// JWT登录鉴权
package utils

import (
	"simple-memo/global"
	"time"

	"github.com/golang-jwt/jwt/v4"
)

// Claims 自定义载荷
type Claims struct {
	UserID uint // 用户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(global.VP.GetInt("jwt.expire")) * time.Second)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}
	// 签发
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(global.VP.GetString("jwt.key")))
}

// GenerateTokenWithExpire 生成Token并返回过期时间
func GenerateTokenWithExpire(userID uint) (string, int64, error) {
	expireSeconds := global.VP.GetInt("jwt.expire")
	if expireSeconds == 0 {
		expireSeconds = 7200 // 默认2小时
	}
	expiresAt := time.Now().Add(time.Duration(expireSeconds) * time.Second).UnixMilli()

	claims := Claims{
		UserID: userID,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.UnixMilli(expiresAt)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenStr, err := token.SignedString([]byte(global.VP.GetString("jwt.key")))
	return tokenStr, expiresAt, err
}

// GetTokenExpireSeconds 获取配置的token过期秒数
func GetTokenExpireSeconds() int64 {
	expireSeconds := global.VP.GetInt("jwt.expire")
	if expireSeconds == 0 {
		return 7200 // 默认2小时
	}
	return int64(expireSeconds)
}

// GenerateRandomString 生成随机字符串
func GenerateRandomString(length int) string {
	const charset = "0123456789"
	b := make([]byte, length)
	for i := range b {
		b[i] = charset[global.Rand.Intn(len(charset))]
	}
	return string(b)
}

// ParseToken 解析Token
func ParseToken(token string) (*Claims, error) {
	t, err := jwt.ParseWithClaims(token, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		return []byte(global.VP.GetString("jwt.key")), nil
	})
	if err != nil {
		return nil, err
	}
	// 校验
	if claims, ok := t.Claims.(*Claims); ok && t.Valid {
		return claims, nil
	}
	return nil, err
}