package service

import (
	"context"
	"fmt"
	"time"

	"github.com/google/uuid"

	"with_you/internal/model"
	"with_you/internal/pkg/redis"
	"with_you/internal/pkg/ws"
)

// Lua 脚本：原子性地检查状态并更新为 scanned
const scanScript = `
	local key = KEYS[1]
	local status = redis.call('HGET', key, 'status')
	if status == 'pending' then
		redis.call('HMSET', key, 'status', 'scanned', 'user_id', ARGV[1])
		return 1
	elseif status == 'scanned' then
		return 2
	else
		return 0
	end
`

const (
	qrcodeSessionPrefix = "qrcode:session:"
	qrcodeSessionTTL    = 5 * time.Minute
)

// QRCodeStatus 二维码状态
type QRCodeStatus string

const (
	QRCodeStatusPending   QRCodeStatus = "pending"
	QRCodeStatusScanned   QRCodeStatus = "scanned"
	QRCodeStatusConfirmed QRCodeStatus = "confirmed"
	QRCodeStatusCancelled QRCodeStatus = "cancelled"
	QRCodeStatusExpired   QRCodeStatus = "expired"
)

// QRCodeSession 二维码会话
type QRCodeSession struct {
	SessionID string       `json:"session_id"`
	Status    QRCodeStatus `json:"status"`
	UserID    string       `json:"user_id"`
	CreatedAt int64        `json:"created_at"`
	ExpiresAt int64        `json:"expires_at"`
}

// QRCodeLoginService 二维码登录服务
type QRCodeLoginService struct {
	redis           *redis.Client
	wsHub           *ws.Hub
	jwtService      *JWTService
	userService     UserService
	activityService UserActivityService
	logService      *LogService
}

// NewQRCodeLoginService 创建二维码登录服务
func NewQRCodeLoginService(redis *redis.Client, wsHub *ws.Hub, jwtService *JWTService, userService UserService, activityService UserActivityService, logService *LogService) *QRCodeLoginService {
	return &QRCodeLoginService{
		redis:           redis,
		wsHub:           wsHub,
		jwtService:      jwtService,
		userService:     userService,
		activityService: activityService,
		logService:      logService,
	}
}

// CreateSession 创建二维码会话
func (s *QRCodeLoginService) CreateSession(ctx context.Context) (*QRCodeSession, error) {
	sessionID := uuid.New().String()
	now := time.Now()
	expiresAt := now.Add(qrcodeSessionTTL)

	session := &QRCodeSession{
		SessionID: sessionID,
		Status:    QRCodeStatusPending,
		CreatedAt: now.Unix(),
		ExpiresAt: expiresAt.Unix(),
	}

	key := qrcodeSessionPrefix + sessionID
	data := map[string]any{
		"status":     string(session.Status),
		"user_id":    "",
		"created_at": session.CreatedAt,
		"expires_at": session.ExpiresAt,
	}

	if err := s.redis.HMSet(ctx, key, data); err != nil {
		return nil, fmt.Errorf("failed to create session: %w", err)
	}

	if _, err := s.redis.Expire(ctx, key, qrcodeSessionTTL); err != nil {
		return nil, fmt.Errorf("failed to set session ttl: %w", err)
	}

	return session, nil
}

// GetSession 获取会话
func (s *QRCodeLoginService) GetSession(ctx context.Context, sessionID string) (*QRCodeSession, error) {
	key := qrcodeSessionPrefix + sessionID
	data, err := s.redis.HGetAll(ctx, key)
	if err != nil {
		return nil, fmt.Errorf("failed to get session: %w", err)
	}

	if len(data) == 0 {
		return nil, fmt.Errorf("session not found or expired")
	}

	session := &QRCodeSession{
		SessionID: sessionID,
		Status:    QRCodeStatus(data["status"]),
		UserID:    data["user_id"],
	}

	// 解析时间戳
	if v := data["created_at"]; v != "" {
		fmt.Sscanf(v, "%d", &session.CreatedAt)
	}
	if v := data["expires_at"]; v != "" {
		fmt.Sscanf(v, "%d", &session.ExpiresAt)
	}

	// 检查是否过期
	if time.Now().Unix() > session.ExpiresAt {
		session.Status = QRCodeStatusExpired
	}

	return session, nil
}

// Scan 扫描二维码
func (s *QRCodeLoginService) Scan(ctx context.Context, sessionID, userID string) error {
	key := qrcodeSessionPrefix + sessionID

	// 使用 Lua 脚本实现原子性检查和更新，避免竞态条件
	result, err := s.redis.GetClient().Eval(ctx, scanScript, []string{key}, userID).Int()
	if err != nil {
		return fmt.Errorf("failed to scan: %w", err)
	}

	switch result {
	case 0:
		return fmt.Errorf("session not found or expired")
	case 2:
		return fmt.Errorf("qrcode already scanned")
	}

	// 获取用户信息用于推送
	user, err := s.userService.GetUserByID(ctx, userID)
	if err != nil {
		return fmt.Errorf("failed to get user info: %w", err)
	}

	// 推送扫码事件
	payload := map[string]any{
		"user": map[string]any{
			"id":       user.ID,
			"nickname": user.Nickname,
			"avatar":   user.Avatar,
		},
	}
	s.wsHub.PublishToUser(sessionID, "scanned", payload)

	return nil
}

// Confirm 确认登录
func (s *QRCodeLoginService) Confirm(ctx context.Context, sessionID, userID string, ip, userAgent string) (*LoginResponse, error) {
	session, err := s.GetSession(ctx, sessionID)
	if err != nil {
		return nil, err
	}

	if session.Status != QRCodeStatusScanned {
		return nil, fmt.Errorf("invalid session status")
	}

	if session.UserID != userID {
		return nil, fmt.Errorf("unauthorized")
	}

	// 获取用户信息
	user, err := s.userService.GetUserByID(ctx, userID)
	if err != nil {
		return nil, fmt.Errorf("user not found: %w", err)
	}

	// 复用JWT生成逻辑
	accessToken, err := s.jwtService.GenerateAccessToken(user.ID, user.Username)
	if err != nil {
		return nil, fmt.Errorf("failed to generate access token: %w", err)
	}

	refreshToken, err := s.jwtService.GenerateRefreshToken(user.ID, user.Username)
	if err != nil {
		return nil, fmt.Errorf("failed to generate refresh token: %w", err)
	}

	// 更新状态
	key := qrcodeSessionPrefix + sessionID
	if err := s.redis.HSet(ctx, key, "status", string(QRCodeStatusConfirmed)); err != nil {
		return nil, fmt.Errorf("failed to update status: %w", err)
	}

	// 复用活跃记录
	if s.activityService != nil {
		go func() {
			s.activityService.RecordUserActive(context.Background(), userID, model.LoginTypeLogin, ip, userAgent)
		}()
	}

	// 复用登录日志
	if s.logService != nil {
		go func() {
			s.logService.LoginLog.RecordLogin(&model.LoginLog{
				UserID:    user.ID,
				UserName:  user.Username,
				NickName:  user.Nickname,
				LoginType: string(model.LoginTypeQRCode),
				Event:     string(model.LoginEventLogin),
				IP:        ip,
				UserAgent: userAgent,
				Result:    string(model.LoginResultSuccess),
			})
		}()
	}

	// 推送确认事件
	response := &LoginResponse{
		Token:        accessToken,
		RefreshToken: refreshToken,
		User:         user,
	}
	s.wsHub.PublishToUser(sessionID, "confirmed", response)

	return response, nil
}

// LoginResponse 登录响应
type LoginResponse struct {
	Token        string      `json:"token"`
	RefreshToken string      `json:"refresh_token"`
	User         *model.User `json:"user"`
}

// Cancel 取消登录
func (s *QRCodeLoginService) Cancel(ctx context.Context, sessionID, userID string) error {
	session, err := s.GetSession(ctx, sessionID)
	if err != nil {
		return err
	}

	if session.Status != QRCodeStatusScanned {
		return fmt.Errorf("invalid session status")
	}

	if session.UserID != userID {
		return fmt.Errorf("unauthorized")
	}

	key := qrcodeSessionPrefix + sessionID
	if err := s.redis.HSet(ctx, key, "status", string(QRCodeStatusCancelled)); err != nil {
		return fmt.Errorf("failed to update status: %w", err)
	}

	// 推送取消事件
	s.wsHub.PublishToUser(sessionID, "cancelled", map[string]any{})

	return nil
}

// GetWSHub 获取WS Hub
func (s *QRCodeLoginService) GetWSHub() *ws.Hub {
	return s.wsHub
}

// GetUserService 获取用户服务
func (s *QRCodeLoginService) GetUserService() UserService {
	return s.userService
}