src/Protocol/ActivityPub/Processor.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2022, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Protocol\ActivityPub;
  23
  24 use Friendica\Content\Text\BBCode;
  25 use Friendica\Content\Text\HTML;
  26 use Friendica\Content\Text\Markdown;
  27 use Friendica\Core\Cache\Enum\Duration;
  28 use Friendica\Core\Logger;
  29 use Friendica\Core\Protocol;
  30 use Friendica\Core\System;
  31 use Friendica\Core\Worker;
  32 use Friendica\Database\DBA;
  33 use Friendica\DI;
  34 use Friendica\Model\APContact;
  35 use Friendica\Model\Contact;
  36 use Friendica\Model\Conversation;
  37 use Friendica\Model\Event;
  38 use Friendica\Model\GServer;
  39 use Friendica\Model\Item;
  40 use Friendica\Model\ItemURI;
  41 use Friendica\Model\Mail;
  42 use Friendica\Model\Tag;
  43 use Friendica\Model\User;
  44 use Friendica\Model\Post;
  45 use Friendica\Protocol\Activity;
  46 use Friendica\Protocol\ActivityPub;
  47 use Friendica\Protocol\Relay;
  48 use Friendica\Util\DateTimeFormat;
  49 use Friendica\Util\HTTPSignature;
  50 use Friendica\Util\JsonLD;
  51 use Friendica\Util\Network;
  52 use Friendica\Util\Strings;
  53 use Friendica\Worker\Delivery;
  54
  55 /**
  56  * ActivityPub Processor Protocol class
  57  */
  58 class Processor
  59 {
  60         const CACHEKEY_FETCH_ACTIVITY = 'processor:fetchMissingActivity:';
  61         const CACHEKEY_JUST_FETCHED   = 'processor:isJustFetched:';
  62
  63         static $processed = [];
  64
  65         /**
  66          * Add an activity id to the list of processed ids
  67          *
  68          * @param string $id
  69          *
  70          * @return void
  71          */
  72         public static function addActivityId(string $id)
  73         {
  74                 self::$processed[] = $id;
  75                 if (count(self::$processed) > 100) {
  76                         self::$processed = array_slice(self::$processed, 1);
  77                 }
  78         }
  79
  80         /**
  81          * Checks if the given has just been processed
  82          *
  83          * @param string $id
  84          *
  85          * @return boolean
  86          */
  87         public static function isProcessed(string $id): bool
  88         {
  89                 return in_array($id, self::$processed);
  90         }
  91
  92         /**
  93          * Extracts the tag character (#, @, !) from mention links
  94          *
  95          * @param string $body
  96          * @return string
  97          */
  98         protected static function normalizeMentionLinks(string $body): string
  99         {
 100                 return preg_replace('%\[url=([^\[\]]*)]([#@!])(.*?)\[/url]%ism', '$2[url=$1]$3[/url]', $body);
 101         }
 102
 103         /**
 104          * Convert the language array into a language JSON
 105          *
 106          * @param array $languages
 107          * @return string language JSON
 108          */
 109         private static function processLanguages(array $languages): string
 110         {
 111                 $codes = array_keys($languages);
 112                 $lang = [];
 113                 foreach ($codes as $code) {
 114                         $lang[$code] = 1;
 115                 }
 116
 117                 if (empty($lang)) {
 118                         return '';
 119                 }
 120
 121                 return json_encode($lang);
 122         }
 123         /**
 124          * Replaces emojis in the body
 125          *
 126          * @param int $uri_id
 127          * @param string $body
 128          * @param array $emojis
 129          *
 130          * @return string with replaced emojis
 131          */
 132         private static function replaceEmojis(int $uri_id, string $body, array $emojis): string
 133         {
 134                 $body = strtr($body,
 135                         array_combine(
 136                                 array_column($emojis, 'name'),
 137                                 array_map(function ($emoji) {
 138                                         return '[emoji=' . $emoji['href'] . ']' . $emoji['name'] . '[/emoji]';
 139                                 }, $emojis)
 140                         )
 141                 );
 142
 143                 // We store the emoji here to be able to avoid storing it in the media
 144                 foreach ($emojis as $emoji) {
 145                         Post\Link::getByLink($uri_id, $emoji['href']);
 146                 }
 147                 return $body;
 148         }
 149
 150         /**
 151          * Store attached media files in the post-media table
 152          *
 153          * @param int $uriid
 154          * @param array $attachment
 155          * @return void
 156          */
 157         private static function storeAttachmentAsMedia(int $uriid, array $attachment)
 158         {
 159                 if (empty($attachment['url'])) {
 160                         return;
 161                 }
 162
 163                 $data = ['uri-id' => $uriid];
 164                 $data['type'] = Post\Media::UNKNOWN;
 165                 $data['url'] = $attachment['url'];
 166                 $data['mimetype'] = $attachment['mediaType'] ?? null;
 167                 $data['height'] = $attachment['height'] ?? null;
 168                 $data['width'] = $attachment['width'] ?? null;
 169                 $data['size'] = $attachment['size'] ?? null;
 170                 $data['preview'] = $attachment['image'] ?? null;
 171                 $data['description'] = $attachment['name'] ?? null;
 172
 173                 Post\Media::insert($data);
 174         }
 175
 176         /**
 177          * Stire attachment data
 178          *
 179          * @param array   $activity
 180          * @param array   $item
 181          */
 182         private static function storeAttachments(array $activity, array $item)
 183         {
 184                 if (empty($activity['attachments'])) {
 185                         return;
 186                 }
 187
 188                 foreach ($activity['attachments'] as $attach) {
 189                         self::storeAttachmentAsMedia($item['uri-id'], $attach);
 190                 }
 191         }
 192
 193         /**
 194          * Store attachment data
 195          *
 196          * @param array   $activity
 197          * @param array   $item
 198          */
 199         private static function storeQuestion(array $activity, array $item)
 200         {
 201                 if (empty($activity['question'])) {
 202                         return;
 203                 }
 204                 $question = ['multiple' => $activity['question']['multiple']];
 205
 206                 if (!empty($activity['question']['voters'])) {
 207                         $question['voters'] = $activity['question']['voters'];
 208                 }
 209
 210                 if (!empty($activity['question']['end-time'])) {
 211                         $question['end-time'] = DateTimeFormat::utc($activity['question']['end-time']);
 212                 }
 213
 214                 Post\Question::update($item['uri-id'], $question);
 215
 216                 foreach ($activity['question']['options'] as $key => $option) {
 217                         $option = ['name' => $option['name'], 'replies' => $option['replies']];
 218                         Post\QuestionOption::update($item['uri-id'], $key, $option);
 219                 }
 220
 221                 Logger::debug('Storing incoming question', ['type' => $activity['type'], 'uri-id' => $item['uri-id'], 'question' => $activity['question']]);
 222         }
 223
 224         /**
 225          * Updates a message
 226          *
 227          * @param array      $activity   Activity array
 228          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 229          * @throws \ImagickException
 230          */
 231         public static function updateItem(array $activity)
 232         {
 233                 $item = Post::selectFirst(['uri', 'uri-id', 'thr-parent', 'gravity', 'post-type'], ['uri' => $activity['id']]);
 234                 if (!DBA::isResult($item)) {
 235                         Logger::warning('No existing item, item will be created', ['uri' => $activity['id']]);
 236                         $item = self::createItem($activity);
 237                         if (empty($item)) {
 238                                 return;
 239                         }
 240
 241                         self::postItem($activity, $item);
 242                         return;
 243                 }
 244
 245                 $item['changed'] = DateTimeFormat::utcNow();
 246                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 247
 248                 $item = self::processContent($activity, $item);
 249                 if (empty($item)) {
 250                         return;
 251                 }
 252
 253                 self::storeAttachments($activity, $item);
 254                 self::storeQuestion($activity, $item);
 255
 256                 Post\History::add($item['uri-id'], $item);
 257                 Item::update($item, ['uri' => $activity['id']]);
 258
 259                 Queue::remove($activity);
 260
 261                 if ($activity['object_type'] == 'as:Event') {
 262                         $posts = Post::select(['event-id', 'uid'], ["`uri` = ? AND `event-id` > ?", $activity['id'], 0]);
 263                         while ($post = DBA::fetch($posts)) {
 264                                 self::updateEvent($post['event-id'], $activity);
 265                         }
 266                 }
 267         }
 268
 269         /**
 270          * Update an existing event
 271          *
 272          * @param int $event_id
 273          * @param array $activity
 274          */
 275         private static function updateEvent(int $event_id, array $activity)
 276         {
 277                 $event = DBA::selectFirst('event', [], ['id' => $event_id]);
 278
 279                 $event['edited']   = DateTimeFormat::utc($activity['updated']);
 280                 $event['summary']  = HTML::toBBCode($activity['name']);
 281                 $event['desc']     = HTML::toBBCode($activity['content']);
 282                 if (!empty($activity['start-time'])) {
 283                         $event['start']  = DateTimeFormat::utc($activity['start-time']);
 284                 }
 285                 if (!empty($activity['end-time'])) {
 286                         $event['finish'] = DateTimeFormat::utc($activity['end-time']);
 287                 }
 288                 $event['nofinish'] = empty($event['finish']);
 289                 $event['location'] = $activity['location'];
 290
 291                 Logger::info('Updating event', ['uri' => $activity['id'], 'id' => $event_id]);
 292                 Event::store($event);
 293         }
 294
 295         /**
 296          * Prepares data for a message
 297          *
 298          * @param array $activity      Activity array
 299          * @param bool  $fetch_parents
 300          *
 301          * @return array Internal item
 302          *
 303          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 304          * @throws \ImagickException
 305          */
 306         public static function createItem(array $activity, bool $fetch_parents = true): array
 307         {
 308                 if (self::isProcessed($activity['id'])) {
 309                         Logger::info('Id is already processed', ['id' => $activity['id']]);
 310                         return [];
 311                 }
 312
 313                 self::addActivityId($activity['id']);
 314
 315                 $item = [];
 316                 $item['verb'] = Activity::POST;
 317                 $item['thr-parent'] = $activity['reply-to-id'];
 318
 319                 if ($activity['reply-to-id'] == $activity['id']) {
 320                         $item['gravity'] = GRAVITY_PARENT;
 321                         $item['object-type'] = Activity\ObjectType::NOTE;
 322                 } else {
 323                         $item['gravity'] = GRAVITY_COMMENT;
 324                         $item['object-type'] = Activity\ObjectType::COMMENT;
 325                 }
 326
 327                 if (!empty($activity['context'])) {
 328                         $item['conversation'] = $activity['context'];
 329                 } elseif (!empty($activity['conversation'])) {
 330                         $item['conversation'] = $activity['conversation'];
 331                 }
 332
 333                 if (!empty($item['conversation'])) {
 334                         $conversation = Post::selectFirstThread(['uri'], ['conversation' => $item['conversation']]);
 335                         if (!empty($conversation)) {
 336                                 Logger::debug('Got conversation', ['conversation' => $item['conversation'], 'parent' => $conversation]);
 337                                 $item['parent-uri'] = $conversation['uri'];
 338                         }
 339                 } else {
 340                         $conversation = [];
 341                 }
 342
 343                 if (empty($activity['author']) && empty($activity['actor'])) {
 344                         Logger::notice('Missing author and actor. We quit here.', ['activity' => $activity]);
 345                         return [];
 346                 }
 347
 348                 if (!in_array(0, $activity['receiver']) && !DI::config()->get('system', 'fetch_parents')) {
 349                         $fetch_parents = false;
 350                 }
 351
 352                 if ($fetch_parents && empty($activity['directmessage']) && ($activity['id'] != $activity['reply-to-id']) && !Post::exists(['uri' => $activity['reply-to-id']])) {
 353                         $result = self::fetchParent($activity);
 354                         if (!empty($result)) {
 355                                 if (($item['thr-parent'] != $result) && Post::exists(['uri' => $result])) {
 356                                         $item['thr-parent'] = $result;
 357                                 }
 358                         } elseif (empty($conversation)) {
 359                                 return [];
 360                         }
 361                 }
 362
 363                 $item['diaspora_signed_text'] = $activity['diaspora:comment'] ?? '';
 364
 365                 if (empty($conversation) && empty($activity['directmessage']) && ($item['gravity'] != GRAVITY_PARENT) && !Post::exists(['uri' => $item['thr-parent']])) {
 366                         Logger::info('Parent not found, message will be discarded.', ['thr-parent' => $item['thr-parent']]);
 367                         return [];
 368                 }
 369
 370                 $item['network'] = Protocol::ACTIVITYPUB;
 371                 $item['author-link'] = $activity['author'];
 372                 $item['author-id'] = Contact::getIdForURL($activity['author']);
 373                 $item['owner-link'] = $activity['actor'];
 374                 $item['owner-id'] = Contact::getIdForURL($activity['actor']);
 375
 376                 if (in_array(0, $activity['receiver']) && !empty($activity['unlisted'])) {
 377                         $item['private'] = Item::UNLISTED;
 378                 } elseif (in_array(0, $activity['receiver'])) {
 379                         $item['private'] = Item::PUBLIC;
 380                 } else {
 381                         $item['private'] = Item::PRIVATE;
 382                 }
 383
 384                 if (!empty($activity['raw'])) {
 385                         $item['source'] = $activity['raw'];
 386                 }
 387
 388                 $item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
 389
 390                 if (isset($activity['push'])) {
 391                         $item['direction'] = $activity['push'] ? Conversation::PUSH : Conversation::PULL;
 392                 }
 393
 394                 if (!empty($activity['from-relay'])) {
 395                         $item['direction'] = Conversation::RELAY;
 396                 }
 397
 398                 if ($activity['object_type'] == 'as:Article') {
 399                         $item['post-type'] = Item::PT_ARTICLE;
 400                 } elseif ($activity['object_type'] == 'as:Audio') {
 401                         $item['post-type'] = Item::PT_AUDIO;
 402                 } elseif ($activity['object_type'] == 'as:Document') {
 403                         $item['post-type'] = Item::PT_DOCUMENT;
 404                 } elseif ($activity['object_type'] == 'as:Event') {
 405                         $item['post-type'] = Item::PT_EVENT;
 406                 } elseif ($activity['object_type'] == 'as:Image') {
 407                         $item['post-type'] = Item::PT_IMAGE;
 408                 } elseif ($activity['object_type'] == 'as:Page') {
 409                         $item['post-type'] = Item::PT_PAGE;
 410                 } elseif ($activity['object_type'] == 'as:Question') {
 411                         $item['post-type'] = Item::PT_POLL;
 412                 } elseif ($activity['object_type'] == 'as:Video') {
 413                         $item['post-type'] = Item::PT_VIDEO;
 414                 } else {
 415                         $item['post-type'] = Item::PT_NOTE;
 416                 }
 417
 418                 $item['isForum'] = false;
 419
 420                 if (!empty($activity['thread-completion'])) {
 421                         if ($activity['thread-completion'] != $item['owner-id']) {
 422                                 $actor = Contact::getById($activity['thread-completion'], ['url']);
 423                                 $item['causer-link'] = $actor['url'];
 424                                 $item['causer-id'] = $activity['thread-completion'];
 425                                 Logger::info('Use inherited actor as causer.', ['id' => $item['owner-id'], 'activity' => $activity['thread-completion'], 'owner' => $item['owner-link'], 'actor' => $actor['url']]);
 426                         } else {
 427                                 // Store the original actor in the "causer" fields to enable the check for ignored or blocked contacts
 428                                 $item['causer-link'] = $item['owner-link'];
 429                                 $item['causer-id']   = $item['owner-id'];
 430                                 Logger::info('Use actor as causer.', ['id' => $item['owner-id'], 'actor' => $item['owner-link']]);
 431                         }
 432
 433                         $item['owner-link'] = $item['author-link'];
 434                         $item['owner-id'] = $item['author-id'];
 435                 } else {
 436                         $actor = APContact::getByURL($item['owner-link'], false);
 437                         $item['isForum'] = ($actor['type'] == 'Group');
 438                 }
 439
 440                 $item['uri'] = $activity['id'];
 441
 442                 if (empty($activity['published']) || empty($activity['updated'])) {
 443                         DI::logger()->notice('published or updated keys are empty for activity', ['activity' => $activity, 'callstack' => System::callstack(10)]);
 444                 }
 445
 446                 $item['created'] = DateTimeFormat::utc($activity['published'] ?? 'now');
 447                 $item['edited'] = DateTimeFormat::utc($activity['updated'] ?? 'now');
 448                 $guid = $activity['sc:identifier'] ?: self::getGUIDByURL($item['uri']);
 449                 $item['guid'] = $activity['diaspora:guid'] ?: $guid;
 450
 451                 $item['uri-id'] = ItemURI::insert(['uri' => $item['uri'], 'guid' => $item['guid']]);
 452                 if (empty($item['uri-id'])) {
 453                         Logger::warning('Unable to get a uri-id for an item uri', ['uri' => $item['uri'], 'guid' => $item['guid']]);
 454                         return [];
 455                 }
 456
 457                 $item = self::processContent($activity, $item);
 458                 if (empty($item)) {
 459                         Logger::info('Message was not processed');
 460                         return [];
 461                 }
 462
 463                 $item['plink'] = $activity['alternate-url'] ?? $item['uri'];
 464
 465                 self::storeAttachments($activity, $item);
 466                 self::storeQuestion($activity, $item);
 467
 468                 // We received the post via AP, so we set the protocol of the server to AP
 469                 $contact = Contact::getById($item['author-id'], ['gsid']);
 470                 if (!empty($contact['gsid'])) {
 471                         GServer::setProtocol($contact['gsid'], Post\DeliveryData::ACTIVITYPUB);
 472                 }
 473
 474                 if ($item['author-id'] != $item['owner-id']) {
 475                         $contact = Contact::getById($item['owner-id'], ['gsid']);
 476                         if (!empty($contact['gsid'])) {
 477                                 GServer::setProtocol($contact['gsid'], Post\DeliveryData::ACTIVITYPUB);
 478                         }
 479                 }
 480
 481                 return $item;
 482         }
 483
 484         /**
 485          * Fetch and process parent posts for the given activity
 486          *
 487          * @param array $activity
 488          *
 489          * @return string
 490          */
 491         private static function fetchParent(array $activity): string
 492         {
 493                 if (self::hasJustBeenFetched($activity['reply-to-id'])) {
 494                         Logger::notice('We just have tried to fetch this activity. We don\'t try it again.', ['parent' => $activity['reply-to-id']]);
 495                         return '';
 496                 }
 497
 498                 $recursion_depth = $activity['recursion-depth'] ?? 0;
 499
 500                 if ($recursion_depth < DI::config()->get('system', 'max_recursion_depth')) {
 501                         Logger::notice('Parent not found. Try to refetch it.', ['parent' => $activity['reply-to-id'], 'recursion-depth' => $recursion_depth]);
 502                         $result = self::fetchMissingActivity($activity['reply-to-id'], $activity, '', Receiver::COMPLETION_AUTO);
 503                         if (empty($result) && self::isActivityGone($activity['reply-to-id'])) {
 504                                 Logger::notice('The activity is gone, the queue entry will be deleted', ['parent' => $activity['reply-to-id']]);
 505                                 if (!empty($activity['entry-id'])) {
 506                                         Queue::deleteById($activity['entry-id']);
 507                                 }
 508                                 return '';
 509                         } elseif (!empty($result)) {
 510                                 $exists = Post::exists(['uri' => [$result, $activity['reply-to-id']]]);
 511                                 if ($exists) {
 512                                         Logger::notice('The activity has been fetched and created.', ['parent' => $result]);
 513                                         return $result;
 514                                 } elseif (DI::config()->get('system', 'fetch_by_worker') || DI::config()->get('system', 'decoupled_receiver')) {
 515                                         Logger::notice('The activity has been fetched and will hopefully be created later.', ['parent' => $result]);
 516                                 } else {
 517                                         Logger::notice('The activity exists but has not been created, the queue entry will be deleted.', ['parent' => $result]);
 518                                         if (!empty($activity['entry-id'])) {
 519                                                 Queue::deleteById($activity['entry-id']);
 520                                         }
 521                                 }
 522                                 return '';
 523                         }
 524                         if (empty($result) && !DI::config()->get('system', 'fetch_by_worker')) {
 525                                 return '';
 526                         }
 527                 } elseif (self::isActivityGone($activity['reply-to-id'])) {
 528                         Logger::notice('The activity is gone. We will not spawn a worker. The queue entry will be deleted', ['parent' => $activity['reply-to-id']]);
 529                         if (!empty($activity['entry-id'])) {
 530                                 Queue::deleteById($activity['entry-id']);
 531                         }
 532                         return '';
 533                 } else {
 534                         Logger::notice('Recursion level is too high.', ['parent' => $activity['reply-to-id'], 'recursion-depth' => $recursion_depth]);
 535                 }
 536
 537                 if (Queue::hasWorker($activity['worker-id'] ?? 0)) {
 538                         Logger::notice('There is already a worker task to fetch the post.', ['id' => $activity['id'], 'parent' => $activity['reply-to-id']]);
 539                         return '';
 540                 }
 541
 542                 if (!Fetch::hasWorker($activity['reply-to-id'])) {
 543                         Logger::notice('Fetching is done by worker.', ['parent' => $activity['reply-to-id'], 'recursion-depth' => $recursion_depth]);
 544                         Fetch::add($activity['reply-to-id']);
 545                         $activity['recursion-depth'] = 0;
 546                         $wid = Worker::add(PRIORITY_HIGH, 'FetchMissingActivity', $activity['reply-to-id'], $activity, '', Receiver::COMPLETION_AUTO);
 547                         Fetch::setWorkerId($activity['reply-to-id'], $wid);
 548                 } else {
 549                         Logger::debug('Activity will already be fetched via a worker.', ['url' => $activity['reply-to-id']]);
 550                 }
 551
 552                 return '';
 553         }
 554
 555         /**
 556          * Check if a given activity has recently been fetched
 557          *
 558          * @param string $url
 559          * @return boolean
 560          */
 561         private static function hasJustBeenFetched(string $url): bool
 562         {
 563                 $cachekey = self::CACHEKEY_JUST_FETCHED . $url;
 564                 $time = DI::cache()->get($cachekey);
 565                 if (is_null($time)) {
 566                         DI::cache()->set($cachekey, time(), Duration::FIVE_MINUTES);
 567                         return false;
 568                 }
 569                 return ($time + 300) > time();
 570         }
 571
 572         /**
 573          * Check if a given activity is no longer available
 574          *
 575          * @param string $url
 576          *
 577          * @return boolean
 578          */
 579         public static function isActivityGone(string $url): bool
 580         {
 581                 $curlResult = HTTPSignature::fetchRaw($url, 0);
 582
 583                 if (Network::isUrlBlocked($url)) {
 584                         return true;
 585                 }
 586
 587                 // @todo To ensure that the remote system is working correctly, we can check if the "Content-Type" contains JSON
 588                 if (in_array($curlResult->getReturnCode(), [404])) {
 589                         return true;
 590                 }
 591
 592                 $object = json_decode($curlResult->getBody(), true);
 593                 if (!empty($object)) {
 594                         $activity = JsonLD::compact($object);
 595                         if (JsonLD::fetchElement($activity, '@type') == 'as:Tombstone') {
 596                                 return true;
 597                         }
 598                 }
 599
 600                 return false;
 601         }
 602         /**
 603          * Delete items
 604          *
 605          * @param array $activity
 606          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 607          * @throws \ImagickException
 608          */
 609         public static function deleteItem(array $activity)
 610         {
 611                 $owner = Contact::getIdForURL($activity['actor']);
 612
 613                 Logger::info('Deleting item', ['object' => $activity['object_id'], 'owner'  => $owner]);
 614                 Item::markForDeletion(['uri' => $activity['object_id'], 'owner-id' => $owner]);
 615                 Queue::remove($activity);
 616         }
 617
 618         /**
 619          * Prepare the item array for an activity
 620          *
 621          * @param array $activity Activity array
 622          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 623          * @throws \ImagickException
 624          */
 625         public static function addTag(array $activity)
 626         {
 627                 if (empty($activity['object_content']) || empty($activity['object_id'])) {
 628                         return;
 629                 }
 630
 631                 foreach ($activity['receiver'] as $receiver) {
 632                         $item = Post::selectFirst(['id', 'uri-id', 'origin', 'author-link'], ['uri' => $activity['target_id'], 'uid' => $receiver]);
 633                         if (!DBA::isResult($item)) {
 634                                 // We don't fetch missing content for this purpose
 635                                 continue;
 636                         }
 637
 638                         if (($item['author-link'] != $activity['actor']) && !$item['origin']) {
 639                                 Logger::info('Not origin, not from the author, skipping update', ['id' => $item['id'], 'author' => $item['author-link'], 'actor' => $activity['actor']]);
 640                                 continue;
 641                         }
 642
 643                         Tag::store($item['uri-id'], Tag::HASHTAG, $activity['object_content'], $activity['object_id']);
 644                         Logger::info('Tagged item', ['id' => $item['id'], 'tag' => $activity['object_content'], 'uri' => $activity['target_id'], 'actor' => $activity['actor']]);
 645                 }
 646         }
 647
 648         /**
 649          * Prepare the item array for an activity
 650          *
 651          * @param array      $activity   Activity array
 652          * @param string     $verb       Activity verb
 653          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 654          * @throws \ImagickException
 655          */
 656         public static function createActivity(array $activity, string $verb)
 657         {
 658                 $activity['reply-to-id'] = $activity['object_id'];
 659                 $item = self::createItem($activity);
 660                 if (empty($item)) {
 661                         return;
 662                 }
 663
 664                 $item['verb'] = $verb;
 665                 $item['thr-parent'] = $activity['object_id'];
 666                 $item['gravity'] = GRAVITY_ACTIVITY;
 667                 unset($item['post-type']);
 668                 $item['object-type'] = Activity\ObjectType::NOTE;
 669
 670                 if (!empty($activity['content'])) {
 671                         $item['body'] = HTML::toBBCode($activity['content']);
 672                 }
 673
 674                 $item['diaspora_signed_text'] = $activity['diaspora:like'] ?? '';
 675
 676                 self::postItem($activity, $item);
 677         }
 678
 679         /**
 680          * Fetch the Uri-Id of a post for the "featured" collection
 681          *
 682          * @param array $activity
 683          * @return null|int
 684          */
 685         private static function getUriIdForFeaturedCollection(array $activity)
 686         {
 687                 $actor = APContact::getByURL($activity['actor']);
 688                 if (empty($actor)) {
 689                         return null;
 690                 }
 691
 692                 // Refetch the account when the "featured" collection is missing.
 693                 // This can be removed in a future version (end of 2022 should be good).
 694                 if (empty($actor['featured'])) {
 695                         $actor = APContact::getByURL($activity['actor'], true);
 696                         if (empty($actor)) {
 697                                 return null;
 698                         }
 699                 }
 700
 701                 $parent = Post::selectFirst(['uri-id'], ['uri' => $activity['object_id']]);
 702                 if (empty($parent['uri-id'])) {
 703                         if (self::fetchMissingActivity($activity['object_id'], $activity, '', Receiver::COMPLETION_AUTO)) {
 704                                 $parent = Post::selectFirst(['uri-id'], ['uri' => $activity['object_id']]);
 705                         }
 706                 }
 707
 708                 if (!empty($parent['uri-id'])) {
 709                         return $parent['uri-id'];
 710                 }
 711
 712                 return null;
 713         }
 714
 715         /**
 716          * Add a post to the "Featured" collection
 717          *
 718          * @param array $activity
 719          */
 720         public static function addToFeaturedCollection(array $activity)
 721         {
 722                 $uriid = self::getUriIdForFeaturedCollection($activity);
 723                 if (empty($uriid)) {
 724                         return;
 725                 }
 726
 727                 Logger::debug('Add post to featured collection', ['uri-id' => $uriid]);
 728
 729                 Post\Collection::add($uriid, Post\Collection::FEATURED);
 730                 Queue::remove($activity);
 731         }
 732
 733         /**
 734          * Remove a post to the "Featured" collection
 735          *
 736          * @param array $activity
 737          */
 738         public static function removeFromFeaturedCollection(array $activity)
 739         {
 740                 $uriid = self::getUriIdForFeaturedCollection($activity);
 741                 if (empty($uriid)) {
 742                         return;
 743                 }
 744
 745                 Logger::debug('Remove post from featured collection', ['uri-id' => $uriid]);
 746
 747                 Post\Collection::remove($uriid, Post\Collection::FEATURED);
 748                 Queue::remove($activity);
 749         }
 750
 751         /**
 752          * Create an event
 753          *
 754          * @param array $activity Activity array
 755          * @param array $item
 756          *
 757          * @return int event id
 758          * @throws \Exception
 759          */
 760         public static function createEvent(array $activity, array $item): int
 761         {
 762                 $event['summary']   = HTML::toBBCode($activity['name'] ?: $activity['summary']);
 763                 $event['desc']      = HTML::toBBCode($activity['content']);
 764                 if (!empty($activity['start-time'])) {
 765                         $event['start']  = DateTimeFormat::utc($activity['start-time']);
 766                 }
 767                 if (!empty($activity['end-time'])) {
 768                         $event['finish'] = DateTimeFormat::utc($activity['end-time']);
 769                 }
 770                 $event['nofinish']  = empty($event['finish']);
 771                 $event['location']  = $activity['location'];
 772                 $event['cid']       = $item['contact-id'];
 773                 $event['uid']       = $item['uid'];
 774                 $event['uri']       = $item['uri'];
 775                 $event['edited']    = $item['edited'];
 776                 $event['private']   = $item['private'];
 777                 $event['guid']      = $item['guid'];
 778                 $event['plink']     = $item['plink'];
 779                 $event['network']   = $item['network'];
 780                 $event['protocol']  = $item['protocol'];
 781                 $event['direction'] = $item['direction'];
 782                 $event['source']    = $item['source'];
 783
 784                 $ev = DBA::selectFirst('event', ['id'], ['uri' => $item['uri'], 'uid' => $item['uid']]);
 785                 if (DBA::isResult($ev)) {
 786                         $event['id'] = $ev['id'];
 787                 }
 788
 789                 $event_id = Event::store($event);
 790
 791                 Logger::info('Event was stored', ['id' => $event_id]);
 792
 793                 return $event_id;
 794         }
 795
 796         /**
 797          * Process the content
 798          *
 799          * @param array $activity Activity array
 800          * @param array $item
 801          * @return array|bool Returns the item array or false if there was an unexpected occurrence
 802          * @throws \Exception
 803          */
 804         private static function processContent(array $activity, array $item)
 805         {
 806                 if (!empty($activity['mediatype']) && ($activity['mediatype'] == 'text/markdown')) {
 807                         $item['title'] = strip_tags($activity['name']);
 808                         $content = Markdown::toBBCode($activity['content']);
 809                 } elseif (!empty($activity['mediatype']) && ($activity['mediatype'] == 'text/bbcode')) {
 810                         $item['title'] = $activity['name'];
 811                         $content = $activity['content'];
 812                 } else {
 813                         // By default assume "text/html"
 814                         $item['title'] = HTML::toBBCode($activity['name'] ?? '');
 815                         $content = HTML::toBBCode($activity['content'] ?? '');
 816                 }
 817
 818                 $item['title'] = trim(BBCode::toPlaintext($item['title']));
 819
 820                 if (!empty($activity['languages'])) {
 821                         $item['language'] = self::processLanguages($activity['languages']);
 822                 }
 823
 824                 if (!empty($activity['emojis'])) {
 825                         $content = self::replaceEmojis($item['uri-id'], $content, $activity['emojis']);
 826                 }
 827
 828                 $content = self::addMentionLinks($content, $activity['tags']);
 829
 830                 if (!empty($activity['source'])) {
 831                         $item['body'] = $activity['source'];
 832                         $item['raw-body'] = $content;
 833                         $item['body'] = Item::improveSharedDataInBody($item);
 834                 } else {
 835                         $parent_uri = $item['parent-uri'] ?? $item['thr-parent'];
 836                         if (empty($activity['directmessage']) && ($parent_uri != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
 837                                 $parent = Post::selectFirst(['id', 'uri-id', 'private', 'author-link', 'alias'], ['uri' => $parent_uri]);
 838                                 if (!DBA::isResult($parent)) {
 839                                         Logger::warning('Unknown parent item.', ['uri' => $parent_uri]);
 840                                         return false;
 841                                 }
 842                                 if (($item['private'] == Item::PRIVATE) && ($parent['private'] != Item::PRIVATE)) {
 843                                         Logger::warning('Item is private but the parent is not. Dropping.', ['item-uri' => $item['uri'], 'thr-parent' => $item['thr-parent']]);
 844                                         return false;
 845                                 }
 846
 847                                 $content = self::removeImplicitMentionsFromBody($content, $parent);
 848                         }
 849                         $item['content-warning'] = HTML::toBBCode($activity['summary'] ?? '');
 850                         $item['raw-body'] = $item['body'] = $content;
 851                 }
 852
 853                 self::storeFromBody($item);
 854                 self::storeTags($item['uri-id'], $activity['tags']);
 855
 856                 self::storeReceivers($item['uri-id'], $activity['receiver_urls'] ?? []);
 857
 858                 $item['location'] = $activity['location'];
 859
 860                 if (!empty($activity['latitude']) && !empty($activity['longitude'])) {
 861                         $item['coord'] = $activity['latitude'] . ' ' . $activity['longitude'];
 862                 }
 863
 864                 $item['app'] = $activity['generator'];
 865
 866                 return $item;
 867         }
 868
 869         /**
 870          * Store hashtags and mentions
 871          *
 872          * @param array $item
 873          */
 874         private static function storeFromBody(array $item)
 875         {
 876                 // Make sure to delete all existing tags (can happen when called via the update functionality)
 877                 DBA::delete('post-tag', ['uri-id' => $item['uri-id']]);
 878
 879                 Tag::storeFromBody($item['uri-id'], $item['body'], '@!');
 880         }
 881
 882         /**
 883          * Generate a GUID out of an URL of an ActivityPub post.
 884          *
 885          * @param string $url message URL
 886          * @return string with GUID
 887          */
 888         private static function getGUIDByURL(string $url): string
 889         {
 890                 $parsed = parse_url($url);
 891
 892                 $host_hash = hash('crc32', $parsed['host']);
 893
 894                 unset($parsed["scheme"]);
 895                 unset($parsed["host"]);
 896
 897                 $path = implode("/", $parsed);
 898
 899                 return $host_hash . '-'. hash('fnv164', $path) . '-'. hash('joaat', $path);
 900         }
 901
 902         /**
 903          * Checks if an incoming message is wanted
 904          *
 905          * @param array $activity
 906          * @param array $item
 907          * @return boolean Is the message wanted?
 908          */
 909         private static function isSolicitedMessage(array $activity, array $item): bool
 910         {
 911                 // The checks are split to improve the support when searching why a message was accepted.
 912                 if (count($activity['receiver']) != 1) {
 913                         // The message has more than one receiver, so it is wanted.
 914                         Logger::debug('Message has got several receivers - accepted', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 915                         return true;
 916                 }
 917
 918                 if ($item['private'] == Item::PRIVATE) {
 919                         // We only look at public posts here. Private posts are expected to be intentionally posted to the single receiver.
 920                         Logger::debug('Message is private - accepted', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 921                         return true;
 922                 }
 923
 924                 if (!empty($activity['from-relay'])) {
 925                         // We check relay posts at another place. When it arrived here, the message is already checked.
 926                         Logger::debug('Message is a relay post that is already checked - accepted', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 927                         return true;
 928                 }
 929
 930                 if (in_array($activity['completion-mode'] ?? Receiver::COMPLETION_NONE, [Receiver::COMPLETION_MANUAL, Receiver::COMPLETION_ANNOUCE])) {
 931                         // Manual completions and completions caused by reshares are allowed without any further checks.
 932                         Logger::debug('Message is in completion mode - accepted', ['mode' => $activity['completion-mode'], 'uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 933                         return true;
 934                 }
 935
 936                 if ($item['gravity'] != GRAVITY_PARENT) {
 937                         // We cannot reliably check at this point if a comment or activity belongs to an accepted post or needs to be fetched
 938                         // This can possibly be improved in the future.
 939                         Logger::debug('Message is no parent - accepted', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 940                         return true;
 941                 }
 942
 943                 $tags = array_column(Tag::getByURIId($item['uri-id'], [Tag::HASHTAG]), 'name');
 944                 if (Relay::isSolicitedPost($tags, $item['body'], $item['author-id'], $item['uri'], Protocol::ACTIVITYPUB)) {
 945                         Logger::debug('Post is accepted because of the relay settings', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 946                         return true;
 947                 } else {
 948                         return false;
 949                 }
 950         }
 951
 952         /**
 953          * Creates an item post
 954          *
 955          * @param array $activity Activity data
 956          * @param array $item     item array
 957          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 958          * @throws \ImagickException
 959          */
 960         public static function postItem(array $activity, array $item)
 961         {
 962                 if (empty($item)) {
 963                         return;
 964                 }
 965
 966                 $stored = false;
 967                 $success = false;
 968                 ksort($activity['receiver']);
 969
 970                 if (!self::isSolicitedMessage($activity, $item)) {
 971                         DBA::delete('item-uri', ['id' => $item['uri-id']]);
 972                         return;
 973                 }
 974
 975                 foreach ($activity['receiver'] as $receiver) {
 976                         if ($receiver == -1) {
 977                                 continue;
 978                         }
 979
 980                         $item['uid'] = $receiver;
 981
 982                         $type = $activity['reception_type'][$receiver] ?? Receiver::TARGET_UNKNOWN;
 983                         switch($type) {
 984                                 case Receiver::TARGET_TO:
 985                                         $item['post-reason'] = Item::PR_TO;
 986                                         break;
 987                                 case Receiver::TARGET_CC:
 988                                         $item['post-reason'] = Item::PR_CC;
 989                                         break;
 990                                 case Receiver::TARGET_BTO:
 991                                         $item['post-reason'] = Item::PR_BTO;
 992                                         break;
 993                                 case Receiver::TARGET_BCC:
 994                                         $item['post-reason'] = Item::PR_BCC;
 995                                         break;
 996                                 case Receiver::TARGET_FOLLOWER:
 997                                         $item['post-reason'] = Item::PR_FOLLOWER;
 998                                         break;
 999                                 case Receiver::TARGET_ANSWER:
1000                                         $item['post-reason'] = Item::PR_COMMENT;
1001                                         break;
1002                                 case Receiver::TARGET_GLOBAL:
1003                                         $item['post-reason'] = Item::PR_GLOBAL;
1004                                         break;
1005                                 default:
1006                                         $item['post-reason'] = Item::PR_NONE;
1007                         }
1008
1009                         if (!empty($activity['from-relay'])) {
1010                                 $item['post-reason'] = Item::PR_RELAY;
1011                         } elseif (!empty($activity['thread-completion'])) {
1012                                 $item['post-reason'] = Item::PR_FETCHED;
1013                         } elseif (in_array($item['post-reason'], [Item::PR_GLOBAL, Item::PR_NONE]) && !empty($activity['push'])) {
1014                                 $item['post-reason'] = Item::PR_PUSHED;
1015                         }
1016
1017                         if ($item['isForum'] ?? false) {
1018                                 $item['contact-id'] = Contact::getIdForURL($activity['actor'], $receiver);
1019                         } else {
1020                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver);
1021                         }
1022
1023                         if (($receiver != 0) && empty($item['contact-id'])) {
1024                                 $item['contact-id'] = Contact::getIdForURL($activity['author']);
1025                         }
1026
1027                         if (!empty($activity['directmessage'])) {
1028                                 self::postMail($activity, $item);
1029                                 continue;
1030                         }
1031
1032                         if (!($item['isForum'] ?? false) && ($receiver != 0) && ($item['gravity'] == GRAVITY_PARENT) && !Contact::isSharingByURL($activity['author'], $receiver)) {
1033                                 if ($item['post-reason'] == Item::PR_BCC) {
1034                                         Logger::info('Top level post via BCC from a non sharer, ignoring', ['uid' => $receiver, 'contact' => $item['contact-id']]);
1035                                         continue;
1036                                 }
1037
1038                                 if (
1039                                         !empty($activity['thread-children-type'])
1040                                         && in_array($activity['thread-children-type'], Receiver::ACTIVITY_TYPES)
1041                                         && DI::pConfig()->get($receiver, 'system', 'accept_only_sharer') != Item::COMPLETION_LIKE
1042                                 ) {
1043                                         Logger::info('Top level post from thread completion from a non sharer had been initiated via an activity, ignoring',
1044                                                 ['type' => $activity['thread-children-type'], 'user' => $item['uid'], 'causer' => $item['causer-link'], 'author' => $activity['author'], 'url' => $item['uri']]);
1045                                         continue;
1046                                 }
1047                         }
1048
1049                         $is_forum = false;
1050
1051                         if ($receiver != 0) {
1052                                 $user = User::getById($receiver, ['account-type']);
1053                                 if (!empty($user['account-type'])) {
1054                                         $is_forum = ($user['account-type'] == User::ACCOUNT_TYPE_COMMUNITY);
1055                                 }
1056                         }
1057
1058                         if (!$is_forum && DI::pConfig()->get($receiver, 'system', 'accept_only_sharer') == Item::COMPLETION_NONE && ($receiver != 0) && ($item['gravity'] == GRAVITY_PARENT)) {
1059                                 $skip = !Contact::isSharingByURL($activity['author'], $receiver);
1060
1061                                 if ($skip && (($activity['type'] == 'as:Announce') || ($item['isForum'] ?? false))) {
1062                                         $skip = !Contact::isSharingByURL($activity['actor'], $receiver);
1063                                 }
1064
1065                                 if ($skip) {
1066                                         Logger::info('Skipping post', ['uid' => $receiver, 'url' => $item['uri']]);
1067                                         continue;
1068                                 }
1069
1070                                 Logger::info('Accepting post', ['uid' => $receiver, 'url' => $item['uri']]);
1071                         }
1072
1073                         if (($item['gravity'] != GRAVITY_ACTIVITY) && ($activity['object_type'] == 'as:Event')) {
1074                                 $event_id = self::createEvent($activity, $item);
1075
1076                                 $item = Event::getItemArrayForImportedId($event_id, $item);
1077                         }
1078
1079                         $item_id = Item::insert($item);
1080                         if ($item_id) {
1081                                 Logger::info('Item insertion successful', ['user' => $item['uid'], 'item_id' => $item_id]);
1082                                 $success = true;
1083                         } else {
1084                                 Logger::notice('Item insertion aborted', ['uri' => $item['uri'], 'uid' => $item['uid']]);
1085                         }
1086
1087                         if ($item['uid'] == 0) {
1088                                 $stored = $item_id;
1089                         }
1090                 }
1091
1092                 Queue::remove($activity);
1093
1094                 if ($success && Queue::hasChildren($item['uri']) && Post::exists(['uri' => $item['uri']])) {
1095                         Queue::processReplyByUri($item['uri']);
1096                 }
1097
1098                 // Store send a follow request for every reshare - but only when the item had been stored
1099                 if ($stored && ($item['private'] != Item::PRIVATE) && ($item['gravity'] == GRAVITY_PARENT) && !empty($item['author-link']) && ($item['author-link'] != $item['owner-link'])) {
1100                         $author = APContact::getByURL($item['owner-link'], false);
1101                         // We send automatic follow requests for reshared messages. (We don't need though for forum posts)
1102                         if ($author['type'] != 'Group') {
1103                                 Logger::info('Send follow request', ['uri' => $item['uri'], 'stored' => $stored, 'to' => $item['author-link']]);
1104                                 ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
1105                         }
1106                 }
1107         }
1108
1109         /**
1110          * Store tags and mentions into the tag table
1111          *
1112          * @param integer $uriid
1113          * @param array $tags
1114          */
1115         private static function storeTags(int $uriid, array $tags = null)
1116         {
1117                 foreach ($tags as $tag) {
1118                         if (empty($tag['name']) || empty($tag['type']) || !in_array($tag['type'], ['Mention', 'Hashtag'])) {
1119                                 continue;
1120                         }
1121
1122                         $hash = substr($tag['name'], 0, 1);
1123
1124                         if ($tag['type'] == 'Mention') {
1125                                 if (in_array($hash, [Tag::TAG_CHARACTER[Tag::MENTION],
1126                                         Tag::TAG_CHARACTER[Tag::EXCLUSIVE_MENTION],
1127                                         Tag::TAG_CHARACTER[Tag::IMPLICIT_MENTION]])) {
1128                                         $tag['name'] = substr($tag['name'], 1);
1129                                 }
1130                                 $type = Tag::IMPLICIT_MENTION;
1131
1132                                 if (!empty($tag['href'])) {
1133                                         $apcontact = APContact::getByURL($tag['href']);
1134                                         if (!empty($apcontact['name']) || !empty($apcontact['nick'])) {
1135                                                 $tag['name'] = $apcontact['name'] ?: $apcontact['nick'];
1136                                         }
1137                                 }
1138                         } elseif ($tag['type'] == 'Hashtag') {
1139                                 if ($hash == Tag::TAG_CHARACTER[Tag::HASHTAG]) {
1140                                         $tag['name'] = substr($tag['name'], 1);
1141                                 }
1142                                 $type = Tag::HASHTAG;
1143                         }
1144
1145                         if (empty($tag['name'])) {
1146                                 continue;
1147                         }
1148
1149                         Tag::store($uriid, $type, $tag['name'], $tag['href']);
1150                 }
1151         }
1152
1153         public static function storeReceivers(int $uriid, array $receivers)
1154         {
1155                 foreach (['as:to' => Tag::TO, 'as:cc' => Tag::CC, 'as:bto' => Tag::BTO, 'as:bcc' => Tag::BCC] as $element => $type) {
1156                         if (!empty($receivers[$element])) {
1157                                 foreach ($receivers[$element] as $receiver) {
1158                                         if ($receiver == ActivityPub::PUBLIC_COLLECTION) {
1159                                                 $name = Receiver::PUBLIC_COLLECTION;
1160                                         } else {
1161                                                 $name = trim(parse_url($receiver, PHP_URL_PATH), '/');
1162                                         }
1163
1164                                         $target = Tag::getTargetType($receiver);
1165                                         Logger::debug('Got target type', ['type' => $target, 'url' => $receiver]);
1166                                         Tag::store($uriid, $type, $name, $receiver, $target);
1167                                 }
1168                         }
1169                 }
1170         }
1171
1172         /**
1173          * Creates an mail post
1174          *
1175          * @param array $activity Activity data
1176          * @param array $item     item array
1177          * @return int|bool New mail table row id or false on error
1178          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1179          */
1180         private static function postMail(array $activity, array $item)
1181         {
1182                 if (($item['gravity'] != GRAVITY_PARENT) && !DBA::exists('mail', ['uri' => $item['thr-parent'], 'uid' => $item['uid']])) {
1183                         Logger::info('Parent not found, mail will be discarded.', ['uid' => $item['uid'], 'uri' => $item['thr-parent']]);
1184                         return false;
1185                 }
1186
1187                 Logger::info('Direct Message', $item);
1188
1189                 $msg = [];
1190                 $msg['uid'] = $item['uid'];
1191
1192                 $msg['contact-id'] = $item['contact-id'];
1193
1194                 $contact = Contact::getById($item['contact-id'], ['name', 'url', 'photo']);
1195                 $msg['from-name'] = $contact['name'];
1196                 $msg['from-url'] = $contact['url'];
1197                 $msg['from-photo'] = $contact['photo'];
1198
1199                 $msg['uri'] = $item['uri'];
1200                 $msg['created'] = $item['created'];
1201
1202                 $parent = DBA::selectFirst('mail', ['parent-uri', 'title'], ['uri' => $item['thr-parent']]);
1203                 if (DBA::isResult($parent)) {
1204                         $msg['parent-uri'] = $parent['parent-uri'];
1205                         $msg['title'] = $parent['title'];
1206                 } else {
1207                         $msg['parent-uri'] = $item['thr-parent'];
1208
1209                         if (!empty($item['title'])) {
1210                                 $msg['title'] = $item['title'];
1211                         } elseif (!empty($item['content-warning'])) {
1212                                 $msg['title'] = $item['content-warning'];
1213                         } else {
1214                                 // Trying to generate a title out of the body
1215                                 $title = $item['body'];
1216
1217                                 while (preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $title, $matches)) {
1218                                         $title = $matches[3];
1219                                 }
1220
1221                                 $title = trim(BBCode::toPlaintext($title));
1222
1223                                 if (strlen($title) > 20) {
1224                                         $title = substr($title, 0, 20) . '...';
1225                                 }
1226
1227                                 $msg['title'] = $title;
1228                         }
1229                 }
1230                 $msg['body'] = $item['body'];
1231
1232                 return Mail::insert($msg);
1233         }
1234
1235         /**
1236          * Fetch featured posts from a contact with the given url
1237          *
1238          * @param string $url
1239          * @return void
1240          */
1241         public static function fetchFeaturedPosts(string $url)
1242         {
1243                 Logger::info('Fetch featured posts', ['contact' => $url]);
1244
1245                 $apcontact = APContact::getByURL($url);
1246                 if (empty($apcontact['featured'])) {
1247                         Logger::info('Contact does not have a featured collection', ['contact' => $url]);
1248                         return;
1249                 }
1250
1251                 $pcid = Contact::getIdForURL($url, 0, false);
1252                 if (empty($pcid)) {
1253                         Logger::info('Contact not found', ['contact' => $url]);
1254                         return;
1255                 }
1256
1257                 $posts = Post\Collection::selectToArrayForContact($pcid, Post\Collection::FEATURED);
1258                 if (!empty($posts)) {
1259                         $old_featured = array_column($posts, 'uri-id');
1260                 } else {
1261                         $old_featured = [];
1262                 }
1263
1264                 $featured = ActivityPub::fetchItems($apcontact['featured']);
1265                 if (empty($featured)) {
1266                         Logger::info('Contact does not have featured posts', ['contact' => $url]);
1267
1268                         foreach ($old_featured as $uri_id) {
1269                                 Post\Collection::remove($uri_id, Post\Collection::FEATURED);
1270                                 Logger::debug('Removed no longer featured post', ['uri-id' => $uri_id, 'contact' => $url]);
1271                         }
1272                         return;
1273                 }
1274
1275                 $new = 0;
1276                 $old = 0;
1277
1278                 foreach ($featured as $post) {
1279                         if (empty($post['id'])) {
1280                                 continue;
1281                         }
1282                         $id = Item::fetchByLink($post['id']);
1283                         if (!empty($id)) {
1284                                 $item = Post::selectFirst(['uri-id', 'featured'], ['id' => $id]);
1285                                 if (!empty($item['uri-id'])) {
1286                                         if (!$item['featured']) {
1287                                                 Post\Collection::add($item['uri-id'], Post\Collection::FEATURED);
1288                                                 Logger::debug('Added featured post', ['uri-id' => $item['uri-id'], 'contact' => $url]);
1289                                                 $new++;
1290                                         } else {
1291                                                 Logger::debug('Post already had been featured', ['uri-id' => $item['uri-id'], 'contact' => $url]);
1292                                                 $old++;
1293                                         }
1294
1295                                         $index = array_search($item['uri-id'], $old_featured);
1296                                         if (!($index === false)) {
1297                                                 unset($old_featured[$index]);
1298                                         }
1299                                 }
1300                         }
1301                 }
1302
1303                 foreach ($old_featured as $uri_id) {
1304                         Post\Collection::remove($uri_id, Post\Collection::FEATURED);
1305                         Logger::debug('Removed no longer featured post', ['uri-id' => $uri_id, 'contact' => $url]);
1306                 }
1307
1308                 Logger::info('Fetched featured posts', ['new' => $new, 'old' => $old, 'contact' => $url]);
1309         }
1310
1311         public static function fetchCachedActivity(string $url, int $uid): array
1312         {
1313                 $cachekey = self::CACHEKEY_FETCH_ACTIVITY . $uid . ':' . $url;
1314                 $object = DI::cache()->get($cachekey);
1315
1316                 if (!is_null($object)) {
1317                         if (!empty($object)) {
1318                                 Logger::debug('Fetch from cache', ['url' => $url, 'uid' => $uid]);
1319                         } else {
1320                                 Logger::debug('Fetch from negative cache', ['url' => $url, 'uid' => $uid]);
1321                         }
1322                         return $object;
1323                 }
1324
1325                 $object = ActivityPub::fetchContent($url, $uid);
1326                 if (empty($object)) {
1327                         Logger::notice('Activity was not fetchable, aborting.', ['url' => $url, 'uid' => $uid]);
1328                         // We perform negative caching.
1329                         DI::cache()->set($cachekey, [], Duration::FIVE_MINUTES);
1330                         return [];
1331                 }
1332
1333                 if (empty($object['id'])) {
1334                         Logger::notice('Activity has got not id, aborting. ', ['url' => $url, 'object' => $object]);
1335                         return [];
1336                 }
1337                 DI::cache()->set($cachekey, $object, Duration::FIVE_MINUTES);
1338
1339                 Logger::debug('Activity was fetched successfully', ['url' => $url, 'uid' => $uid]);
1340
1341                 return $object;
1342         }
1343
1344         /**
1345          * Fetches missing posts
1346          *
1347          * @param string     $url         message URL
1348          * @param array      $child       activity array with the child of this message
1349          * @param string     $relay_actor Relay actor
1350          * @param int        $completion  Completion mode, see Receiver::COMPLETION_*
1351          * @return string fetched message URL
1352          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1353          * @throws \ImagickException
1354          */
1355         public static function fetchMissingActivity(string $url, array $child = [], string $relay_actor = '', int $completion = Receiver::COMPLETION_MANUAL): string
1356         {
1357                 if (!empty($child['receiver'])) {
1358                         $uid = ActivityPub\Receiver::getFirstUserFromReceivers($child['receiver']);
1359                 } else {
1360                         $uid = 0;
1361                 }
1362
1363                 $object = self::fetchCachedActivity($url, $uid);
1364                 if (empty($object)) {
1365                         return '';
1366                 }
1367
1368                 $signer = [];
1369
1370                 if (!empty($object['attributedTo'])) {
1371                         $attributed_to = $object['attributedTo'];
1372                         if (is_array($attributed_to)) {
1373                                 $compacted = JsonLD::compact($object);
1374                                 $attributed_to = JsonLD::fetchElement($compacted, 'as:attributedTo', '@id');
1375                         }
1376                         $signer[] = $attributed_to;
1377                 }
1378
1379                 if (!empty($object['actor'])) {
1380                         $object_actor = $object['actor'];
1381                 } elseif (!empty($attributed_to)) {
1382                         $object_actor = $attributed_to;
1383                 } else {
1384                         // Shouldn't happen
1385                         $object_actor = '';
1386                 }
1387
1388                 $signer[] = $object_actor;
1389
1390                 if (!empty($child['author'])) {
1391                         $actor = $child['author'];
1392                         $signer[] = $actor;
1393                 } else {
1394                         $actor = $object_actor;
1395                 }
1396
1397                 if (!empty($object['published'])) {
1398                         $published = $object['published'];
1399                 } elseif (!empty($child['published'])) {
1400                         $published = $child['published'];
1401                 } else {
1402                         $published = DateTimeFormat::utcNow();
1403                 }
1404
1405                 $activity = [];
1406                 $activity['@context'] = $object['@context'] ?? ActivityPub::CONTEXT;
1407                 unset($object['@context']);
1408                 $activity['id'] = $object['id'];
1409                 $activity['to'] = $object['to'] ?? [];
1410                 $activity['cc'] = $object['cc'] ?? [];
1411                 $activity['actor'] = $actor;
1412                 $activity['object'] = $object;
1413                 $activity['published'] = $published;
1414                 $activity['type'] = 'Create';
1415
1416                 $ldactivity = JsonLD::compact($activity);
1417
1418                 $ldactivity['recursion-depth'] = !empty($child['recursion-depth']) ? $child['recursion-depth'] + 1 : 1;
1419
1420                 if (!empty($relay_actor)) {
1421                         $ldactivity['thread-completion'] = $ldactivity['from-relay'] = Contact::getIdForURL($relay_actor);
1422                         $ldactivity['completion-mode']   = Receiver::COMPLETION_RELAY;
1423                 } elseif (!empty($child['thread-completion'])) {
1424                         $ldactivity['thread-completion'] = $child['thread-completion'];
1425                         $ldactivity['completion-mode']   = $child['completion-mode'] ?? Receiver::COMPLETION_NONE;
1426                 } else {
1427                         $ldactivity['thread-completion'] = Contact::getIdForURL($actor);
1428                         $ldactivity['completion-mode']   = $completion;
1429                 }
1430
1431                 if (!empty($child['type'])) {
1432                         $ldactivity['thread-children-type'] = $child['type'];
1433                 }
1434
1435                 if (!empty($relay_actor) && !self::acceptIncomingMessage($ldactivity, $object['id'])) {
1436                         return '';
1437                 }
1438
1439                 if (($completion == Receiver::COMPLETION_RELAY) && Queue::exists($url, 'as:Create')) {
1440                         Logger::notice('Activity has already been queued.', ['url' => $url, 'object' => $activity['id']]);
1441                 } elseif (ActivityPub\Receiver::processActivity($ldactivity, json_encode($activity), $uid, true, false, $signer, '', $completion)) {
1442                         Logger::notice('Activity had been fetched and processed.', ['url' => $url, 'entry' => $child['entry-id'] ?? 0, 'completion' => $completion, 'object' => $activity['id']]);
1443                 } else {
1444                         Logger::notice('Activity had been fetched and will be processed later.', ['url' => $url, 'entry' => $child['entry-id'] ?? 0, 'completion' => $completion, 'object' => $activity['id']]);
1445                 }
1446
1447                 return $activity['id'];
1448         }
1449
1450         /**
1451          * Test if incoming relay messages should be accepted
1452          *
1453          * @param array $activity activity array
1454          * @param string $id      object ID
1455          * @return boolean true if message is accepted
1456          */
1457         private static function acceptIncomingMessage(array $activity, string $id): bool
1458         {
1459                 if (empty($activity['as:object'])) {
1460                         Logger::info('No object field in activity - accepted', ['id' => $id]);
1461                         return true;
1462                 }
1463
1464                 $replyto = JsonLD::fetchElement($activity['as:object'], 'as:inReplyTo', '@id');
1465                 $uriid = ItemURI::getIdByURI($replyto ?? '');
1466                 if (Post::exists(['uri-id' => $uriid])) {
1467                         Logger::info('Post is a reply to an existing post - accepted', ['id' => $id, 'uri-id' => $uriid, 'replyto' => $replyto]);
1468                         return true;
1469                 }
1470
1471                 $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
1472                 $authorid = Contact::getIdForURL($attributed_to);
1473
1474                 $body = HTML::toBBCode(JsonLD::fetchElement($activity['as:object'], 'as:content', '@value') ?? '');
1475
1476                 $messageTags = [];
1477                 $tags = Receiver::processTags(JsonLD::fetchElementArray($activity['as:object'], 'as:tag') ?? []);
1478                 if (!empty($tags)) {
1479                         foreach ($tags as $tag) {
1480                                 if ($tag['type'] != 'Hashtag') {
1481                                         continue;
1482                                 }
1483                                 $messageTags[] = ltrim(mb_strtolower($tag['name']), '#');
1484                         }
1485                 }
1486
1487                 return Relay::isSolicitedPost($messageTags, $body, $authorid, $id, Protocol::ACTIVITYPUB);
1488         }
1489
1490         /**
1491          * perform a "follow" request
1492          *
1493          * @param array $activity
1494          * @return void
1495          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1496          * @throws \ImagickException
1497          */
1498         public static function followUser(array $activity)
1499         {
1500                 $uid = User::getIdForURL($activity['object_id']);
1501                 if (empty($uid)) {
1502                         Queue::remove($activity);
1503                         return;
1504                 }
1505
1506                 $owner = User::getOwnerDataById($uid);
1507                 if (empty($owner)) {
1508                         return;
1509                 }
1510
1511                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1512                 if (!empty($cid)) {
1513                         self::switchContact($cid);
1514                         Contact::update(['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
1515                 }
1516
1517                 $item = [
1518                         'author-id' => Contact::getIdForURL($activity['actor']),
1519                         'author-link' => $activity['actor'],
1520                 ];
1521
1522                 // Ensure that the contact has got the right network type
1523                 self::switchContact($item['author-id']);
1524
1525                 $result = Contact::addRelationship($owner, [], $item, false, $activity['content'] ?? '');
1526                 if ($result === true) {
1527                         ActivityPub\Transmitter::sendContactAccept($item['author-link'], $activity['id'], $owner['uid']);
1528                 }
1529
1530                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1531                 if (empty($cid)) {
1532                         return;
1533                 }
1534
1535                 if ($result && DI::config()->get('system', 'transmit_pending_events') && ($owner['contact-type'] == Contact::TYPE_COMMUNITY)) {
1536                         self::transmitPendingEvents($cid, $owner['uid']);
1537                 }
1538
1539                 if (empty($contact)) {
1540                         Contact::update(['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
1541                 }
1542                 Logger::notice('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
1543                 Queue::remove($activity);
1544         }
1545
1546         /**
1547          * Transmit pending events to the new follower
1548          *
1549          * @param integer $cid Contact id
1550          * @param integer $uid User id
1551          * @return void
1552          */
1553         private static function transmitPendingEvents(int $cid, int $uid)
1554         {
1555                 $account = DBA::selectFirst('account-user-view', ['ap-inbox', 'ap-sharedinbox'], ['id' => $cid]);
1556                 $inbox = $account['ap-sharedinbox'] ?: $account['ap-inbox'];
1557
1558                 $events = DBA::select('event', ['id'], ["`uid` = ? AND `start` > ? AND `type` != ?", $uid, DateTimeFormat::utcNow(), 'birthday']);
1559                 while ($event = DBA::fetch($events)) {
1560                         $post = Post::selectFirst(['id', 'uri-id', 'created'], ['event-id' => $event['id']]);
1561                         if (empty($post)) {
1562                                 continue;
1563                         }
1564                         if (DI::config()->get('system', 'bulk_delivery')) {
1565                                 Post\Delivery::add($post['uri-id'], $uid, $inbox, $post['created'], Delivery::POST, [$cid]);
1566                                 Worker::add(PRIORITY_HIGH, 'APDelivery', '', 0, $inbox, 0);
1567                         } else {
1568                                 Worker::add(PRIORITY_HIGH, 'APDelivery', Delivery::POST, $post['id'], $inbox, $uid, [$cid], $post['uri-id']);
1569                         }
1570                 }
1571         }
1572
1573         /**
1574          * Update the given profile
1575          *
1576          * @param array $activity
1577          * @throws \Exception
1578          */
1579         public static function updatePerson(array $activity)
1580         {
1581                 if (empty($activity['object_id'])) {
1582                         return;
1583                 }
1584
1585                 Logger::info('Updating profile', ['object' => $activity['object_id']]);
1586                 Contact::updateFromProbeByURL($activity['object_id']);
1587                 Queue::remove($activity);
1588         }
1589
1590         /**
1591          * Delete the given profile
1592          *
1593          * @param array $activity
1594          * @return void
1595          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1596          */
1597         public static function deletePerson(array $activity)
1598         {
1599                 if (empty($activity['object_id']) || empty($activity['actor'])) {
1600                         Logger::info('Empty object id or actor.');
1601                         return;
1602                 }
1603
1604                 if ($activity['object_id'] != $activity['actor']) {
1605                         Logger::info('Object id does not match actor.');
1606                         return;
1607                 }
1608
1609                 $contacts = DBA::select('contact', ['id'], ['nurl' => Strings::normaliseLink($activity['object_id'])]);
1610                 while ($contact = DBA::fetch($contacts)) {
1611                         Contact::remove($contact['id']);
1612                 }
1613                 DBA::close($contacts);
1614
1615                 Logger::info('Deleted contact', ['object' => $activity['object_id']]);
1616                 Queue::remove($activity);
1617         }
1618
1619         /**
1620          * Blocks the user by the contact
1621          *
1622          * @param array $activity
1623          * @return void
1624          * @throws \Exception
1625          */
1626         public static function blockAccount(array $activity)
1627         {
1628                 $cid = Contact::getIdForURL($activity['actor']);
1629                 if (empty($cid)) {
1630                         return;
1631                 }
1632
1633                 $uid = User::getIdForURL($activity['object_id']);
1634                 if (empty($uid)) {
1635                         return;
1636                 }
1637
1638                 Contact\User::setIsBlocked($cid, $uid, true);
1639
1640                 Logger::info('Contact blocked user', ['contact' => $cid, 'user' => $uid]);
1641                 Queue::remove($activity);
1642         }
1643
1644         /**
1645          * Unblocks the user by the contact
1646          *
1647          * @param array $activity
1648          * @return void
1649          * @throws \Exception
1650          */
1651         public static function unblockAccount(array $activity)
1652         {
1653                 $cid = Contact::getIdForURL($activity['actor']);
1654                 if (empty($cid)) {
1655                         return;
1656                 }
1657
1658                 $uid = User::getIdForURL($activity['object_object']);
1659                 if (empty($uid)) {
1660                         return;
1661                 }
1662
1663                 Contact\User::setIsBlocked($cid, $uid, false);
1664
1665                 Logger::info('Contact unblocked user', ['contact' => $cid, 'user' => $uid]);
1666                 Queue::remove($activity);
1667         }
1668
1669         /**
1670          * Accept a follow request
1671          *
1672          * @param array $activity
1673          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1674          * @throws \ImagickException
1675          */
1676         public static function acceptFollowUser(array $activity)
1677         {
1678                 $uid = User::getIdForURL($activity['object_actor']);
1679                 if (empty($uid)) {
1680                         return;
1681                 }
1682
1683                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1684                 if (empty($cid)) {
1685                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1686                         return;
1687                 }
1688
1689                 self::switchContact($cid);
1690
1691                 $fields = ['pending' => false];
1692
1693                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
1694                 if ($contact['rel'] == Contact::FOLLOWER) {
1695                         $fields['rel'] = Contact::FRIEND;
1696                 }
1697
1698                 $condition = ['id' => $cid];
1699                 Contact::update($fields, $condition);
1700                 Logger::info('Accept contact request', ['contact' => $cid, 'user' => $uid]);
1701                 Queue::remove($activity);
1702         }
1703
1704         /**
1705          * Reject a follow request
1706          *
1707          * @param array $activity
1708          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1709          * @throws \ImagickException
1710          */
1711         public static function rejectFollowUser(array $activity)
1712         {
1713                 $uid = User::getIdForURL($activity['object_actor']);
1714                 if (empty($uid)) {
1715                         return;
1716                 }
1717
1718                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1719                 if (empty($cid)) {
1720                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1721                         return;
1722                 }
1723
1724                 self::switchContact($cid);
1725
1726                 $contact = Contact::getById($cid, ['rel']);
1727                 if ($contact['rel'] == Contact::SHARING) {
1728                         Contact::remove($cid);
1729                         Logger::info('Rejected contact request - contact removed', ['contact' => $cid, 'user' => $uid]);
1730                 } elseif ($contact['rel'] == Contact::FRIEND) {
1731                         Contact::update(['rel' => Contact::FOLLOWER], ['id' => $cid]);
1732                 } else {
1733                         Logger::info('Rejected contact request', ['contact' => $cid, 'user' => $uid]);
1734                 }
1735                 Queue::remove($activity);
1736         }
1737
1738         /**
1739          * Undo activity like "like" or "dislike"
1740          *
1741          * @param array $activity
1742          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1743          * @throws \ImagickException
1744          */
1745         public static function undoActivity(array $activity)
1746         {
1747                 if (empty($activity['object_id'])) {
1748                         return;
1749                 }
1750
1751                 if (empty($activity['object_actor'])) {
1752                         return;
1753                 }
1754
1755                 $author_id = Contact::getIdForURL($activity['object_actor']);
1756                 if (empty($author_id)) {
1757                         return;
1758                 }
1759
1760                 Item::markForDeletion(['uri' => $activity['object_id'], 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
1761                 Queue::remove($activity);
1762         }
1763
1764         /**
1765          * Activity to remove a follower
1766          *
1767          * @param array $activity
1768          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1769          * @throws \ImagickException
1770          */
1771         public static function undoFollowUser(array $activity)
1772         {
1773                 $uid = User::getIdForURL($activity['object_object']);
1774                 if (empty($uid)) {
1775                         return;
1776                 }
1777
1778                 $owner = User::getOwnerDataById($uid);
1779                 if (empty($owner)) {
1780                         return;
1781                 }
1782
1783                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1784                 if (empty($cid)) {
1785                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1786                         return;
1787                 }
1788
1789                 self::switchContact($cid);
1790
1791                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1792                 if (!DBA::isResult($contact)) {
1793                         return;
1794                 }
1795
1796                 Contact::removeFollower($contact);
1797                 Logger::info('Undo following request', ['contact' => $cid, 'user' => $uid]);
1798                 Queue::remove($activity);
1799         }
1800
1801         /**
1802          * Switches a contact to AP if needed
1803          *
1804          * @param integer $cid Contact ID
1805          * @return void
1806          * @throws \Exception
1807          */
1808         private static function switchContact(int $cid)
1809         {
1810                 $contact = DBA::selectFirst('contact', ['network', 'url'], ['id' => $cid]);
1811                 if (!DBA::isResult($contact) || in_array($contact['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN]) || Contact::isLocal($contact['url'])) {
1812                         return;
1813                 }
1814
1815                 Logger::info('Change existing contact', ['cid' => $cid, 'previous' => $contact['network']]);
1816                 Contact::updateFromProbe($cid);
1817         }
1818
1819         /**
1820          * Collects implicit mentions like:
1821          * - the author of the parent item
1822          * - all the mentioned conversants in the parent item
1823          *
1824          * @param array $parent Item array with at least ['id', 'author-link', 'alias']
1825          * @return array
1826          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1827          */
1828         private static function getImplicitMentionList(array $parent): array
1829         {
1830                 $parent_terms = Tag::getByURIId($parent['uri-id'], [Tag::MENTION, Tag::IMPLICIT_MENTION, Tag::EXCLUSIVE_MENTION]);
1831
1832                 $parent_author = Contact::getByURL($parent['author-link'], false, ['url', 'nurl', 'alias']);
1833
1834                 $implicit_mentions = [];
1835                 if (empty($parent_author['url'])) {
1836                         Logger::notice('Author public contact unknown.', ['author-link' => $parent['author-link'], 'parent-id' => $parent['id']]);
1837                 } else {
1838                         $implicit_mentions[] = $parent_author['url'];
1839                         $implicit_mentions[] = $parent_author['nurl'];
1840                         $implicit_mentions[] = $parent_author['alias'];
1841                 }
1842
1843                 if (!empty($parent['alias'])) {
1844                         $implicit_mentions[] = $parent['alias'];
1845                 }
1846
1847                 foreach ($parent_terms as $term) {
1848                         $contact = Contact::getByURL($term['url'], false, ['url', 'nurl', 'alias']);
1849                         if (!empty($contact['url'])) {
1850                                 $implicit_mentions[] = $contact['url'];
1851                                 $implicit_mentions[] = $contact['nurl'];
1852                                 $implicit_mentions[] = $contact['alias'];
1853                         }
1854                 }
1855
1856                 return $implicit_mentions;
1857         }
1858
1859         /**
1860          * Strips from the body prepended implicit mentions
1861          *
1862          * @param string $body
1863          * @param array $parent
1864          * @return string
1865          */
1866         private static function removeImplicitMentionsFromBody(string $body, array $parent): string
1867         {
1868                 if (DI::config()->get('system', 'disable_implicit_mentions')) {
1869                         return $body;
1870                 }
1871
1872                 $potential_mentions = self::getImplicitMentionList($parent);
1873
1874                 $kept_mentions = [];
1875
1876                 // Extract one prepended mention at a time from the body
1877                 while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $body, $matches)) {
1878                         if (!in_array($matches[2], $potential_mentions)) {
1879                                 $kept_mentions[] = $matches[1];
1880                         }
1881
1882                         $body = $matches[3];
1883                 }
1884
1885                 // Re-appending the kept mentions to the body after extraction
1886                 $kept_mentions[] = $body;
1887
1888                 return implode('', $kept_mentions);
1889         }
1890
1891         /**
1892          * Adds links to string mentions
1893          *
1894          * @param string $body
1895          * @param array  $tags
1896          * @return string
1897          */
1898         protected static function addMentionLinks(string $body, array $tags): string
1899         {
1900                 // This prevents links to be added again to Pleroma-style mention links
1901                 $body = self::normalizeMentionLinks($body);
1902
1903                 $body = BBCode::performWithEscapedTags($body, ['url'], function ($body) use ($tags) {
1904                         foreach ($tags as $tag) {
1905                                 if (empty($tag['name']) || empty($tag['type']) || empty($tag['href']) || !in_array($tag['type'], ['Mention', 'Hashtag'])) {
1906                                         continue;
1907                                 }
1908
1909                                 $hash = substr($tag['name'], 0, 1);
1910                                 $name = substr($tag['name'], 1);
1911                                 if (!in_array($hash, Tag::TAG_CHARACTER)) {
1912                                         $hash = '';
1913                                         $name = $tag['name'];
1914                                 }
1915
1916                                 $body = str_replace($tag['name'], $hash . '[url=' . $tag['href'] . ']' . $name . '[/url]', $body);
1917                         }
1918
1919                         return $body;
1920                 });
1921
1922                 return $body;
1923         }
1924 }