package auth

import (
	"backend/config"
	"backend/internal/dto"
	"backend/internal/model"
	"backend/utils"
	"errors"
	"time"

	"gorm.io/gorm"
)

// AuthService 认证业务逻辑层 // Logan.Li
type AuthService struct {
	db  *gorm.DB
	cfg *config.Config
}

// NewAuthService 创建 service 实例 // Logan.Li
func NewAuthService(db *gorm.DB, cfg *config.Config) *AuthService {
	return &AuthService{db: db, cfg: cfg}
}

// Login 校验账号密码并签发 JWT // Logan.Li
func (s *AuthService) Login(req dto.LoginRequest) (*dto.LoginResponse, error) {
	var user model.User
	if err := s.db.Where("username = ?", req.Username).First(&user).Error; err != nil {
		return nil, errors.New("用户名或密码错误")
	}

	if !user.IsActive {
		return nil, errors.New("账号已被禁用")
	}

	if !utils.CheckPassword(req.Password, user.Password) {
		return nil, errors.New("用户名或密码错误")
	}

	// 更新最后登录时间 // Logan.Li
	now := time.Now()
	s.db.Model(&user).Update("last_login", now)

	// 签发 JWT // Logan.Li
	token, err := utils.GenerateToken(user.ID, user.Username, user.Role, s.cfg.JWTSecret)
	if err != nil {
		return nil, errors.New("令牌生成失败")
	}

	return &dto.LoginResponse{
		Token: token,
		UserInfo: dto.UserInfoResponse{
			ID:       user.ID,
			Username: user.Username,
			Email:    user.Email,
			Avatar:   user.Avatar,
			Role:     user.Role,
		},
	}, nil
}

// GetCurrentUser 根据 ID 获取当前用户信息 // Logan.Li
func (s *AuthService) GetCurrentUser(userID uint) (*dto.UserInfoResponse, error) {
	var user model.User
	if err := s.db.First(&user, userID).Error; err != nil {
		return nil, errors.New("用户不存在")
	}

	return &dto.UserInfoResponse{
		ID:       user.ID,
		Username: user.Username,
		Email:    user.Email,
		Avatar:   user.Avatar,
		Role:     user.Role,
	}, nil
}

// ChangePassword 修改当前用户密码 // Logan.Li
func (s *AuthService) ChangePassword(userID uint, req dto.ChangePasswordRequest) error {
	var user model.User
	if err := s.db.First(&user, userID).Error; err != nil {
		return errors.New("用户不存在")
	}

	if !utils.CheckPassword(req.OldPassword, user.Password) {
		return errors.New("原密码错误")
	}

	user.Password = utils.HashPassword(req.NewPassword)
	return s.db.Save(&user).Error
}