// internal/auth/jwt.go
package auth

import (
	"time"

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

var secret = []byte("change-me-in-env")

type Claims struct {
	UserID   int64  `json:"user_id"`
	Username string `json:"username"`
	jwt.RegisteredClaims
}

func GenerateToken(userID int64, username string) (string, error) {
	now := time.Now()

	claims := Claims{
		UserID:   userID,
		Username: username,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(now.Add(24 * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(now),
			NotBefore: jwt.NewNumericDate(now),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)

	return token.SignedString(secret)
}

func ParseToken(tokenString string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(
		tokenString,
		&Claims{},
		func(token *jwt.Token) (interface{}, error) {
			return secret, nil
		},
	)
	if err != nil {
		return nil, err
	}

	claims, ok := token.Claims.(*Claims)
	if !ok || !token.Valid {
		return nil, jwt.ErrTokenInvalidClaims
	}

	return claims, nil
}