package jwt

import (
	"dianshang/internal/config"
	"errors"
	"time"

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

// Claims JWT声明结构
type Claims struct {
	UserID   uint   `json:"user_id"`
	UserType string `json:"user_type"` // user, admin
	jwt.RegisteredClaims
}

var jwtSecret []byte

// Init 初始化JWT
func Init(cfg config.JWTConfig) {
	jwtSecret = []byte(cfg.Secret)
}

// GenerateToken 生成JWT token
func GenerateToken(userID uint, userType string, expire int) (string, error) {
	nowTime := time.Now()
	expireTime := nowTime.Add(time.Duration(expire) * time.Second)

	claims := Claims{
		UserID:   userID,
		UserType: userType,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(expireTime),
			IssuedAt:  jwt.NewNumericDate(nowTime),
			NotBefore: jwt.NewNumericDate(nowTime),
			Issuer:    "dianshang",
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(jwtSecret)
}

// ParseToken 解析JWT token
func ParseToken(tokenString string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		return jwtSecret, nil
	})

	if err != nil {
		return nil, err
	}

	if claims, ok := token.Claims.(*Claims); ok && token.Valid {
		return claims, nil
	}

	return nil, errors.New("invalid token")
}

// RefreshToken 刷新token
func RefreshToken(tokenString string, expire int) (string, error) {
	claims, err := ParseToken(tokenString)
	if err != nil {
		return "", err
	}

	// 检查token是否即将过期（剩余时间少于30分钟）
	if time.Until(claims.ExpiresAt.Time) > 30*time.Minute {
		return tokenString, nil
	}

	// 生成新token
	return GenerateToken(claims.UserID, claims.UserType, expire)
}

// ValidateToken 验证token有效性
func ValidateToken(tokenString string) bool {
	_, err := ParseToken(tokenString)
	return err == nil
}