package auth

import (
	"fmt"
	"time"

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

type Claims struct {
	UserID string `json:"user_id"`
	Email  string `json:"email"`
	jwt.RegisteredClaims
}

func GenerateToken(userID, email string, secret []byte, expiration time.Duration) (string, error) {
	claims := Claims{
		UserID: userID,
		Email:  email,
		RegisteredClaims: jwt.RegisteredClaims{
			Subject:   userID,
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(expiration)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}

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

func ValidateToken(tokenString string, secret []byte) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(t *jwt.Token) (interface{}, error) {
		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
		}
		return secret, nil
	})
	if err != nil {
		return nil, err
	}

	claims, ok := token.Claims.(*Claims)
	if !ok || !token.Valid {
		return nil, fmt.Errorf("invalid token")
	}

	return claims, nil
}