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 $body
  48          *
  49          * @return string with replaced emojis
  50          */
  51         public static function replaceEmojis($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 $item
 255          * @return array
 256          * @throws \Exception
 257          */
 258         private static function processContent($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                         $content = self::replaceEmojis($content, $activity['emojis']);
 267                         $content = self::convertMentions($content);
 268
 269                         if (($item['thr-parent'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
 270                                 $item_private = !in_array(0, $activity['item_receiver']);
 271                                 $parent = Item::selectFirst(['id', 'private', 'author-link', 'alias'], ['uri' => $item['thr-parent']]);
 272                                 if (!DBA::isResult($parent)) {
 273                                         Logger::warning('Unknown parent item.', ['uri' => $item['thr-parent']]);
 274                                         return false;
 275                                 }
 276                                 if ($item_private && !$parent['private']) {
 277                                         Logger::warning('Item is private but the parent is not. Dropping.', ['item-uri' => $item['uri'], 'thr-parent' => $item['thr-parent']]);
 278                                         return false;
 279                                 }
 280
 281                                 $potential_implicit_mentions = self::getImplicitMentionList($parent);
 282                                 $content = self::removeImplicitMentionsFromBody($content, $potential_implicit_mentions);
 283                                 $activity['tags'] = self::convertImplicitMentionsInTags($activity['tags'], $potential_implicit_mentions);
 284                         }
 285                         $item['content-warning'] = HTML::toBBCode($activity['summary']);
 286                         $item['body'] = $content;
 287
 288                         if (($activity['object_type'] == 'as:Video') && !empty($activity['alternate-url'])) {
 289                                 $item['body'] .= "\n[video]" . $activity['alternate-url'] . '[/video]';
 290                         }
 291                 }
 292
 293                 $item['tag'] = self::constructTagString($activity['tags'], $activity['sensitive']);
 294
 295                 $item['location'] = $activity['location'];
 296
 297                 if (!empty($item['latitude']) && !empty($item['longitude'])) {
 298                         $item['coord'] = $item['latitude'] . ' ' . $item['longitude'];
 299                 }
 300
 301                 $item['app'] = $activity['generator'];
 302
 303                 return $item;
 304         }
 305
 306         /**
 307          * Creates an item post
 308          *
 309          * @param array $activity Activity data
 310          * @param array $item     item array
 311          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 312          * @throws \ImagickException
 313          */
 314         private static function postItem($activity, $item)
 315         {
 316                 /// @todo What to do with $activity['context']?
 317
 318                 if (($item['gravity'] != GRAVITY_PARENT) && !Item::exists(['uri' => $item['thr-parent']])) {
 319                         Logger::info('Parent not found, message will be discarded.', ['thr-parent' => $item['thr-parent']]);
 320                         return;
 321                 }
 322
 323                 $item['network'] = Protocol::ACTIVITYPUB;
 324                 $item['private'] = !in_array(0, $activity['receiver']);
 325                 $item['author-link'] = $activity['author'];
 326                 $item['author-id'] = Contact::getIdForURL($activity['author'], 0, true);
 327
 328                 if (empty($activity['thread-completion'])) {
 329                         $item['owner-link'] = $activity['actor'];
 330                         $item['owner-id'] = Contact::getIdForURL($activity['actor'], 0, true);
 331                 } else {
 332                         Logger::info('Ignoring actor because of thread completion.');
 333                         $item['owner-link'] = $item['author-link'];
 334                         $item['owner-id'] = $item['author-id'];
 335                 }
 336
 337                 $item['uri'] = $activity['id'];
 338
 339                 $item['created'] = $activity['published'];
 340                 $item['edited'] = $activity['updated'];
 341                 $item['guid'] = $activity['diaspora:guid'];
 342
 343                 $item = self::processContent($activity, $item);
 344                 if (empty($item)) {
 345                         return;
 346                 }
 347
 348                 $item['plink'] = defaults($activity, 'alternate-url', $item['uri']);
 349
 350                 $item = self::constructAttachList($activity['attachments'], $item);
 351
 352                 $stored = false;
 353
 354                 foreach ($activity['receiver'] as $receiver) {
 355                         $item['uid'] = $receiver;
 356                         $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver, true);
 357
 358                         if (($receiver != 0) && empty($item['contact-id'])) {
 359                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], 0, true);
 360                         }
 361
 362                         if ($activity['object_type'] == 'as:Event') {
 363                                 self::createEvent($activity, $item);
 364                         }
 365
 366                         $item_id = Item::insert($item);
 367                         if ($item_id) {
 368                                 Logger::info('Item insertion successful', ['user' => $item['uid'], 'item_id' => $item_id]);
 369                         } else {
 370                                 Logger::notice('Item insertion aborted', ['user' => $item['uid']]);
 371                         }
 372
 373                         if ($item['uid'] == 0) {
 374                                 $stored = $item_id;
 375                         }
 376                 }
 377
 378                 // Store send a follow request for every reshare - but only when the item had been stored
 379                 if ($stored && !$item['private'] && ($item['gravity'] == GRAVITY_PARENT) && ($item['author-link'] != $item['owner-link'])) {
 380                         $author = APContact::getByURL($item['owner-link'], false);
 381                         // We send automatic follow requests for reshared messages. (We don't need though for forum posts)
 382                         if ($author['type'] != 'Group') {
 383                                 Logger::log('Send follow request for ' . $item['uri'] . ' (' . $stored . ') to ' . $item['author-link'], Logger::DEBUG);
 384                                 ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
 385                         }
 386                 }
 387         }
 388
 389         /**
 390          * Fetches missing posts
 391          *
 392          * @param $url
 393          * @param $child
 394          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 395          */
 396         private static function fetchMissingActivity($url, $child)
 397         {
 398                 if (Config::get('system', 'ostatus_full_threads')) {
 399                         return;
 400                 }
 401
 402                 $uid = ActivityPub\Receiver::getFirstUserFromReceivers($child['receiver']);
 403
 404                 $object = ActivityPub::fetchContent($url, $uid);
 405                 if (empty($object)) {
 406                         Logger::log('Activity ' . $url . ' was not fetchable, aborting.');
 407                         return;
 408                 }
 409
 410                 if (empty($object['id'])) {
 411                         Logger::log('Activity ' . $url . ' has got not id, aborting. ' . json_encode($object));
 412                         return;
 413                 }
 414
 415                 $activity = [];
 416                 $activity['@context'] = $object['@context'];
 417                 unset($object['@context']);
 418                 $activity['id'] = $object['id'];
 419                 $activity['to'] = defaults($object, 'to', []);
 420                 $activity['cc'] = defaults($object, 'cc', []);
 421                 $activity['actor'] = $child['author'];
 422                 $activity['object'] = $object;
 423                 $activity['published'] = defaults($object, 'published', $child['published']);
 424                 $activity['type'] = 'Create';
 425
 426                 $ldactivity = JsonLD::compact($activity);
 427
 428                 $ldactivity['thread-completion'] = true;
 429
 430                 ActivityPub\Receiver::processActivity($ldactivity);
 431                 Logger::log('Activity ' . $url . ' had been fetched and processed.');
 432         }
 433
 434         /**
 435          * perform a "follow" request
 436          *
 437          * @param array $activity
 438          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 439          * @throws \ImagickException
 440          */
 441         public static function followUser($activity)
 442         {
 443                 $uid = User::getIdForURL($activity['object_id']);
 444                 if (empty($uid)) {
 445                         return;
 446                 }
 447
 448                 $owner = User::getOwnerDataById($uid);
 449
 450                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 451                 if (!empty($cid)) {
 452                         self::switchContact($cid);
 453                         DBA::update('contact', ['hub-verify' => $activity['id']], ['id' => $cid]);
 454                         $contact = DBA::selectFirst('contact', [], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
 455                 } else {
 456                         $contact = false;
 457                 }
 458
 459                 $item = ['author-id' => Contact::getIdForURL($activity['actor']),
 460                         'author-link' => $activity['actor']];
 461
 462                 // Ensure that the contact has got the right network type
 463                 self::switchContact($item['author-id']);
 464
 465                 Contact::addRelationship($owner, $contact, $item);
 466                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 467                 if (empty($cid)) {
 468                         return;
 469                 }
 470
 471                 if (empty($contact)) {
 472                         DBA::update('contact', ['hub-verify' => $activity['id']], ['id' => $cid]);
 473                 }
 474
 475                 Logger::log('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
 476         }
 477
 478         /**
 479          * Update the given profile
 480          *
 481          * @param array $activity
 482          * @throws \Exception
 483          */
 484         public static function updatePerson($activity)
 485         {
 486                 if (empty($activity['object_id'])) {
 487                         return;
 488                 }
 489
 490                 Logger::log('Updating profile for ' . $activity['object_id'], Logger::DEBUG);
 491                 APContact::getByURL($activity['object_id'], true);
 492         }
 493
 494         /**
 495          * Delete the given profile
 496          *
 497          * @param array $activity
 498          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 499          */
 500         public static function deletePerson($activity)
 501         {
 502                 if (empty($activity['object_id']) || empty($activity['actor'])) {
 503                         Logger::log('Empty object id or actor.', Logger::DEBUG);
 504                         return;
 505                 }
 506
 507                 if ($activity['object_id'] != $activity['actor']) {
 508                         Logger::log('Object id does not match actor.', Logger::DEBUG);
 509                         return;
 510                 }
 511
 512                 $contacts = DBA::select('contact', ['id'], ['nurl' => Strings::normaliseLink($activity['object_id'])]);
 513                 while ($contact = DBA::fetch($contacts)) {
 514                         Contact::remove($contact['id']);
 515                 }
 516                 DBA::close($contacts);
 517
 518                 Logger::log('Deleted contact ' . $activity['object_id'], Logger::DEBUG);
 519         }
 520
 521         /**
 522          * Accept a follow request
 523          *
 524          * @param array $activity
 525          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 526          * @throws \ImagickException
 527          */
 528         public static function acceptFollowUser($activity)
 529         {
 530                 $uid = User::getIdForURL($activity['object_actor']);
 531                 if (empty($uid)) {
 532                         return;
 533                 }
 534
 535                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 536                 if (empty($cid)) {
 537                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 538                         return;
 539                 }
 540
 541                 self::switchContact($cid);
 542
 543                 $fields = ['pending' => false];
 544
 545                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
 546                 if ($contact['rel'] == Contact::FOLLOWER) {
 547                         $fields['rel'] = Contact::FRIEND;
 548                 }
 549
 550                 $condition = ['id' => $cid];
 551                 DBA::update('contact', $fields, $condition);
 552                 Logger::log('Accept contact request from contact ' . $cid . ' for user ' . $uid, Logger::DEBUG);
 553         }
 554
 555         /**
 556          * Reject a follow request
 557          *
 558          * @param array $activity
 559          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 560          * @throws \ImagickException
 561          */
 562         public static function rejectFollowUser($activity)
 563         {
 564                 $uid = User::getIdForURL($activity['object_actor']);
 565                 if (empty($uid)) {
 566                         return;
 567                 }
 568
 569                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 570                 if (empty($cid)) {
 571                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 572                         return;
 573                 }
 574
 575                 self::switchContact($cid);
 576
 577                 if (DBA::exists('contact', ['id' => $cid, 'rel' => Contact::SHARING, 'pending' => true])) {
 578                         Contact::remove($cid);
 579                         Logger::log('Rejected contact request from contact ' . $cid . ' for user ' . $uid . ' - contact had been removed.', Logger::DEBUG);
 580                 } else {
 581                         Logger::log('Rejected contact request from contact ' . $cid . ' for user ' . $uid . '.', Logger::DEBUG);
 582                 }
 583         }
 584
 585         /**
 586          * Undo activity like "like" or "dislike"
 587          *
 588          * @param array $activity
 589          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 590          * @throws \ImagickException
 591          */
 592         public static function undoActivity($activity)
 593         {
 594                 if (empty($activity['object_id'])) {
 595                         return;
 596                 }
 597
 598                 if (empty($activity['object_actor'])) {
 599                         return;
 600                 }
 601
 602                 $author_id = Contact::getIdForURL($activity['object_actor']);
 603                 if (empty($author_id)) {
 604                         return;
 605                 }
 606
 607                 Item::delete(['uri' => $activity['object_id'], 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
 608         }
 609
 610         /**
 611          * Activity to remove a follower
 612          *
 613          * @param array $activity
 614          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 615          * @throws \ImagickException
 616          */
 617         public static function undoFollowUser($activity)
 618         {
 619                 $uid = User::getIdForURL($activity['object_object']);
 620                 if (empty($uid)) {
 621                         return;
 622                 }
 623
 624                 $owner = User::getOwnerDataById($uid);
 625
 626                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 627                 if (empty($cid)) {
 628                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 629                         return;
 630                 }
 631
 632                 self::switchContact($cid);
 633
 634                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
 635                 if (!DBA::isResult($contact)) {
 636                         return;
 637                 }
 638
 639                 Contact::removeFollower($owner, $contact);
 640                 Logger::log('Undo following request from contact ' . $cid . ' for user ' . $uid, Logger::DEBUG);
 641         }
 642
 643         /**
 644          * Switches a contact to AP if needed
 645          *
 646          * @param integer $cid Contact ID
 647          * @throws \Exception
 648          */
 649         private static function switchContact($cid)
 650         {
 651                 $contact = DBA::selectFirst('contact', ['network'], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
 652                 if (!DBA::isResult($contact) || ($contact['network'] == Protocol::ACTIVITYPUB)) {
 653                         return;
 654                 }
 655
 656                 Logger::log('Change existing contact ' . $cid . ' from ' . $contact['network'] . ' to ActivityPub.');
 657                 Contact::updateFromProbe($cid, Protocol::ACTIVITYPUB);
 658         }
 659
 660         /**
 661          * Collects implicit mentions like:
 662          * - the author of the parent item
 663          * - all the mentioned conversants in the parent item
 664          *
 665          * @param array $parent Item array with at least ['id', 'author-link', 'alias']
 666          * @return array
 667          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 668          */
 669         private static function getImplicitMentionList(array $parent)
 670         {
 671                 if (Config::get('system', 'disable_implicit_mentions')) {
 672                         return [];
 673                 }
 674
 675                 $parent_terms = Term::tagArrayFromItemId($parent['id'], [Term::MENTION, Term::IMPLICIT_MENTION]);
 676
 677                 $parent_author = Contact::getDetailsByURL($parent['author-link'], 0);
 678
 679                 $implicit_mentions = [];
 680                 if (empty($parent_author)) {
 681                         Logger::notice('Author public contact unknown.', ['author-link' => $parent['author-link'], 'item-id' => $parent['id']]);
 682                 } else {
 683                         $implicit_mentions[] = $parent_author['url'];
 684                         $implicit_mentions[] = $parent_author['nurl'];
 685                         $implicit_mentions[] = $parent_author['alias'];
 686                 }
 687
 688                 if (!empty($parent['alias'])) {
 689                         $implicit_mentions[] = $parent['alias'];
 690                 }
 691
 692                 foreach ($parent_terms as $term) {
 693                         $contact = Contact::getDetailsByURL($term['url'], 0);
 694                         if (!empty($contact)) {
 695                                 $implicit_mentions[] = $contact['url'];
 696                                 $implicit_mentions[] = $contact['nurl'];
 697                                 $implicit_mentions[] = $contact['alias'];
 698                         }
 699                 }
 700
 701                 return $implicit_mentions;
 702         }
 703
 704         /**
 705          * Strips from the body prepended implicit mentions
 706          *
 707          * @param string $body
 708          * @param array $potential_mentions
 709          * @return string
 710          */
 711         private static function removeImplicitMentionsFromBody($body, array $potential_mentions)
 712         {
 713                 if (Config::get('system', 'disable_implicit_mentions')) {
 714                         return $body;
 715                 }
 716
 717                 $kept_mentions = [];
 718
 719                 // Extract one prepended mention at a time from the body
 720                 while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $body, $matches)) {
 721                         if (!in_array($matches[2], $potential_mentions) ) {
 722                                 $kept_mentions[] = $matches[1];
 723                         }
 724
 725                         $body = $matches[3];
 726                 }
 727
 728                 // Re-appending the kept mentions to the body after extraction
 729                 $kept_mentions[] = $body;
 730
 731                 return implode('', $kept_mentions);
 732         }
 733
 734         private static function convertImplicitMentionsInTags($activity_tags, array $potential_mentions)
 735         {
 736                 if (Config::get('system', 'disable_implicit_mentions')) {
 737                         return $activity_tags;
 738                 }
 739
 740                 foreach ($activity_tags as $index => $tag) {
 741                         if (in_array($tag['href'], $potential_mentions)) {
 742                                 $activity_tags[$index]['name'] = preg_replace(
 743                                         '/' . preg_quote(Term::TAG_CHARACTER[Term::MENTION], '/') . '/',
 744                                         Term::TAG_CHARACTER[Term::IMPLICIT_MENTION],
 745                                         $activity_tags[$index]['name'],
 746                                         1
 747                                 );
 748                         }
 749                 }
 750
 751                 return $activity_tags;
 752         }
 753 }