Add Assign Companies Feature for Customers

- Introduced a new endpoint to assign companies to a customer, enhancing the customer management capabilities.
- Implemented the AssignCompanies handler in the customer service layer, including validation and structured responses.
- Updated the routes to include the new PATCH /admin/v1/customers/{id}/companies endpoint, improving administrative functionalities.
- Enhanced API documentation with Swagger comments for the new endpoint, ensuring clarity for API consumers.

internal/customer/service.go

@@ -46,6 +46,7 @@ type Service interface {
 
 	// Role assignment operations
 	AssignRole(ctx context.Context, customerID string, form *AssignRoleForm) (*AssignRoleResponse, error)
+	AssignCompanies(ctx context.Context, customerID string, Companies []string) error
 }
 
 // customerService implements the Service interface
@@ -360,6 +361,7 @@ func (s *customerService) AssignCompanies(ctx context.Context, customerID string
 	}
 
 	// Update customer's company IDs
+	customer.Companies = make([]string, 0)
 	customer.Companies = append(customer.Companies, validCompanies...)
 	customer.UpdatedAt = time.Now().Unix()
 
@@ -380,7 +382,7 @@ func (s *customerService) AssignCompanies(ctx context.Context, customerID string
 	return nil
 }
 
-// RemoveCompaniesFromCustomer removes companies from a customer
+// RemoveCompanies removes companies from a customer
 func (s *customerService) RemoveCompanies(ctx context.Context, customerID string, Companies []string) error {
 	// Get customer to check if exists
 	customer, err := s.repository.GetByID(ctx, customerID)
@@ -409,7 +411,7 @@ func (s *customerService) RemoveCompanies(ctx context.Context, customerID string
 
 	err = s.repository.Update(ctx, customer)
 	if err != nil {
-		s.logger.Error("Failed to update customer after removing company assignments", map[string]interface{}{
+		s.logger.Error("Failed to update customer after removing companies", map[string]interface{}{
 			"error":       err.Error(),
 			"customer_id": customerID,
 		})