update unique letter number

internal/service/letter_outgoing_service.go

@@ -94,6 +94,12 @@ func (s *LetterOutgoingServiceImpl) CreateOutgoingLetter(ctx context.Context, re
 	departmentID := getDepartmentIDFromContext(ctx)
 	userID := getUserIDFromContext(ctx)
 
+	existingOutgoing, err := s.processor.GetOutgoingLetterByReferenceNumber(ctx, req.ReferenceNumber)
+
+	if err == nil && existingOutgoing != nil {
+		return nil, fmt.Errorf("surat dengan nomor %s sudah ada", *req.ReferenceNumber)
+	}
+
 	// Create letter entity
 	letter := &entities.LetterOutgoing{
 		Subject:               req.Subject,
@@ -125,7 +131,7 @@ func (s *LetterOutgoingServiceImpl) CreateOutgoingLetter(ctx context.Context, re
 	}
 
 	// Execute creation with transaction in service layer
-	err := s.txManager.WithTransaction(ctx, func(txCtx context.Context) error {
+	err = s.txManager.WithTransaction(ctx, func(txCtx context.Context) error {
 		// Step 1: Validate letter
 		if err := s.validationProcessor.ValidateCreateOutgoingLetter(txCtx, letter); err != nil {
 			return err
@@ -660,7 +666,7 @@ func (s *LetterOutgoingServiceImpl) ApproveOutgoingLetter(ctx context.Context, l
 	if s.notificationProcessor != nil {
 		// Get next parallel group to determine notification message
 		nextParallelGroup := s.getNextParallelGroup(approvals, currentApproval.ParallelGroup)
-		
+
 		if nextParallelGroup > 0 {
 			// Notify creator about group completion AND next group approvers
 			creatorMessage := fmt.Sprintf("Surat keluar '%s' telah disetujui pada grup %d, menunggu persetujuan grup berikutnya", letter.Subject, currentApproval.ParallelGroup)
@@ -1896,14 +1902,14 @@ func (s *LetterOutgoingServiceImpl) getNextParallelGroup(approvals []entities.Le
 	for _, approval := range approvals {
 		groupsMap[approval.ParallelGroup] = true
 	}
-	
+
 	// Convert to sorted slice
 	var groups []int
 	for group := range groupsMap {
 		groups = append(groups, group)
 	}
 	sort.Ints(groups)
-	
+
 	// Find the next group after current
 	for _, group := range groups {
 		if group > currentGroup {
@@ -1915,45 +1921,45 @@ func (s *LetterOutgoingServiceImpl) getNextParallelGroup(approvals []entities.Le
 			}
 		}
 	}
-	
+
 	return 0 // No next group
 }
 
 // Send notifications to approvers in a specific parallel group
 func (s *LetterOutgoingServiceImpl) sendParallelGroupApprovalNotifications(ctx context.Context, letterID uuid.UUID, subject string, parallelGroup int) {
 	log.Printf("[DEBUG] sendParallelGroupApprovalNotifications START - LetterID: %s, ParallelGroup: %d", letterID.String(), parallelGroup)
-	
+
 	// Get the letter to know the current revision
 	letter, err := s.processor.GetOutgoingLetterByID(ctx, letterID)
 	if err != nil {
 		log.Printf("[ERROR] Failed to get letter: %v", err)
 		return
 	}
-	
+
 	// Get approvals for the current revision only
 	approvals, err := s.processor.GetApprovalsByLetterAndRevision(ctx, letterID, letter.RevisionNumber)
 	if err != nil {
 		log.Printf("[ERROR] Failed to get approvals: %v", err)
 		return
 	}
-	
+
 	log.Printf("[DEBUG] Found %d approvals", len(approvals))
-	
+
 	// Find approvers for the specified parallel group
 	for _, approval := range approvals {
 		log.Printf("[DEBUG] Checking approval: ParallelGroup=%d, Status=%s, ApproverID=%v",
 			approval.ParallelGroup, approval.Status, approval.ApproverID)
-		
+
 		if approval.ParallelGroup == parallelGroup && approval.ApproverID != nil {
 			log.Printf("[DEBUG] Sending notification to approver %s for parallel group %d", approval.ApproverID.String(), parallelGroup)
-			
+
 			err := s.notificationProcessor.SendOutgoingLetterNotification(
 				ctx,
 				letterID,
 				*approval.ApproverID,
 				"Surat Keluar Perlu Persetujuan",
 				fmt.Sprintf("Surat keluar '%s' memerlukan persetujuan Anda pada grup %d", subject, parallelGroup))
-			
+
 			if err != nil {
 				log.Printf("[ERROR] Failed to send notification to approver %s: %v", approval.ApproverID.String(), err)
 			} else {