package jwt

import (
	"errors"
	"time"

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

var (
	jwtSecret   []byte
	expireHours int
)

// Init 初始化JWT配置
func Init(secret string, hours int) {
	jwtSecret = []byte(secret)
	expireHours = hours
}

// Claims JWT声明
type Claims struct {
	UserID uint `json:"user_id"`
	jwt.RegisteredClaims
}

// GenerateToken 生成Token
func GenerateToken(userID uint) (string, error) {
	claims := Claims{
		UserID: userID,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Duration(expireHours) * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			NotBefore: jwt.NewNumericDate(time.Now()),
		},
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(jwtSecret)
}

// ParseToken 解析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) (string, error) {
	claims, err := ParseToken(tokenString)
	if err != nil {
		return "", err
	}
	// 生成新Token
	return GenerateToken(claims.UserID)
}