src/Protocol/ActivityPub/Processor.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2022, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Protocol\ActivityPub;
  23
  24 use Friendica\Content\Text\BBCode;
  25 use Friendica\Content\Text\HTML;
  26 use Friendica\Content\Text\Markdown;
  27 use Friendica\Core\Logger;
  28 use Friendica\Core\Protocol;
  29 use Friendica\Core\System;
  30 use Friendica\Database\DBA;
  31 use Friendica\DI;
  32 use Friendica\Model\APContact;
  33 use Friendica\Model\Contact;
  34 use Friendica\Model\Conversation;
  35 use Friendica\Model\Event;
  36 use Friendica\Model\GServer;
  37 use Friendica\Model\Item;
  38 use Friendica\Model\ItemURI;
  39 use Friendica\Model\Mail;
  40 use Friendica\Model\Tag;
  41 use Friendica\Model\User;
  42 use Friendica\Model\Post;
  43 use Friendica\Protocol\Activity;
  44 use Friendica\Protocol\ActivityPub;
  45 use Friendica\Protocol\Relay;
  46 use Friendica\Util\DateTimeFormat;
  47 use Friendica\Util\JsonLD;
  48 use Friendica\Util\Strings;
  49
  50 /**
  51  * ActivityPub Processor Protocol class
  52  */
  53 class Processor
  54 {
  55         /**
  56          * Extracts the tag character (#, @, !) from mention links
  57          *
  58          * @param string $body
  59          * @return string
  60          */
  61         protected static function normalizeMentionLinks(string $body): string
  62         {
  63                 return preg_replace('%\[url=([^\[\]]*)]([#@!])(.*?)\[/url]%ism', '$2[url=$1]$3[/url]', $body);
  64         }
  65
  66         /**
  67          * Convert the language array into a language JSON
  68          *
  69          * @param array $languages
  70          * @return string language JSON
  71          */
  72         private static function processLanguages(array $languages)
  73         {
  74                 $codes = array_keys($languages);
  75                 $lang = [];
  76                 foreach ($codes as $code) {
  77                         $lang[$code] = 1;
  78                 }
  79
  80                 if (empty($lang)) {
  81                         return '';
  82                 }
  83
  84                 return json_encode($lang);
  85         }
  86         /**
  87          * Replaces emojis in the body
  88          *
  89          * @param array $emojis
  90          * @param string $body
  91          *
  92          * @return string with replaced emojis
  93          */
  94         private static function replaceEmojis(int $uri_id, $body, array $emojis)
  95         {
  96                 $body = strtr($body,
  97                         array_combine(
  98                                 array_column($emojis, 'name'),
  99                                 array_map(function ($emoji) {
 100                                         return '[emoji=' . $emoji['href'] . ']' . $emoji['name'] . '[/emoji]';
 101                                 }, $emojis)
 102                         )
 103                 );
 104
 105                 // We store the emoji here to be able to avoid storing it in the media
 106                 foreach ($emojis as $emoji) {
 107                         Post\Link::getByLink($uri_id, $emoji['href']);
 108                 }
 109                 return $body;
 110         }
 111
 112         /**
 113          * Store attached media files in the post-media table
 114          *
 115          * @param int $uriid
 116          * @param array $attachment
 117          * @return void
 118          */
 119         private static function storeAttachmentAsMedia(int $uriid, array $attachment)
 120         {
 121                 if (empty($attachment['url'])) {
 122                         return;
 123                 }
 124
 125                 $data = ['uri-id' => $uriid];
 126                 $data['type'] = Post\Media::UNKNOWN;
 127                 $data['url'] = $attachment['url'];
 128                 $data['mimetype'] = $attachment['mediaType'] ?? null;
 129                 $data['height'] = $attachment['height'] ?? null;
 130                 $data['width'] = $attachment['width'] ?? null;
 131                 $data['size'] = $attachment['size'] ?? null;
 132                 $data['preview'] = $attachment['image'] ?? null;
 133                 $data['description'] = $attachment['name'] ?? null;
 134
 135                 Post\Media::insert($data);
 136         }
 137
 138         /**
 139          * Stire attachment data
 140          *
 141          * @param array   $activity
 142          * @param array   $item
 143          */
 144         private static function storeAttachments($activity, $item)
 145         {
 146                 if (empty($activity['attachments'])) {
 147                         return;
 148                 }
 149
 150                 foreach ($activity['attachments'] as $attach) {
 151                         self::storeAttachmentAsMedia($item['uri-id'], $attach);
 152                 }
 153         }
 154
 155         /**
 156          * Updates a message
 157          *
 158          * @param array $activity Activity array
 159          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 160          */
 161         public static function updateItem($activity)
 162         {
 163                 $item = Post::selectFirst(['uri', 'uri-id', 'thr-parent', 'gravity', 'post-type'], ['uri' => $activity['id']]);
 164                 if (!DBA::isResult($item)) {
 165                         Logger::warning('No existing item, item will be created', ['uri' => $activity['id']]);
 166                         $item = self::createItem($activity);
 167                         if (empty($item)) {
 168                                 return;
 169                         }
 170
 171                         self::postItem($activity, $item);
 172                         return;
 173                 }
 174
 175                 $item['changed'] = DateTimeFormat::utcNow();
 176                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 177
 178                 $item = self::processContent($activity, $item);
 179
 180                 self::storeAttachments($activity, $item);
 181
 182                 if (empty($item)) {
 183                         return;
 184                 }
 185
 186                 Item::update($item, ['uri' => $activity['id']]);
 187
 188                 if ($activity['object_type'] == 'as:Event') {
 189                         $posts = Post::select(['event-id', 'uid'], ["`uri` = ? AND `event-id` > ?", $activity['id'], 0]);
 190                         while ($post = DBA::fetch($posts)) {
 191                                 self::updateEvent($post['event-id'], $activity);
 192                         }
 193                 }
 194         }
 195
 196         /**
 197          * Update an existing event
 198          *
 199          * @param int $event_id
 200          * @param array $activity
 201          */
 202         private static function updateEvent(int $event_id, array $activity)
 203         {
 204                 $event = DBA::selectFirst('event', [], ['id' => $event_id]);
 205
 206                 $event['edited']   = DateTimeFormat::utc($activity['updated']);
 207                 $event['summary']  = HTML::toBBCode($activity['name']);
 208                 $event['desc']     = HTML::toBBCode($activity['content']);
 209                 $event['start']    = $activity['start-time'];
 210                 $event['finish']   = $activity['end-time'];
 211                 $event['nofinish'] = empty($event['finish']);
 212                 $event['location'] = $activity['location'];
 213
 214                 Logger::info('Updating event', ['uri' => $activity['id'], 'id' => $event_id]);
 215                 Event::store($event);
 216         }
 217
 218         /**
 219          * Prepares data for a message
 220          *
 221          * @param array $activity Activity array
 222          * @return array Internal item
 223          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 224          * @throws \ImagickException
 225          */
 226         public static function createItem($activity)
 227         {
 228                 $item = [];
 229                 $item['verb'] = Activity::POST;
 230                 $item['thr-parent'] = $activity['reply-to-id'];
 231
 232                 if ($activity['reply-to-id'] == $activity['id']) {
 233                         $item['gravity'] = GRAVITY_PARENT;
 234                         $item['object-type'] = Activity\ObjectType::NOTE;
 235                 } else {
 236                         $item['gravity'] = GRAVITY_COMMENT;
 237                         $item['object-type'] = Activity\ObjectType::COMMENT;
 238                 }
 239
 240                 if (empty($activity['directmessage']) && ($activity['id'] != $activity['reply-to-id']) && !Post::exists(['uri' => $activity['reply-to-id']])) {
 241                         Logger::notice('Parent not found. Try to refetch it.', ['parent' => $activity['reply-to-id']]);
 242                         self::fetchMissingActivity($activity['reply-to-id'], $activity, '', Receiver::COMPLETION_AUTO);
 243                 }
 244
 245                 $item['diaspora_signed_text'] = $activity['diaspora:comment'] ?? '';
 246
 247                 /// @todo What to do with $activity['context']?
 248                 if (empty($activity['directmessage']) && ($item['gravity'] != GRAVITY_PARENT) && !Post::exists(['uri' => $item['thr-parent']])) {
 249                         Logger::info('Parent not found, message will be discarded.', ['thr-parent' => $item['thr-parent']]);
 250                         return [];
 251                 }
 252
 253                 $item['network'] = Protocol::ACTIVITYPUB;
 254                 $item['author-link'] = $activity['author'];
 255                 $item['author-id'] = Contact::getIdForURL($activity['author']);
 256                 $item['owner-link'] = $activity['actor'];
 257                 $item['owner-id'] = Contact::getIdForURL($activity['actor']);
 258
 259                 if (in_array(0, $activity['receiver']) && !empty($activity['unlisted'])) {
 260                         $item['private'] = Item::UNLISTED;
 261                 } elseif (in_array(0, $activity['receiver'])) {
 262                         $item['private'] = Item::PUBLIC;
 263                 } else {
 264                         $item['private'] = Item::PRIVATE;
 265                 }
 266
 267                 if (!empty($activity['raw'])) {
 268                         $item['source'] = $activity['raw'];
 269                         $item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
 270                         $item['conversation-href'] = $activity['context'] ?? '';
 271                         $item['conversation-uri'] = $activity['conversation'] ?? '';
 272
 273                         if (isset($activity['push'])) {
 274                                 $item['direction'] = $activity['push'] ? Conversation::PUSH : Conversation::PULL;
 275                         }
 276                 }
 277
 278                 if (!empty($activity['from-relay'])) {
 279                         $item['direction'] = Conversation::RELAY;
 280                 }
 281
 282                 if ($activity['object_type'] == 'as:Article') {
 283                         $item['post-type'] = Item::PT_ARTICLE;
 284                 } elseif ($activity['object_type'] == 'as:Audio') {
 285                         $item['post-type'] = Item::PT_AUDIO;
 286                 } elseif ($activity['object_type'] == 'as:Document') {
 287                         $item['post-type'] = Item::PT_DOCUMENT;
 288                 } elseif ($activity['object_type'] == 'as:Event') {
 289                         $item['post-type'] = Item::PT_EVENT;
 290                 } elseif ($activity['object_type'] == 'as:Image') {
 291                         $item['post-type'] = Item::PT_IMAGE;
 292                 } elseif ($activity['object_type'] == 'as:Page') {
 293                         $item['post-type'] = Item::PT_PAGE;
 294                 } elseif ($activity['object_type'] == 'as:Question') {
 295                         $item['post-type'] = Item::PT_POLL;
 296                 } elseif ($activity['object_type'] == 'as:Video') {
 297                         $item['post-type'] = Item::PT_VIDEO;
 298                 } else {
 299                         $item['post-type'] = Item::PT_NOTE;
 300                 }
 301
 302                 $item['isForum'] = false;
 303
 304                 if (!empty($activity['thread-completion'])) {
 305                         if ($activity['thread-completion'] != $item['owner-id']) {
 306                                 $actor = Contact::getById($activity['thread-completion'], ['url']);
 307                                 $item['causer-link'] = $actor['url'];
 308                                 $item['causer-id'] = $activity['thread-completion'];
 309                                 Logger::info('Use inherited actor as causer.', ['id' => $item['owner-id'], 'activity' => $activity['thread-completion'], 'owner' => $item['owner-link'], 'actor' => $actor['url']]);
 310                         } else {
 311                                 // Store the original actor in the "causer" fields to enable the check for ignored or blocked contacts
 312                                 $item['causer-link'] = $item['owner-link'];
 313                                 $item['causer-id']   = $item['owner-id'];
 314                                 Logger::info('Use actor as causer.', ['id' => $item['owner-id'], 'actor' => $item['owner-link']]);
 315                         }
 316
 317                         $item['owner-link'] = $item['author-link'];
 318                         $item['owner-id'] = $item['author-id'];
 319                 } else {
 320                         $actor = APContact::getByURL($item['owner-link'], false);
 321                         $item['isForum'] = ($actor['type'] == 'Group');
 322                 }
 323
 324                 $item['uri'] = $activity['id'];
 325
 326                 if (empty($activity['published']) || empty($activity['updated'])) {
 327                         DI::logger()->notice('published or updated keys are empty for activity', ['activity' => $activity, 'callstack' => System::callstack(10)]);
 328                 }
 329
 330                 $item['created'] = DateTimeFormat::utc($activity['published'] ?? 'now');
 331                 $item['edited'] = DateTimeFormat::utc($activity['updated'] ?? 'now');
 332                 $guid = $activity['sc:identifier'] ?: self::getGUIDByURL($item['uri']);
 333                 $item['guid'] = $activity['diaspora:guid'] ?: $guid;
 334
 335                 $item['uri-id'] = ItemURI::insert(['uri' => $item['uri'], 'guid' => $item['guid']]);
 336                 if (empty($item['uri-id'])) {
 337                         Logger::warning('Unable to get a uri-id for an item uri', ['uri' => $item['uri'], 'guid' => $item['guid']]);
 338                         return [];
 339                 }
 340
 341                 $item = self::processContent($activity, $item);
 342                 if (empty($item)) {
 343                         Logger::info('Message was not processed');
 344                         return [];
 345                 }
 346
 347                 $item['plink'] = $activity['alternate-url'] ?? $item['uri'];
 348
 349                 self::storeAttachments($activity, $item);
 350
 351                 // We received the post via AP, so we set the protocol of the server to AP
 352                 $contact = Contact::getById($item['author-id'], ['gsid']);
 353                 if (!empty($contact['gsid'])) {
 354                         GServer::setProtocol($contact['gsid'], Post\DeliveryData::ACTIVITYPUB);
 355                 }
 356
 357                 if ($item['author-id'] != $item['owner-id']) {
 358                         $contact = Contact::getById($item['owner-id'], ['gsid']);
 359                         if (!empty($contact['gsid'])) {
 360                                 GServer::setProtocol($contact['gsid'], Post\DeliveryData::ACTIVITYPUB);
 361                         }
 362                 }
 363
 364                 return $item;
 365         }
 366
 367         /**
 368          * Delete items
 369          *
 370          * @param array $activity
 371          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 372          * @throws \ImagickException
 373          */
 374         public static function deleteItem($activity)
 375         {
 376                 $owner = Contact::getIdForURL($activity['actor']);
 377
 378                 Logger::info('Deleting item', ['object' => $activity['object_id'], 'owner'  => $owner]);
 379                 Item::markForDeletion(['uri' => $activity['object_id'], 'owner-id' => $owner]);
 380         }
 381
 382         /**
 383          * Prepare the item array for an activity
 384          *
 385          * @param array $activity Activity array
 386          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 387          * @throws \ImagickException
 388          */
 389         public static function addTag($activity)
 390         {
 391                 if (empty($activity['object_content']) || empty($activity['object_id'])) {
 392                         return;
 393                 }
 394
 395                 foreach ($activity['receiver'] as $receiver) {
 396                         $item = Post::selectFirst(['id', 'uri-id', 'origin', 'author-link'], ['uri' => $activity['target_id'], 'uid' => $receiver]);
 397                         if (!DBA::isResult($item)) {
 398                                 // We don't fetch missing content for this purpose
 399                                 continue;
 400                         }
 401
 402                         if (($item['author-link'] != $activity['actor']) && !$item['origin']) {
 403                                 Logger::info('Not origin, not from the author, skipping update', ['id' => $item['id'], 'author' => $item['author-link'], 'actor' => $activity['actor']]);
 404                                 continue;
 405                         }
 406
 407                         Tag::store($item['uri-id'], Tag::HASHTAG, $activity['object_content'], $activity['object_id']);
 408                         Logger::info('Tagged item', ['id' => $item['id'], 'tag' => $activity['object_content'], 'uri' => $activity['target_id'], 'actor' => $activity['actor']]);
 409                 }
 410         }
 411
 412         /**
 413          * Prepare the item array for an activity
 414          *
 415          * @param array  $activity Activity array
 416          * @param string $verb     Activity verb
 417          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 418          * @throws \ImagickException
 419          */
 420         public static function createActivity($activity, $verb)
 421         {
 422                 $item = self::createItem($activity);
 423                 if (empty($item)) {
 424                         return;
 425                 }
 426
 427                 $item['verb'] = $verb;
 428                 $item['thr-parent'] = $activity['object_id'];
 429                 $item['gravity'] = GRAVITY_ACTIVITY;
 430                 unset($item['post-type']);
 431                 $item['object-type'] = Activity\ObjectType::NOTE;
 432
 433                 $item['diaspora_signed_text'] = $activity['diaspora:like'] ?? '';
 434
 435                 self::postItem($activity, $item);
 436         }
 437
 438         /**
 439          * Create an event
 440          *
 441          * @param array $activity Activity array
 442          * @param array $item
 443          *
 444          * @return int event id
 445          * @throws \Exception
 446          */
 447         public static function createEvent($activity, $item)
 448         {
 449                 $event['summary']   = HTML::toBBCode($activity['name'] ?: $activity['summary']);
 450                 $event['desc']      = HTML::toBBCode($activity['content']);
 451                 $event['start']     = $activity['start-time'];
 452                 $event['finish']    = $activity['end-time'];
 453                 $event['nofinish']  = empty($event['finish']);
 454                 $event['location']  = $activity['location'];
 455                 $event['cid']       = $item['contact-id'];
 456                 $event['uid']       = $item['uid'];
 457                 $event['uri']       = $item['uri'];
 458                 $event['edited']    = $item['edited'];
 459                 $event['private']   = $item['private'];
 460                 $event['guid']      = $item['guid'];
 461                 $event['plink']     = $item['plink'];
 462                 $event['network']   = $item['network'];
 463                 $event['protocol']  = $item['protocol'];
 464                 $event['direction'] = $item['direction'];
 465                 $event['source']    = $item['source'];
 466
 467                 $ev = DBA::selectFirst('event', ['id'], ['uri' => $item['uri'], 'uid' => $item['uid']]);
 468                 if (DBA::isResult($ev)) {
 469                         $event['id'] = $ev['id'];
 470                 }
 471
 472                 $event_id = Event::store($event);
 473
 474                 Logger::info('Event was stored', ['id' => $event_id]);
 475
 476                 return $event_id;
 477         }
 478
 479         /**
 480          * Process the content
 481          *
 482          * @param array $activity Activity array
 483          * @param array $item
 484          * @return array|bool Returns the item array or false if there was an unexpected occurrence
 485          * @throws \Exception
 486          */
 487         private static function processContent($activity, $item)
 488         {
 489                 if (!empty($activity['mediatype']) && ($activity['mediatype'] == 'text/markdown')) {
 490                         $item['title'] = Markdown::toBBCode($activity['name']);
 491                         $content = Markdown::toBBCode($activity['content']);
 492                 } elseif (!empty($activity['mediatype']) && ($activity['mediatype'] == 'text/bbcode')) {
 493                         $item['title'] = $activity['name'];
 494                         $content = $activity['content'];
 495                 } else {
 496                         // By default assume "text/html"
 497                         $item['title'] = HTML::toBBCode($activity['name']);
 498                         $content = HTML::toBBCode($activity['content']);
 499                 }
 500
 501                 if (!empty($activity['languages'])) {
 502                         $item['language'] = self::processLanguages($activity['languages']);
 503                 }
 504
 505                 if (!empty($activity['emojis'])) {
 506                         $content = self::replaceEmojis($item['uri-id'], $content, $activity['emojis']);
 507                 }
 508
 509                 $content = self::addMentionLinks($content, $activity['tags']);
 510
 511                 if (!empty($activity['source'])) {
 512                         $item['body'] = $activity['source'];
 513                         $item['raw-body'] = $content;
 514                         $item['body'] = Item::improveSharedDataInBody($item);
 515                 } else {
 516                         if (empty($activity['directmessage']) && ($item['thr-parent'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
 517                                 $item_private = !in_array(0, $activity['item_receiver']);
 518                                 $parent = Post::selectFirst(['id', 'uri-id', 'private', 'author-link', 'alias'], ['uri' => $item['thr-parent']]);
 519                                 if (!DBA::isResult($parent)) {
 520                                         Logger::warning('Unknown parent item.', ['uri' => $item['thr-parent']]);
 521                                         return false;
 522                                 }
 523                                 if ($item_private && ($parent['private'] != Item::PRIVATE)) {
 524                                         Logger::warning('Item is private but the parent is not. Dropping.', ['item-uri' => $item['uri'], 'thr-parent' => $item['thr-parent']]);
 525                                         return false;
 526                                 }
 527
 528                                 $content = self::removeImplicitMentionsFromBody($content, $parent);
 529                         }
 530                         $item['content-warning'] = HTML::toBBCode($activity['summary']);
 531                         $item['raw-body'] = $item['body'] = $content;
 532                 }
 533
 534                 self::storeFromBody($item);
 535                 self::storeTags($item['uri-id'], $activity['tags']);
 536
 537                 self::storeReceivers($item['uri-id'], $activity['receiver_urls'] ?? []);
 538
 539                 $item['location'] = $activity['location'];
 540
 541                 if (!empty($activity['latitude']) && !empty($activity['longitude'])) {
 542                         $item['coord'] = $activity['latitude'] . ' ' . $activity['longitude'];
 543                 }
 544
 545                 $item['app'] = $activity['generator'];
 546
 547                 return $item;
 548         }
 549
 550         /**
 551          * Store hashtags and mentions
 552          *
 553          * @param array $item
 554          */
 555         private static function storeFromBody(array $item)
 556         {
 557                 // Make sure to delete all existing tags (can happen when called via the update functionality)
 558                 DBA::delete('post-tag', ['uri-id' => $item['uri-id']]);
 559
 560                 Tag::storeFromBody($item['uri-id'], $item['body'], '@!');
 561         }
 562
 563         /**
 564          * Generate a GUID out of an URL of an ActivityPub post.
 565          *
 566          * @param string $url message URL
 567          * @return string with GUID
 568          */
 569         private static function getGUIDByURL(string $url)
 570         {
 571                 $parsed = parse_url($url);
 572
 573                 $host_hash = hash('crc32', $parsed['host']);
 574
 575                 unset($parsed["scheme"]);
 576                 unset($parsed["host"]);
 577
 578                 $path = implode("/", $parsed);
 579
 580                 return $host_hash . '-'. hash('fnv164', $path) . '-'. hash('joaat', $path);
 581         }
 582
 583         /**
 584          * Checks if an incoming message is wanted
 585          *
 586          * @param array $activity
 587          * @param array $item
 588          * @return boolean Is the message wanted?
 589          */
 590         private static function isSolicitedMessage(array $activity, array $item)
 591         {
 592                 // The checks are split to improve the support when searching why a message was accepted.
 593                 if (count($activity['receiver']) != 1) {
 594                         // The message has more than one receiver, so it is wanted.
 595                         Logger::debug('Message has got several receivers - accepted', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 596                         return true;
 597                 }
 598
 599                 if ($item['private'] == Item::PRIVATE) {
 600                         // We only look at public posts here. Private posts are expected to be intentionally posted to the single receiver.
 601                         Logger::debug('Message is private - accepted', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 602                         return true;
 603                 }
 604
 605                 if (!empty($activity['from-relay'])) {
 606                         // We check relay posts at another place. When it arrived here, the message is already checked.
 607                         Logger::debug('Message is a relay post that is already checked - accepted', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 608                         return true;
 609                 }
 610
 611                 if (in_array($activity['completion-mode'] ?? Receiver::COMPLETION_NONE, [Receiver::COMPLETION_MANUAL, Receiver::COMPLETION_ANNOUCE])) {
 612                         // Manual completions and completions caused by reshares are allowed without any further checks.
 613                         Logger::debug('Message is in completion mode - accepted', ['mode' => $activity['completion-mode'], 'uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 614                         return true;
 615                 }
 616
 617                 if ($item['gravity'] != GRAVITY_PARENT) {
 618                         // We cannot reliably check at this point if a comment or activity belongs to an accepted post or needs to be fetched
 619                         // This can possibly be improved in the future.
 620                         Logger::debug('Message is no parent - accepted', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 621                         return true;
 622                 }
 623
 624                 $tags = array_column(Tag::getByURIId($item['uri-id'], [Tag::HASHTAG]), 'name');
 625                 if (Relay::isSolicitedPost($tags, $item['body'], $item['author-id'], $item['uri'], Protocol::ACTIVITYPUB)) {
 626                         Logger::debug('Post is accepted because of the relay settings', ['uri-id' => $item['uri-id'], 'guid' => $item['guid'], 'url' => $item['uri']]);
 627                         return true;
 628                 } else {
 629                         return false;
 630                 }
 631         }
 632
 633         /**
 634          * Creates an item post
 635          *
 636          * @param array $activity Activity data
 637          * @param array $item     item array
 638          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 639          * @throws \ImagickException
 640          */
 641         public static function postItem(array $activity, array $item)
 642         {
 643                 if (empty($item)) {
 644                         return;
 645                 }
 646
 647                 $stored = false;
 648                 ksort($activity['receiver']);
 649
 650                 if (!self::isSolicitedMessage($activity, $item)) {
 651                         DBA::delete('item-uri', ['id' => $item['uri-id']]);
 652                         return;
 653                 }
 654
 655                 foreach ($activity['receiver'] as $receiver) {
 656                         if ($receiver == -1) {
 657                                 continue;
 658                         }
 659
 660                         $item['uid'] = $receiver;
 661
 662                         $type = $activity['reception_type'][$receiver] ?? Receiver::TARGET_UNKNOWN;
 663                         switch($type) {
 664                                 case Receiver::TARGET_TO:
 665                                         $item['post-reason'] = Item::PR_TO;
 666                                         break;
 667                                 case Receiver::TARGET_CC:
 668                                         $item['post-reason'] = Item::PR_CC;
 669                                         break;
 670                                 case Receiver::TARGET_BTO:
 671                                         $item['post-reason'] = Item::PR_BTO;
 672                                         break;
 673                                 case Receiver::TARGET_BCC:
 674                                         $item['post-reason'] = Item::PR_BCC;
 675                                         break;
 676                                 case Receiver::TARGET_FOLLOWER:
 677                                         $item['post-reason'] = Item::PR_FOLLOWER;
 678                                         break;
 679                                 case Receiver::TARGET_ANSWER:
 680                                         $item['post-reason'] = Item::PR_COMMENT;
 681                                         break;
 682                                 case Receiver::TARGET_GLOBAL:
 683                                         $item['post-reason'] = Item::PR_GLOBAL;
 684                                         break;
 685                                 default:
 686                                         $item['post-reason'] = Item::PR_NONE;
 687                         }
 688
 689                         if (!empty($activity['from-relay'])) {
 690                                 $item['post-reason'] = Item::PR_RELAY;
 691                         } elseif (!empty($activity['thread-completion'])) {
 692                                 $item['post-reason'] = Item::PR_FETCHED;
 693                         }
 694
 695                         if ($item['isForum'] ?? false) {
 696                                 $item['contact-id'] = Contact::getIdForURL($activity['actor'], $receiver);
 697                         } else {
 698                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver);
 699                         }
 700
 701                         if (($receiver != 0) && empty($item['contact-id'])) {
 702                                 $item['contact-id'] = Contact::getIdForURL($activity['author']);
 703                         }
 704
 705                         if (!empty($activity['directmessage'])) {
 706                                 self::postMail($activity, $item);
 707                                 continue;
 708                         }
 709
 710                         if (!($item['isForum'] ?? false) && ($receiver != 0) && ($item['gravity'] == GRAVITY_PARENT) && !Contact::isSharingByURL($activity['author'], $receiver)) {
 711                                 if ($item['post-reason'] == Item::PR_BCC) {
 712                                         Logger::info('Top level post via BCC from a non sharer, ignoring', ['uid' => $receiver, 'contact' => $item['contact-id']]);
 713                                         continue;
 714                                 }
 715
 716                                 if (
 717                                         !empty($activity['thread-children-type'])
 718                                         && in_array($activity['thread-children-type'], Receiver::ACTIVITY_TYPES)
 719                                         && DI::pConfig()->get($receiver, 'system', 'accept_only_sharer') != Item::COMPLETION_LIKE
 720                                 ) {
 721                                         Logger::info('Top level post from thread completion from a non sharer had been initiated via an activity, ignoring',
 722                                                 ['type' => $activity['thread-children-type'], 'user' => $item['uid'], 'causer' => $item['causer-link'], 'author' => $activity['author'], 'url' => $item['uri']]);
 723                                         continue;
 724                                 }
 725                         }
 726
 727                         $is_forum = false;
 728
 729                         if ($receiver != 0) {
 730                                 $user = User::getById($receiver, ['account-type']);
 731                                 if (!empty($user['account-type'])) {
 732                                         $is_forum = ($user['account-type'] == User::ACCOUNT_TYPE_COMMUNITY);
 733                                 }
 734                         }
 735
 736                         if (!$is_forum && DI::pConfig()->get($receiver, 'system', 'accept_only_sharer') == Item::COMPLETION_NONE && ($receiver != 0) && ($item['gravity'] == GRAVITY_PARENT)) {
 737                                 $skip = !Contact::isSharingByURL($activity['author'], $receiver);
 738
 739                                 if ($skip && (($activity['type'] == 'as:Announce') || ($item['isForum'] ?? false))) {
 740                                         $skip = !Contact::isSharingByURL($activity['actor'], $receiver);
 741                                 }
 742
 743                                 if ($skip) {
 744                                         Logger::info('Skipping post', ['uid' => $receiver, 'url' => $item['uri']]);
 745                                         continue;
 746                                 }
 747
 748                                 Logger::info('Accepting post', ['uid' => $receiver, 'url' => $item['uri']]);
 749                         }
 750
 751                         if (($item['gravity'] != GRAVITY_ACTIVITY) && ($activity['object_type'] == 'as:Event')) {
 752                                 $event_id = self::createEvent($activity, $item);
 753
 754                                 $item = Event::getItemArrayForImportedId($event_id, $item);
 755                         }
 756
 757                         $item_id = Item::insert($item);
 758                         if ($item_id) {
 759                                 Logger::info('Item insertion successful', ['user' => $item['uid'], 'item_id' => $item_id]);
 760                         } else {
 761                                 Logger::notice('Item insertion aborted', ['user' => $item['uid']]);
 762                         }
 763
 764                         if ($item['uid'] == 0) {
 765                                 $stored = $item_id;
 766                         }
 767                 }
 768
 769                 // Store send a follow request for every reshare - but only when the item had been stored
 770                 if ($stored && ($item['private'] != Item::PRIVATE) && ($item['gravity'] == GRAVITY_PARENT) && ($item['author-link'] != $item['owner-link'])) {
 771                         $author = APContact::getByURL($item['owner-link'], false);
 772                         // We send automatic follow requests for reshared messages. (We don't need though for forum posts)
 773                         if ($author['type'] != 'Group') {
 774                                 Logger::info('Send follow request', ['uri' => $item['uri'], 'stored' => $stored, 'to' => $item['author-link']]);
 775                                 ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
 776                         }
 777                 }
 778         }
 779
 780         /**
 781          * Store tags and mentions into the tag table
 782          *
 783          * @param integer $uriid
 784          * @param array $tags
 785          */
 786         private static function storeTags(int $uriid, array $tags = null)
 787         {
 788                 foreach ($tags as $tag) {
 789                         if (empty($tag['name']) || empty($tag['type']) || !in_array($tag['type'], ['Mention', 'Hashtag'])) {
 790                                 continue;
 791                         }
 792
 793                         $hash = substr($tag['name'], 0, 1);
 794
 795                         if ($tag['type'] == 'Mention') {
 796                                 if (in_array($hash, [Tag::TAG_CHARACTER[Tag::MENTION],
 797                                         Tag::TAG_CHARACTER[Tag::EXCLUSIVE_MENTION],
 798                                         Tag::TAG_CHARACTER[Tag::IMPLICIT_MENTION]])) {
 799                                         $tag['name'] = substr($tag['name'], 1);
 800                                 }
 801                                 $type = Tag::IMPLICIT_MENTION;
 802
 803                                 if (!empty($tag['href'])) {
 804                                         $apcontact = APContact::getByURL($tag['href']);
 805                                         if (!empty($apcontact['name']) || !empty($apcontact['nick'])) {
 806                                                 $tag['name'] = $apcontact['name'] ?: $apcontact['nick'];
 807                                         }
 808                                 }
 809                         } elseif ($tag['type'] == 'Hashtag') {
 810                                 if ($hash == Tag::TAG_CHARACTER[Tag::HASHTAG]) {
 811                                         $tag['name'] = substr($tag['name'], 1);
 812                                 }
 813                                 $type = Tag::HASHTAG;
 814                         }
 815
 816                         if (empty($tag['name'])) {
 817                                 continue;
 818                         }
 819
 820                         Tag::store($uriid, $type, $tag['name'], $tag['href']);
 821                 }
 822         }
 823
 824         public static function storeReceivers(int $uriid, array $receivers)
 825         {
 826                 foreach (['as:to' => Tag::TO, 'as:cc' => Tag::CC, 'as:bto' => Tag::BTO, 'as:bcc' => Tag::BCC] as $element => $type) {
 827                         if (!empty($receivers[$element])) {
 828                                 foreach ($receivers[$element] as $receiver) {
 829                                         if ($receiver == ActivityPub::PUBLIC_COLLECTION) {
 830                                                 $name = Receiver::PUBLIC_COLLECTION;
 831                                         } else {
 832                                                 $name = trim(parse_url($receiver, PHP_URL_PATH), '/');
 833                                         }
 834                                         Tag::store($uriid, $type, $name, $receiver);
 835                                 }
 836                         }
 837                 }
 838         }
 839
 840         /**
 841          * Creates an mail post
 842          *
 843          * @param array $activity Activity data
 844          * @param array $item     item array
 845          * @return int|bool New mail table row id or false on error
 846          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 847          */
 848         private static function postMail($activity, $item)
 849         {
 850                 if (($item['gravity'] != GRAVITY_PARENT) && !DBA::exists('mail', ['uri' => $item['thr-parent'], 'uid' => $item['uid']])) {
 851                         Logger::info('Parent not found, mail will be discarded.', ['uid' => $item['uid'], 'uri' => $item['thr-parent']]);
 852                         return false;
 853                 }
 854
 855                 Logger::info('Direct Message', $item);
 856
 857                 $msg = [];
 858                 $msg['uid'] = $item['uid'];
 859
 860                 $msg['contact-id'] = $item['contact-id'];
 861
 862                 $contact = Contact::getById($item['contact-id'], ['name', 'url', 'photo']);
 863                 $msg['from-name'] = $contact['name'];
 864                 $msg['from-url'] = $contact['url'];
 865                 $msg['from-photo'] = $contact['photo'];
 866
 867                 $msg['uri'] = $item['uri'];
 868                 $msg['created'] = $item['created'];
 869
 870                 $parent = DBA::selectFirst('mail', ['parent-uri', 'title'], ['uri' => $item['thr-parent']]);
 871                 if (DBA::isResult($parent)) {
 872                         $msg['parent-uri'] = $parent['parent-uri'];
 873                         $msg['title'] = $parent['title'];
 874                 } else {
 875                         $msg['parent-uri'] = $item['thr-parent'];
 876
 877                         if (!empty($item['title'])) {
 878                                 $msg['title'] = $item['title'];
 879                         } elseif (!empty($item['content-warning'])) {
 880                                 $msg['title'] = $item['content-warning'];
 881                         } else {
 882                                 // Trying to generate a title out of the body
 883                                 $title = $item['body'];
 884
 885                                 while (preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $title, $matches)) {
 886                                         $title = $matches[3];
 887                                 }
 888
 889                                 $title = trim(BBCode::toPlaintext($title));
 890
 891                                 if (strlen($title) > 20) {
 892                                         $title = substr($title, 0, 20) . '...';
 893                                 }
 894
 895                                 $msg['title'] = $title;
 896                         }
 897                 }
 898                 $msg['body'] = $item['body'];
 899
 900                 return Mail::insert($msg);
 901         }
 902
 903         /**
 904          * Fetches missing posts
 905          *
 906          * @param string $url         message URL
 907          * @param array  $child       activity array with the child of this message
 908          * @param string $relay_actor Relay actor
 909          * @param int    $completion  Completion mode, see Receiver::COMPLETION_*
 910          * @return string fetched message URL
 911          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 912          */
 913         public static function fetchMissingActivity(string $url, array $child = [], string $relay_actor = '', int $completion = Receiver::COMPLETION_MANUAL)
 914         {
 915                 if (!empty($child['receiver'])) {
 916                         $uid = ActivityPub\Receiver::getFirstUserFromReceivers($child['receiver']);
 917                 } else {
 918                         $uid = 0;
 919                 }
 920
 921                 $object = ActivityPub::fetchContent($url, $uid);
 922                 if (empty($object)) {
 923                         Logger::notice('Activity was not fetchable, aborting.', ['url' => $url]);
 924                         return '';
 925                 }
 926
 927                 if (empty($object['id'])) {
 928                         Logger::notice('Activity has got not id, aborting. ', ['url' => $url, 'object' => $object]);
 929                         return '';
 930                 }
 931
 932                 if (!empty($object['actor'])) {
 933                         $object_actor = $object['actor'];
 934                 } elseif (!empty($object['attributedTo'])) {
 935                         $object_actor = $object['attributedTo'];
 936                         if (is_array($object_actor)) {
 937                                 $compacted = JsonLD::compact($object);
 938                                 $object_actor = JsonLD::fetchElement($compacted, 'as:attributedTo', '@id');
 939                         }
 940                 } else {
 941                         // Shouldn't happen
 942                         $object_actor = '';
 943                 }
 944
 945                 $signer = [$object_actor];
 946
 947                 if (!empty($child['author'])) {
 948                         $actor = $child['author'];
 949                         $signer[] = $actor;
 950                 } else {
 951                         $actor = $object_actor;
 952                 }
 953
 954                 if (!empty($object['published'])) {
 955                         $published = $object['published'];
 956                 } elseif (!empty($child['published'])) {
 957                         $published = $child['published'];
 958                 } else {
 959                         $published = DateTimeFormat::utcNow();
 960                 }
 961
 962                 $activity = [];
 963                 $activity['@context'] = $object['@context'] ?? ActivityPub::CONTEXT;
 964                 unset($object['@context']);
 965                 $activity['id'] = $object['id'];
 966                 $activity['to'] = $object['to'] ?? [];
 967                 $activity['cc'] = $object['cc'] ?? [];
 968                 $activity['actor'] = $actor;
 969                 $activity['object'] = $object;
 970                 $activity['published'] = $published;
 971                 $activity['type'] = 'Create';
 972
 973                 $ldactivity = JsonLD::compact($activity);
 974
 975                 if (!empty($relay_actor)) {
 976                         $ldactivity['thread-completion'] = $ldactivity['from-relay'] = Contact::getIdForURL($relay_actor);
 977                         $ldactivity['completion-mode']   = Receiver::COMPLETION_RELAY;
 978                 } elseif (!empty($child['thread-completion'])) {
 979                         $ldactivity['thread-completion'] = $child['thread-completion'];
 980                         $ldactivity['completion-mode']   = $child['completion-mode'] ?? Receiver::COMPLETION_NONE;
 981                 } else {
 982                         $ldactivity['thread-completion'] = Contact::getIdForURL($actor);
 983                         $ldactivity['completion-mode']   = $completion;
 984                 }
 985
 986                 if (!empty($child['type'])) {
 987                         $ldactivity['thread-children-type'] = $child['type'];
 988                 }
 989
 990                 if (!empty($relay_actor) && !self::acceptIncomingMessage($ldactivity, $object['id'])) {
 991                         return '';
 992                 }
 993
 994                 ActivityPub\Receiver::processActivity($ldactivity, json_encode($activity), $uid, true, false, $signer);
 995
 996                 Logger::notice('Activity had been fetched and processed.', ['url' => $url, 'object' => $activity['id']]);
 997
 998                 return $activity['id'];
 999         }
1000
1001         /**
1002          * Test if incoming relay messages should be accepted
1003          *
1004          * @param array $activity activity array
1005          * @param string $id      object ID
1006          * @return boolean true if message is accepted
1007          */
1008         private static function acceptIncomingMessage(array $activity, string $id)
1009         {
1010                 if (empty($activity['as:object'])) {
1011                         Logger::info('No object field in activity - accepted', ['id' => $id]);
1012                         return true;
1013                 }
1014
1015                 $replyto = JsonLD::fetchElement($activity['as:object'], 'as:inReplyTo', '@id');
1016                 $uriid = ItemURI::getIdByURI($replyto);
1017                 if (Post::exists(['uri-id' => $uriid])) {
1018                         Logger::info('Post is a reply to an existing post - accepted', ['id' => $id, 'uri-id' => $uriid, 'replyto' => $replyto]);
1019                         return true;
1020                 }
1021
1022                 $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
1023                 $authorid = Contact::getIdForURL($attributed_to);
1024
1025                 $body = HTML::toBBCode(JsonLD::fetchElement($activity['as:object'], 'as:content', '@value'));
1026
1027                 $messageTags = [];
1028                 $tags = Receiver::processTags(JsonLD::fetchElementArray($activity['as:object'], 'as:tag') ?? []);
1029                 if (!empty($tags)) {
1030                         foreach ($tags as $tag) {
1031                                 if ($tag['type'] != 'Hashtag') {
1032                                         continue;
1033                                 }
1034                                 $messageTags[] = ltrim(mb_strtolower($tag['name']), '#');
1035                         }
1036                 }
1037
1038                 return Relay::isSolicitedPost($messageTags, $body, $authorid, $id, Protocol::ACTIVITYPUB);
1039         }
1040
1041         /**
1042          * perform a "follow" request
1043          *
1044          * @param array $activity
1045          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1046          * @throws \ImagickException
1047          */
1048         public static function followUser($activity)
1049         {
1050                 $uid = User::getIdForURL($activity['object_id']);
1051                 if (empty($uid)) {
1052                         return;
1053                 }
1054
1055                 $owner = User::getOwnerDataById($uid);
1056                 if (empty($owner)) {
1057                         return;
1058                 }
1059
1060                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1061                 if (!empty($cid)) {
1062                         self::switchContact($cid);
1063                         Contact::update(['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
1064                 }
1065
1066                 $item = ['author-id' => Contact::getIdForURL($activity['actor']),
1067                         'author-link' => $activity['actor']];
1068
1069                 // Ensure that the contact has got the right network type
1070                 self::switchContact($item['author-id']);
1071
1072                 $result = Contact::addRelationship($owner, [], $item, false, $activity['content'] ?? '');
1073                 if ($result === true) {
1074                         ActivityPub\Transmitter::sendContactAccept($item['author-link'], $activity['id'], $owner['uid']);
1075                 }
1076
1077                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1078                 if (empty($cid)) {
1079                         return;
1080                 }
1081
1082                 if (empty($contact)) {
1083                         Contact::update(['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
1084                 }
1085
1086                 Logger::notice('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
1087         }
1088
1089         /**
1090          * Update the given profile
1091          *
1092          * @param array $activity
1093          * @throws \Exception
1094          */
1095         public static function updatePerson($activity)
1096         {
1097                 if (empty($activity['object_id'])) {
1098                         return;
1099                 }
1100
1101                 Logger::info('Updating profile', ['object' => $activity['object_id']]);
1102                 Contact::updateFromProbeByURL($activity['object_id']);
1103         }
1104
1105         /**
1106          * Delete the given profile
1107          *
1108          * @param array $activity
1109          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1110          */
1111         public static function deletePerson($activity)
1112         {
1113                 if (empty($activity['object_id']) || empty($activity['actor'])) {
1114                         Logger::info('Empty object id or actor.');
1115                         return;
1116                 }
1117
1118                 if ($activity['object_id'] != $activity['actor']) {
1119                         Logger::info('Object id does not match actor.');
1120                         return;
1121                 }
1122
1123                 $contacts = DBA::select('contact', ['id'], ['nurl' => Strings::normaliseLink($activity['object_id'])]);
1124                 while ($contact = DBA::fetch($contacts)) {
1125                         Contact::remove($contact['id']);
1126                 }
1127                 DBA::close($contacts);
1128
1129                 Logger::info('Deleted contact', ['object' => $activity['object_id']]);
1130         }
1131
1132         /**
1133          * Accept a follow request
1134          *
1135          * @param array $activity
1136          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1137          * @throws \ImagickException
1138          */
1139         public static function acceptFollowUser($activity)
1140         {
1141                 $uid = User::getIdForURL($activity['object_actor']);
1142                 if (empty($uid)) {
1143                         return;
1144                 }
1145
1146                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1147                 if (empty($cid)) {
1148                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1149                         return;
1150                 }
1151
1152                 self::switchContact($cid);
1153
1154                 $fields = ['pending' => false];
1155
1156                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
1157                 if ($contact['rel'] == Contact::FOLLOWER) {
1158                         $fields['rel'] = Contact::FRIEND;
1159                 }
1160
1161                 $condition = ['id' => $cid];
1162                 Contact::update($fields, $condition);
1163                 Logger::info('Accept contact request', ['contact' => $cid, 'user' => $uid]);
1164         }
1165
1166         /**
1167          * Reject a follow request
1168          *
1169          * @param array $activity
1170          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1171          * @throws \ImagickException
1172          */
1173         public static function rejectFollowUser($activity)
1174         {
1175                 $uid = User::getIdForURL($activity['object_actor']);
1176                 if (empty($uid)) {
1177                         return;
1178                 }
1179
1180                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1181                 if (empty($cid)) {
1182                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1183                         return;
1184                 }
1185
1186                 self::switchContact($cid);
1187
1188                 $contact = Contact::getById($cid, ['rel']);
1189                 if ($contact['rel'] == Contact::SHARING) {
1190                         Contact::remove($cid);
1191                         Logger::info('Rejected contact request - contact removed', ['contact' => $cid, 'user' => $uid]);
1192                 } elseif ($contact['rel'] == Contact::FRIEND) {
1193                         Contact::update(['rel' => Contact::FOLLOWER], ['id' => $cid]);
1194                 } else {
1195                         Logger::info('Rejected contact request', ['contact' => $cid, 'user' => $uid]);
1196                 }
1197         }
1198
1199         /**
1200          * Undo activity like "like" or "dislike"
1201          *
1202          * @param array $activity
1203          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1204          * @throws \ImagickException
1205          */
1206         public static function undoActivity($activity)
1207         {
1208                 if (empty($activity['object_id'])) {
1209                         return;
1210                 }
1211
1212                 if (empty($activity['object_actor'])) {
1213                         return;
1214                 }
1215
1216                 $author_id = Contact::getIdForURL($activity['object_actor']);
1217                 if (empty($author_id)) {
1218                         return;
1219                 }
1220
1221                 Item::markForDeletion(['uri' => $activity['object_id'], 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
1222         }
1223
1224         /**
1225          * Activity to remove a follower
1226          *
1227          * @param array $activity
1228          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1229          * @throws \ImagickException
1230          */
1231         public static function undoFollowUser($activity)
1232         {
1233                 $uid = User::getIdForURL($activity['object_object']);
1234                 if (empty($uid)) {
1235                         return;
1236                 }
1237
1238                 $owner = User::getOwnerDataById($uid);
1239                 if (empty($owner)) {
1240                         return;
1241                 }
1242
1243                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1244                 if (empty($cid)) {
1245                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1246                         return;
1247                 }
1248
1249                 self::switchContact($cid);
1250
1251                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1252                 if (!DBA::isResult($contact)) {
1253                         return;
1254                 }
1255
1256                 Contact::removeFollower($contact);
1257                 Logger::info('Undo following request', ['contact' => $cid, 'user' => $uid]);
1258         }
1259
1260         /**
1261          * Switches a contact to AP if needed
1262          *
1263          * @param integer $cid Contact ID
1264          * @throws \Exception
1265          */
1266         private static function switchContact($cid)
1267         {
1268                 $contact = DBA::selectFirst('contact', ['network', 'url'], ['id' => $cid]);
1269                 if (!DBA::isResult($contact) || in_array($contact['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN]) || Contact::isLocal($contact['url'])) {
1270                         return;
1271                 }
1272
1273                 Logger::info('Change existing contact', ['cid' => $cid, 'previous' => $contact['network']]);
1274                 Contact::updateFromProbe($cid);
1275         }
1276
1277         /**
1278          * Collects implicit mentions like:
1279          * - the author of the parent item
1280          * - all the mentioned conversants in the parent item
1281          *
1282          * @param array $parent Item array with at least ['id', 'author-link', 'alias']
1283          * @return array
1284          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1285          */
1286         private static function getImplicitMentionList(array $parent)
1287         {
1288                 $parent_terms = Tag::getByURIId($parent['uri-id'], [Tag::MENTION, Tag::IMPLICIT_MENTION, Tag::EXCLUSIVE_MENTION]);
1289
1290                 $parent_author = Contact::getByURL($parent['author-link'], false, ['url', 'nurl', 'alias']);
1291
1292                 $implicit_mentions = [];
1293                 if (empty($parent_author['url'])) {
1294                         Logger::notice('Author public contact unknown.', ['author-link' => $parent['author-link'], 'parent-id' => $parent['id']]);
1295                 } else {
1296                         $implicit_mentions[] = $parent_author['url'];
1297                         $implicit_mentions[] = $parent_author['nurl'];
1298                         $implicit_mentions[] = $parent_author['alias'];
1299                 }
1300
1301                 if (!empty($parent['alias'])) {
1302                         $implicit_mentions[] = $parent['alias'];
1303                 }
1304
1305                 foreach ($parent_terms as $term) {
1306                         $contact = Contact::getByURL($term['url'], false, ['url', 'nurl', 'alias']);
1307                         if (!empty($contact['url'])) {
1308                                 $implicit_mentions[] = $contact['url'];
1309                                 $implicit_mentions[] = $contact['nurl'];
1310                                 $implicit_mentions[] = $contact['alias'];
1311                         }
1312                 }
1313
1314                 return $implicit_mentions;
1315         }
1316
1317         /**
1318          * Strips from the body prepended implicit mentions
1319          *
1320          * @param string $body
1321          * @param array $parent
1322          * @return string
1323          */
1324         private static function removeImplicitMentionsFromBody(string $body, array $parent)
1325         {
1326                 if (DI::config()->get('system', 'disable_implicit_mentions')) {
1327                         return $body;
1328                 }
1329
1330                 $potential_mentions = self::getImplicitMentionList($parent);
1331
1332                 $kept_mentions = [];
1333
1334                 // Extract one prepended mention at a time from the body
1335                 while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $body, $matches)) {
1336                         if (!in_array($matches[2], $potential_mentions)) {
1337                                 $kept_mentions[] = $matches[1];
1338                         }
1339
1340                         $body = $matches[3];
1341                 }
1342
1343                 // Re-appending the kept mentions to the body after extraction
1344                 $kept_mentions[] = $body;
1345
1346                 return implode('', $kept_mentions);
1347         }
1348
1349         /**
1350          * Adds links to string mentions
1351          *
1352          * @param string $body
1353          * @param array  $tags
1354          * @return string
1355          */
1356         protected static function addMentionLinks(string $body, array $tags): string
1357         {
1358                 // This prevents links to be added again to Pleroma-style mention links
1359                 $body = self::normalizeMentionLinks($body);
1360
1361                 $body = BBCode::performWithEscapedTags($body, ['url'], function ($body) use ($tags) {
1362                         foreach ($tags as $tag) {
1363                                 if (empty($tag['name']) || empty($tag['type']) || empty($tag['href']) || !in_array($tag['type'], ['Mention', 'Hashtag'])) {
1364                                         continue;
1365                                 }
1366
1367                                 $hash = substr($tag['name'], 0, 1);
1368                                 $name = substr($tag['name'], 1);
1369                                 if (!in_array($hash, Tag::TAG_CHARACTER)) {
1370                                         $hash = '';
1371                                         $name = $tag['name'];
1372                                 }
1373
1374                                 $body = str_replace($tag['name'], $hash . '[url=' . $tag['href'] . ']' . $name . '[/url]', $body);
1375                         }
1376
1377                         return $body;
1378                 });
1379
1380                 return $body;
1381         }
1382 }