src/Protocol/ActivityPub/Processor.php

   1 <?php
   2 /**
   3  * @file src/Protocol/ActivityPub/Processor.php
   4  */
   5 namespace Friendica\Protocol\ActivityPub;
   6
   7 use Friendica\Database\DBA;
   8 use Friendica\Content\Text\HTML;
   9 use Friendica\Core\Config;
  10 use Friendica\Core\Logger;
  11 use Friendica\Core\Protocol;
  12 use Friendica\Model\Contact;
  13 use Friendica\Model\APContact;
  14 use Friendica\Model\Item;
  15 use Friendica\Model\Event;
  16 use Friendica\Model\Term;
  17 use Friendica\Model\User;
  18 use Friendica\Protocol\ActivityPub;
  19 use Friendica\Util\DateTimeFormat;
  20 use Friendica\Util\JsonLD;
  21 use Friendica\Util\Strings;
  22
  23 /**
  24  * ActivityPub Processor Protocol class
  25  */
  26 class Processor
  27 {
  28         /**
  29          * Converts mentions from Pleroma into the Friendica format
  30          *
  31          * @param string $body
  32          *
  33          * @return string converted body
  34          */
  35         private static function convertMentions($body)
  36         {
  37                 $URLSearchString = "^\[\]";
  38                 $body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
  39
  40                 return $body;
  41         }
  42
  43         /**
  44          * Replaces emojis in the body
  45          *
  46          * @param array $emojis
  47          * @param string $body
  48          *
  49          * @return string with replaced emojis
  50          */
  51         private static function replaceEmojis($body, array $emojis)
  52         {
  53                 foreach ($emojis as $emoji) {
  54                         $replace = '[class=emoji mastodon][img=' . $emoji['href'] . ']' . $emoji['name'] . '[/img][/class]';
  55                         $body = str_replace($emoji['name'], $replace, $body);
  56                 }
  57                 return $body;
  58         }
  59
  60         /**
  61          * Constructs a string with tags for a given tag array
  62          *
  63          * @param array   $tags
  64          * @param boolean $sensitive
  65          * @param array   $implicit_mentions List of profile URLs to skip
  66          * @return string with tags
  67          */
  68         private static function constructTagString(array $tags, $sensitive)
  69         {
  70                 if (empty($tags)) {
  71                         return '';
  72                 }
  73
  74                 $tag_text = '';
  75                 foreach ($tags as $tag) {
  76                         if (in_array(defaults($tag, 'type', ''), ['Mention', 'Hashtag'])) {
  77                                 if (!empty($tag_text)) {
  78                                         $tag_text .= ',';
  79                                 }
  80
  81                                 $tag_text .= substr($tag['name'], 0, 1) . '[url=' . $tag['href'] . ']' . substr($tag['name'], 1) . '[/url]';
  82                         }
  83                 }
  84
  85                 /// @todo add nsfw for $sensitive
  86
  87                 return $tag_text;
  88         }
  89
  90         /**
  91          * Add attachment data to the item array
  92          *
  93          * @param array   $attachments
  94          * @param array   $item
  95          * @param boolean $no_images
  96          *
  97          * @return array array
  98          */
  99         private static function constructAttachList($attachments, $item, $no_images)
 100         {
 101                 if (empty($attachments)) {
 102                         return $item;
 103                 }
 104
 105                 foreach ($attachments as $attach) {
 106                         $filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
 107                         if ($filetype == 'image') {
 108                                 if ($no_images) {
 109                                         continue;
 110                                 }
 111
 112                                 $item['body'] .= "\n[img]" . $attach['url'] . '[/img]';
 113                         } else {
 114                                 if (!empty($item["attach"])) {
 115                                         $item["attach"] .= ',';
 116                                 } else {
 117                                         $item["attach"] = '';
 118                                 }
 119                                 if (!isset($attach['length'])) {
 120                                         $attach['length'] = "0";
 121                                 }
 122                                 $item["attach"] .= '[attach]href="'.$attach['url'].'" length="'.$attach['length'].'" type="'.$attach['mediaType'].'" title="'.defaults($attach, 'name', '').'"[/attach]';
 123                         }
 124                 }
 125
 126                 return $item;
 127         }
 128
 129         /**
 130          * Updates a message
 131          *
 132          * @param array $activity Activity array
 133          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 134          */
 135         public static function updateItem($activity)
 136         {
 137                 $item = Item::selectFirst(['uri', 'thr-parent', 'gravity'], ['uri' => $activity['id']]);
 138                 if (!DBA::isResult($item)) {
 139                         Logger::warning('Unknown item', ['uri' => $activity['id']]);
 140                         return;
 141                 }
 142
 143                 $item['changed'] = DateTimeFormat::utcNow();
 144                 $item['edited'] = $activity['updated'];
 145
 146                 $item = self::processContent($activity, $item);
 147                 if (empty($item)) {
 148                         return;
 149                 }
 150
 151                 Item::update($item, ['uri' => $activity['id']]);
 152         }
 153
 154         /**
 155          * Prepares data for a message
 156          *
 157          * @param array $activity Activity array
 158          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 159          * @throws \ImagickException
 160          */
 161         public static function createItem($activity)
 162         {
 163                 $item = [];
 164                 $item['verb'] = ACTIVITY_POST;
 165                 $item['thr-parent'] = $activity['reply-to-id'];
 166
 167                 if ($activity['reply-to-id'] == $activity['id']) {
 168                         $item['gravity'] = GRAVITY_PARENT;
 169                         $item['object-type'] = ACTIVITY_OBJ_NOTE;
 170                 } else {
 171                         $item['gravity'] = GRAVITY_COMMENT;
 172                         $item['object-type'] = ACTIVITY_OBJ_COMMENT;
 173                 }
 174
 175                 if (($activity['id'] != $activity['reply-to-id']) && !Item::exists(['uri' => $activity['reply-to-id']])) {
 176                         Logger::log('Parent ' . $activity['reply-to-id'] . ' not found. Try to refetch it.');
 177                         self::fetchMissingActivity($activity['reply-to-id'], $activity);
 178                 }
 179
 180                 $item['diaspora_signed_text'] = defaults($activity, 'diaspora:comment', '');
 181
 182                 self::postItem($activity, $item);
 183         }
 184
 185         /**
 186          * Delete items
 187          *
 188          * @param array $activity
 189          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 190          * @throws \ImagickException
 191          */
 192         public static function deleteItem($activity)
 193         {
 194                 $owner = Contact::getIdForURL($activity['actor']);
 195
 196                 Logger::log('Deleting item ' . $activity['object_id'] . ' from ' . $owner, Logger::DEBUG);
 197                 Item::delete(['uri' => $activity['object_id'], 'owner-id' => $owner]);
 198         }
 199
 200         /**
 201          * Prepare the item array for an activity
 202          *
 203          * @param array  $activity Activity array
 204          * @param string $verb     Activity verb
 205          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 206          * @throws \ImagickException
 207          */
 208         public static function createActivity($activity, $verb)
 209         {
 210                 $item = [];
 211                 $item['verb'] = $verb;
 212                 $item['thr-parent'] = $activity['object_id'];
 213                 $item['gravity'] = GRAVITY_ACTIVITY;
 214                 $item['object-type'] = ACTIVITY_OBJ_NOTE;
 215
 216                 $item['diaspora_signed_text'] = defaults($activity, 'diaspora:like', '');
 217
 218                 self::postItem($activity, $item);
 219         }
 220
 221         /**
 222          * Create an event
 223          *
 224          * @param array $activity Activity array
 225          * @param array $item
 226          * @throws \Exception
 227          */
 228         public static function createEvent($activity, $item)
 229         {
 230                 $event['summary']  = HTML::toBBCode($activity['name']);
 231                 $event['desc']     = HTML::toBBCode($activity['content']);
 232                 $event['start']    = $activity['start-time'];
 233                 $event['finish']   = $activity['end-time'];
 234                 $event['nofinish'] = empty($event['finish']);
 235                 $event['location'] = $activity['location'];
 236                 $event['adjust']   = true;
 237                 $event['cid']      = $item['contact-id'];
 238                 $event['uid']      = $item['uid'];
 239                 $event['uri']      = $item['uri'];
 240                 $event['edited']   = $item['edited'];
 241                 $event['private']  = $item['private'];
 242                 $event['guid']     = $item['guid'];
 243                 $event['plink']    = $item['plink'];
 244
 245                 $condition = ['uri' => $item['uri'], 'uid' => $item['uid']];
 246                 $ev = DBA::selectFirst('event', ['id'], $condition);
 247                 if (DBA::isResult($ev)) {
 248                         $event['id'] = $ev['id'];
 249                 }
 250
 251                 $event_id = Event::store($event);
 252                 Logger::log('Event '.$event_id.' was stored', Logger::DEBUG);
 253         }
 254
 255         /**
 256          * Process the content
 257          *
 258          * @param array $activity Activity array
 259          * @param array $item
 260          * @return array|bool Returns the item array or false if there was an unexpected occurrence
 261          * @throws \Exception
 262          */
 263         private static function processContent($activity, $item)
 264         {
 265                 $item['title'] = HTML::toBBCode($activity['name']);
 266
 267                 if (!empty($activity['source'])) {
 268                         $item['body'] = $activity['source'];
 269                 } else {
 270                         $content = HTML::toBBCode($activity['content']);
 271
 272                         if (!empty($activity['emojis'])) {
 273                                 $content = self::replaceEmojis($content, $activity['emojis']);
 274                         }
 275
 276                         $content = self::convertMentions($content);
 277
 278                         if (($item['thr-parent'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
 279                                 $item_private = !in_array(0, $activity['item_receiver']);
 280                                 $parent = Item::selectFirst(['id', 'private', 'author-link', 'alias'], ['uri' => $item['thr-parent']]);
 281                                 if (!DBA::isResult($parent)) {
 282                                         Logger::warning('Unknown parent item.', ['uri' => $item['thr-parent']]);
 283                                         return false;
 284                                 }
 285                                 if ($item_private && !$parent['private']) {
 286                                         Logger::warning('Item is private but the parent is not. Dropping.', ['item-uri' => $item['uri'], 'thr-parent' => $item['thr-parent']]);
 287                                         return false;
 288                                 }
 289
 290                                 $potential_implicit_mentions = self::getImplicitMentionList($parent);
 291                                 $content = self::removeImplicitMentionsFromBody($content, $potential_implicit_mentions);
 292                                 $activity['tags'] = self::convertImplicitMentionsInTags($activity['tags'], $potential_implicit_mentions);
 293                         }
 294                         $item['content-warning'] = HTML::toBBCode($activity['summary']);
 295                         $item['body'] = $content;
 296
 297                         if (($activity['object_type'] == 'as:Video') && !empty($activity['alternate-url'])) {
 298                                 $item['body'] .= "\n[video]" . $activity['alternate-url'] . '[/video]';
 299                         }
 300                 }
 301
 302                 $item['tag'] = self::constructTagString($activity['tags'], $activity['sensitive']);
 303
 304                 $item['location'] = $activity['location'];
 305
 306                 if (!empty($item['latitude']) && !empty($item['longitude'])) {
 307                         $item['coord'] = $item['latitude'] . ' ' . $item['longitude'];
 308                 }
 309
 310                 $item['app'] = $activity['generator'];
 311
 312                 return $item;
 313         }
 314
 315         /**
 316          * Creates an item post
 317          *
 318          * @param array $activity Activity data
 319          * @param array $item     item array
 320          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 321          * @throws \ImagickException
 322          */
 323         private static function postItem($activity, $item)
 324         {
 325                 /// @todo What to do with $activity['context']?
 326
 327                 if (($item['gravity'] != GRAVITY_PARENT) && !Item::exists(['uri' => $item['thr-parent']])) {
 328                         Logger::info('Parent not found, message will be discarded.', ['thr-parent' => $item['thr-parent']]);
 329                         return;
 330                 }
 331
 332                 $item['network'] = Protocol::ACTIVITYPUB;
 333                 $item['private'] = !in_array(0, $activity['receiver']);
 334                 $item['author-link'] = $activity['author'];
 335                 $item['author-id'] = Contact::getIdForURL($activity['author'], 0, true);
 336
 337                 if (empty($activity['thread-completion'])) {
 338                         $item['owner-link'] = $activity['actor'];
 339                         $item['owner-id'] = Contact::getIdForURL($activity['actor'], 0, true);
 340                 } else {
 341                         Logger::info('Ignoring actor because of thread completion.');
 342                         $item['owner-link'] = $item['author-link'];
 343                         $item['owner-id'] = $item['author-id'];
 344                 }
 345
 346                 $item['uri'] = $activity['id'];
 347
 348                 $item['created'] = $activity['published'];
 349                 $item['edited'] = $activity['updated'];
 350                 $item['guid'] = $activity['diaspora:guid'];
 351
 352                 $item = self::processContent($activity, $item);
 353                 if (empty($item)) {
 354                         return;
 355                 }
 356
 357                 $item['plink'] = defaults($activity, 'alternate-url', $item['uri']);
 358
 359                 $item = self::constructAttachList($activity['attachments'], $item, !empty($activity['source']));
 360
 361                 $stored = false;
 362
 363                 foreach ($activity['receiver'] as $receiver) {
 364                         $item['uid'] = $receiver;
 365                         $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver, true);
 366
 367                         if (($receiver != 0) && empty($item['contact-id'])) {
 368                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], 0, true);
 369                         }
 370
 371                         if ($activity['object_type'] == 'as:Event') {
 372                                 self::createEvent($activity, $item);
 373                         }
 374
 375                         $item_id = Item::insert($item);
 376                         if ($item_id) {
 377                                 Logger::info('Item insertion successful', ['user' => $item['uid'], 'item_id' => $item_id]);
 378                         } else {
 379                                 Logger::notice('Item insertion aborted', ['user' => $item['uid']]);
 380                         }
 381
 382                         if ($item['uid'] == 0) {
 383                                 $stored = $item_id;
 384                         }
 385                 }
 386
 387                 // Store send a follow request for every reshare - but only when the item had been stored
 388                 if ($stored && !$item['private'] && ($item['gravity'] == GRAVITY_PARENT) && ($item['author-link'] != $item['owner-link'])) {
 389                         $author = APContact::getByURL($item['owner-link'], false);
 390                         // We send automatic follow requests for reshared messages. (We don't need though for forum posts)
 391                         if ($author['type'] != 'Group') {
 392                                 Logger::log('Send follow request for ' . $item['uri'] . ' (' . $stored . ') to ' . $item['author-link'], Logger::DEBUG);
 393                                 ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
 394                         }
 395                 }
 396         }
 397
 398         /**
 399          * Fetches missing posts
 400          *
 401          * @param $url
 402          * @param $child
 403          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 404          */
 405         private static function fetchMissingActivity($url, $child)
 406         {
 407                 if (Config::get('system', 'ostatus_full_threads')) {
 408                         return;
 409                 }
 410
 411                 $uid = ActivityPub\Receiver::getFirstUserFromReceivers($child['receiver']);
 412
 413                 $object = ActivityPub::fetchContent($url, $uid);
 414                 if (empty($object)) {
 415                         Logger::log('Activity ' . $url . ' was not fetchable, aborting.');
 416                         return;
 417                 }
 418
 419                 if (empty($object['id'])) {
 420                         Logger::log('Activity ' . $url . ' has got not id, aborting. ' . json_encode($object));
 421                         return;
 422                 }
 423
 424                 $activity = [];
 425                 $activity['@context'] = $object['@context'];
 426                 unset($object['@context']);
 427                 $activity['id'] = $object['id'];
 428                 $activity['to'] = defaults($object, 'to', []);
 429                 $activity['cc'] = defaults($object, 'cc', []);
 430                 $activity['actor'] = $child['author'];
 431                 $activity['object'] = $object;
 432                 $activity['published'] = defaults($object, 'published', $child['published']);
 433                 $activity['type'] = 'Create';
 434
 435                 $ldactivity = JsonLD::compact($activity);
 436
 437                 $ldactivity['thread-completion'] = true;
 438
 439                 ActivityPub\Receiver::processActivity($ldactivity);
 440                 Logger::log('Activity ' . $url . ' had been fetched and processed.');
 441         }
 442
 443         /**
 444          * perform a "follow" request
 445          *
 446          * @param array $activity
 447          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 448          * @throws \ImagickException
 449          */
 450         public static function followUser($activity)
 451         {
 452                 $uid = User::getIdForURL($activity['object_id']);
 453                 if (empty($uid)) {
 454                         return;
 455                 }
 456
 457                 $owner = User::getOwnerDataById($uid);
 458
 459                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 460                 if (!empty($cid)) {
 461                         self::switchContact($cid);
 462                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
 463                         $contact = DBA::selectFirst('contact', [], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
 464                 } else {
 465                         $contact = false;
 466                 }
 467
 468                 $item = ['author-id' => Contact::getIdForURL($activity['actor']),
 469                         'author-link' => $activity['actor']];
 470
 471                 $note = Strings::escapeTags(trim(defaults($activity, 'content', '')));
 472
 473                 // Ensure that the contact has got the right network type
 474                 self::switchContact($item['author-id']);
 475
 476                 Contact::addRelationship($owner, $contact, $item, '', false, $note);
 477                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 478                 if (empty($cid)) {
 479                         return;
 480                 }
 481
 482                 if (empty($contact)) {
 483                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
 484                 }
 485
 486                 Logger::log('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
 487         }
 488
 489         /**
 490          * Update the given profile
 491          *
 492          * @param array $activity
 493          * @throws \Exception
 494          */
 495         public static function updatePerson($activity)
 496         {
 497                 if (empty($activity['object_id'])) {
 498                         return;
 499                 }
 500
 501                 Logger::log('Updating profile for ' . $activity['object_id'], Logger::DEBUG);
 502                 APContact::getByURL($activity['object_id'], true);
 503         }
 504
 505         /**
 506          * Delete the given profile
 507          *
 508          * @param array $activity
 509          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 510          */
 511         public static function deletePerson($activity)
 512         {
 513                 if (empty($activity['object_id']) || empty($activity['actor'])) {
 514                         Logger::log('Empty object id or actor.', Logger::DEBUG);
 515                         return;
 516                 }
 517
 518                 if ($activity['object_id'] != $activity['actor']) {
 519                         Logger::log('Object id does not match actor.', Logger::DEBUG);
 520                         return;
 521                 }
 522
 523                 $contacts = DBA::select('contact', ['id'], ['nurl' => Strings::normaliseLink($activity['object_id'])]);
 524                 while ($contact = DBA::fetch($contacts)) {
 525                         Contact::remove($contact['id']);
 526                 }
 527                 DBA::close($contacts);
 528
 529                 Logger::log('Deleted contact ' . $activity['object_id'], Logger::DEBUG);
 530         }
 531
 532         /**
 533          * Accept a follow request
 534          *
 535          * @param array $activity
 536          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 537          * @throws \ImagickException
 538          */
 539         public static function acceptFollowUser($activity)
 540         {
 541                 $uid = User::getIdForURL($activity['object_actor']);
 542                 if (empty($uid)) {
 543                         return;
 544                 }
 545
 546                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 547                 if (empty($cid)) {
 548                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 549                         return;
 550                 }
 551
 552                 self::switchContact($cid);
 553
 554                 $fields = ['pending' => false];
 555
 556                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
 557                 if ($contact['rel'] == Contact::FOLLOWER) {
 558                         $fields['rel'] = Contact::FRIEND;
 559                 }
 560
 561                 $condition = ['id' => $cid];
 562                 DBA::update('contact', $fields, $condition);
 563                 Logger::log('Accept contact request from contact ' . $cid . ' for user ' . $uid, Logger::DEBUG);
 564         }
 565
 566         /**
 567          * Reject a follow request
 568          *
 569          * @param array $activity
 570          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 571          * @throws \ImagickException
 572          */
 573         public static function rejectFollowUser($activity)
 574         {
 575                 $uid = User::getIdForURL($activity['object_actor']);
 576                 if (empty($uid)) {
 577                         return;
 578                 }
 579
 580                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 581                 if (empty($cid)) {
 582                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 583                         return;
 584                 }
 585
 586                 self::switchContact($cid);
 587
 588                 if (DBA::exists('contact', ['id' => $cid, 'rel' => Contact::SHARING])) {
 589                         Contact::remove($cid);
 590                         Logger::log('Rejected contact request from contact ' . $cid . ' for user ' . $uid . ' - contact had been removed.', Logger::DEBUG);
 591                 } else {
 592                         Logger::log('Rejected contact request from contact ' . $cid . ' for user ' . $uid . '.', Logger::DEBUG);
 593                 }
 594         }
 595
 596         /**
 597          * Undo activity like "like" or "dislike"
 598          *
 599          * @param array $activity
 600          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 601          * @throws \ImagickException
 602          */
 603         public static function undoActivity($activity)
 604         {
 605                 if (empty($activity['object_id'])) {
 606                         return;
 607                 }
 608
 609                 if (empty($activity['object_actor'])) {
 610                         return;
 611                 }
 612
 613                 $author_id = Contact::getIdForURL($activity['object_actor']);
 614                 if (empty($author_id)) {
 615                         return;
 616                 }
 617
 618                 Item::delete(['uri' => $activity['object_id'], 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
 619         }
 620
 621         /**
 622          * Activity to remove a follower
 623          *
 624          * @param array $activity
 625          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 626          * @throws \ImagickException
 627          */
 628         public static function undoFollowUser($activity)
 629         {
 630                 $uid = User::getIdForURL($activity['object_object']);
 631                 if (empty($uid)) {
 632                         return;
 633                 }
 634
 635                 $owner = User::getOwnerDataById($uid);
 636
 637                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 638                 if (empty($cid)) {
 639                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 640                         return;
 641                 }
 642
 643                 self::switchContact($cid);
 644
 645                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
 646                 if (!DBA::isResult($contact)) {
 647                         return;
 648                 }
 649
 650                 Contact::removeFollower($owner, $contact);
 651                 Logger::log('Undo following request from contact ' . $cid . ' for user ' . $uid, Logger::DEBUG);
 652         }
 653
 654         /**
 655          * Switches a contact to AP if needed
 656          *
 657          * @param integer $cid Contact ID
 658          * @throws \Exception
 659          */
 660         private static function switchContact($cid)
 661         {
 662                 $contact = DBA::selectFirst('contact', ['network'], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
 663                 if (!DBA::isResult($contact) || in_array($contact['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN])) {
 664                         return;
 665                 }
 666
 667                 Logger::log('Change existing contact ' . $cid . ' from ' . $contact['network'] . ' to ActivityPub.');
 668                 Contact::updateFromProbe($cid, Protocol::ACTIVITYPUB);
 669         }
 670
 671         /**
 672          * Collects implicit mentions like:
 673          * - the author of the parent item
 674          * - all the mentioned conversants in the parent item
 675          *
 676          * @param array $parent Item array with at least ['id', 'author-link', 'alias']
 677          * @return array
 678          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 679          */
 680         private static function getImplicitMentionList(array $parent)
 681         {
 682                 if (Config::get('system', 'disable_implicit_mentions')) {
 683                         return [];
 684                 }
 685
 686                 $parent_terms = Term::tagArrayFromItemId($parent['id'], [Term::MENTION, Term::IMPLICIT_MENTION]);
 687
 688                 $parent_author = Contact::getDetailsByURL($parent['author-link'], 0);
 689
 690                 $implicit_mentions = [];
 691                 if (empty($parent_author)) {
 692                         Logger::notice('Author public contact unknown.', ['author-link' => $parent['author-link'], 'item-id' => $parent['id']]);
 693                 } else {
 694                         $implicit_mentions[] = $parent_author['url'];
 695                         $implicit_mentions[] = $parent_author['nurl'];
 696                         $implicit_mentions[] = $parent_author['alias'];
 697                 }
 698
 699                 if (!empty($parent['alias'])) {
 700                         $implicit_mentions[] = $parent['alias'];
 701                 }
 702
 703                 foreach ($parent_terms as $term) {
 704                         $contact = Contact::getDetailsByURL($term['url'], 0);
 705                         if (!empty($contact)) {
 706                                 $implicit_mentions[] = $contact['url'];
 707                                 $implicit_mentions[] = $contact['nurl'];
 708                                 $implicit_mentions[] = $contact['alias'];
 709                         }
 710                 }
 711
 712                 return $implicit_mentions;
 713         }
 714
 715         /**
 716          * Strips from the body prepended implicit mentions
 717          *
 718          * @param string $body
 719          * @param array $potential_mentions
 720          * @return string
 721          */
 722         private static function removeImplicitMentionsFromBody($body, array $potential_mentions)
 723         {
 724                 if (Config::get('system', 'disable_implicit_mentions')) {
 725                         return $body;
 726                 }
 727
 728                 $kept_mentions = [];
 729
 730                 // Extract one prepended mention at a time from the body
 731                 while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $body, $matches)) {
 732                         if (!in_array($matches[2], $potential_mentions) ) {
 733                                 $kept_mentions[] = $matches[1];
 734                         }
 735
 736                         $body = $matches[3];
 737                 }
 738
 739                 // Re-appending the kept mentions to the body after extraction
 740                 $kept_mentions[] = $body;
 741
 742                 return implode('', $kept_mentions);
 743         }
 744
 745         private static function convertImplicitMentionsInTags($activity_tags, array $potential_mentions)
 746         {
 747                 if (Config::get('system', 'disable_implicit_mentions')) {
 748                         return $activity_tags;
 749                 }
 750
 751                 foreach ($activity_tags as $index => $tag) {
 752                         if (in_array($tag['href'], $potential_mentions)) {
 753                                 $activity_tags[$index]['name'] = preg_replace(
 754                                         '/' . preg_quote(Term::TAG_CHARACTER[Term::MENTION], '/') . '/',
 755                                         Term::TAG_CHARACTER[Term::IMPLICIT_MENTION],
 756                                         $activity_tags[$index]['name'],
 757                                         1
 758                                 );
 759                         }
 760                 }
 761
 762                 return $activity_tags;
 763         }
 764 }