package services

import (
	"errors"
	"time"

	"oidc-oauth2-server/models"

	"golang.org/x/crypto/bcrypt"
	"gorm.io/gorm"
)

type AdminService struct {
	db *gorm.DB
}

func NewAdminService(db *gorm.DB) *AdminService {
	return &AdminService{db: db}
}

type AdminCreateRequest struct {
	Username string `json:"username" binding:"required"`
	Password string `json:"password" binding:"required"`
	Email    string `json:"email" binding:"required,email"`
	Role     string `json:"role"`
}

type AdminUpdateRequest struct {
	Password string `json:"password"`
	Email    string `json:"email" binding:"omitempty,email"`
	IsActive *bool  `json:"is_active"`
	Role     string `json:"role"`
}

type AdminResponse struct {
	ID        uint      `json:"id"`
	Username  string    `json:"username"`
	Email     string    `json:"email"`
	LastLogin time.Time `json:"last_login"`
	IsActive  bool      `json:"is_active"`
	Role      string    `json:"role"`
	CreatedAt time.Time `json:"created_at"`
	UpdatedAt time.Time `json:"updated_at"`
}

func (s *AdminService) Create(req *AdminCreateRequest) (*AdminResponse, error) {
	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
	if err != nil {
		return nil, err
	}

	admin := &models.Admin{
		Username: req.Username,
		Password: string(hashedPassword),
		Email:    req.Email,
		Role:     req.Role,
	}

	if err := s.db.Create(admin).Error; err != nil {
		return nil, err
	}

	return s.toResponse(admin), nil
}

func (s *AdminService) Update(id uint, req *AdminUpdateRequest) (*AdminResponse, error) {
	admin := &models.Admin{}
	if err := s.db.First(admin, id).Error; err != nil {
		return nil, err
	}

	if req.Password != "" {
		hashedPassword, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
		if err != nil {
			return nil, err
		}
		admin.Password = string(hashedPassword)
	}

	if req.Email != "" {
		admin.Email = req.Email
	}

	if req.IsActive != nil {
		admin.IsActive = *req.IsActive
	}

	if req.Role != "" {
		admin.Role = req.Role
	}

	if err := s.db.Save(admin).Error; err != nil {
		return nil, err
	}

	return s.toResponse(admin), nil
}

func (s *AdminService) Delete(id uint) error {
	return s.db.Delete(&models.Admin{}, id).Error
}

func (s *AdminService) Get(id uint) (*AdminResponse, error) {
	admin := &models.Admin{}
	if err := s.db.First(admin, id).Error; err != nil {
		return nil, err
	}
	return s.toResponse(admin), nil
}

func (s *AdminService) List(page, pageSize int) ([]AdminResponse, int64, error) {
	var admins []models.Admin
	var total int64

	query := s.db.Model(&models.Admin{})
	query.Count(&total)

	if err := query.Offset((page - 1) * pageSize).Limit(pageSize).Find(&admins).Error; err != nil {
		return nil, 0, err
	}

	responses := make([]AdminResponse, len(admins))
	for i, admin := range admins {
		responses[i] = *s.toResponse(&admin)
	}

	return responses, total, nil
}

func (s *AdminService) Authenticate(username, password string) (*AdminResponse, error) {
	admin := &models.Admin{}
	if err := s.db.Where("username = ?", username).First(admin).Error; err != nil {
		return nil, errors.New("invalid credentials")
	}

	if err := bcrypt.CompareHashAndPassword([]byte(admin.Password), []byte(password)); err != nil {
		return nil, errors.New("invalid credentials")
	}

	admin.LastLogin = time.Now()
	if err := s.db.Save(admin).Error; err != nil {
		return nil, err
	}

	return s.toResponse(admin), nil
}

func (s *AdminService) toResponse(admin *models.Admin) *AdminResponse {
	return &AdminResponse{
		ID:        admin.ID,
		Username:  admin.Username,
		Email:     admin.Email,
		LastLogin: admin.LastLogin,
		IsActive:  admin.IsActive,
		Role:      admin.Role,
		CreatedAt: admin.CreatedAt,
		UpdatedAt: admin.UpdatedAt,
	}
}

func (s *AdminService) ListUsers(page, pageSize int) ([]models.User, int64, error) {
	var users []models.User
	var total int64

	s.db.Model(&models.User{}).Count(&total)

	err := s.db.Offset((page - 1) * pageSize).Limit(pageSize).Find(&users).Error
	return users, total, err
}

func (s *AdminService) ListClients(page, pageSize int) ([]models.Client, int64, error) {
	var clients []models.Client
	var total int64

	s.db.Model(&models.Client{}).Count(&total)

	err := s.db.Offset((page - 1) * pageSize).Limit(pageSize).Find(&clients).Error
	return clients, total, err
}