+<?php
+/**
+ * @copyright Copyright (C) 2010-2023, the Friendica project
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * 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 <https://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Friendica\Protocol\ActivityPub;
+
+use Friendica\Content\Text\Markdown;
+use Friendica\Core\Logger;
+use Friendica\Core\Protocol;
+use Friendica\DI;
+use Friendica\Model\APContact;
+use Friendica\Model\Contact;
+use Friendica\Model\Group;
+use Friendica\Model\Item;
+use Friendica\Model\Post;
+use Friendica\Model\User;
+use Friendica\Protocol\Activity;
+use Friendica\Util\JsonLD;
+
+/**
+ * ActivityPub Client To Server class
+ */
+class ClientToServer
+{
+ /**
+ * Process client to server activities
+ *
+ * @param array $activity
+ * @param integer $uid
+ * @param array $application
+ * @return array
+ */
+ public static function processActivity(array $activity, int $uid, array $application): array
+ {
+ $ldactivity = JsonLD::compact($activity);
+ if (empty($ldactivity)) {
+ Logger::notice('Invalid activity', ['activity' => $activity, 'uid' => $uid]);
+ return [];
+ }
+
+ $type = JsonLD::fetchElement($ldactivity, '@type');
+ if (!$type) {
+ Logger::notice('Empty type', ['activity' => $ldactivity, 'uid' => $uid]);
+ return [];
+ }
+
+ $object_id = JsonLD::fetchElement($ldactivity, 'as:object', '@id') ?? '';
+ $object_type = Receiver::fetchObjectType($ldactivity, $object_id, $uid);
+ if (!$object_type && !$object_id) {
+ Logger::notice('Empty object type or id', ['activity' => $ldactivity, 'uid' => $uid]);
+ return [];
+ }
+
+ Logger::debug('Processing activity', ['type' => $type, 'object_type' => $object_type, 'object_id' => $object_id, 'activity' => $ldactivity]);
+ return self::routeActivities($type, $object_type, $object_id, $uid, $application, $ldactivity);
+ }
+
+ /**
+ * Route client to server activities
+ *
+ * @param string $type
+ * @param string $object_type
+ * @param string $object_id
+ * @param integer $uid
+ * @param array $application
+ * @param array $ldactivity
+ * @return array
+ */
+ private static function routeActivities(string $type, string $object_type, string $object_id, int $uid, array $application, array $ldactivity): array
+ {
+ switch ($type) {
+ case 'as:Create':
+ if (in_array($object_type, Receiver::CONTENT_TYPES)) {
+ return self::createContent($uid, $application, $ldactivity);
+ }
+ break;
+ case 'as:Update':
+ if (in_array($object_type, Receiver::CONTENT_TYPES) && !empty($object_id)) {
+ return self::updateContent($uid, $object_id, $application, $ldactivity);
+ }
+ break;
+ case 'as:Follow':
+ if (in_array($object_type, Receiver::ACCOUNT_TYPES) && !empty($object_id)) {
+ return self::followAccount($uid, $object_id, $ldactivity);
+ }
+ break;
+ }
+ return [];
+ }
+
+ /**
+ * Create a new post or comment
+ *
+ * @param integer $uid
+ * @param array $application
+ * @param array $ldactivity
+ * @return array
+ */
+ private static function createContent(int $uid, array $application, array $ldactivity): array
+ {
+ $object_data = self::processObject($ldactivity['as:object']);
+ $item = ClientToServer::processContent($object_data, $application, $uid);
+ Logger::debug('Got data', ['item' => $item, 'object' => $object_data]);
+
+ $id = Item::insert($item, true);
+ if (!empty($id)) {
+ $item = Post::selectFirst(['uri-id'], ['id' => $id]);
+ if (!empty($item['uri-id'])) {
+ return Transmitter::createActivityFromItem($id);
+ }
+ }
+ return [];
+ }
+
+ /**
+ * Update an existing post or comment
+ *
+ * @param integer $uid
+ * @param string $object_id
+ * @param array $application
+ * @param array $ldactivity
+ * @return array
+ */
+ private static function updateContent(int $uid, string $object_id, array $application, array $ldactivity):array
+ {
+ $id = Item::fetchByLink($object_id, $uid);
+ $original_post = Post::selectFirst(['uri-id'], ['uid' => $uid, 'origin' => true, 'id' => $id]);
+ if (empty($original_post)) {
+ Logger::debug('Item not found or does not belong to the user', ['id' => $id, 'uid' => $uid, 'object_id' => $object_id, 'activity' => $ldactivity]);
+ return [];
+ }
+
+ $object_data = self::processObject($ldactivity['as:object']);
+ $item = ClientToServer::processContent($object_data, $application, $uid);
+ if (empty($item['title']) && empty($item['body'])) {
+ Logger::debug('Empty body and title', ['id' => $id, 'uid' => $uid, 'object_id' => $object_id, 'activity' => $ldactivity]);
+ return [];
+ }
+ $post = ['title' => $item['title'], 'body' => $item['body']];
+ Logger::debug('Got data', ['id' => $id, 'uid' => $uid, 'item' => $post]);
+ Item::update($post, ['id' => $id]);
+ Item::updateDisplayCache($original_post['uri-id']);
+
+ return Transmitter::createActivityFromItem($id);
+ }
+
+ /**
+ * Follow a given account
+ * @todo Check the expected return value
+ *
+ * @param integer $uid
+ * @param string $object_id
+ * @param array $ldactivity
+ * @return array
+ */
+ private static function followAccount(int $uid, string $object_id, array $ldactivity): array
+ {
+ return [];
+ }
+
+ /**
+ * Fetches data from the object part of an client to server activity
+ *
+ * @param array $object
+ *
+ * @return array Object data
+ */
+ private static function processObject(array $object): array
+ {
+ $object_data = Receiver::getObjectDataFromActivity($object);
+
+ $object_data['target'] = self::getTargets($object, $object_data['actor'] ?? '');
+ $object_data['receiver'] = [];
+
+ return $object_data;
+ }
+
+ /**
+ * Accumulate the targets and visibility of this post
+ *
+ * @param array $object
+ * @param string $actor
+ * @return array
+ */
+ private static function getTargets(array $object, string $actor): array
+ {
+ $profile = APContact::getByURL($actor);
+ $followers = $profile['followers'];
+
+ $targets = [];
+
+ foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
+ switch ($element) {
+ case 'as:to':
+ $type = Receiver::TARGET_TO;
+ break;
+ case 'as:cc':
+ $type = Receiver::TARGET_CC;
+ break;
+ case 'as:bto':
+ $type = Receiver::TARGET_BTO;
+ break;
+ case 'as:bcc':
+ $type = Receiver::TARGET_BCC;
+ break;
+ }
+ $receiver_list = JsonLD::fetchElementArray($object, $element, '@id');
+ if (empty($receiver_list)) {
+ continue;
+ }
+
+ foreach ($receiver_list as $receiver) {
+ if ($receiver == Receiver::PUBLIC_COLLECTION) {
+ $targets[Receiver::TARGET_GLOBAL] = ($element == 'as:to');
+ continue;
+ }
+
+ if ($receiver == $followers) {
+ $targets[Receiver::TARGET_FOLLOWER] = true;
+ continue;
+ }
+ $targets[$type][] = Contact::getIdForURL($receiver);
+ }
+ }
+ return $targets;
+ }
+
+ /**
+ * Create an item array from client to server object data
+ *
+ * @param array $object_data
+ * @param array $application
+ * @param integer $uid
+ * @return array
+ */
+ private static function processContent(array $object_data, array $application, int $uid): array
+ {
+ $owner = User::getOwnerDataById($uid);
+
+ $item = [];
+
+ $item['network'] = Protocol::DFRN;
+ $item['uid'] = $uid;
+ $item['verb'] = Activity::POST;
+ $item['contact-id'] = $owner['id'];
+ $item['author-id'] = $item['owner-id'] = Contact::getPublicIdByUserId($uid);
+ $item['title'] = $object_data['name'];
+ $item['body'] = Markdown::toBBCode($object_data['content']);
+ $item['app'] = $application['name'] ?? 'API';
+
+ if (!empty($object_data['target'][Receiver::TARGET_GLOBAL])) {
+ $item['allow_cid'] = '';
+ $item['allow_gid'] = '';
+ $item['deny_cid'] = '';
+ $item['deny_gid'] = '';
+ $item['private'] = Item::PUBLIC;
+ } elseif (isset($object_data['target'][Receiver::TARGET_GLOBAL])) {
+ $item['allow_cid'] = '';
+ $item['allow_gid'] = '';
+ $item['deny_cid'] = '';
+ $item['deny_gid'] = '';
+ $item['private'] = Item::UNLISTED;
+ } elseif (!empty($object_data['target'][Receiver::TARGET_FOLLOWER])) {
+ $item['allow_cid'] = '';
+ $item['allow_gid'] = '<' . Group::FOLLOWERS . '>';
+ $item['deny_cid'] = '';
+ $item['deny_gid'] = '';
+ $item['private'] = Item::PRIVATE;
+ } else {
+ // @todo Set permissions via the $object_data['target'] array
+ $item['allow_cid'] = '<' . $owner['id'] . '>';
+ $item['allow_gid'] = '';
+ $item['deny_cid'] = '';
+ $item['deny_gid'] = '';
+ $item['private'] = Item::PRIVATE;
+ }
+
+ if (!empty($object_data['summary'])) {
+ $item['body'] = '[abstract=' . Protocol::ACTIVITYPUB . ']' . $object_data['summary'] . "[/abstract]\n" . $item['body'];
+ }
+
+ if ($object_data['reply-to-id']) {
+ $item['thr-parent'] = $object_data['reply-to-id'];
+ $item['gravity'] = Item::GRAVITY_COMMENT;
+ } else {
+ $item['gravity'] = Item::GRAVITY_PARENT;
+ }
+
+ $item = DI::contentItem()->expandTags($item);
+
+ return $item;
+ }
+}