package services

import (
	"crypto/rand"
	"encoding/base64"
	"errors"
	"fmt"
	"strings"
	"time"
	"smart-customer-service/config"
	"smart-customer-service/internal/models"
	"smart-customer-service/pkg/database"
	"smart-customer-service/pkg/jwt"

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

type AuthService struct {
	cfg    *config.Config
	db     *gorm.DB
	jwt    *jwt.JWTManager
}

func NewAuthService(cfg *config.Config, db *gorm.DB) *AuthService {
	return &AuthService{
		cfg:    cfg,
		db:     db,
		jwt:    jwt.NewJWTManager(cfg.JWT.Secret),
	}
}

// LoginRequest 登录请求
type LoginRequest struct {
	Email    string `json:"email" binding:"required,email"`
	Password string `json:"password" binding:"required,min=6"`
	DeviceID string `json:"device_id"`
	DeviceName string `json:"device_name"`
	DeviceType string `json:"device_type"`
	IPAddress string `json:"ip_address"`
	UserAgent string `json:"user_agent"`
}

// LoginResponse 登录响应
type LoginResponse struct {
	User         *models.User `json:"user"`
	AccessToken  string       `json:"access_token"`
	RefreshToken string       `json:"refresh_token"`
	ExpiresAt    time.Time    `json:"expires_at"`
	TokenType    string       `json:"token_type"`
}

// RegisterRequest 注册请求
type RegisterRequest struct {
	TenantID   uint   `json:"tenant_id"`
	Username   string `json:"username" binding:"required,min=3,max=50"`
	Email      string `json:"email" binding:"required,email"`
	Password   string `json:"password" binding:"required,min=6"`
	FullName   string `json:"full_name"`
	Phone      string `json:"phone"`
}

// RegisterResponse 注册响应
type RegisterResponse struct {
	User  *models.User `json:"user"`
	Token string       `json:"token"`
}

// Login 用户登录
func (s *AuthService) Login(req *LoginRequest) (*LoginResponse, error) {
	// 记录登录尝试
	loginAttempt := &models.LoginAttempt{
		Email:     req.Email,
		IPAddress: req.IPAddress,
		UserAgent: req.UserAgent,
		Success:   false,
	}
	defer s.recordLoginAttempt(loginAttempt)

	// 查找用户
	var user models.User
	if err := s.db.Where("email = ?", req.Email).First(&user).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			loginAttempt.FailureReason = "用户不存在"
			return nil, errors.New("用户名或密码错误")
		}
		loginAttempt.FailureReason = "数据库错误"
		return nil, err
	}

	// 检查用户状态
	if user.Status != "active" {
		loginAttempt.FailureReason = "用户状态异常: " + user.Status
		return nil, errors.New("用户账户不可用")
	}

	// 验证密码
	if err := bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(req.Password)); err != nil {
		loginAttempt.UserID = &user.ID
		loginAttempt.FailureReason = "密码错误"
		return nil, errors.New("用户名或密码错误")
	}

	// 更新最后登录时间
	now := time.Now()
	user.LastLoginAt = &now
	user.LastIP = req.IPAddress
	if err := s.db.Save(&user).Error; err != nil {
		loginAttempt.FailureReason = "更新登录信息失败"
		return nil, err
	}

	// 生成JWT令牌
	accessToken, accessExpiresAt, err := s.jwt.GenerateAccessToken(user.ID, user.TenantID, user.Role)
	if err != nil {
		loginAttempt.FailureReason = "生成令牌失败"
		return nil, err
	}

	refreshToken, refreshExpiresAt, err := s.jwt.GenerateRefreshToken(user.ID, user.TenantID)
	if err != nil {
		loginAttempt.FailureReason = "生成刷新令牌失败"
		return nil, err
	}

	// 保存令牌到数据库
	authToken := &models.AuthToken{
		TenantID:   user.TenantID,
		UserID:     user.ID,
		Token:      refreshToken,
		TokenType:  "refresh",
		ExpiresAt:  refreshExpiresAt,
		DeviceID:   req.DeviceID,
		DeviceName: req.DeviceName,
		DeviceType: req.DeviceType,
		IPAddress:  req.IPAddress,
		UserAgent:  req.UserAgent,
	}

	if err := s.db.Create(authToken).Error; err != nil {
		loginAttempt.FailureReason = "保存令牌失败"
		return nil, err
	}

	// 创建会话
	session := &models.Session{
		TenantID:     user.TenantID,
		UserID:       user.ID,
		SessionID:    generateSessionID(),
		ExpiresAt:    refreshExpiresAt,
		DeviceID:     req.DeviceID,
		DeviceName:   req.DeviceName,
		DeviceType:   req.DeviceType,
		IPAddress:    req.IPAddress,
		UserAgent:    req.UserAgent,
		LastActivity: now,
	}

	if err := s.db.Create(session).Error; err != nil {
		// 不影响主要登录流程，只记录日志
		fmt.Printf("创建会话失败: %v\n", err)
	}

	// 标记登录尝试为成功
	loginAttempt.UserID = &user.ID
	loginAttempt.Success = true
	loginAttempt.FailureReason = ""
	s.recordLoginAttempt(loginAttempt)

	return &LoginResponse{
		User:         &user,
		AccessToken:  accessToken,
		RefreshToken: refreshToken,
		ExpiresAt:    accessExpiresAt,
		TokenType:    "Bearer",
	}, nil
}

// Register 用户注册
func (s *AuthService) Register(req *RegisterRequest) (*RegisterResponse, error) {
	// 检查邮箱是否已存在
	var existingUser models.User
	if err := s.db.Where("email = ? AND tenant_id = ?", req.Email, req.TenantID).First(&existingUser).Error; err == nil {
		return nil, errors.New("邮箱已被注册")
	}

	// 检查用户名是否已存在
	if err := s.db.Where("username = ? AND tenant_id = ?", req.Username, req.TenantID).First(&existingUser).Error; err == nil {
		return nil, errors.New("用户名已被使用")
	}

	// 加密密码
	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
	if err != nil {
		return nil, err
	}

	// 创建用户
	user := &models.User{
		TenantID:   req.TenantID,
		Username:   req.Username,
		Email:      req.Email,
		Password:   string(hashedPassword),
		FullName:   req.FullName,
		Phone:      req.Phone,
		Role:       "user",
		Status:     "active",
		IsVerified: false,
	}

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

	// 生成验证令牌（简化版，实际应发送验证邮件）
	verificationToken := generateRandomToken(32)

	return &RegisterResponse{
		User:  user,
		Token: verificationToken,
	}, nil
}

// RefreshToken 刷新访问令牌
func (s *AuthService) RefreshToken(refreshToken string) (*LoginResponse, error) {
	// 查找刷新令牌
	var authToken models.AuthToken
	if err := s.db.Where("token = ? AND token_type = 'refresh' AND is_revoked = false", refreshToken).First(&authToken).Error; err != nil {
		return nil, errors.New("无效的刷新令牌")
	}

	// 检查令牌是否过期
	if time.Now().After(authToken.ExpiresAt) {
		// 标记令牌为已撤销
		now := time.Now()
		authToken.IsRevoked = true
		authToken.RevokedAt = &now
		authToken.RevokedReason = "令牌过期"
		s.db.Save(&authToken)
		return nil, errors.New("刷新令牌已过期")
	}

	// 查找用户
	var user models.User
	if err := s.db.First(&user, authToken.UserID).Error; err != nil {
		return nil, errors.New("用户不存在")
	}

	// 检查用户状态
	if user.Status != "active" {
		return nil, errors.New("用户账户不可用")
	}

	// 生成新的访问令牌
	accessToken, expiresAt, err := s.jwt.GenerateAccessToken(user.ID, user.TenantID, user.Role)
	if err != nil {
		return nil, err
	}

	return &LoginResponse{
		User:        &user,
		AccessToken: accessToken,
		ExpiresAt:   expiresAt,
		TokenType:   "Bearer",
	}, nil
}

// Logout 用户登出
func (s *AuthService) Logout(token string, userID uint) error {
	// 撤销刷新令牌
	var authToken models.AuthToken
	if err := s.db.Where("token = ? AND user_id = ?", token, userID).First(&authToken).Error; err != nil {
		return nil // 令牌不存在，无需处理
	}

	now := time.Now()
	authToken.IsRevoked = true
	authToken.RevokedAt = &now
	authToken.RevokedReason = "用户主动登出"

	return s.db.Save(&authToken).Error
}

// ValidateToken 验证访问令牌
func (s *AuthService) ValidateToken(token string) (*jwt.Claims, error) {
	return s.jwt.ValidateToken(token)
}

// ChangePassword 修改密码
func (s *AuthService) ChangePassword(userID uint, oldPassword, newPassword string) error {
	var user models.User
	if err := s.db.First(&user, userID).Error; err != nil {
		return errors.New("用户不存在")
	}

	// 验证旧密码
	if err := bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(oldPassword)); err != nil {
		return errors.New("旧密码错误")
	}

	// 加密新密码
	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(newPassword), bcrypt.DefaultCost)
	if err != nil {
		return err
	}

	user.Password = string(hashedPassword)
	return s.db.Save(&user).Error
}

// RequestPasswordReset 请求密码重置
func (s *AuthService) RequestPasswordReset(email string, tenantID uint) (string, error) {
	var user models.User
	if err := s.db.Where("email = ? AND tenant_id = ?", email, tenantID).First(&user).Error; err != nil {
		// 出于安全考虑，即使用户不存在也返回成功
		return "", nil
	}

	// 生成重置令牌
	token := generateRandomToken(32)
	expiresAt := time.Now().Add(24 * time.Hour) // 24小时有效

	resetRequest := &models.PasswordReset{
		TenantID:  tenantID,
		UserID:    user.ID,
		Token:     token,
		ExpiresAt: expiresAt,
	}

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

	return token, nil
}

// ResetPassword 重置密码
func (s *AuthService) ResetPassword(token, newPassword string) error {
	var resetRequest models.PasswordReset
	if err := s.db.Where("token = ? AND is_used = false", token).First(&resetRequest).Error; err != nil {
		return errors.New("无效的重置令牌")
	}

	// 检查令牌是否过期
	if time.Now().After(resetRequest.ExpiresAt) {
		return errors.New("重置令牌已过期")
	}

	// 查找用户
	var user models.User
	if err := s.db.First(&user, resetRequest.UserID).Error; err != nil {
		return errors.New("用户不存在")
	}

	// 加密新密码
	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(newPassword), bcrypt.DefaultCost)
	if err != nil {
		return err
	}

	// 更新密码
	user.Password = string(hashedPassword)
	if err := s.db.Save(&user).Error; err != nil {
		return err
	}

	// 标记重置令牌为已使用
	now := time.Now()
	resetRequest.IsUsed = true
	resetRequest.UsedAt = &now
	return s.db.Save(&resetRequest).Error
}

// 辅助函数

func (s *AuthService) recordLoginAttempt(attempt *models.LoginAttempt) {
	if err := s.db.Create(attempt).Error; err != nil {
		fmt.Printf("记录登录尝试失败: %v\n", err)
	}
}

func generateSessionID() string {
	b := make([]byte, 32)
	rand.Read(b)
	return base64.URLEncoding.EncodeToString(b)
}

func generateRandomToken(length int) string {
	b := make([]byte, length)
	rand.Read(b)
	return base64.URLEncoding.EncodeToString(b)
}

// GetUserByToken 通过令牌获取用户信息
func (s *AuthService) GetUserByToken(token string) (*models.User, error) {
	claims, err := s.ValidateToken(token)
	if err != nil {
		return nil, err
	}

	var user models.User
	if err := s.db.First(&user, claims.UserID).Error; err != nil {
		return nil, err
	}

	return &user, nil
}

// GetUserSessions 获取用户会话列表
func (s *AuthService) GetUserSessions(userID uint) ([]models.Session, error) {
	var sessions []models.Session
	err := s.db.Where("user_id = ? AND is_active = true", userID).Find(&sessions).Error
	return sessions, err
}

// RevokeSession 撤销会话
func (s *AuthService) RevokeSession(sessionID string, userID uint) error {
	var session models.Session
	if err := s.db.Where("session_id = ? AND user_id = ?", sessionID, userID).First(&session).Error; err != nil {
		return errors.New("会话不存在")
	}

	session.IsActive = false
	return s.db.Save(&session).Error
}