package jwtx

import (
	"allapp/config"
	"context"
	"errors"
	"sync"
	"time"

	"github.com/golang-jwt/jwt/v5"
)

type CustomClaims struct {
	UserID int64 `json:"user_id"`
	jwt.RegisteredClaims
}

// jwtManager 单例管理
type jwtManager struct {
	secret      string
	tokenExpiry time.Duration
}

var (
	manager *jwtManager
	once    sync.Once
)

// InitJwt 初始化 JWT 单例
func InitJwt() {
	once.Do(func() {
		cfg := config.GetConf().JWT
		manager = &jwtManager{
			secret:      cfg.Secret,
			tokenExpiry: cfg.AccessExpiry,
		}
	})
}

// CreateToken 生成 JWT
func CreateToken(ctx context.Context, userID int64) (string, error) {
	if manager == nil {
		return "", errors.New("jwt manager not initialized")
	}
	return manager.createToken(userID)
}

// VerifyToken 校验 token 并返回 claims
func VerifyToken(ctx context.Context, tokenString string) (*CustomClaims, error) {
	if tokenString == "" || manager == nil {
		return nil, errors.New("token empty or manager not initialized")
	}

	token, err := jwt.ParseWithClaims(tokenString, &CustomClaims{}, func(token *jwt.Token) (interface{}, error) {
		return []byte(manager.secret), nil
	})

	if err != nil || !token.Valid {
		return nil, errors.New("invalid token")
	}

	claims, ok := token.Claims.(*CustomClaims)
	if !ok {
		return nil, errors.New("invalid claims")
	}

	return claims, nil
}

// createToken 私有方法
func (j *jwtManager) createToken(userID int64) (string, error) {
	now := time.Now()
	claims := &CustomClaims{
		UserID: userID,
		RegisteredClaims: jwt.RegisteredClaims{
			IssuedAt: jwt.NewNumericDate(now),
		},
	}

	if j.tokenExpiry > 0 {
		claims.ExpiresAt = jwt.NewNumericDate(now.Add(j.tokenExpiry))
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(j.secret))
}