<?php
// This file is part of GNU social - https://www.gnu.org/software/social
//
// GNU social is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GNU social is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Class to ping an rssCloud endpoint when a feed has been updated
 *
 * @category  Plugin
 * @package   GNUsocial
 * @author    Zach Copley <zach@status.net>
 * @copyright 2009 StatusNet, Inc.
 * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
 */

defined('STATUSNET') || die();

/**
 * Class for notifying cloud-enabled RSS aggregators that StatusNet
 * feeds have been updated.
 *
 * @category  Plugin
 * @package   GNUsocial
 * @author    Zach Copley <zach@status.net>
 * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
 */
class RSSCloudNotifier
{
    const MAX_FAILURES = 3;

    /**
     * Send an HTTP GET to the notification handler with a
     * challenge string to see if it repsonds correctly.
     *
     * @param string $endpoint URL of the notification handler
     * @param string $feed     the feed being subscribed to
     *
     * @return boolean success
     */
    public function challenge($endpoint, $feed)
    {
        $code   = common_confirmation_code(128);
        $params = array('url' => $feed, 'challenge' => $code);
        $url    = $endpoint . '?' . http_build_query($params);

        try {
            $client   = new HTTPClient();
            $response = $client->get($url);
        } catch (Exception $e) {
            common_log(
                LOG_INFO,
                'RSSCloud plugin - failure testing notify handler '
                . $endpoint . ' - ' . $e->getMessage()
            );
            return false;
        }

        // Check response is betweet 200 and 299 and body contains challenge data

        $status = $response->getStatus();
        $body   = $response->getBody();

        if ($status >= 200 && $status < 300) {
            // NOTE: the spec says that the body must contain the string
            // challenge.  It doesn't say that the body must contain the
            // challenge string ONLY, although that seems to be the way
            // the other implementors have interpreted it.

            if (strpos($body, $code) !== false) {
                common_log(LOG_INFO, 'RSSCloud plugin - ' .
                           "success testing notify handler:  $endpoint");
                return true;
            } else {
                common_log(LOG_INFO, 'RSSCloud plugin - ' .
                          'challenge/repsonse failed for notify handler ' .
                           $endpoint);
                common_debug('body = ' . var_export($body, true));
                return false;
            }
        } else {
            common_log(LOG_INFO, 'RSSCloud plugin - ' .
                       "failure testing notify handler:  $endpoint " .
                       ' - got HTTP ' . $status);
            common_debug('body = ' . var_export($body, true));
            return false;
        }
    }

    /**
     * HTTP POST a notification that a feed has been updated
     * ('ping the cloud').
     *
     * @param String $endpoint URL of the notification handler
     * @param String $feed     the feed being subscribed to
     *
     * @return boolean success
     */
    public function postUpdate($endpoint, $feed)
    {
        $headers  = array();
        $postdata = array('url' => $feed);

        try {
            $client   = new HTTPClient();
            $response = $client->post($endpoint, $headers, $postdata);
        } catch (Exception $e) {
            common_log(LOG_INFO, 'RSSCloud plugin - failure notifying ' .
                       $endpoint . ' that feed ' . $feed .
                       ' has changed: ' . $e->getMessage());
            return false;
        }

        $status = $response->getStatus();

        if ($status >= 200 && $status < 300) {
            common_log(LOG_INFO, 'RSSCloud plugin - success notifying ' .
                       $endpoint . ' that feed ' . $feed . ' has changed.');
            return true;
        } else {
            common_log(LOG_INFO, 'RSSCloud plugin - failure notifying ' .
                       $endpoint . ' that feed ' . $feed .
                       ' has changed: got HTTP ' . $status);
            return false;
        }
    }

    /**
     * Notify all subscribers to a profile feed that it has changed.
     *
     * @param Profile $profile the profile whose feed has been
     *        updated
     *
     * @return boolean success
     */
    public function notify($profile)
    {
        $feed = common_path('api/statuses/user_timeline/') .
          $profile->id . '.rss';

        $cloudSub = new RSSCloudSubscription();

        $cloudSub->subscribed = $profile->id;

        if ($cloudSub->find()) {
            while ($cloudSub->fetch()) {
                $result = $this->postUpdate($cloudSub->url, $feed);
                if ($result == false) {
                    $this->handleFailure($cloudSub);
                }
            }
        }

        return true;
    }

    /**
     * Handle problems posting cloud notifications. Increment the failure
     * count, or delete the subscription if the maximum number of failures
     * is exceeded.
     *
     * XXX: Redo with proper DB_DataObject methods once I figure out what
     * what the problem is with pluginized DB_DataObjects. -Z
     *
     * @param RSSCloudSubscription $cloudSub the subscription in question
     *
     * @return boolean success
     */
    public function handleFailure($cloudSub)
    {
        $failCnt = $cloudSub->failures + 1;

        if ($failCnt == self::MAX_FAILURES) {
            common_log(
                LOG_INFO,
                'Deleting RSSCloud subcription (max failure count reached), '
                . "profile: {$cloudSub->subscribed} handler: {$cloudSub->url}"
            );

            // XXX: WTF! ->delete() doesn't work. Clearly, there are some issues with
            // the DB_DataObject, or my understanding of it.  Have to drop into SQL.

            // $result = $cloudSub->delete();

            $qry = 'DELETE from rsscloud_subscription' .
              ' WHERE subscribed = ' . $cloudSub->subscribed .
              ' AND url = \'' . $cloudSub->url . '\'';

            $result = $cloudSub->query($qry);

            if (!$result) {
                common_log_db_error($cloudSub, 'DELETE', __FILE__);
                common_log(LOG_ERR, 'Could not delete RSSCloud subscription.');
            }
        } else {
            common_debug('Updating failure count on RSSCloud subscription. ' .
                         $failCnt);

            $failCnt = $cloudSub->failures + 1;

            // XXX: ->update() not working either, gar!

            $result = $cloudSub->query(sprintf(
                <<<'END'
                UPDATE rsscloud_subscription
                  SET failures = %1$d, modified = CURRENT_TIMESTAMP
                  WHERE subscribed = %2$d AND url = %3$s
                END,
                $failCnt,
                $cloudSub->subscribed,
                $cloudSub->_quote($cloudSub->url)
            ));

            if (!$result) {
                common_log_db_error($cloudsub, 'UPDATE', __FILE__);
                common_log(
                    LOG_ERR,
                    'Could not update failure count on RSSCloud subscription'
                );
            }
        }
    }
}