gnu-social-v2-archive-activitypub-plugin/actions/inbox/Undo.php

<?php
/**
 * GNU social - a federating social network
 *
 * ActivityPubPlugin implementation for GNU Social
 *
 * LICENCE: This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  Plugin
 * @package   GNUsocial
 * @author    Diogo Cordeiro <diogo@fc.up.pt>
 * @author    Daniel Supernault <danielsupernault@gmail.com>
 * @copyright 2018 Free Software Foundation http://fsf.org
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link      https://www.gnu.org/software/social/
 */
if (!defined('GNUSOCIAL')) {
    exit(1);
}

// Validate data
if (!isset($data->type)) {
    ActivityPubReturn::error('Type was not specified.');
}

switch ($data->object->type) {
    case 'Like':
        try {
            // Validate data
            if (!isset($data->object->object)) {
                ActivityPubReturn::error('Notice URI was not specified.');
            }
            Fave::removeEntry($actor_profile, ActivityPubPlugin::get_local_notice_from_url($data->object->object));
            // Notice disfavorited successfully.
            ActivityPubReturn::answer();
        } catch (Exception $e) {
            ActivityPubReturn::error($e->getMessage(), 403);
        }
        break;
    case 'Follow':
        // Validate data
        if (!isset($data->object->object)) {
            ActivityPubReturn::error('Object Actor URL was not specified.');
        }
        // Get valid Object profile
        try {
            $object_profile = new Activitypub_explorer;
            $object_profile = $object_profile->lookup($data->object->object)[0];
        } catch (Exception $e) {
            ActivityPubReturn::error('Invalid Object Actor URL.', 404);
        }

        if (Subscription::exists($actor_profile, $object_profile)) {
            Subscription::cancel($actor_profile, $object_profile);
            // You are no longer following this person.
            ActivityPubReturn::answer();
        } else {
            // 409: You are not following this person already.
            ActivityPubReturn::answer();
        }
        break;
    case 'Announce':
        // This is a dummy entry point as GNU Social doesn't allow Undo Announce
        ActivityPubReturn::answer();
    default:
        ActivityPubReturn::error('Invalid object type.');
        break;
}