package usecase

import (
	"chat/internal/domain/repository"
	"chat/internal/domain/usecase"
	"chat/internal/utils"
	"context"
	"fmt"
	"time"

	"github.com/golang-jwt/jwt/v4"
	"github.com/zeromicro/go-zero/core/logx"
)

type authUseCase struct {
	jwtSecret        string
	jwtExpire        int64
	centrifugoSecret string
	matchmakingRepo  repository.MatchmakingRepository
}

// NewAuthUseCase 創建新的認證 UseCase
func NewAuthUseCase(jwtSecret string, jwtExpire int64, centrifugoSecret string, matchmakingRepo repository.MatchmakingRepository) usecase.AuthUseCase {
	if centrifugoSecret == "" {
		centrifugoSecret = jwtSecret
	}

	return &authUseCase{
		jwtSecret:        jwtSecret,
		jwtExpire:        jwtExpire,
		centrifugoSecret: centrifugoSecret,
		matchmakingRepo:  matchmakingRepo,
	}
}

// AnonLogin 匿名登入
func (u *authUseCase) AnonLogin(ctx context.Context, name string) (uid string, token string, centrifugoToken string, expireAt int64, err error) {
	// 生成匿名 UID
	uid = utils.GenerateUID()

	// 生成 API JWT token
	now := time.Now()
	expireAt = now.Add(time.Duration(u.jwtExpire) * time.Second).Unix()

	claims := jwt.MapClaims{
		"uid":  uid,
		"exp":  expireAt,
		"iat":  now.Unix(),
		"name": name,
	}

	jwtToken := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	token, err = jwtToken.SignedString([]byte(u.jwtSecret))
	if err != nil {
		return "", "", "", 0, fmt.Errorf("failed to sign JWT: %w", err)
	}

	// 匿名登入時還未加入房間，只給予個人頻道的權限
	centrifugoExpireAt := expireAt
	centrifugoClaims := jwt.MapClaims{
		"sub":      uid,
		"exp":      centrifugoExpireAt,
		"iat":      now.Unix(),
		"channels": []string{fmt.Sprintf("user:%s", uid)},
		"name":     name,
	}

	centrifugoJwtToken := jwt.NewWithClaims(jwt.SigningMethodHS256, centrifugoClaims)
	centrifugoToken, err = centrifugoJwtToken.SignedString([]byte(u.centrifugoSecret))
	if err != nil {
		return "", "", "", 0, fmt.Errorf("failed to sign Centrifugo JWT: %w", err)
	}

	logx.Infof("User %s logged in anonymously", uid)
	return uid, token, centrifugoToken, expireAt, nil
}

// RefreshToken 刷新 token
func (u *authUseCase) RefreshToken(ctx context.Context, oldToken string) (uid string, token string, centrifugoToken string, expireAt int64, err error) {
	// 解析舊 token
	parser := jwt.NewParser(jwt.WithoutClaimsValidation())
	tokenObj, err := parser.Parse(oldToken, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, jwt.ErrSignatureInvalid
		}
		return []byte(u.jwtSecret), nil
	})

	if err != nil {
		return "", "", "", 0, fmt.Errorf("failed to parse old token: %w", err)
	}

	claims, ok := tokenObj.Claims.(jwt.MapClaims)
	if !ok {
		return "", "", "", 0, fmt.Errorf("invalid token claims")
	}

	uid, ok = claims["uid"].(string)
	if !ok || uid == "" {
		return "", "", "", 0, fmt.Errorf("UID not found in token")
	}

	name, _ := claims["name"].(string)

	// 檢查使用者當前的房間狀態
	_, roomID, err := u.matchmakingRepo.GetMatchStatus(ctx, uid)
	if err != nil {
		logx.Errorf("Failed to get match status for refresh token: %v", err)
		// 不中斷流程，只是不給房間權限
	}

	// 生成新的 API JWT token
	now := time.Now()
	expireAt = now.Add(time.Duration(u.jwtExpire) * time.Second).Unix()

	newClaims := jwt.MapClaims{
		"uid":  uid,
		"exp":  expireAt,
		"iat":  now.Unix(),
		"name": name,
	}

	jwtToken := jwt.NewWithClaims(jwt.SigningMethodHS256, newClaims)
	token, err = jwtToken.SignedString([]byte(u.jwtSecret))
	if err != nil {
		return "", "", "", 0, fmt.Errorf("failed to sign new JWT: %w", err)
	}

	// 生成新的 Centrifugo JWT token
	channels := []string{fmt.Sprintf("user:%s", uid)}
	// 如果已經在房間中，添加房間頻道的權限
	if roomID != "" {
		channels = append(channels, fmt.Sprintf("room:%s", roomID))
	}

	centrifugoExpireAt := expireAt
	centrifugoClaims := jwt.MapClaims{
		"sub":      uid,
		"exp":      centrifugoExpireAt,
		"iat":      now.Unix(),
		"channels": channels,
		"name":     name,
	}

	centrifugoJwtToken := jwt.NewWithClaims(jwt.SigningMethodHS256, centrifugoClaims)
	centrifugoToken, err = centrifugoJwtToken.SignedString([]byte(u.centrifugoSecret))
	if err != nil {
		return "", "", "", 0, fmt.Errorf("failed to sign new Centrifugo JWT: %w", err)
	}

	logx.Infof("User %s refreshed token, room: %s", uid, roomID)
	return uid, token, centrifugoToken, expireAt, nil
}