package jwt

import (
	"crypto/rsa"
	"errors"
	"fmt"
	"github.com/dgrijalva/jwt-go"
)

// TokenService 是用于 JWT 操作的服务
type TokenService struct {
	publicKey *rsa.PublicKey
}

// NewTokenService 创建一个新的 TokenService 实例
func NewTokenService(publicKeyString string) (*TokenService, error) {
	publicKey, err := jwt.ParseRSAPublicKeyFromPEM([]byte(publicKeyString))
	if err != nil {
		return nil, fmt.Errorf("解析公钥失败: %v", err)
	}

	return &TokenService{
		publicKey: publicKey,
	}, nil
}

// TokenData 用于存储解析的 token 数据
type TokenData struct {
	Expired   float64
	Frequency float64
}

// VerifyToken 解析并验证 JWT，返回 TokenData 或错误
func (j *TokenService) VerifyToken(tokenString string) (*TokenData, error) {
	// 解析并验证 JWT
	token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
		return j.publicKey, nil
	})

	if err != nil {
		return nil, fmt.Errorf("令牌解析失败: %v", err)
	}

	if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
		expired, okExp := claims["expired"].(float64)
		frequency, okFreq := claims["frequency"].(float64)

		if !okExp || !okFreq {
			return nil, errors.New("无效的令牌负载")
		}

		return &TokenData{
			Expired:   expired,
			Frequency: frequency,
		}, nil
	} else {
		return nil, errors.New("无效令牌")
	}
}