first commit

internal/service/admin_service.go

@@ -0,0 +1,62 @@
+package service
+
+import (
+	"errors"
+
+	"homework-manager/internal/models"
+	"homework-manager/internal/repository"
+)
+
+var (
+	ErrCannotDeleteSelf = errors.New("cannot delete yourself")
+	ErrCannotChangeSelfRole = errors.New("cannot change your own role")
+)
+
+type AdminService struct {
+	userRepo *repository.UserRepository
+}
+
+func NewAdminService() *AdminService {
+	return &AdminService{
+		userRepo: repository.NewUserRepository(),
+	}
+}
+
+func (s *AdminService) GetAllUsers() ([]models.User, error) {
+	return s.userRepo.FindAll()
+}
+
+func (s *AdminService) GetUserByID(id uint) (*models.User, error) {
+	return s.userRepo.FindByID(id)
+}
+
+func (s *AdminService) DeleteUser(adminID, targetID uint) error {
+	if adminID == targetID {
+		return ErrCannotDeleteSelf
+	}
+
+	_, err := s.userRepo.FindByID(targetID)
+	if err != nil {
+		return ErrUserNotFound
+	}
+
+	return s.userRepo.Delete(targetID)
+}
+
+func (s *AdminService) ChangeRole(adminID, targetID uint, newRole string) error {
+	if adminID == targetID {
+		return ErrCannotChangeSelfRole
+	}
+
+	if newRole != "admin" && newRole != "user" {
+		return errors.New("invalid role")
+	}
+
+	user, err := s.userRepo.FindByID(targetID)
+	if err != nil {
+		return ErrUserNotFound
+	}
+
+	user.Role = newRole
+	return s.userRepo.Update(user)
+}