package jwt

import (
	"errors"
	"time"

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

type Claims struct {
	UserID uint64 `json:"user_id"`
	Name   string `json:"name"`
	Role   string `json:"role"`
	gojwt.RegisteredClaims
}

// GenerateTokenPair 生成 access + refresh token
func GenerateTokenPair(userID uint64, name, role, secret string, accessExpire, refreshExpire time.Duration) (accessToken, refreshToken string, err error) {
	accessToken, err = generateToken(userID, name, role, "access", secret, accessExpire)
	if err != nil {
		return "", "", err
	}
	refreshToken, err = generateToken(userID, name, role, "refresh", secret, refreshExpire)
	if err != nil {
		return "", "", err
	}
	return
}

func generateToken(userID uint64, name, role, tokenType, secret string, expire time.Duration) (string, error) {
	now := time.Now()
	claims := Claims{
		UserID: userID,
		Name:   name,
		Role:   role,
		RegisteredClaims: gojwt.RegisteredClaims{
			ExpiresAt: gojwt.NewNumericDate(now.Add(expire)),
			IssuedAt:  gojwt.NewNumericDate(now),
			NotBefore: gojwt.NewNumericDate(now),
		},
	}
	token := gojwt.NewWithClaims(gojwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(secret))
}

// ValidateToken 校验 JWT
func ValidateToken(tokenString, secret string) (*Claims, error) {
	token, err := gojwt.ParseWithClaims(tokenString, &Claims{}, func(token *gojwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*gojwt.SigningMethodHMAC); !ok {
			return nil, errors.New("unexpected signing method")
		}
		return []byte(secret), nil
	})
	if err != nil {
		return nil, err
	}
	if claims, ok := token.Claims.(*Claims); ok && token.Valid {
		return claims, nil
	}
	return nil, gojwt.ErrInvalidKey
}