<?php

declare(strict_types=1);

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2020 Spomky-Labs
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */

namespace Jose\Component\Signature\Algorithm;

use Base64Url\Base64Url;
use function in_array;
use InvalidArgumentException;
use function is_string;
use Jose\Component\Core\JWK;

abstract class HMAC implements MacAlgorithm
{
    public function allowedKeyTypes(): array
    {
        return ['oct'];
    }

    public function verify(JWK $key, string $input, string $signature): bool
    {
        return hash_equals($this->hash($key, $input), $signature);
    }

    public function hash(JWK $key, string $input): string
    {
        $k = $this->getKey($key);

        return hash_hmac($this->getHashAlgorithm(), $input, $k, true);
    }

    /**
     * @throws InvalidArgumentException if the key is invalid
     */
    protected function getKey(JWK $key): string
    {
        if (!in_array($key->get('kty'), $this->allowedKeyTypes(), true)) {
            throw new InvalidArgumentException('Wrong key type.');
        }
        if (!$key->has('k')) {
            throw new InvalidArgumentException('The key parameter "k" is missing.');
        }
        $k = $key->get('k');
        if (!is_string($k)) {
            throw new InvalidArgumentException('The key parameter "k" is invalid.');
        }

        return Base64Url::decode($k);
    }

    abstract protected function getHashAlgorithm(): string;
}