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