<?php

/*
 * Copyright 2023 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
namespace FluentSmtpLib\Google\Auth\CredentialSource;

use FluentSmtpLib\Google\Auth\ExternalAccountCredentialSourceInterface;
use FluentSmtpLib\Google\Auth\HttpHandler\HttpClientCache;
use FluentSmtpLib\Google\Auth\HttpHandler\HttpHandlerFactory;
use FluentSmtpLib\GuzzleHttp\Psr7\Request;
use InvalidArgumentException;
use UnexpectedValueException;
/**
 * Retrieve a token from a URL.
 */
class UrlSource implements \FluentSmtpLib\Google\Auth\ExternalAccountCredentialSourceInterface
{
    private string $url;
    private ?string $format;
    private ?string $subjectTokenFieldName;
    /**
     * @var array<string, string|string[]>
     */
    private ?array $headers;
    /**
     * @param string $url                   The URL to fetch the subject token from.
     * @param string $format                The format of the token in the response. Can be null or "json".
     * @param string $subjectTokenFieldName The name of the field containing the token in the response. This is required
     *                                      when format is "json".
     * @param array<string, string|string[]> $headers Request headers to send in with the request to the URL.
     */
    public function __construct(string $url, ?string $format = null, ?string $subjectTokenFieldName = null, ?array $headers = null)
    {
        $this->url = $url;
        if ($format === 'json' && \is_null($subjectTokenFieldName)) {
            throw new \InvalidArgumentException('subject_token_field_name must be set when format is JSON');
        }
        $this->format = $format;
        $this->subjectTokenFieldName = $subjectTokenFieldName;
        $this->headers = $headers;
    }
    public function fetchSubjectToken(?callable $httpHandler = null) : string
    {
        if (\is_null($httpHandler)) {
            $httpHandler = \FluentSmtpLib\Google\Auth\HttpHandler\HttpHandlerFactory::build(\FluentSmtpLib\Google\Auth\HttpHandler\HttpClientCache::getHttpClient());
        }
        $request = new \FluentSmtpLib\GuzzleHttp\Psr7\Request('GET', $this->url, $this->headers ?: []);
        $response = $httpHandler($request);
        $body = (string) $response->getBody();
        if ($this->format === 'json') {
            if (!($json = \json_decode((string) $body, \true))) {
                throw new \UnexpectedValueException('Unable to decode JSON response');
            }
            if (!isset($json[$this->subjectTokenFieldName])) {
                throw new \UnexpectedValueException('subject_token_field_name not found in JSON file');
            }
            $body = $json[$this->subjectTokenFieldName];
        }
        return $body;
    }
}
