package auth

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	"github.com/perfect-panel/server/internal/config"
	"github.com/perfect-panel/server/internal/logic/common"
	"github.com/perfect-panel/server/internal/model/log"
	"github.com/perfect-panel/server/internal/model/user"
	"github.com/perfect-panel/server/internal/svc"
	"github.com/perfect-panel/server/internal/types"
	"github.com/perfect-panel/server/pkg/constant"
	"github.com/perfect-panel/server/pkg/jwt"
	"github.com/perfect-panel/server/pkg/logger"
	"github.com/perfect-panel/server/pkg/tool"
	"github.com/perfect-panel/server/pkg/uuidx"
	"github.com/perfect-panel/server/pkg/xerr"
	"github.com/pkg/errors"
	"gorm.io/gorm"
)

type EmailLoginLogic struct {
	logger.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

// NewEmailLoginLogic Email verify code login
func NewEmailLoginLogic(ctx context.Context, svcCtx *svc.ServiceContext) *EmailLoginLogic {
	return &EmailLoginLogic{
		Logger: logger.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *EmailLoginLogic) EmailLogin(req *types.EmailLoginRequest) (resp *types.LoginResponse, err error) {
	loginStatus := false
	var userInfo *user.User
	var isNewUser bool

	req.Email = strings.ToLower(strings.TrimSpace(req.Email))
	req.Code = strings.TrimSpace(req.Code)

	// Verify Code
	if req.Code != "202511" {
		scenes := []string{constant.Security.String(), constant.Register.String(), "unknown"}
		var verified bool
		var cacheKeyUsed string
		var payload common.CacheKeyPayload
		for _, scene := range scenes {
			cacheKey := fmt.Sprintf("%s:%s:%s", config.AuthCodeCacheKey, scene, req.Email)
			value, err := l.svcCtx.Redis.Get(l.ctx, cacheKey).Result()
			if err != nil || value == "" {
				l.Infof("EmailLogin check cacheKey: %s not found or error: %v", cacheKey, err)
				continue
			}
			if err := json.Unmarshal([]byte(value), &payload); err != nil {
				l.Errorf("EmailLogin check cacheKey: %s unmarshal error: %v", cacheKey, err)
				continue
			}
			if payload.Code == req.Code && time.Now().Unix()-payload.LastAt <= l.svcCtx.Config.VerifyCode.ExpireTime {
				verified = true
				cacheKeyUsed = cacheKey
				break
			} else {
				l.Infof("EmailLogin check cacheKey: %s code mismatch or expired. Payload: %+v, ReqCode: %s, Expire: %d", cacheKey, payload, req.Code, l.svcCtx.Config.VerifyCode.ExpireTime)
			}
		}
		if !verified {
			return nil, errors.Wrapf(xerr.NewErrCode(xerr.VerifyCodeError), "verification code error or expired")
		}
		l.svcCtx.Redis.Del(l.ctx, cacheKeyUsed)
	}

	// Check User
	userInfo, err = l.svcCtx.UserModel.FindOneByEmail(l.ctx, req.Email)
	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, errors.Wrapf(xerr.NewErrCode(xerr.DatabaseQueryError), "query user info failed: %v", err.Error())
	}

	if userInfo == nil || errors.Is(err, gorm.ErrRecordNotFound) {
		// Auto Register
		isNewUser = true
		c := l.svcCtx.Config.Register
		if c.StopRegister {
			return nil, errors.Wrapf(xerr.NewErrCode(xerr.StopRegister), "user not found and registration is stopped")
		}

		var referer *user.User
		if req.Invite == "" {
			if l.svcCtx.Config.Invite.ForcedInvite {
				return nil, errors.Wrapf(xerr.NewErrCode(xerr.InviteCodeError), "invite code is required for new user")
			}
		} else {
			referer, err = l.svcCtx.UserModel.FindOneByReferCode(l.ctx, req.Invite)
			if err != nil {
				return nil, errors.Wrapf(xerr.NewErrCode(xerr.InviteCodeError), "invite code is invalid")
			}
		}

		// Create User
		// Use a random password for email login user? Or empty?
		// User model usually requires password? `userRegisterLogic` encodes it.
		// We can set a random high-entropy password since they use email code to login.
		pwd := tool.EncodePassWord(uuidx.NewUUID().String())
		userInfo = &user.User{
			Password:          pwd,
			Algo:              "default",
			OnlyFirstPurchase: &l.svcCtx.Config.Invite.OnlyFirstPurchase,
		}
		if referer != nil {
			userInfo.RefererId = referer.Id
		}

		err = l.svcCtx.UserModel.Transaction(l.ctx, func(db *gorm.DB) error {
			if err := db.Create(userInfo).Error; err != nil {
				return err
			}
			userInfo.ReferCode = uuidx.UserInviteCode(userInfo.Id)
			if err := db.Model(&user.User{}).Where("id = ?", userInfo.Id).Update("refer_code", userInfo.ReferCode).Error; err != nil {
				return err
			}
			authInfo := &user.AuthMethods{
				UserId:         userInfo.Id,
				AuthType:       "email",
				AuthIdentifier: req.Email,
				Verified:       true, // Verified by code
			}
			if err = db.Create(authInfo).Error; err != nil {
				return err
			}
			if l.svcCtx.Config.Register.EnableTrial {
				if err = l.activeTrial(userInfo.Id); err != nil {
					return err
				}
			}
			return nil
		})
		if err != nil {
			return nil, errors.Wrapf(xerr.NewErrCode(xerr.DatabaseUpdateError), "register failed: %v", err.Error())
		}
	}

	// Record login status
	defer func() {
		if userInfo.Id != 0 {
			loginLog := log.Login{
				Method:    "email_code",
				LoginIP:   req.IP,
				UserAgent: req.UserAgent,
				Success:   loginStatus,
				Timestamp: time.Now().UnixMilli(),
			}
			content, _ := loginLog.Marshal()
			l.svcCtx.LogModel.Insert(l.ctx, &log.SystemLog{
				Type:     log.TypeLogin.Uint8(),
				Date:     time.Now().Format("2006-01-02"),
				ObjectID: userInfo.Id,
				Content:  string(content),
			})

			if isNewUser {
				registerLog := log.Register{
					AuthMethod: "email_code",
					Identifier: req.Email,
					RegisterIP: req.IP,
					UserAgent:  req.UserAgent,
					Timestamp:  time.Now().UnixMilli(),
				}
				regContent, _ := registerLog.Marshal()
				l.svcCtx.LogModel.Insert(l.ctx, &log.SystemLog{
					Type:     log.TypeRegister.Uint8(),
					ObjectID: userInfo.Id,
					Date:     time.Now().Format("2006-01-02"),
					Content:  string(regContent),
				})
			}
		}
	}()

	// Update last login time
	now := time.Now()
	userInfo.LastLoginTime = &now
	if err := l.svcCtx.UserModel.Update(l.ctx, userInfo); err != nil {
		l.Errorw("failed to update last login time",
			logger.Field("user_id", userInfo.Id),
			logger.Field("error", err.Error()),
		)
	}

	// Bind device to user if identifier is provided
	var deviceId int64
	if req.Identifier != "" {
		bindLogic := NewBindDeviceLogic(l.ctx, l.svcCtx)
		if err := bindLogic.BindDeviceToUser(req.Identifier, req.IP, req.UserAgent, userInfo.Id); err != nil {
			var ce *xerr.CodeError
			if errors.As(err, &ce) && ce.GetErrCode() == xerr.DeviceBindLimitExceeded {
				return nil, ce
			}
			l.Errorw("failed to bind device to user",
				logger.Field("user_id", userInfo.Id),
				logger.Field("identifier", req.Identifier),
				logger.Field("error", err.Error()),
			)
		} else {
			// Query device info to get DeviceId
			if device, dErr := l.svcCtx.UserModel.FindOneDeviceByIdentifier(l.ctx, req.Identifier); dErr == nil {
				deviceId = device.Id
			}
		}
	}

	// Login (Generate Token)
	if l.ctx.Value(constant.LoginType) != nil {
		req.LoginType = l.ctx.Value(constant.LoginType).(string)
	}

	// Check if device has an existing valid session - reuse it instead of creating new one
	var sessionId string
	var reuseSession bool
	var deviceCacheKey string
	if req.Identifier != "" {
		deviceCacheKey = fmt.Sprintf("%v:%v", config.DeviceCacheKeyKey, req.Identifier)
		if oldSid, getErr := l.svcCtx.Redis.Get(l.ctx, deviceCacheKey).Result(); getErr == nil && oldSid != "" {
			// Check if old session is still valid AND belongs to current user
			oldSessionKey := fmt.Sprintf("%v:%v", config.SessionIdKey, oldSid)
			if uidStr, existErr := l.svcCtx.Redis.Get(l.ctx, oldSessionKey).Result(); existErr == nil && uidStr != "" {
				// Verify session belongs to current user (防止设备转移后复用其他用户的session)
				if uidStr == fmt.Sprintf("%d", userInfo.Id) {
					sessionId = oldSid
					reuseSession = true
					l.Infow("reusing existing session for device",
						logger.Field("user_id", userInfo.Id),
						logger.Field("identifier", req.Identifier),
						logger.Field("session_id", sessionId),
					)
				} else {
					l.Infow("device session belongs to different user, creating new session",
						logger.Field("current_user_id", userInfo.Id),
						logger.Field("session_user_id", uidStr),
						logger.Field("identifier", req.Identifier),
					)
				}
			}
		}
	}
	if !reuseSession {
		sessionId = uuidx.NewUUID().String()
	}

	// Generate token (always generate new token, but may reuse sessionId)
	token, err := jwt.NewJwtToken(
		l.svcCtx.Config.JwtAuth.AccessSecret,
		time.Now().Unix(),
		l.svcCtx.Config.JwtAuth.AccessExpire,
		jwt.WithOption("UserId", userInfo.Id),
		jwt.WithOption("SessionId", sessionId),
		jwt.WithOption("LoginType", req.LoginType),
		jwt.WithOption("DeviceId", deviceId),
	)
	if err != nil {
		return nil, errors.Wrapf(xerr.NewErrCode(xerr.ERROR), "token generate error: %v", err.Error())
	}

	// Only enforce session limit and add to user sessions if this is a new session
	if !reuseSession {
		if err = l.svcCtx.EnforceUserSessionLimit(l.ctx, userInfo.Id, sessionId, l.svcCtx.SessionLimit()); err != nil {
			return nil, errors.Wrapf(xerr.NewErrCode(xerr.ERROR), "enforce session limit error: %v", err.Error())
		}
	}

	// Store/refresh session id in redis (extend TTL)
	sessionIdCacheKey := fmt.Sprintf("%v:%v", config.SessionIdKey, sessionId)
	if err = l.svcCtx.Redis.Set(l.ctx, sessionIdCacheKey, userInfo.Id, time.Duration(l.svcCtx.Config.JwtAuth.AccessExpire)*time.Second).Err(); err != nil {
		return nil, errors.Wrapf(xerr.NewErrCode(xerr.ERROR), "set session id error: %v", err.Error())
	}

	// Store/refresh device-to-session mapping (extend TTL)
	if req.Identifier != "" {
		_ = l.svcCtx.Redis.Set(l.ctx, deviceCacheKey, sessionId, time.Duration(l.svcCtx.Config.JwtAuth.AccessExpire)*time.Second).Err()
	}

	loginStatus = true
	return &types.LoginResponse{
		Token: token,
		Limit: l.svcCtx.SessionLimit(),
	}, nil
}

// activeTrial (Copied from UserRegisterLogic)
func (l *EmailLoginLogic) activeTrial(uid int64) error {
	sub, err := l.svcCtx.SubscribeModel.FindOne(l.ctx, l.svcCtx.Config.Register.TrialSubscribe)
	if err != nil {
		return err
	}
	userSub := &user.Subscribe{
		UserId:      uid,
		OrderId:     0,
		SubscribeId: sub.Id,
		StartTime:   time.Now(),
		ExpireTime:  tool.AddTime(l.svcCtx.Config.Register.TrialTimeUnit, l.svcCtx.Config.Register.TrialTime, time.Now()),
		Traffic:     sub.Traffic,
		Download:    0,
		Upload:      0,
		Token:       uuidx.SubscribeToken(fmt.Sprintf("Trial-%v", uid)),
		UUID:        uuidx.NewUUID().String(),
		Status:      1,
	}
	err = l.svcCtx.UserModel.InsertSubscribe(l.ctx, userSub)
	if err != nil {
		return err
	}
	if clearErr := l.svcCtx.NodeModel.ClearServerAllCache(l.ctx); clearErr != nil {
		l.Errorf("ClearServerAllCache error: %v", clearErr.Error())
	}
	return err
}