Add documentation headers across system modules

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

@@ -121,6 +121,15 @@ void Controller::removeComboPackage(const std::string& comboPackageID)
 {
 }
 
+/*
+Function: getInvoicesByUser
+Description: Retrieves all invoices associated with the currently authenticated user.
+             Converts them into a read-only map before returning.
+Parameters:
+    - None
+Returns:
+    - util::Map<std::string, const Invoice*> containing the user’s invoices
+*/
 util::Map<std::string, const Invoice*> Controller::getInvoicesByUser()
 {
     User* currentUser = m_authenticationManagementService.getAuthenticatedUser();
@@ -134,6 +143,15 @@ util::Map<std::string, const Invoice*> Controller::getInvoicesByUser()
     return userInvoicesReadOnly;
 }
 
+/*
+Function: completePayment
+Description: Completes payment for a specific invoice using the given payment mode.
+Parameters:
+    - invoiceID: std::string, ID of the invoice to be paid
+    - paymentMode: util::PaymentMode, mode of payment (e.g., ONLINE, OFFLINE)
+Returns:
+    - void
+*/
 void Controller::completePayment(const std::string& invoiceID, util::PaymentMode paymentMode)
 {
     m_paymentManagementService.completePayment(invoiceID, paymentMode);
@@ -154,5 +172,4 @@ void Controller::configureNotifications(const std::string& userID, bool paymentN
 
 void Controller::runSystemChecks()
 {
-}
-
+}