added more general response handler

internal/services/user_service.go

@@ -11,7 +11,7 @@ import (
 )
 
 type UserService interface {
-	RegisterUser(user *models.User) error
+	RegisterUser(user *models.User) (int64, error)
 	// AuthenticateUser(email, password string) (*models.User, error)
 }
 
@@ -23,16 +23,16 @@ func NewUserService(repo repositories.UserRepository) UserService {
 	return &userService{repo}
 }
 
-func (service *userService) RegisterUser(user *models.User) error {
+func (service *userService) RegisterUser(user *models.User) (int64, error) {
 	salt := make([]byte, 16)
 	if _, err := rand.Read(salt); err != nil {
-		return err
+		return -1, err
 	}
 	user.Salt = base64.StdEncoding.EncodeToString(salt)
 
 	hashedPassword, err := HashPassword(user.Password, user.Salt)
 	if err != nil {
-		return err
+		return -1, err
 	}
 	user.Password = string(hashedPassword)
 	user.CreatedAt = time.Now()