package jwtx

import (
	"cn/oneao/base-go/conf"
	"sync"
	"time"

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

type CustomClaims struct {
	UserID int64 `json:"user_id"`
	jwt.RegisteredClaims
}

type TokenResult struct {
	Claims    *CustomClaims
	IsValid   bool
	IsExpired bool
}

type jwtManager struct {
	secret        string
	accessExpiry  time.Duration
	refreshExpiry time.Duration
}

var (
	manager *jwtManager
	once    sync.Once
)

// InitJwt 初始化全局 JWT 配置，只能调用一次
func InitJwt() {
	once.Do(func() {
		manager = &jwtManager{
			secret:        conf.GetConf().JWT.Secret,
			accessExpiry:  conf.GetConf().JWT.AccessExpiry,
			refreshExpiry: conf.GetConf().JWT.RefreshExpiry,
		}
	})
}

// CreateAccessToken 全局函数创建 Access Token
func CreateAccessToken(userID int64) (string, error) {
	return manager.createToken(userID, manager.accessExpiry)
}

// CreateRefreshToken 全局函数创建 Refresh Token
func CreateRefreshToken(userID int64) (string, error) {
	return manager.createToken(userID, manager.refreshExpiry)
}

// VerifyToken 全局函数验证 Token
func VerifyToken(tokenString string) TokenResult {
	result := TokenResult{IsValid: false, IsExpired: false}

	if tokenString == "" || manager == nil {
		return result
	}

	token, err := jwt.ParseWithClaims(tokenString, &CustomClaims{}, func(token *jwt.Token) (interface{}, error) {
		return []byte(manager.secret), nil
	})

	if token == nil {
		return result
	}

	claims, ok := token.Claims.(*CustomClaims)
	if !ok {
		return result
	}

	if err != nil || !token.Valid {
		return result
	}

	result.Claims = claims
	result.IsValid = true
	if claims.ExpiresAt != nil && time.Now().After(claims.ExpiresAt.Time) {
		result.IsExpired = true
	}
	return result
}

// 内部方法，生成 Token
func (j *jwtManager) createToken(userID int64, expiry time.Duration) (string, error) {
	claims := &CustomClaims{
		UserID: userID,
		RegisteredClaims: jwt.RegisteredClaims{
			IssuedAt: jwt.NewNumericDate(time.Now()),
		},
	}

	switch {
	case expiry > 0:
		claims.ExpiresAt = jwt.NewNumericDate(time.Now().Add(expiry))
	case expiry == -1:
		claims.ExpiresAt = nil // 永不过期
	default:
		claims.ExpiresAt = jwt.NewNumericDate(time.Now().Add(time.Hour))
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(j.secret))
}