package jwt

import (
	"time"

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

// JWTManager JWT管理器接口
type JWTManager interface {
	GenerateToken(claims map[string]interface{}, expiration time.Duration) (string, error)
	ValidateToken(tokenString string) (map[string]interface{}, error)
	RefreshToken(tokenString string, expiration time.Duration) (string, error)
}

// jwtManager JWT管理器实现
type jwtManager struct {
	secretKey []byte
	issuer    string
}

// NewJWTManager 创建新的JWT管理器
func NewJWTManager(secretKey string, issuer string) JWTManager {
	return &jwtManager{
		secretKey: []byte(secretKey),
		issuer:    issuer,
	}
}

// GenerateToken 生成JWT令牌
func (j *jwtManager) GenerateToken(claims map[string]interface{}, expiration time.Duration) (string, error) {
	// 创建标准声明
	standardClaims := jwt.RegisteredClaims{
		ExpiresAt: jwt.NewNumericDate(time.Now().Add(expiration)),
		IssuedAt:  jwt.NewNumericDate(time.Now()),
		Issuer:    j.issuer,
	}

	// 合并自定义声明和标准声明
	allClaims := make(map[string]interface{})
	for k, v := range claims {
		allClaims[k] = v
	}
	allClaims["exp"] = standardClaims.ExpiresAt
	allClaims["iat"] = standardClaims.IssuedAt
	allClaims["iss"] = standardClaims.Issuer

	// 创建令牌
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims(allClaims))

	// 签名令牌
	return token.SignedString(j.secretKey)
}

// ValidateToken 验证JWT令牌
func (j *jwtManager) ValidateToken(tokenString string) (map[string]interface{}, error) {
	token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
		// 验证签名方法
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, jwt.ErrSignatureInvalid
		}
		return j.secretKey, nil
	})

	if err != nil {
		return nil, err
	}

	if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
		return claims, nil
	}

	return nil, jwt.ErrInvalidKey
}

// RefreshToken 刷新JWT令牌
func (j *jwtManager) RefreshToken(tokenString string, expiration time.Duration) (string, error) {
	// 验证原令牌
	claims, err := j.ValidateToken(tokenString)
	if err != nil {
		return "", err
	}

	// 移除时间相关声明
	delete(claims, "exp")
	delete(claims, "iat")
	delete(claims, "nbf")

	// 生成新令牌
	return j.GenerateToken(claims, expiration)
}