gnu-social/plugins/ActivityPub/Util/DiscoveryHints.php

<?php

declare(strict_types = 1);

// {{{ License
// 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/>.
// }}}

/**
 * ActivityPub implementation for GNU social
 *
 * @package   GNUsocial
 * @category  ActivityPub
 *
 * @author    Diogo Peralta Cordeiro <@diogo.site>
 * @copyright 2018-2019, 2021 Free Software Foundation, Inc http://www.fsf.org
 * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
 */

namespace Plugin\ActivityPub\Util;

// 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/>.
use App\Core\Event;
use XML_XRD;

/**
 * DiscoveryHints implementation for GNU social
 *
 * @copyright 2018-2019, 2021 Free Software Foundation, Inc http://www.fsf.org
 * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
 */
class DiscoveryHints
{
    /**
     * Search the WebFinger XRD after an ActivityPub URI
     */
    public static function fromXRD(XML_XRD $xrd): array
    {
        $hints = [];

        if (Event::handle('StartDiscoveryHintsFromXRD', [$xrd, &$hints])) {
            foreach ($xrd->links as $link) {
                if ($link->rel === 'self' && $link->type === 'application/activity+json') {
                    $hints['activitypub'] = $link->href;
                    break;
                }
            }
            Event::handle('EndDiscoveryHintsFromXRD', [$xrd, &$hints]);
        }

        return $hints;
    }
}