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\BBCode;
   9 use Friendica\Content\Text\HTML;
  10 use Friendica\Core\Config;
  11 use Friendica\Core\Logger;
  12 use Friendica\Core\Protocol;
  13 use Friendica\Model\Contact;
  14 use Friendica\Model\APContact;
  15 use Friendica\Model\Item;
  16 use Friendica\Model\Event;
  17 use Friendica\Model\Term;
  18 use Friendica\Model\User;
  19 use Friendica\Model\Mail;
  20 use Friendica\Protocol\ActivityPub;
  21 use Friendica\Util\DateTimeFormat;
  22 use Friendica\Util\JsonLD;
  23 use Friendica\Util\Strings;
  24
  25 /**
  26  * ActivityPub Processor Protocol class
  27  */
  28 class Processor
  29 {
  30         /**
  31          * Converts mentions from Pleroma into the Friendica format
  32          *
  33          * @param string $body
  34          *
  35          * @return string converted body
  36          */
  37         private static function convertMentions($body)
  38         {
  39                 $URLSearchString = "^\[\]";
  40                 $body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
  41
  42                 return $body;
  43         }
  44
  45         /**
  46          * Replaces emojis in the body
  47          *
  48          * @param array $emojis
  49          * @param string $body
  50          *
  51          * @return string with replaced emojis
  52          */
  53         private static function replaceEmojis($body, array $emojis)
  54         {
  55                 foreach ($emojis as $emoji) {
  56                         $replace = '[class=emoji mastodon][img=' . $emoji['href'] . ']' . $emoji['name'] . '[/img][/class]';
  57                         $body = str_replace($emoji['name'], $replace, $body);
  58                 }
  59                 return $body;
  60         }
  61
  62         /**
  63          * Constructs a string with tags for a given tag array
  64          *
  65          * @param array   $tags
  66          * @param boolean $sensitive
  67          * @return string with tags
  68          */
  69         private static function constructTagString(array $tags = null, $sensitive = false)
  70         {
  71                 if (empty($tags)) {
  72                         return '';
  73                 }
  74
  75                 $tag_text = '';
  76                 foreach ($tags as $tag) {
  77                         if (in_array(defaults($tag, 'type', ''), ['Mention', 'Hashtag'])) {
  78                                 if (!empty($tag_text)) {
  79                                         $tag_text .= ',';
  80                                 }
  81
  82                                 $tag_text .= substr($tag['name'], 0, 1) . '[url=' . $tag['href'] . ']' . substr($tag['name'], 1) . '[/url]';
  83                         }
  84                 }
  85
  86                 /// @todo add nsfw for $sensitive
  87
  88                 return $tag_text;
  89         }
  90
  91         /**
  92          * Add attachment data to the item array
  93          *
  94          * @param array   $attachments
  95          * @param array   $item
  96          * @param boolean $no_images
  97          *
  98          * @return array array
  99          */
 100         private static function constructAttachList($attachments, $item, $no_images)
 101         {
 102                 if (empty($attachments)) {
 103                         return $item;
 104                 }
 105
 106                 foreach ($attachments as $attach) {
 107                         $filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
 108                         if ($filetype == 'image') {
 109                                 if ($no_images) {
 110                                         continue;
 111                                 }
 112
 113                                 $item['body'] .= "\n[img]" . $attach['url'] . '[/img]';
 114                         } else {
 115                                 if (!empty($item["attach"])) {
 116                                         $item["attach"] .= ',';
 117                                 } else {
 118                                         $item["attach"] = '';
 119                                 }
 120                                 if (!isset($attach['length'])) {
 121                                         $attach['length'] = "0";
 122                                 }
 123                                 $item["attach"] .= '[attach]href="'.$attach['url'].'" length="'.$attach['length'].'" type="'.$attach['mediaType'].'" title="'.defaults($attach, 'name', '').'"[/attach]';
 124                         }
 125                 }
 126
 127                 return $item;
 128         }
 129
 130         /**
 131          * Updates a message
 132          *
 133          * @param array $activity Activity array
 134          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 135          */
 136         public static function updateItem($activity)
 137         {
 138                 $item = Item::selectFirst(['uri', 'thr-parent', 'gravity'], ['uri' => $activity['id']]);
 139                 if (!DBA::isResult($item)) {
 140                         Logger::warning('Unknown item', ['uri' => $activity['id']]);
 141                         return;
 142                 }
 143
 144                 $item['changed'] = DateTimeFormat::utcNow();
 145                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 146
 147                 $item = self::processContent($activity, $item);
 148                 if (empty($item)) {
 149                         return;
 150                 }
 151
 152                 Item::update($item, ['uri' => $activity['id']]);
 153         }
 154
 155         /**
 156          * Prepares data for a message
 157          *
 158          * @param array $activity Activity array
 159          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 160          * @throws \ImagickException
 161          */
 162         public static function createItem($activity)
 163         {
 164                 $item = [];
 165                 $item['verb'] = ACTIVITY_POST;
 166                 $item['thr-parent'] = $activity['reply-to-id'];
 167
 168                 if ($activity['reply-to-id'] == $activity['id']) {
 169                         $item['gravity'] = GRAVITY_PARENT;
 170                         $item['object-type'] = ACTIVITY_OBJ_NOTE;
 171                 } else {
 172                         $item['gravity'] = GRAVITY_COMMENT;
 173                         $item['object-type'] = ACTIVITY_OBJ_COMMENT;
 174                 }
 175
 176                 if (empty($activity['directmessage']) && ($activity['id'] != $activity['reply-to-id']) && !Item::exists(['uri' => $activity['reply-to-id']])) {
 177                         Logger::log('Parent ' . $activity['reply-to-id'] . ' not found. Try to refetch it.');
 178                         self::fetchMissingActivity($activity['reply-to-id'], $activity);
 179                 }
 180
 181                 $item['diaspora_signed_text'] = defaults($activity, 'diaspora:comment', '');
 182
 183                 self::postItem($activity, $item);
 184         }
 185
 186         /**
 187          * Delete items
 188          *
 189          * @param array $activity
 190          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 191          * @throws \ImagickException
 192          */
 193         public static function deleteItem($activity)
 194         {
 195                 $owner = Contact::getIdForURL($activity['actor']);
 196
 197                 Logger::log('Deleting item ' . $activity['object_id'] . ' from ' . $owner, Logger::DEBUG);
 198                 Item::delete(['uri' => $activity['object_id'], 'owner-id' => $owner]);
 199         }
 200
 201         /**
 202          * Prepare the item array for an activity
 203          *
 204          * @param array $activity Activity array
 205          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 206          * @throws \ImagickException
 207          */
 208         public static function addTag($activity)
 209         {
 210                 if (empty($activity['object_content']) || empty($activity['object_id'])) {
 211                         return;
 212                 }
 213
 214                 foreach ($activity['receiver'] as $receiver) {
 215                         $item = Item::selectFirst(['id', 'tag', 'origin', 'author-link'], ['uri' => $activity['target_id'], 'uid' => $receiver]);
 216                         if (!DBA::isResult($item)) {
 217                                 // We don't fetch missing content for this purpose
 218                                 continue;
 219                         }
 220
 221                         if (($item['author-link'] != $activity['actor']) && !$item['origin']) {
 222                                 Logger::info('Not origin, not from the author, skipping update', ['id' => $item['id'], 'author' => $item['author-link'], 'actor' => $activity['actor']]);
 223                                 continue;
 224                         }
 225
 226                         // To-Do:
 227                         // - Check if "blocktag" is set
 228                         // - Check if actor is a contact
 229
 230                         if (!stristr($item['tag'], trim($activity['object_content']))) {
 231                                 $tag = $item['tag'] . (strlen($item['tag']) ? ',' : '') . '#[url=' . $activity['object_id'] . ']'. $activity['object_content'] . '[/url]';
 232                                 Item::update(['tag' => $tag], ['id' => $item['id']]);
 233                                 Logger::info('Tagged item', ['id' => $item['id'], 'tag' => $activity['object_content'], 'uri' => $activity['target_id'], 'actor' => $activity['actor']]);
 234                         }
 235                 }
 236         }
 237
 238         /**
 239          * Prepare the item array for an activity
 240          *
 241          * @param array  $activity Activity array
 242          * @param string $verb     Activity verb
 243          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 244          * @throws \ImagickException
 245          */
 246         public static function createActivity($activity, $verb)
 247         {
 248                 $item = [];
 249                 $item['verb'] = $verb;
 250                 $item['thr-parent'] = $activity['object_id'];
 251                 $item['gravity'] = GRAVITY_ACTIVITY;
 252                 $item['object-type'] = ACTIVITY_OBJ_NOTE;
 253
 254                 $item['diaspora_signed_text'] = defaults($activity, 'diaspora:like', '');
 255
 256                 self::postItem($activity, $item);
 257         }
 258
 259         /**
 260          * Create an event
 261          *
 262          * @param array $activity Activity array
 263          * @param array $item
 264          * @throws \Exception
 265          */
 266         public static function createEvent($activity, $item)
 267         {
 268                 $event['summary']  = HTML::toBBCode($activity['name']);
 269                 $event['desc']     = HTML::toBBCode($activity['content']);
 270                 $event['start']    = $activity['start-time'];
 271                 $event['finish']   = $activity['end-time'];
 272                 $event['nofinish'] = empty($event['finish']);
 273                 $event['location'] = $activity['location'];
 274                 $event['adjust']   = true;
 275                 $event['cid']      = $item['contact-id'];
 276                 $event['uid']      = $item['uid'];
 277                 $event['uri']      = $item['uri'];
 278                 $event['edited']   = $item['edited'];
 279                 $event['private']  = $item['private'];
 280                 $event['guid']     = $item['guid'];
 281                 $event['plink']    = $item['plink'];
 282
 283                 $condition = ['uri' => $item['uri'], 'uid' => $item['uid']];
 284                 $ev = DBA::selectFirst('event', ['id'], $condition);
 285                 if (DBA::isResult($ev)) {
 286                         $event['id'] = $ev['id'];
 287                 }
 288
 289                 $event_id = Event::store($event);
 290                 Logger::log('Event '.$event_id.' was stored', Logger::DEBUG);
 291         }
 292
 293         /**
 294          * Process the content
 295          *
 296          * @param array $activity Activity array
 297          * @param array $item
 298          * @return array|bool Returns the item array or false if there was an unexpected occurrence
 299          * @throws \Exception
 300          */
 301         private static function processContent($activity, $item)
 302         {
 303                 $item['title'] = HTML::toBBCode($activity['name']);
 304
 305                 if (!empty($activity['source'])) {
 306                         $item['body'] = $activity['source'];
 307                 } else {
 308                         $content = HTML::toBBCode($activity['content']);
 309
 310                         if (!empty($activity['emojis'])) {
 311                                 $content = self::replaceEmojis($content, $activity['emojis']);
 312                         }
 313
 314                         $content = self::convertMentions($content);
 315
 316                         if (empty($activity['directmessage']) && ($item['thr-parent'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
 317                                 $item_private = !in_array(0, $activity['item_receiver']);
 318                                 $parent = Item::selectFirst(['id', 'private', 'author-link', 'alias'], ['uri' => $item['thr-parent']]);
 319                                 if (!DBA::isResult($parent)) {
 320                                         Logger::warning('Unknown parent item.', ['uri' => $item['thr-parent']]);
 321                                         return false;
 322                                 }
 323                                 if ($item_private && !$parent['private']) {
 324                                         Logger::warning('Item is private but the parent is not. Dropping.', ['item-uri' => $item['uri'], 'thr-parent' => $item['thr-parent']]);
 325                                         return false;
 326                                 }
 327
 328                                 $potential_implicit_mentions = self::getImplicitMentionList($parent);
 329                                 $content = self::removeImplicitMentionsFromBody($content, $potential_implicit_mentions);
 330                                 $activity['tags'] = self::convertImplicitMentionsInTags($activity['tags'], $potential_implicit_mentions);
 331                         }
 332                         $item['content-warning'] = HTML::toBBCode($activity['summary']);
 333                         $item['body'] = $content;
 334
 335                         if (($activity['object_type'] == 'as:Video') && !empty($activity['alternate-url'])) {
 336                                 $item['body'] .= "\n[video]" . $activity['alternate-url'] . '[/video]';
 337                         }
 338                 }
 339
 340                 $item['tag'] = self::constructTagString($activity['tags'], $activity['sensitive']);
 341
 342                 $item['location'] = $activity['location'];
 343
 344                 if (!empty($item['latitude']) && !empty($item['longitude'])) {
 345                         $item['coord'] = $item['latitude'] . ' ' . $item['longitude'];
 346                 }
 347
 348                 $item['app'] = $activity['generator'];
 349
 350                 return $item;
 351         }
 352
 353         /**
 354          * Creates an item post
 355          *
 356          * @param array $activity Activity data
 357          * @param array $item     item array
 358          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 359          * @throws \ImagickException
 360          */
 361         private static function postItem($activity, $item)
 362         {
 363                 /// @todo What to do with $activity['context']?
 364                 if (empty($activity['directmessage']) && ($item['gravity'] != GRAVITY_PARENT) && !Item::exists(['uri' => $item['thr-parent']])) {
 365                         Logger::info('Parent not found, message will be discarded.', ['thr-parent' => $item['thr-parent']]);
 366                         return;
 367                 }
 368
 369                 $item['network'] = Protocol::ACTIVITYPUB;
 370                 $item['private'] = !in_array(0, $activity['receiver']);
 371                 $item['author-link'] = $activity['author'];
 372                 $item['author-id'] = Contact::getIdForURL($activity['author'], 0, true);
 373                 $item['owner-link'] = $activity['actor'];
 374                 $item['owner-id'] = Contact::getIdForURL($activity['actor'], 0, true);
 375
 376                 if (!empty($activity['thread-completion'])) {
 377                         // Store the original actor in the "causer" fields to enable the check for ignored or blocked contacts
 378                         $item['causer-link'] = $item['owner-link'];
 379                         $item['causer-id'] = $item['owner-id'];
 380
 381                         Logger::info('Ignoring actor because of thread completion.', ['actor' => $item['owner-link']]);
 382                         $item['owner-link'] = $item['author-link'];
 383                         $item['owner-id'] = $item['author-id'];
 384                 }
 385
 386                 $item['uri'] = $activity['id'];
 387
 388                 $item['created'] = DateTimeFormat::utc($activity['published']);
 389                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 390                 $item['guid'] = $activity['diaspora:guid'];
 391
 392                 $item = self::processContent($activity, $item);
 393                 if (empty($item)) {
 394                         return;
 395                 }
 396
 397                 $item['plink'] = defaults($activity, 'alternate-url', $item['uri']);
 398
 399                 $item = self::constructAttachList($activity['attachments'], $item, !empty($activity['source']));
 400
 401                 $stored = false;
 402
 403                 foreach ($activity['receiver'] as $receiver) {
 404                         $item['uid'] = $receiver;
 405                         $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver, true);
 406
 407                         if (($receiver != 0) && empty($item['contact-id'])) {
 408                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], 0, true);
 409                         }
 410
 411                         if (!empty($activity['directmessage'])) {
 412                                 self::postMail($activity, $item);
 413                                 continue;
 414                         }
 415
 416                         if ($activity['object_type'] == 'as:Event') {
 417                                 self::createEvent($activity, $item);
 418                         }
 419
 420                         $item_id = Item::insert($item);
 421                         if ($item_id) {
 422                                 Logger::info('Item insertion successful', ['user' => $item['uid'], 'item_id' => $item_id]);
 423                         } else {
 424                                 Logger::notice('Item insertion aborted', ['user' => $item['uid']]);
 425                         }
 426
 427                         if ($item['uid'] == 0) {
 428                                 $stored = $item_id;
 429                         }
 430                 }
 431
 432                 // Store send a follow request for every reshare - but only when the item had been stored
 433                 if ($stored && !$item['private'] && ($item['gravity'] == GRAVITY_PARENT) && ($item['author-link'] != $item['owner-link'])) {
 434                         $author = APContact::getByURL($item['owner-link'], false);
 435                         // We send automatic follow requests for reshared messages. (We don't need though for forum posts)
 436                         if ($author['type'] != 'Group') {
 437                                 Logger::log('Send follow request for ' . $item['uri'] . ' (' . $stored . ') to ' . $item['author-link'], Logger::DEBUG);
 438                                 ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
 439                         }
 440                 }
 441         }
 442
 443         /**
 444          * Creates an mail post
 445          *
 446          * @param array $activity Activity data
 447          * @param array $item     item array
 448          * @return int|bool New mail table row id or false on error
 449          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 450          */
 451         private static function postMail($activity, $item)
 452         {
 453                 if (($item['gravity'] != GRAVITY_PARENT) && !DBA::exists('mail', ['uri' => $item['thr-parent'], 'uid' => $item['uid']])) {
 454                         Logger::info('Parent not found, mail will be discarded.', ['uid' => $item['uid'], 'uri' => $item['thr-parent']]);
 455                         return false;
 456                 }
 457
 458                 Logger::info('Direct Message', $item);
 459
 460                 $msg = [];
 461                 $msg['uid'] = $item['uid'];
 462
 463                 $msg['contact-id'] = $item['contact-id'];
 464
 465                 $contact = Contact::getById($item['contact-id'], ['name', 'url', 'photo']);
 466                 $msg['from-name'] = $contact['name'];
 467                 $msg['from-url'] = $contact['url'];
 468                 $msg['from-photo'] = $contact['photo'];
 469
 470                 $msg['uri'] = $item['uri'];
 471                 $msg['created'] = $item['created'];
 472
 473                 $parent = DBA::selectFirst('mail', ['parent-uri', 'title'], ['uri' => $item['thr-parent']]);
 474                 if (DBA::isResult($parent)) {
 475                         $msg['parent-uri'] = $parent['parent-uri'];
 476                         $msg['title'] = $parent['title'];
 477                 } else {
 478                         $msg['parent-uri'] = $item['thr-parent'];
 479
 480                         if (!empty($item['title'])) {
 481                                 $msg['title'] = $item['title'];
 482                         } elseif (!empty($item['content-warning'])) {
 483                                 $msg['title'] = $item['content-warning'];
 484                         } else {
 485                                 // Trying to generate a title out of the body
 486                                 $title = $item['body'];
 487
 488                                 while (preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $title, $matches)) {
 489                                         $title = $matches[3];
 490                                 }
 491
 492                                 $title = trim(HTML::toPlaintext(BBCode::convert($title, false, 2, true), 0));
 493
 494                                 if (strlen($title) > 20) {
 495                                         $title = substr($title, 0, 20) . '...';
 496                                 }
 497
 498                                 $msg['title'] = $title;
 499                         }
 500                 }
 501                 $msg['body'] = $item['body'];
 502
 503                 return Mail::insert($msg);
 504         }
 505
 506         /**
 507          * Fetches missing posts
 508          *
 509          * @param $url
 510          * @param $child
 511          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 512          */
 513         private static function fetchMissingActivity($url, $child)
 514         {
 515                 if (Config::get('system', 'ostatus_full_threads')) {
 516                         return;
 517                 }
 518
 519                 $uid = ActivityPub\Receiver::getFirstUserFromReceivers($child['receiver']);
 520
 521                 $object = ActivityPub::fetchContent($url, $uid);
 522                 if (empty($object)) {
 523                         Logger::log('Activity ' . $url . ' was not fetchable, aborting.');
 524                         return;
 525                 }
 526
 527                 if (empty($object['id'])) {
 528                         Logger::log('Activity ' . $url . ' has got not id, aborting. ' . json_encode($object));
 529                         return;
 530                 }
 531
 532                 $activity = [];
 533                 $activity['@context'] = $object['@context'];
 534                 unset($object['@context']);
 535                 $activity['id'] = $object['id'];
 536                 $activity['to'] = defaults($object, 'to', []);
 537                 $activity['cc'] = defaults($object, 'cc', []);
 538                 $activity['actor'] = $child['author'];
 539                 $activity['object'] = $object;
 540                 $activity['published'] = defaults($object, 'published', $child['published']);
 541                 $activity['type'] = 'Create';
 542
 543                 $ldactivity = JsonLD::compact($activity);
 544
 545                 $ldactivity['thread-completion'] = true;
 546
 547                 ActivityPub\Receiver::processActivity($ldactivity);
 548                 Logger::log('Activity ' . $url . ' had been fetched and processed.');
 549         }
 550
 551         /**
 552          * perform a "follow" request
 553          *
 554          * @param array $activity
 555          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 556          * @throws \ImagickException
 557          */
 558         public static function followUser($activity)
 559         {
 560                 $uid = User::getIdForURL($activity['object_id']);
 561                 if (empty($uid)) {
 562                         return;
 563                 }
 564
 565                 $owner = User::getOwnerDataById($uid);
 566
 567                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 568                 if (!empty($cid)) {
 569                         self::switchContact($cid);
 570                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
 571                         $contact = DBA::selectFirst('contact', [], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
 572                 } else {
 573                         $contact = [];
 574                 }
 575
 576                 $item = ['author-id' => Contact::getIdForURL($activity['actor']),
 577                         'author-link' => $activity['actor']];
 578
 579                 $note = Strings::escapeTags(trim(defaults($activity, 'content', '')));
 580
 581                 // Ensure that the contact has got the right network type
 582                 self::switchContact($item['author-id']);
 583
 584                 $result = Contact::addRelationship($owner, $contact, $item, false, $note);
 585                 if ($result === true) {
 586                         ActivityPub\Transmitter::sendContactAccept($item['author-link'], $item['author-id'], $owner['uid']);
 587                 }
 588
 589                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 590                 if (empty($cid)) {
 591                         return;
 592                 }
 593
 594                 if (empty($contact)) {
 595                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
 596                 }
 597
 598                 Logger::log('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
 599         }
 600
 601         /**
 602          * Update the given profile
 603          *
 604          * @param array $activity
 605          * @throws \Exception
 606          */
 607         public static function updatePerson($activity)
 608         {
 609                 if (empty($activity['object_id'])) {
 610                         return;
 611                 }
 612
 613                 Logger::log('Updating profile for ' . $activity['object_id'], Logger::DEBUG);
 614                 APContact::getByURL($activity['object_id'], true);
 615 //              Contact::updateFromProbe($activity['object_id'], $network = '', $force = false)
 616         }
 617
 618         /**
 619          * Delete the given profile
 620          *
 621          * @param array $activity
 622          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 623          */
 624         public static function deletePerson($activity)
 625         {
 626                 if (empty($activity['object_id']) || empty($activity['actor'])) {
 627                         Logger::log('Empty object id or actor.', Logger::DEBUG);
 628                         return;
 629                 }
 630
 631                 if ($activity['object_id'] != $activity['actor']) {
 632                         Logger::log('Object id does not match actor.', Logger::DEBUG);
 633                         return;
 634                 }
 635
 636                 $contacts = DBA::select('contact', ['id'], ['nurl' => Strings::normaliseLink($activity['object_id'])]);
 637                 while ($contact = DBA::fetch($contacts)) {
 638                         Contact::remove($contact['id']);
 639                 }
 640                 DBA::close($contacts);
 641
 642                 Logger::log('Deleted contact ' . $activity['object_id'], Logger::DEBUG);
 643         }
 644
 645         /**
 646          * Accept a follow request
 647          *
 648          * @param array $activity
 649          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 650          * @throws \ImagickException
 651          */
 652         public static function acceptFollowUser($activity)
 653         {
 654                 $uid = User::getIdForURL($activity['object_actor']);
 655                 if (empty($uid)) {
 656                         return;
 657                 }
 658
 659                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 660                 if (empty($cid)) {
 661                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 662                         return;
 663                 }
 664
 665                 self::switchContact($cid);
 666
 667                 $fields = ['pending' => false];
 668
 669                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
 670                 if ($contact['rel'] == Contact::FOLLOWER) {
 671                         $fields['rel'] = Contact::FRIEND;
 672                 }
 673
 674                 $condition = ['id' => $cid];
 675                 DBA::update('contact', $fields, $condition);
 676                 Logger::log('Accept contact request from contact ' . $cid . ' for user ' . $uid, Logger::DEBUG);
 677         }
 678
 679         /**
 680          * Reject a follow request
 681          *
 682          * @param array $activity
 683          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 684          * @throws \ImagickException
 685          */
 686         public static function rejectFollowUser($activity)
 687         {
 688                 $uid = User::getIdForURL($activity['object_actor']);
 689                 if (empty($uid)) {
 690                         return;
 691                 }
 692
 693                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 694                 if (empty($cid)) {
 695                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 696                         return;
 697                 }
 698
 699                 self::switchContact($cid);
 700
 701                 if (DBA::exists('contact', ['id' => $cid, 'rel' => Contact::SHARING])) {
 702                         Contact::remove($cid);
 703                         Logger::log('Rejected contact request from contact ' . $cid . ' for user ' . $uid . ' - contact had been removed.', Logger::DEBUG);
 704                 } else {
 705                         Logger::log('Rejected contact request from contact ' . $cid . ' for user ' . $uid . '.', Logger::DEBUG);
 706                 }
 707         }
 708
 709         /**
 710          * Undo activity like "like" or "dislike"
 711          *
 712          * @param array $activity
 713          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 714          * @throws \ImagickException
 715          */
 716         public static function undoActivity($activity)
 717         {
 718                 if (empty($activity['object_id'])) {
 719                         return;
 720                 }
 721
 722                 if (empty($activity['object_actor'])) {
 723                         return;
 724                 }
 725
 726                 $author_id = Contact::getIdForURL($activity['object_actor']);
 727                 if (empty($author_id)) {
 728                         return;
 729                 }
 730
 731                 Item::delete(['uri' => $activity['object_id'], 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
 732         }
 733
 734         /**
 735          * Activity to remove a follower
 736          *
 737          * @param array $activity
 738          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 739          * @throws \ImagickException
 740          */
 741         public static function undoFollowUser($activity)
 742         {
 743                 $uid = User::getIdForURL($activity['object_object']);
 744                 if (empty($uid)) {
 745                         return;
 746                 }
 747
 748                 $owner = User::getOwnerDataById($uid);
 749
 750                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 751                 if (empty($cid)) {
 752                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 753                         return;
 754                 }
 755
 756                 self::switchContact($cid);
 757
 758                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
 759                 if (!DBA::isResult($contact)) {
 760                         return;
 761                 }
 762
 763                 Contact::removeFollower($owner, $contact);
 764                 Logger::log('Undo following request from contact ' . $cid . ' for user ' . $uid, Logger::DEBUG);
 765         }
 766
 767         /**
 768          * Switches a contact to AP if needed
 769          *
 770          * @param integer $cid Contact ID
 771          * @throws \Exception
 772          */
 773         private static function switchContact($cid)
 774         {
 775                 $contact = DBA::selectFirst('contact', ['network'], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
 776                 if (!DBA::isResult($contact) || in_array($contact['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN])) {
 777                         return;
 778                 }
 779
 780                 Logger::log('Change existing contact ' . $cid . ' from ' . $contact['network'] . ' to ActivityPub.');
 781                 Contact::updateFromProbe($cid, Protocol::ACTIVITYPUB);
 782         }
 783
 784         /**
 785          * Collects implicit mentions like:
 786          * - the author of the parent item
 787          * - all the mentioned conversants in the parent item
 788          *
 789          * @param array $parent Item array with at least ['id', 'author-link', 'alias']
 790          * @return array
 791          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 792          */
 793         private static function getImplicitMentionList(array $parent)
 794         {
 795                 if (Config::get('system', 'disable_implicit_mentions')) {
 796                         return [];
 797                 }
 798
 799                 $parent_terms = Term::tagArrayFromItemId($parent['id'], [Term::MENTION, Term::IMPLICIT_MENTION]);
 800
 801                 $parent_author = Contact::getDetailsByURL($parent['author-link'], 0);
 802
 803                 $implicit_mentions = [];
 804                 if (empty($parent_author)) {
 805                         Logger::notice('Author public contact unknown.', ['author-link' => $parent['author-link'], 'item-id' => $parent['id']]);
 806                 } else {
 807                         $implicit_mentions[] = $parent_author['url'];
 808                         $implicit_mentions[] = $parent_author['nurl'];
 809                         $implicit_mentions[] = $parent_author['alias'];
 810                 }
 811
 812                 if (!empty($parent['alias'])) {
 813                         $implicit_mentions[] = $parent['alias'];
 814                 }
 815
 816                 foreach ($parent_terms as $term) {
 817                         $contact = Contact::getDetailsByURL($term['url'], 0);
 818                         if (!empty($contact)) {
 819                                 $implicit_mentions[] = $contact['url'];
 820                                 $implicit_mentions[] = $contact['nurl'];
 821                                 $implicit_mentions[] = $contact['alias'];
 822                         }
 823                 }
 824
 825                 return $implicit_mentions;
 826         }
 827
 828         /**
 829          * Strips from the body prepended implicit mentions
 830          *
 831          * @param string $body
 832          * @param array $potential_mentions
 833          * @return string
 834          */
 835         private static function removeImplicitMentionsFromBody($body, array $potential_mentions)
 836         {
 837                 if (Config::get('system', 'disable_implicit_mentions')) {
 838                         return $body;
 839                 }
 840
 841                 $kept_mentions = [];
 842
 843                 // Extract one prepended mention at a time from the body
 844                 while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $body, $matches)) {
 845                         if (!in_array($matches[2], $potential_mentions) ) {
 846                                 $kept_mentions[] = $matches[1];
 847                         }
 848
 849                         $body = $matches[3];
 850                 }
 851
 852                 // Re-appending the kept mentions to the body after extraction
 853                 $kept_mentions[] = $body;
 854
 855                 return implode('', $kept_mentions);
 856         }
 857
 858         private static function convertImplicitMentionsInTags($activity_tags, array $potential_mentions)
 859         {
 860                 if (Config::get('system', 'disable_implicit_mentions')) {
 861                         return $activity_tags;
 862                 }
 863
 864                 foreach ($activity_tags as $index => $tag) {
 865                         if (in_array($tag['href'], $potential_mentions)) {
 866                                 $activity_tags[$index]['name'] = preg_replace(
 867                                         '/' . preg_quote(Term::TAG_CHARACTER[Term::MENTION], '/') . '/',
 868                                         Term::TAG_CHARACTER[Term::IMPLICIT_MENTION],
 869                                         $activity_tags[$index]['name'],
 870                                         1
 871                                 );
 872                         }
 873                 }
 874
 875                 return $activity_tags;
 876         }
 877 }