package auth

import (
	"errors"
	"time"

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

type Claims struct {
	UserID uuid.UUID `json:"user_id"`
	jwt.RegisteredClaims
}

func GenerateToken(userID uuid.UUID, secret []byte, expiry time.Duration) (string, error) {
	if userID == uuid.Nil {
		return "", errors.New("user ID cannot be nil")
	}
	if secret == nil {
		return "", errors.New("JWT secret not set")
	}

	claims := Claims{
		UserID: userID,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(expiry)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}

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

func ParseToken(tokenString string, secret []byte) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		return secret, nil
	}, jwt.WithValidMethods([]string{jwt.SigningMethodHS256.Alg()}))

	if err != nil {
		return nil, err
	}

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

	return nil, errors.New("invalid token claims")
}