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