<?php
/**
 * This is a PHP library that handles calling reCAPTCHA.
 *
 * @copyright Copyright (c) 2015, Google Inc.
 * @link      http://www.google.com/recaptcha
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * Sends POST requests to the reCAPTCHA service.
 */
class ReCaptchaPost implements ReCaptchaRequestMethod
{
    /**
     * URL to which requests are POSTed.
     * @const string
     */
    const SITE_VERIFY_URL = 'https://www.google.com/recaptcha/api/siteverify';

    /**
     * Submit the POST request with the specified parameters.
     *
     * @param ReCaptchaRequestParameters $params Request parameters
     * @return string Body of the reCAPTCHA response
     */
    public function submit(ReCaptchaRequestParameters $params)
    {
        /**
         * PHP 5.6.0 changed the way you specify the peer name for SSL context options.
         * Using "CN_name" will still work, but it will raise deprecated errors.
         */
        $peer_key = version_compare(PHP_VERSION, '5.6.0', '<') ? 'CN_name' : 'peer_name';
        $options = array(
            'http' => array(
                'header' => "Content-type: application/x-www-form-urlencoded\r\n",
                'method' => 'POST',
                'content' => $params->toQueryString(),
                // Force the peer to validate (not needed in 5.6.0+, but still works
                'verify_peer' => true,
                // Force the peer validation to use www.google.com
                $peer_key => 'www.google.com',
            ),
        );
        $context = stream_context_create($options);
        return file_get_contents(self::SITE_VERIFY_URL, false, $context);
    }
}
