, std::ios::trunc);
-        if (!file.is_open())
-        {
-            throw std::runtime_error("Failed to open file " + filePath);
-        }
-        file << "Values" << '\n';
-        int numberOfRecords = records.getSize();
-        for (int index = 0; index < numberOfRecords; index++)
-        {
-            file << records[index] << '\n';
-        }
-    }
 }

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

@@ -1,119 +0,0 @@
-/*
-File: FileManager.h
-Description: Declares and implements a generic FileManager template class for
-			 loading and saving objects to and from files. Uses serialization
-			 and deserialization methods defined in the object type T.
-			 Provides persistence support for system entities such as Users,
-			 Services, InventoryItems, etc.
-Author: Trenser
-Date: 22-May-2026
-*/
-
-#pragma once
-#include <stdexcept>
-#include <string>
-#include <fstream>
-#include "Vector.h"
-#include "Map.h"
-#include "FileHelper.h"
-
-namespace util
-{
-	template <typename T> using objects = util::Map<std::string, T*>;
-
-	template <typename T>
-	class FileManager
-	{
-	private:
-		std::string m_filePath;
-	public:
-		FileManager() : m_filePath("") {}
-		FileManager(const std::string& filePath) : m_filePath(filePath) {}
-		objects<T> load();
-		void save(const objects<T>&);
-	};
-
-	/*
-	Function: load
-	Description: Loads records from the file into a map of objects.
-				 Skips the header line, deserializes each record into an object of type T,
-				 and stores them in a map keyed by object ID.
-	Parameters:
-		- None
-	Returns:
-		- util::Map<std::string, T*> containing deserialized objects
-	Throws:
-		- std::runtime_error if deserialization fails for any record
-	*/
-	template <typename T>
-	objects<T> FileManager<T>::load()
-	{
-		objects<T> records;
-		std::ifstream file(m_filePath);
-		if (!file.is_open())
-		{
-			ensureDirectoryExists(m_filePath);
-			std::ofstream newFile(m_filePath);
-			newFile.close();
-			file.open(m_filePath);
-		}
-		util::Vector<std::string> lines;
-		std::string line;
-		while (std::getline(file, line))
-		{
-			lines.push_back(line);
-		}
-		int numberOfLines = lines.getSize();
-		bool isHeader = true;
-		for (int lineIndex = 0; lineIndex < numberOfLines; lineIndex++)
-		{
-			const auto& record = lines[lineIndex];
-			if (isHeader)
-			{
-				isHeader = false;
-				continue;
-			}
-			auto object = T::deserialize(record);
-			if (!object)
-			{
-				throw std::runtime_error("Failed to deserialize record");
-			}
-			records[object->getId()] = object;
-		}
-		return records;
-	}
-
-	/*
-	Function: save
-	Description: Saves records to the file. Serializes each object of type T into a string,
-				 writes a header line, and then writes all serialized records to the file.
-	Parameters:
-		- records: const util::Map<std::string, T*>&, map of objects to save
-	Returns:
-		- void
-	Throws:
-		- std::runtime_error if the file cannot be opened for writing
-	*/
-	template <typename T>
-	void FileManager<T>::save(const objects<T>& records)
-	{
-		util::Vector<std::string> lines;
-		lines.push_back(T::getHeaders());
-		int numberOfRecords = records.getSize();
-		for (int recordIndex = 0; recordIndex < numberOfRecords; recordIndex++)
-		{
-			const auto& record = records.getValueAt(recordIndex);
-			lines.push_back(record->serialize());
-		}
-		std::ofstream file(m_filePath, std::ios::trunc);
-		if (!file.is_open())
-		{
-			throw std::runtime_error("Failed to open file " + m_filePath);
-		}
-		int numberOfLines = lines.getSize();
-		for (int lineIndex = 0; lineIndex < numberOfLines; lineIndex++)
-		{
-			file << lines[lineIndex] << '\n';
-		}
-	}
-}

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

@@ -28,7 +28,7 @@ namespace util
         if (!(std::cin >> value))
         {
             std::cin.clear();
-            std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+            std::cin.ignore((std::numeric_limits<std::streamsize>::max)(), '\n');
             throw std::runtime_error("Invalid console input");
         }
     }

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

@@ -54,52 +54,6 @@ namespace util
         return cost;
     }
 
-    /*
-    Function: loadObservers
-    Description: Loads observer IDs from a file and attaches the corresponding users
-                 to the notification management service. Validates that each observer ID
-                 exists in the datastore before attaching.
-    Parameters:
-        - filePath: const std::string&, path to the file containing observer IDs
-        - service: NotificationManagementService*, pointer to the notification service
-        - dataStore: DataStore&, reference to the datastore containing users
-    Returns:
-        - void
-    Throws:
-        - std::runtime_error if an observer ID is invalid (not found in datastore)
-    */
-    inline void loadObservers(const std::string& filePath, NotificationManagementService* service, DataStore& dataStore)
-    {
-        auto observerIDs = util::loadRecords(filePath);
-        auto& users = dataStore.getUsers();
-        for (int index = 0; index < observerIDs.getSize(); index++)
-        {
-            const std::string& observerID = observerIDs[index];
-            int userIndex = users.find(observerID);
-            if (userIndex == -1)
-            {
-                throw std::runtime_error("Invalid Observer ID");
-            }
-            service->attach(users.getValueAt(userIndex));
-        }
-    }
-
-    /*
-    Function: saveObservers
-    Description: Saves the current observer IDs from the notification management service
-                 to a file for persistence.
-    Parameters:
-        - filePath: const std::string&, path to the file where observer IDs will be saved
-        - service: NotificationManagementService*, pointer to the notification service
-    Returns:
-        - void
-    */
-    inline void saveObservers(const std::string& filePath, NotificationManagementService* service)
-    {
-        auto observerIDs = service->getObserverIDs();
-        util::saveRecords(filePath, observerIDs);
-    }
-
     template<typename TObject>
     Map<std::string, TObject*> getObjects(const Map<std::string, TrackedRecord<TObject>>& trackedRecords);
 

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

@@ -27,8 +27,11 @@ void UserInterface::run()
 {
 	try
 	{
-		m_controller.loadSystemData();
-		m_controller.runSystemChecks();
+		if (!m_controller.initialize())
+		{
+			std::cout << "Error: Failed to initialize the system!";
+			return;
+		}
 		bool isMenuActive = true;
 		while (isMenuActive)
 		{
@@ -49,7 +52,7 @@ void UserInterface::run()
 				util::pressEnter();
 			}
 		}
-		m_controller.saveSystemData();
+		m_controller.shutdown();
 	}
 	catch (const std::invalid_argument& exception)
 	{