fix user update role and department

internal/processor/user_processor.go

@@ -136,6 +136,12 @@ func (p *UserProcessorImpl) UpdateUser(ctx context.Context, id uuid.UUID, req *c
 		}
 	}
 
+	if req.Role != nil {
+		if err := p.userRoleProc.ReplaceUserRole(ctx, updated.ID, *req.Role); err != nil {
+			return nil, fmt.Errorf("failed to assign role to user: %w", err)
+		}
+	}
+
 	// Update departments if provided
 	if req.DepartmentIDs != nil {
 		departments := make([]entities.Department, len(*req.DepartmentIDs))

internal/processor/user_role_processor.go

@@ -15,6 +15,7 @@ type UserRoleProcessor interface {
 	RemoveRoleFromUser(ctx context.Context, userID, roleID uuid.UUID) error
 	GetUserRoles(ctx context.Context, userID uuid.UUID) ([]entities.Role, error)
 	HasRole(ctx context.Context, userID uuid.UUID, roleCode string) (bool, error)
+	ReplaceUserRole(ctx context.Context, userID, roleID uuid.UUID) error
 }
 
 type UserRoleProcessorImpl struct {
@@ -94,4 +95,37 @@ func (p *UserRoleProcessorImpl) HasRole(ctx context.Context, userID uuid.UUID, r
 	}
 	
 	return count > 0, nil
+}
+
+func (p *UserRoleProcessorImpl) ReplaceUserRole(ctx context.Context, userID uuid.UUID, roleID uuid.UUID) error {
+	return p.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+		// Delete old role
+		if err := tx.Where("user_id = ?", userID).
+			Delete(&UserRoleEntry{}).Error; err != nil {
+			return err
+		}
+
+		// Check if new role already exists
+		var existingEntry UserRoleEntry
+		err := tx.Where("user_id = ?", userID).
+			First(&existingEntry).Error
+
+		if err == nil {
+			// Role already assigned
+			return nil
+		}
+
+		if err != gorm.ErrRecordNotFound {
+			return err
+		}
+
+		// Assign new role
+		newEntry := UserRoleEntry{
+			UserID:     userID,
+			RoleID:     roleID,
+			AssignedAt: time.Now(),
+		}
+
+		return tx.Create(&newEntry).Error
+	})
 }