src/Protocol/ActivityPub/Processor.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2021, 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\PageInfo;
  25 use Friendica\Content\Text\BBCode;
  26 use Friendica\Content\Text\HTML;
  27 use Friendica\Content\Text\Markdown;
  28 use Friendica\Core\Logger;
  29 use Friendica\Core\Protocol;
  30 use Friendica\Database\DBA;
  31 use Friendica\DI;
  32 use Friendica\Model\APContact;
  33 use Friendica\Model\Contact;
  34 use Friendica\Model\Conversation;
  35 use Friendica\Model\Event;
  36 use Friendica\Model\GServer;
  37 use Friendica\Model\Item;
  38 use Friendica\Model\ItemURI;
  39 use Friendica\Model\Mail;
  40 use Friendica\Model\Tag;
  41 use Friendica\Model\User;
  42 use Friendica\Model\Post;
  43 use Friendica\Protocol\Activity;
  44 use Friendica\Protocol\ActivityPub;
  45 use Friendica\Protocol\Relay;
  46 use Friendica\Util\DateTimeFormat;
  47 use Friendica\Util\JsonLD;
  48 use Friendica\Util\Strings;
  49
  50 /**
  51  * ActivityPub Processor Protocol class
  52  */
  53 class Processor
  54 {
  55         /**
  56          * Converts mentions from Pleroma into the Friendica format
  57          *
  58          * @param string $body
  59          *
  60          * @return string converted body
  61          */
  62         private static function convertMentions($body)
  63         {
  64                 $URLSearchString = "^\[\]";
  65                 $body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
  66
  67                 return $body;
  68         }
  69
  70         /**
  71          * Convert the language array into a language JSON
  72          *
  73          * @param array $languages
  74          * @return string language JSON
  75          */
  76         private static function processLanguages(array $languages)
  77         {
  78                 $codes = array_keys($languages);
  79                 $lang = [];
  80                 foreach ($codes as $code) {
  81                         $lang[$code] = 1;
  82                 }
  83
  84                 if (empty($lang)) {
  85                         return '';
  86                 }
  87
  88                 return json_encode($lang);
  89         }
  90         /**
  91          * Replaces emojis in the body
  92          *
  93          * @param array $emojis
  94          * @param string $body
  95          *
  96          * @return string with replaced emojis
  97          */
  98         private static function replaceEmojis($body, array $emojis)
  99         {
 100                 $body = strtr($body,
 101                         array_combine(
 102                                 array_column($emojis, 'name'),
 103                                 array_map(function ($emoji) {
 104                                         return '[class=emoji mastodon][img=' . $emoji['href'] . ']' . $emoji['name'] . '[/img][/class]';
 105                                 }, $emojis)
 106                         )
 107                 );
 108
 109                 return $body;
 110         }
 111
 112         /**
 113          * Store attached media files in the post-media table
 114          *
 115          * @param int $uriid
 116          * @param array $attachment
 117          * @return void
 118          */
 119         private static function storeAttachmentAsMedia(int $uriid, array $attachment)
 120         {
 121                 if (empty($attachment['url'])) {
 122                         return;
 123                 }
 124
 125                 $data = ['uri-id' => $uriid];
 126
 127                 $filetype = strtolower(substr($attachment['mediaType'], 0, strpos($attachment['mediaType'], '/')));
 128                 if ($filetype == 'image') {
 129                         $data['type'] = Post\Media::IMAGE;
 130                 } elseif ($filetype == 'video') {
 131                         $data['type'] = Post\Media::VIDEO;
 132                 } elseif ($filetype == 'audio') {
 133                         $data['type'] = Post\Media::AUDIO;
 134                 } elseif (in_array($attachment['mediaType'], ['application/x-bittorrent', 'application/x-bittorrent;x-scheme-handler/magnet'])) {
 135                         $data['type'] = Post\Media::TORRENT;
 136                 } else {
 137                         Logger::info('Unknown type', ['attachment' => $attachment]);
 138                         return;
 139                 }
 140
 141                 $data['url'] = $attachment['url'];
 142                 $data['mimetype'] = $attachment['mediaType'];
 143                 $data['height'] = $attachment['height'] ?? null;
 144                 $data['size'] = $attachment['size'] ?? null;
 145                 $data['preview'] = $attachment['image'] ?? null;
 146                 $data['description'] = $attachment['name'] ?? null;
 147
 148                 Post\Media::insert($data);
 149         }
 150
 151         /**
 152          * Add attachment data to the item array
 153          *
 154          * @param array   $activity
 155          * @param array   $item
 156          *
 157          * @return array array
 158          */
 159         private static function constructAttachList($activity, $item)
 160         {
 161                 if (empty($activity['attachments'])) {
 162                         return $item;
 163                 }
 164
 165                 $leading = '';
 166                 $trailing = '';
 167
 168                 foreach ($activity['attachments'] as $attach) {
 169                         switch ($attach['type']) {
 170                                 case 'link':
 171                                         $data = [
 172                                                 'url'      => $attach['url'],
 173                                                 'type'     => $attach['type'],
 174                                                 'title'    => $attach['title'] ?? '',
 175                                                 'text'     => $attach['desc']  ?? '',
 176                                                 'image'    => $attach['image'] ?? '',
 177                                                 'images'   => [],
 178                                                 'keywords' => [],
 179                                         ];
 180                                         $item['body'] = PageInfo::appendDataToBody($item['body'], $data);
 181                                         break;
 182                                 default:
 183                                         self::storeAttachmentAsMedia($item['uri-id'], $attach);
 184
 185                                         $filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
 186                                         if ($filetype == 'image') {
 187                                                 if (!empty($activity['source'])) {
 188                                                         foreach ([0, 1, 2] as $size) {
 189                                                                 if (preg_match('#/photo/.*-' . $size . '\.#ism', $attach['url']) &&
 190                                                                         strpos(preg_replace('#(/photo/.*)-[012]\.#ism', '$1-' . $size . '.', $activity['source']), $attach['url'])) {
 191                                                                         continue 3;
 192                                                                 }
 193                                                         }
 194                                                         if (strpos($activity['source'], $attach['url'])) {
 195                                                                 continue 2;
 196                                                         }
 197                                                 }
 198
 199                                                 // image is the preview/thumbnail URL
 200                                                 if (!empty($attach['image'])) {
 201                                                         $media = '[url=' . $attach['url'] . ']';
 202                                                         $attach['url'] = $attach['image'];
 203                                                 } else {
 204                                                         $media = '';
 205                                                 }
 206
 207                                                 if (empty($attach['name'])) {
 208                                                         $media .= '[img]' . $attach['url'] . '[/img]';
 209                                                 } else {
 210                                                         $media .= '[img=' . $attach['url'] . ']' . $attach['name'] . '[/img]';
 211                                                 }
 212
 213                                                 if (!empty($attach['image'])) {
 214                                                         $media .= '[/url]';
 215                                                 }
 216
 217                                                 if ($item['post-type'] == Item::PT_IMAGE) {
 218                                                         $leading .= $media;
 219                                                 } else {
 220                                                         $trailing .= $media;
 221                                                 }
 222                                         } elseif ($filetype == 'audio') {
 223                                                 if (!empty($activity['source']) && strpos($activity['source'], $attach['url'])) {
 224                                                         continue 2;
 225                                                 }
 226
 227                                                 if ($item['post-type'] == Item::PT_AUDIO) {
 228                                                         $leading .= '[audio]' . $attach['url'] . "[/audio]\n";
 229                                                 } else {
 230                                                         $trailing .= '[audio]' . $attach['url'] . "[/audio]\n";
 231                                                 }
 232                                         } elseif ($filetype == 'video') {
 233                                                 if (!empty($activity['source']) && strpos($activity['source'], $attach['url'])) {
 234                                                         continue 2;
 235                                                 }
 236
 237                                                 if ($item['post-type'] == Item::PT_VIDEO) {
 238                                                         $leading .= '[video]' . $attach['url'] . "[/video]\n";
 239                                                 } else {
 240                                                         $trailing .= '[video]' . $attach['url'] . "[/video]\n";
 241                                                 }
 242                                         }
 243                         }
 244                 }
 245
 246                 if (!empty($leading) && !empty(trim($item['body']))) {
 247                         $item['body'] = $leading . "[hr]\n" . $item['body'];
 248                 } elseif (!empty($leading)) {
 249                         $item['body'] = $leading;
 250                 }
 251
 252                 if (!empty($trailing) && !empty(trim($item['body']))) {
 253                         $item['body'] = $item['body'] . "\n[hr]" . $trailing;
 254                 } elseif (!empty($trailing)) {
 255                         $item['body'] = $trailing;
 256                 }
 257
 258                 return $item;
 259         }
 260
 261         /**
 262          * Updates a message
 263          *
 264          * @param array $activity Activity array
 265          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 266          */
 267         public static function updateItem($activity)
 268         {
 269                 $item = Post::selectFirst(['uri', 'uri-id', 'thr-parent', 'gravity', 'post-type'], ['uri' => $activity['id']]);
 270                 if (!DBA::isResult($item)) {
 271                         Logger::warning('No existing item, item will be created', ['uri' => $activity['id']]);
 272                         $item = self::createItem($activity);
 273                         self::postItem($activity, $item);
 274                         return;
 275                 }
 276
 277                 $item['changed'] = DateTimeFormat::utcNow();
 278                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 279
 280                 $item = self::processContent($activity, $item);
 281
 282                 $item = self::constructAttachList($activity, $item);
 283
 284                 if (empty($item)) {
 285                         return;
 286                 }
 287
 288                 Item::update($item, ['uri' => $activity['id']]);
 289         }
 290
 291         /**
 292          * Prepares data for a message
 293          *
 294          * @param array $activity Activity array
 295          * @return array Internal item
 296          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 297          * @throws \ImagickException
 298          */
 299         public static function createItem($activity)
 300         {
 301                 $item = [];
 302                 $item['verb'] = Activity::POST;
 303                 $item['thr-parent'] = $activity['reply-to-id'];
 304
 305                 if ($activity['reply-to-id'] == $activity['id']) {
 306                         $item['gravity'] = GRAVITY_PARENT;
 307                         $item['object-type'] = Activity\ObjectType::NOTE;
 308                 } else {
 309                         $item['gravity'] = GRAVITY_COMMENT;
 310                         $item['object-type'] = Activity\ObjectType::COMMENT;
 311                 }
 312
 313                 if (empty($activity['directmessage']) && ($activity['id'] != $activity['reply-to-id']) && !Post::exists(['uri' => $activity['reply-to-id']])) {
 314                         Logger::notice('Parent not found. Try to refetch it.', ['parent' => $activity['reply-to-id']]);
 315                         self::fetchMissingActivity($activity['reply-to-id'], $activity);
 316                 }
 317
 318                 $item['diaspora_signed_text'] = $activity['diaspora:comment'] ?? '';
 319
 320                 /// @todo What to do with $activity['context']?
 321                 if (empty($activity['directmessage']) && ($item['gravity'] != GRAVITY_PARENT) && !Post::exists(['uri' => $item['thr-parent']])) {
 322                         Logger::info('Parent not found, message will be discarded.', ['thr-parent' => $item['thr-parent']]);
 323                         return [];
 324                 }
 325
 326                 $item['network'] = Protocol::ACTIVITYPUB;
 327                 $item['author-link'] = $activity['author'];
 328                 $item['author-id'] = Contact::getIdForURL($activity['author']);
 329                 $item['owner-link'] = $activity['actor'];
 330                 $item['owner-id'] = Contact::getIdForURL($activity['actor']);
 331
 332                 if (in_array(0, $activity['receiver']) && !empty($activity['unlisted'])) {
 333                         $item['private'] = Item::UNLISTED;
 334                 } elseif (in_array(0, $activity['receiver'])) {
 335                         $item['private'] = Item::PUBLIC;
 336                 } else {
 337                         $item['private'] = Item::PRIVATE;
 338                 }
 339
 340                 if (!empty($activity['raw'])) {
 341                         $item['source'] = $activity['raw'];
 342                         $item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
 343                         $item['conversation-href'] = $activity['context'] ?? '';
 344                         $item['conversation-uri'] = $activity['conversation'] ?? '';
 345
 346                         if (isset($activity['push'])) {
 347                                 $item['direction'] = $activity['push'] ? Conversation::PUSH : Conversation::PULL;
 348                         }
 349                 }
 350
 351                 if (!empty($activity['from-relay'])) {
 352                         $item['direction'] = Conversation::RELAY;
 353                 }
 354
 355                 if ($activity['object_type'] == 'as:Article') {
 356                         $item['post-type'] = Item::PT_ARTICLE;
 357                 } elseif ($activity['object_type'] == 'as:Audio') {
 358                         $item['post-type'] = Item::PT_AUDIO;
 359                 } elseif ($activity['object_type'] == 'as:Document') {
 360                         $item['post-type'] = Item::PT_DOCUMENT;
 361                 } elseif ($activity['object_type'] == 'as:Event') {
 362                         $item['post-type'] = Item::PT_EVENT;
 363                 } elseif ($activity['object_type'] == 'as:Image') {
 364                         $item['post-type'] = Item::PT_IMAGE;
 365                 } elseif ($activity['object_type'] == 'as:Page') {
 366                         $item['post-type'] = Item::PT_PAGE;
 367                 } elseif ($activity['object_type'] == 'as:Video') {
 368                         $item['post-type'] = Item::PT_VIDEO;
 369                 } else {
 370                         $item['post-type'] = Item::PT_NOTE;
 371                 }
 372
 373                 $item['isForum'] = false;
 374
 375                 if (!empty($activity['thread-completion'])) {
 376                         if ($activity['thread-completion'] != $item['owner-id']) {
 377                                 $actor = Contact::getById($activity['thread-completion'], ['url']);
 378                                 $item['causer-link'] = $actor['url'];
 379                                 $item['causer-id'] = $activity['thread-completion'];
 380                                 Logger::info('Use inherited actor as causer.', ['id' => $item['owner-id'], 'activity' => $activity['thread-completion'], 'owner' => $item['owner-link'], 'actor' => $actor['url']]);
 381                         } else {
 382                                 // Store the original actor in the "causer" fields to enable the check for ignored or blocked contacts
 383                                 $item['causer-link'] = $item['owner-link'];
 384                                 $item['causer-id'] = $item['owner-id'];
 385                                 Logger::info('Use actor as causer.', ['id' => $item['owner-id'], 'actor' => $item['owner-link']]);
 386                         }
 387
 388                         $item['owner-link'] = $item['author-link'];
 389                         $item['owner-id'] = $item['author-id'];
 390                 } else {
 391                         $actor = APContact::getByURL($item['owner-link'], false);
 392                         $item['isForum'] = ($actor['type'] == 'Group');
 393                 }
 394
 395                 $item['uri'] = $activity['id'];
 396
 397                 $item['created'] = DateTimeFormat::utc($activity['published']);
 398                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 399                 $guid = $activity['sc:identifier'] ?: self::getGUIDByURL($item['uri']);
 400                 $item['guid'] = $activity['diaspora:guid'] ?: $guid;
 401
 402                 $item['uri-id'] = ItemURI::insert(['uri' => $item['uri'], 'guid' => $item['guid']]);
 403                 if (empty($item['uri-id'])) {
 404                         Logger::warning('Unable to get a uri-id for an item uri', ['uri' => $item['uri'], 'guid' => $item['guid']]);
 405                         return [];
 406                 }
 407
 408                 $item = self::processContent($activity, $item);
 409                 if (empty($item)) {
 410                         Logger::info('Message was not processed');
 411                         return [];
 412                 }
 413
 414                 $item['plink'] = $activity['alternate-url'] ?? $item['uri'];
 415
 416                 $item = self::constructAttachList($activity, $item);
 417
 418                 // We received the post via AP, so we set the protocol of the server to AP
 419                 $contact = Contact::getById($item['author-id'], ['gsid']);
 420                 if (!empty($contact['gsid'])) {
 421                         GServer::setProtocol($contact['gsid'], Post\DeliveryData::ACTIVITYPUB);
 422                 }
 423
 424                 if ($item['author-id'] != $item['owner-id']) {
 425                         $contact = Contact::getById($item['owner-id'], ['gsid']);
 426                         if (!empty($contact['gsid'])) {
 427                                 GServer::setProtocol($contact['gsid'], Post\DeliveryData::ACTIVITYPUB);
 428                         }
 429                 }
 430
 431                 return $item;
 432         }
 433
 434         /**
 435          * Delete items
 436          *
 437          * @param array $activity
 438          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 439          * @throws \ImagickException
 440          */
 441         public static function deleteItem($activity)
 442         {
 443                 $owner = Contact::getIdForURL($activity['actor']);
 444
 445                 Logger::info('Deleting item', ['object' => $activity['object_id'], 'owner'  => $owner]);
 446                 Item::markForDeletion(['uri' => $activity['object_id'], 'owner-id' => $owner]);
 447         }
 448
 449         /**
 450          * Prepare the item array for an activity
 451          *
 452          * @param array $activity Activity array
 453          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 454          * @throws \ImagickException
 455          */
 456         public static function addTag($activity)
 457         {
 458                 if (empty($activity['object_content']) || empty($activity['object_id'])) {
 459                         return;
 460                 }
 461
 462                 foreach ($activity['receiver'] as $receiver) {
 463                         $item = Post::selectFirst(['id', 'uri-id', 'origin', 'author-link'], ['uri' => $activity['target_id'], 'uid' => $receiver]);
 464                         if (!DBA::isResult($item)) {
 465                                 // We don't fetch missing content for this purpose
 466                                 continue;
 467                         }
 468
 469                         if (($item['author-link'] != $activity['actor']) && !$item['origin']) {
 470                                 Logger::info('Not origin, not from the author, skipping update', ['id' => $item['id'], 'author' => $item['author-link'], 'actor' => $activity['actor']]);
 471                                 continue;
 472                         }
 473
 474                         Tag::store($item['uri-id'], Tag::HASHTAG, $activity['object_content'], $activity['object_id']);
 475                         Logger::info('Tagged item', ['id' => $item['id'], 'tag' => $activity['object_content'], 'uri' => $activity['target_id'], 'actor' => $activity['actor']]);
 476                 }
 477         }
 478
 479         /**
 480          * Prepare the item array for an activity
 481          *
 482          * @param array  $activity Activity array
 483          * @param string $verb     Activity verb
 484          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 485          * @throws \ImagickException
 486          */
 487         public static function createActivity($activity, $verb)
 488         {
 489                 $item = self::createItem($activity);
 490                 $item['verb'] = $verb;
 491                 $item['thr-parent'] = $activity['object_id'];
 492                 $item['gravity'] = GRAVITY_ACTIVITY;
 493                 unset($item['post-type']);
 494                 $item['object-type'] = Activity\ObjectType::NOTE;
 495
 496                 $item['diaspora_signed_text'] = $activity['diaspora:like'] ?? '';
 497
 498                 self::postItem($activity, $item);
 499         }
 500
 501         /**
 502          * Create an event
 503          *
 504          * @param array $activity Activity array
 505          * @param array $item
 506          * @throws \Exception
 507          */
 508         public static function createEvent($activity, $item)
 509         {
 510                 $event['summary']   = HTML::toBBCode($activity['name']);
 511                 $event['desc']      = HTML::toBBCode($activity['content']);
 512                 $event['start']     = $activity['start-time'];
 513                 $event['finish']    = $activity['end-time'];
 514                 $event['nofinish']  = empty($event['finish']);
 515                 $event['location']  = $activity['location'];
 516                 $event['adjust']    = $activity['adjust'] ?? true;
 517                 $event['cid']       = $item['contact-id'];
 518                 $event['uid']       = $item['uid'];
 519                 $event['uri']       = $item['uri'];
 520                 $event['edited']    = $item['edited'];
 521                 $event['private']   = $item['private'];
 522                 $event['guid']      = $item['guid'];
 523                 $event['plink']     = $item['plink'];
 524                 $event['network']   = $item['network'];
 525                 $event['protocol']  = $item['protocol'];
 526                 $event['direction'] = $item['direction'];
 527                 $event['source']    = $item['source'];
 528
 529                 $condition = ['uri' => $item['uri'], 'uid' => $item['uid']];
 530                 $ev = DBA::selectFirst('event', ['id'], $condition);
 531                 if (DBA::isResult($ev)) {
 532                         $event['id'] = $ev['id'];
 533                 }
 534
 535                 $event_id = Event::store($event);
 536                 Logger::info('Event was stored', ['id' => $event_id]);
 537         }
 538
 539         /**
 540          * Process the content
 541          *
 542          * @param array $activity Activity array
 543          * @param array $item
 544          * @return array|bool Returns the item array or false if there was an unexpected occurrence
 545          * @throws \Exception
 546          */
 547         private static function processContent($activity, $item)
 548         {
 549                 if (!empty($activity['mediatype']) && ($activity['mediatype'] == 'text/markdown')) {
 550                         $item['title'] = Markdown::toBBCode($activity['name']);
 551                         $content = Markdown::toBBCode($activity['content']);
 552                 } elseif (!empty($activity['mediatype']) && ($activity['mediatype'] == 'text/bbcode')) {
 553                         $item['title'] = $activity['name'];
 554                         $content = $activity['content'];
 555                 } else {
 556                         // By default assume "text/html"
 557                         $item['title'] = HTML::toBBCode($activity['name']);
 558                         $content = HTML::toBBCode($activity['content']);
 559                 }
 560
 561                 if (!empty($activity['languages'])) {
 562                         $item['language'] = self::processLanguages($activity['languages']);
 563                 }
 564
 565                 if (!empty($activity['emojis'])) {
 566                         $content = self::replaceEmojis($content, $activity['emojis']);
 567                 }
 568
 569                 $content = self::convertMentions($content);
 570
 571                 if (!empty($activity['source'])) {
 572                         $item['body'] = $activity['source'];
 573                         $item['raw-body'] = $content;
 574                 } else {
 575                         if (empty($activity['directmessage']) && ($item['thr-parent'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
 576                                 $item_private = !in_array(0, $activity['item_receiver']);
 577                                 $parent = Post::selectFirst(['id', 'uri-id', 'private', 'author-link', 'alias'], ['uri' => $item['thr-parent']]);
 578                                 if (!DBA::isResult($parent)) {
 579                                         Logger::warning('Unknown parent item.', ['uri' => $item['thr-parent']]);
 580                                         return false;
 581                                 }
 582                                 if ($item_private && ($parent['private'] != Item::PRIVATE)) {
 583                                         Logger::warning('Item is private but the parent is not. Dropping.', ['item-uri' => $item['uri'], 'thr-parent' => $item['thr-parent']]);
 584                                         return false;
 585                                 }
 586
 587                                 $content = self::removeImplicitMentionsFromBody($content, $parent);
 588                         }
 589                         $item['content-warning'] = HTML::toBBCode($activity['summary']);
 590                         $item['raw-body'] = $item['body'] = $content;
 591                 }
 592
 593                 self::storeFromBody($item);
 594                 self::storeTags($item['uri-id'], $activity['tags']);
 595
 596                 $item['location'] = $activity['location'];
 597
 598                 if (!empty($activity['latitude']) && !empty($activity['longitude'])) {
 599                         $item['coord'] = $activity['latitude'] . ' ' . $activity['longitude'];
 600                 }
 601
 602                 $item['app'] = $activity['generator'];
 603
 604                 return $item;
 605         }
 606
 607         /**
 608          * Store hashtags and mentions
 609          *
 610          * @param array $item
 611          */
 612         private static function storeFromBody(array $item)
 613         {
 614                 // Make sure to delete all existing tags (can happen when called via the update functionality)
 615                 DBA::delete('post-tag', ['uri-id' => $item['uri-id']]);
 616
 617                 Tag::storeFromBody($item['uri-id'], $item['body'], '@!');
 618         }
 619
 620         /**
 621          * Generate a GUID out of an URL
 622          *
 623          * @param string $url message URL
 624          * @return string with GUID
 625          */
 626         private static function getGUIDByURL(string $url)
 627         {
 628                 $parsed = parse_url($url);
 629
 630                 $host_hash = hash('crc32', $parsed['host']);
 631
 632                 unset($parsed["scheme"]);
 633                 unset($parsed["host"]);
 634
 635                 $path = implode("/", $parsed);
 636
 637                 return $host_hash . '-'. hash('fnv164', $path) . '-'. hash('joaat', $path);
 638         }
 639
 640         /**
 641          * Creates an item post
 642          *
 643          * @param array $activity Activity data
 644          * @param array $item     item array
 645          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 646          * @throws \ImagickException
 647          */
 648         public static function postItem(array $activity, array $item)
 649         {
 650                 if (empty($item)) {
 651                         return;
 652                 }
 653
 654                 $stored = false;
 655                 ksort($activity['receiver']);
 656
 657                 foreach ($activity['receiver'] as $receiver) {
 658                         if ($receiver == -1) {
 659                                 continue;
 660                         }
 661
 662                         $item['uid'] = $receiver;
 663
 664                         $type = $activity['reception_type'][$receiver] ?? Receiver::TARGET_UNKNOWN;
 665                         switch($type) {
 666                                 case Receiver::TARGET_TO:
 667                                         $item['post-reason'] = Item::PR_TO;
 668                                         break;
 669                                 case Receiver::TARGET_CC:
 670                                         $item['post-reason'] = Item::PR_CC;
 671                                         break;
 672                                 case Receiver::TARGET_BTO:
 673                                         $item['post-reason'] = Item::PR_BTO;
 674                                         break;
 675                                 case Receiver::TARGET_BCC:
 676                                         $item['post-reason'] = Item::PR_BCC;
 677                                         break;
 678                                 case Receiver::TARGET_FOLLOWER:
 679                                         $item['post-reason'] = Item::PR_FOLLOWER;
 680                                         break;
 681                                 case Receiver::TARGET_ANSWER:
 682                                         $item['post-reason'] = Item::PR_COMMENT;
 683                                         break;
 684                                 case Receiver::TARGET_GLOBAL:
 685                                         $item['post-reason'] = Item::PR_GLOBAL;
 686                                         break;
 687                                 default:
 688                                         $item['post-reason'] = Item::PR_NONE;
 689                         }
 690
 691                         if (!empty($activity['from-relay'])) {
 692                                 $item['post-reason'] = Item::PR_RELAY;
 693                         } elseif (!empty($activity['thread-completion'])) {
 694                                 $item['post-reason'] = Item::PR_FETCHED;
 695                         }
 696
 697                         if ($item['isForum'] ?? false) {
 698                                 $item['contact-id'] = Contact::getIdForURL($activity['actor'], $receiver);
 699                         } else {
 700                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver);
 701                         }
 702
 703                         if (($receiver != 0) && empty($item['contact-id'])) {
 704                                 $item['contact-id'] = Contact::getIdForURL($activity['author']);
 705                         }
 706
 707                         if (!empty($activity['directmessage'])) {
 708                                 self::postMail($activity, $item);
 709                                 continue;
 710                         }
 711
 712                         if (DI::pConfig()->get($receiver, 'system', 'accept_only_sharer', false) && ($receiver != 0) && ($item['gravity'] == GRAVITY_PARENT)) {
 713                                 $skip = !Contact::isSharingByURL($activity['author'], $receiver);
 714
 715                                 if ($skip && (($activity['type'] == 'as:Announce') || ($item['isForum'] ?? false))) {
 716                                         $skip = !Contact::isSharingByURL($activity['actor'], $receiver);
 717                                 }
 718
 719                                 if ($skip) {
 720                                         Logger::info('Skipping post', ['uid' => $receiver, 'url' => $item['uri']]);
 721                                         continue;
 722                                 }
 723
 724                                 Logger::info('Accepting post', ['uid' => $receiver, 'url' => $item['uri']]);
 725                         }
 726
 727                         if (($item['gravity'] != GRAVITY_ACTIVITY) && ($activity['object_type'] == 'as:Event')) {
 728                                 self::createEvent($activity, $item);
 729                         }
 730
 731                         $item_id = Item::insert($item);
 732                         if ($item_id) {
 733                                 Logger::info('Item insertion successful', ['user' => $item['uid'], 'item_id' => $item_id]);
 734                         } else {
 735                                 Logger::notice('Item insertion aborted', ['user' => $item['uid']]);
 736                         }
 737
 738                         if ($item['uid'] == 0) {
 739                                 $stored = $item_id;
 740                         }
 741                 }
 742
 743                 // Store send a follow request for every reshare - but only when the item had been stored
 744                 if ($stored && ($item['private'] != Item::PRIVATE) && ($item['gravity'] == GRAVITY_PARENT) && ($item['author-link'] != $item['owner-link'])) {
 745                         $author = APContact::getByURL($item['owner-link'], false);
 746                         // We send automatic follow requests for reshared messages. (We don't need though for forum posts)
 747                         if ($author['type'] != 'Group') {
 748                                 Logger::info('Send follow request', ['uri' => $item['uri'], 'stored' => $stored, 'to' => $item['author-link']]);
 749                                 ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
 750                         }
 751                 }
 752         }
 753
 754         /**
 755          * Store tags and mentions into the tag table
 756          *
 757          * @param integer $uriid
 758          * @param array $tags
 759          */
 760         private static function storeTags(int $uriid, array $tags = null)
 761         {
 762                 foreach ($tags as $tag) {
 763                         if (empty($tag['name']) || empty($tag['type']) || !in_array($tag['type'], ['Mention', 'Hashtag'])) {
 764                                 continue;
 765                         }
 766
 767                         $hash = substr($tag['name'], 0, 1);
 768
 769                         if ($tag['type'] == 'Mention') {
 770                                 if (in_array($hash, [Tag::TAG_CHARACTER[Tag::MENTION],
 771                                         Tag::TAG_CHARACTER[Tag::EXCLUSIVE_MENTION],
 772                                         Tag::TAG_CHARACTER[Tag::IMPLICIT_MENTION]])) {
 773                                         $tag['name'] = substr($tag['name'], 1);
 774                                 }
 775                                 $type = Tag::IMPLICIT_MENTION;
 776
 777                                 if (!empty($tag['href'])) {
 778                                         $apcontact = APContact::getByURL($tag['href']);
 779                                         if (!empty($apcontact['name']) || !empty($apcontact['nick'])) {
 780                                                 $tag['name'] = $apcontact['name'] ?: $apcontact['nick'];
 781                                         }
 782                                 }
 783                         } elseif ($tag['type'] == 'Hashtag') {
 784                                 if ($hash == Tag::TAG_CHARACTER[Tag::HASHTAG]) {
 785                                         $tag['name'] = substr($tag['name'], 1);
 786                                 }
 787                                 $type = Tag::HASHTAG;
 788                         }
 789
 790                         if (empty($tag['name'])) {
 791                                 continue;
 792                         }
 793
 794                         Tag::store($uriid, $type, $tag['name'], $tag['href']);
 795                 }
 796         }
 797
 798         /**
 799          * Creates an mail post
 800          *
 801          * @param array $activity Activity data
 802          * @param array $item     item array
 803          * @return int|bool New mail table row id or false on error
 804          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 805          */
 806         private static function postMail($activity, $item)
 807         {
 808                 if (($item['gravity'] != GRAVITY_PARENT) && !DBA::exists('mail', ['uri' => $item['thr-parent'], 'uid' => $item['uid']])) {
 809                         Logger::info('Parent not found, mail will be discarded.', ['uid' => $item['uid'], 'uri' => $item['thr-parent']]);
 810                         return false;
 811                 }
 812
 813                 Logger::info('Direct Message', $item);
 814
 815                 $msg = [];
 816                 $msg['uid'] = $item['uid'];
 817
 818                 $msg['contact-id'] = $item['contact-id'];
 819
 820                 $contact = Contact::getById($item['contact-id'], ['name', 'url', 'photo']);
 821                 $msg['from-name'] = $contact['name'];
 822                 $msg['from-url'] = $contact['url'];
 823                 $msg['from-photo'] = $contact['photo'];
 824
 825                 $msg['uri'] = $item['uri'];
 826                 $msg['created'] = $item['created'];
 827
 828                 $parent = DBA::selectFirst('mail', ['parent-uri', 'title'], ['uri' => $item['thr-parent']]);
 829                 if (DBA::isResult($parent)) {
 830                         $msg['parent-uri'] = $parent['parent-uri'];
 831                         $msg['title'] = $parent['title'];
 832                 } else {
 833                         $msg['parent-uri'] = $item['thr-parent'];
 834
 835                         if (!empty($item['title'])) {
 836                                 $msg['title'] = $item['title'];
 837                         } elseif (!empty($item['content-warning'])) {
 838                                 $msg['title'] = $item['content-warning'];
 839                         } else {
 840                                 // Trying to generate a title out of the body
 841                                 $title = $item['body'];
 842
 843                                 while (preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $title, $matches)) {
 844                                         $title = $matches[3];
 845                                 }
 846
 847                                 $title = trim(HTML::toPlaintext(BBCode::convert($title, false, BBCode::API, true), 0));
 848
 849                                 if (strlen($title) > 20) {
 850                                         $title = substr($title, 0, 20) . '...';
 851                                 }
 852
 853                                 $msg['title'] = $title;
 854                         }
 855                 }
 856                 $msg['body'] = $item['body'];
 857
 858                 return Mail::insert($msg);
 859         }
 860
 861         /**
 862          * Fetches missing posts
 863          *
 864          * @param string $url         message URL
 865          * @param array  $child       activity array with the child of this message
 866          * @param string $relay_actor Relay actor
 867          * @return string fetched message URL
 868          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 869          */
 870         public static function fetchMissingActivity(string $url, array $child = [], string $relay_actor = '')
 871         {
 872                 if (!empty($child['receiver'])) {
 873                         $uid = ActivityPub\Receiver::getFirstUserFromReceivers($child['receiver']);
 874                 } else {
 875                         $uid = 0;
 876                 }
 877
 878                 $object = ActivityPub::fetchContent($url, $uid);
 879                 if (empty($object)) {
 880                         Logger::log('Activity ' . $url . ' was not fetchable, aborting.');
 881                         return '';
 882                 }
 883
 884                 if (empty($object['id'])) {
 885                         Logger::log('Activity ' . $url . ' has got not id, aborting. ' . json_encode($object));
 886                         return '';
 887                 }
 888
 889                 if (!empty($object['actor'])) {
 890                         $object_actor = $object['actor'];
 891                 } elseif (!empty($object['attributedTo'])) {
 892                         $object_actor = $object['attributedTo'];
 893                         if (is_array($object_actor)) {
 894                                 $compacted = JsonLD::compact($object);
 895                                 $object_actor = JsonLD::fetchElement($compacted, 'as:attributedTo', '@id');
 896                         }
 897                 } else {
 898                         // Shouldn't happen
 899                         $object_actor = '';
 900                 }
 901
 902                 $signer = [$object_actor];
 903
 904                 if (!empty($child['author'])) {
 905                         $actor = $child['author'];
 906                         $signer[] = $actor;
 907                 } else {
 908                         $actor = $object_actor;
 909                 }
 910
 911                 if (!empty($object['published'])) {
 912                         $published = $object['published'];
 913                 } elseif (!empty($child['published'])) {
 914                         $published = $child['published'];
 915                 } else {
 916                         $published = DateTimeFormat::utcNow();
 917                 }
 918
 919                 $activity = [];
 920                 $activity['@context'] = $object['@context'] ?? ActivityPub::CONTEXT;
 921                 unset($object['@context']);
 922                 $activity['id'] = $object['id'];
 923                 $activity['to'] = $object['to'] ?? [];
 924                 $activity['cc'] = $object['cc'] ?? [];
 925                 $activity['actor'] = $actor;
 926                 $activity['object'] = $object;
 927                 $activity['published'] = $published;
 928                 $activity['type'] = 'Create';
 929
 930                 $ldactivity = JsonLD::compact($activity);
 931
 932                 if (!empty($relay_actor)) {
 933                         $ldactivity['thread-completion'] = $ldactivity['from-relay'] = Contact::getIdForURL($relay_actor);
 934                 } elseif (!empty($child['thread-completion'])) {
 935                         $ldactivity['thread-completion'] = $child['thread-completion'];
 936                 } else {
 937                         $ldactivity['thread-completion'] = Contact::getIdForURL($actor);
 938                 }
 939
 940                 if (!empty($relay_actor) && !self::acceptIncomingMessage($ldactivity, $object['id'])) {
 941                         return '';
 942                 }
 943
 944                 ActivityPub\Receiver::processActivity($ldactivity, json_encode($activity), $uid, true, false, $signer);
 945
 946                 Logger::notice('Activity had been fetched and processed.', ['url' => $url, 'object' => $activity['id']]);
 947
 948                 return $activity['id'];
 949         }
 950
 951         /**
 952          * Test if incoming relay messages should be accepted
 953          *
 954          * @param array $activity activity array
 955          * @param string $id      object ID
 956          * @return boolean true if message is accepted
 957          */
 958         private static function acceptIncomingMessage(array $activity, string $id)
 959         {
 960                 if (empty($activity['as:object'])) {
 961                         Logger::info('No object field in activity - accepted', ['id' => $id]);
 962                         return true;
 963                 }
 964
 965                 $replyto = JsonLD::fetchElement($activity['as:object'], 'as:inReplyTo', '@id');
 966                 $uriid = ItemURI::getIdByURI($replyto);
 967                 if (Post::exists(['uri-id' => $uriid])) {
 968                         Logger::info('Post is a reply to an existing post - accepted', ['id' => $id, 'uri-id' => $uriid, 'replyto' => $replyto]);
 969                         return true;
 970                 }
 971
 972                 $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 973                 $authorid = Contact::getIdForURL($attributed_to);
 974
 975                 $body = HTML::toBBCode(JsonLD::fetchElement($activity['as:object'], 'as:content', '@value'));
 976
 977                 $messageTags = [];
 978                 $tags = Receiver::processTags(JsonLD::fetchElementArray($activity['as:object'], 'as:tag') ?? []);
 979                 if (!empty($tags)) {
 980                         foreach ($tags as $tag) {
 981                                 if ($tag['type'] != 'Hashtag') {
 982                                         continue;
 983                                 }
 984                                 $messageTags[] = ltrim(mb_strtolower($tag['name']), '#');
 985                         }
 986                 }
 987
 988                 return Relay::isSolicitedPost($messageTags, $body, $authorid, $id, Protocol::ACTIVITYPUB);
 989         }
 990
 991         /**
 992          * perform a "follow" request
 993          *
 994          * @param array $activity
 995          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 996          * @throws \ImagickException
 997          */
 998         public static function followUser($activity)
 999         {
1000                 $uid = User::getIdForURL($activity['object_id']);
1001                 if (empty($uid)) {
1002                         return;
1003                 }
1004
1005                 $owner = User::getOwnerDataById($uid);
1006                 if (empty($owner)) {
1007                         return;
1008                 }
1009
1010                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1011                 if (!empty($cid)) {
1012                         self::switchContact($cid);
1013                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
1014                 }
1015
1016                 $item = ['author-id' => Contact::getIdForURL($activity['actor']),
1017                         'author-link' => $activity['actor']];
1018
1019                 // Ensure that the contact has got the right network type
1020                 self::switchContact($item['author-id']);
1021
1022                 $result = Contact::addRelationship($owner, [], $item, false, $activity['content'] ?? '');
1023                 if ($result === true) {
1024                         ActivityPub\Transmitter::sendContactAccept($item['author-link'], $activity['id'], $owner['uid']);
1025                 }
1026
1027                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1028                 if (empty($cid)) {
1029                         return;
1030                 }
1031
1032                 if (empty($contact)) {
1033                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
1034                 }
1035
1036                 Logger::log('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
1037         }
1038
1039         /**
1040          * Update the given profile
1041          *
1042          * @param array $activity
1043          * @throws \Exception
1044          */
1045         public static function updatePerson($activity)
1046         {
1047                 if (empty($activity['object_id'])) {
1048                         return;
1049                 }
1050
1051                 Logger::info('Updating profile', ['object' => $activity['object_id']]);
1052                 Contact::updateFromProbeByURL($activity['object_id']);
1053         }
1054
1055         /**
1056          * Delete the given profile
1057          *
1058          * @param array $activity
1059          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1060          */
1061         public static function deletePerson($activity)
1062         {
1063                 if (empty($activity['object_id']) || empty($activity['actor'])) {
1064                         Logger::info('Empty object id or actor.');
1065                         return;
1066                 }
1067
1068                 if ($activity['object_id'] != $activity['actor']) {
1069                         Logger::info('Object id does not match actor.');
1070                         return;
1071                 }
1072
1073                 $contacts = DBA::select('contact', ['id'], ['nurl' => Strings::normaliseLink($activity['object_id'])]);
1074                 while ($contact = DBA::fetch($contacts)) {
1075                         Contact::remove($contact['id']);
1076                 }
1077                 DBA::close($contacts);
1078
1079                 Logger::info('Deleted contact', ['object' => $activity['object_id']]);
1080         }
1081
1082         /**
1083          * Accept a follow request
1084          *
1085          * @param array $activity
1086          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1087          * @throws \ImagickException
1088          */
1089         public static function acceptFollowUser($activity)
1090         {
1091                 $uid = User::getIdForURL($activity['object_actor']);
1092                 if (empty($uid)) {
1093                         return;
1094                 }
1095
1096                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1097                 if (empty($cid)) {
1098                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1099                         return;
1100                 }
1101
1102                 self::switchContact($cid);
1103
1104                 $fields = ['pending' => false];
1105
1106                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
1107                 if ($contact['rel'] == Contact::FOLLOWER) {
1108                         $fields['rel'] = Contact::FRIEND;
1109                 }
1110
1111                 $condition = ['id' => $cid];
1112                 DBA::update('contact', $fields, $condition);
1113                 Logger::info('Accept contact request', ['contact' => $cid, 'user' => $uid]);
1114         }
1115
1116         /**
1117          * Reject a follow request
1118          *
1119          * @param array $activity
1120          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1121          * @throws \ImagickException
1122          */
1123         public static function rejectFollowUser($activity)
1124         {
1125                 $uid = User::getIdForURL($activity['object_actor']);
1126                 if (empty($uid)) {
1127                         return;
1128                 }
1129
1130                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1131                 if (empty($cid)) {
1132                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1133                         return;
1134                 }
1135
1136                 self::switchContact($cid);
1137
1138                 if (DBA::exists('contact', ['id' => $cid, 'rel' => Contact::SHARING])) {
1139                         Contact::remove($cid);
1140                         Logger::info('Rejected contact request - contact removed', ['contact' => $cid, 'user' => $uid]);
1141                 } else {
1142                         Logger::info('Rejected contact request', ['contact' => $cid, 'user' => $uid]);
1143                 }
1144         }
1145
1146         /**
1147          * Undo activity like "like" or "dislike"
1148          *
1149          * @param array $activity
1150          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1151          * @throws \ImagickException
1152          */
1153         public static function undoActivity($activity)
1154         {
1155                 if (empty($activity['object_id'])) {
1156                         return;
1157                 }
1158
1159                 if (empty($activity['object_actor'])) {
1160                         return;
1161                 }
1162
1163                 $author_id = Contact::getIdForURL($activity['object_actor']);
1164                 if (empty($author_id)) {
1165                         return;
1166                 }
1167
1168                 Item::markForDeletion(['uri' => $activity['object_id'], 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
1169         }
1170
1171         /**
1172          * Activity to remove a follower
1173          *
1174          * @param array $activity
1175          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1176          * @throws \ImagickException
1177          */
1178         public static function undoFollowUser($activity)
1179         {
1180                 $uid = User::getIdForURL($activity['object_object']);
1181                 if (empty($uid)) {
1182                         return;
1183                 }
1184
1185                 $owner = User::getOwnerDataById($uid);
1186                 if (empty($owner)) {
1187                         return;
1188                 }
1189
1190                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1191                 if (empty($cid)) {
1192                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1193                         return;
1194                 }
1195
1196                 self::switchContact($cid);
1197
1198                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1199                 if (!DBA::isResult($contact)) {
1200                         return;
1201                 }
1202
1203                 Contact::removeFollower($owner, $contact);
1204                 Logger::info('Undo following request', ['contact' => $cid, 'user' => $uid]);
1205         }
1206
1207         /**
1208          * Switches a contact to AP if needed
1209          *
1210          * @param integer $cid Contact ID
1211          * @throws \Exception
1212          */
1213         private static function switchContact($cid)
1214         {
1215                 $contact = DBA::selectFirst('contact', ['network', 'url'], ['id' => $cid]);
1216                 if (!DBA::isResult($contact) || in_array($contact['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN]) || Contact::isLocal($contact['url'])) {
1217                         return;
1218                 }
1219
1220                 Logger::info('Change existing contact', ['cid' => $cid, 'previous' => $contact['network']]);
1221                 Contact::updateFromProbe($cid);
1222         }
1223
1224         /**
1225          * Collects implicit mentions like:
1226          * - the author of the parent item
1227          * - all the mentioned conversants in the parent item
1228          *
1229          * @param array $parent Item array with at least ['id', 'author-link', 'alias']
1230          * @return array
1231          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1232          */
1233         private static function getImplicitMentionList(array $parent)
1234         {
1235                 $parent_terms = Tag::getByURIId($parent['uri-id'], [Tag::MENTION, Tag::IMPLICIT_MENTION, Tag::EXCLUSIVE_MENTION]);
1236
1237                 $parent_author = Contact::getByURL($parent['author-link'], false, ['url', 'nurl', 'alias']);
1238
1239                 $implicit_mentions = [];
1240                 if (empty($parent_author['url'])) {
1241                         Logger::notice('Author public contact unknown.', ['author-link' => $parent['author-link'], 'parent-id' => $parent['id']]);
1242                 } else {
1243                         $implicit_mentions[] = $parent_author['url'];
1244                         $implicit_mentions[] = $parent_author['nurl'];
1245                         $implicit_mentions[] = $parent_author['alias'];
1246                 }
1247
1248                 if (!empty($parent['alias'])) {
1249                         $implicit_mentions[] = $parent['alias'];
1250                 }
1251
1252                 foreach ($parent_terms as $term) {
1253                         $contact = Contact::getByURL($term['url'], false, ['url', 'nurl', 'alias']);
1254                         if (!empty($contact['url'])) {
1255                                 $implicit_mentions[] = $contact['url'];
1256                                 $implicit_mentions[] = $contact['nurl'];
1257                                 $implicit_mentions[] = $contact['alias'];
1258                         }
1259                 }
1260
1261                 return $implicit_mentions;
1262         }
1263
1264         /**
1265          * Strips from the body prepended implicit mentions
1266          *
1267          * @param string $body
1268          * @param array $parent
1269          * @return string
1270          */
1271         private static function removeImplicitMentionsFromBody(string $body, array $parent)
1272         {
1273                 if (DI::config()->get('system', 'disable_implicit_mentions')) {
1274                         return $body;
1275                 }
1276
1277                 $potential_mentions = self::getImplicitMentionList($parent);
1278
1279                 $kept_mentions = [];
1280
1281                 // Extract one prepended mention at a time from the body
1282                 while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $body, $matches)) {
1283                         if (!in_array($matches[2], $potential_mentions)) {
1284                                 $kept_mentions[] = $matches[1];
1285                         }
1286
1287                         $body = $matches[3];
1288                 }
1289
1290                 // Re-appending the kept mentions to the body after extraction
1291                 $kept_mentions[] = $body;
1292
1293                 return implode('', $kept_mentions);
1294         }
1295 }