package jwtutil

import (
	"errors"
	"time"

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

// 密钥（后续可从配置中读取）
var secret = []byte("yunzer_jwt_secret_key")

// Claims 定义JWT的claims结构
type Claims struct {
	UserID   int    `json:"user_id"`
	Username string `json:"username"`
	TenantId int    `json:"tenant_id"` // 租户ID
	UserType string `json:"user_type"` // 用户类型："user" / "employee" / "platform" 等
	jwt.RegisteredClaims
}

// GenerateToken 生成JWT token
func GenerateToken(userID int, username string, tenantId int, userType string) (string, error) {
	expirationTime := time.Now().Add(24 * time.Hour)

	claims := &Claims{
		UserID:   userID,
		Username: username,
		TenantId: tenantId,
		UserType: userType,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(expirationTime),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			NotBefore: jwt.NewNumericDate(time.Now()),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenString, err := token.SignedString(secret)
	return tokenString, err
}

// ParseToken 解析JWT token
func ParseToken(tokenString string) (*Claims, error) {
	claims := &Claims{}
	token, err := jwt.ParseWithClaims(tokenString, claims, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, errors.New("unexpected signing method")
		}
		return secret, nil
	})

	if err != nil {
		return nil, err
	}

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

	return claims, nil
}