src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2020, Friendica
   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\Database\DBA;
  26 use Friendica\Content\Text\HTML;
  27 use Friendica\Content\Text\Markdown;
  28 use Friendica\Core\Logger;
  29 use Friendica\Core\Protocol;
  30 use Friendica\Model\Contact;
  31 use Friendica\Model\APContact;
  32 use Friendica\Model\Item;
  33 use Friendica\Model\User;
  34 use Friendica\Protocol\Activity;
  35 use Friendica\Protocol\ActivityPub;
  36 use Friendica\Util\DateTimeFormat;
  37 use Friendica\Util\HTTPSignature;
  38 use Friendica\Util\JsonLD;
  39 use Friendica\Util\LDSignature;
  40 use Friendica\Util\Strings;
  41
  42 /**
  43  * ActivityPub Receiver Protocol class
  44  *
  45  * To-Do:
  46  * @todo Undo Announce
  47  *
  48  * Check what this is meant to do:
  49  * - Add
  50  * - Block
  51  * - Flag
  52  * - Remove
  53  * - Undo Block
  54  */
  55 class Receiver
  56 {
  57         const PUBLIC_COLLECTION = 'as:Public';
  58         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  59         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio'];
  60         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  61
  62         /**
  63          * Checks if the web request is done for the AP protocol
  64          *
  65          * @return bool is it AP?
  66          */
  67         public static function isRequest()
  68         {
  69                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
  70                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
  71         }
  72
  73         /**
  74          * Checks incoming message from the inbox
  75          *
  76          * @param         $body
  77          * @param         $header
  78          * @param integer $uid User ID
  79          * @throws \Exception
  80          */
  81         public static function processInbox($body, $header, $uid)
  82         {
  83                 $http_signer = HTTPSignature::getSigner($body, $header);
  84                 if (empty($http_signer)) {
  85                         Logger::warning('Invalid HTTP signature, message will be discarded.');
  86                         return;
  87                 } else {
  88                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
  89                 }
  90
  91                 $activity = json_decode($body, true);
  92
  93                 if (empty($activity)) {
  94                         Logger::warning('Invalid body.');
  95                         return;
  96                 }
  97
  98                 $ldactivity = JsonLD::compact($activity);
  99
 100                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
 101
 102                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 103
 104                 if (LDSignature::isSigned($activity)) {
 105                         $ld_signer = LDSignature::getSigner($activity);
 106                         if (empty($ld_signer)) {
 107                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
 108                         }
 109                         if (!empty($ld_signer && ($actor == $http_signer))) {
 110                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
 111                                 $trust_source = true;
 112                         } elseif (!empty($ld_signer)) {
 113                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
 114                                 $trust_source = true;
 115                         } elseif ($actor == $http_signer) {
 116                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
 117                                 $trust_source = true;
 118                         } else {
 119                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
 120                                 $trust_source = false;
 121                         }
 122                 } elseif ($actor == $http_signer) {
 123                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 124                         $trust_source = true;
 125                 } else {
 126                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 127                         $trust_source = false;
 128                 }
 129
 130                 self::processActivity($ldactivity, $body, $uid, $trust_source, true);
 131         }
 132
 133         /**
 134          * Fetches the object type for a given object id
 135          *
 136          * @param array   $activity
 137          * @param string  $object_id Object ID of the the provided object
 138          * @param integer $uid       User ID
 139          *
 140          * @return string with object type
 141          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 142          * @throws \ImagickException
 143          */
 144         private static function fetchObjectType($activity, $object_id, $uid = 0)
 145         {
 146                 if (!empty($activity['as:object'])) {
 147                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 148                         if (!empty($object_type)) {
 149                                 return $object_type;
 150                         }
 151                 }
 152
 153                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 154                         // We just assume "note" since it doesn't make a difference for the further processing
 155                         return 'as:Note';
 156                 }
 157
 158                 $profile = APContact::getByURL($object_id);
 159                 if (!empty($profile['type'])) {
 160                         return 'as:' . $profile['type'];
 161                 }
 162
 163                 $data = ActivityPub::fetchContent($object_id, $uid);
 164                 if (!empty($data)) {
 165                         $object = JsonLD::compact($data);
 166                         $type = JsonLD::fetchElement($object, '@type');
 167                         if (!empty($type)) {
 168                                 return $type;
 169                         }
 170                 }
 171
 172                 return null;
 173         }
 174
 175         /**
 176          * Prepare the object array
 177          *
 178          * @param array   $activity     Array with activity data
 179          * @param integer $uid          User ID
 180          * @param boolean $push         Message had been pushed to our system
 181          * @param boolean $trust_source Do we trust the source?
 182          *
 183          * @return array with object data
 184          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 185          * @throws \ImagickException
 186          */
 187         public static function prepareObjectData($activity, $uid, $push, &$trust_source)
 188         {
 189                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 190                 if (empty($actor)) {
 191                         Logger::log('Empty actor', Logger::DEBUG);
 192                         return [];
 193                 }
 194
 195                 $type = JsonLD::fetchElement($activity, '@type');
 196
 197                 // Fetch all receivers from to, cc, bto and bcc
 198                 $receivers = self::getReceivers($activity, $actor);
 199
 200                 // When it is a delivery to a personal inbox we add that user to the receivers
 201                 if (!empty($uid)) {
 202                         $additional = ['uid:' . $uid => $uid];
 203                         $receivers = array_merge($receivers, $additional);
 204                 } else {
 205                         // We possibly need some user to fetch private content,
 206                         // so we fetch the first out ot the list.
 207                         $uid = self::getFirstUserFromReceivers($receivers);
 208                 }
 209
 210                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
 211
 212                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 213                 if (empty($object_id)) {
 214                         Logger::log('No object found', Logger::DEBUG);
 215                         return [];
 216                 }
 217
 218                 if (!is_string($object_id)) {
 219                         Logger::info('Invalid object id', ['object' => $object_id]);
 220                         return [];
 221                 }
 222
 223                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 224
 225                 // Fetch the content only on activities where this matters
 226                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 227                         if ($type == 'as:Announce') {
 228                                 $trust_source = false;
 229                         }
 230
 231                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
 232                         if (empty($object_data)) {
 233                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 234                                 return [];
 235                         }
 236
 237                         $object_data['object_id'] = $object_id;
 238
 239                         if ($type == 'as:Announce') {
 240                                 $object_data['push'] = false;
 241                         } else {
 242                                 $object_data['push'] = $push;
 243                         }
 244
 245                         // Test if it is an answer to a mail
 246                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 247                                 $object_data['directmessage'] = true;
 248                         } else {
 249                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 250                         }
 251
 252                         // We had been able to retrieve the object data - so we can trust the source
 253                         $trust_source = true;
 254                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 255                         // Create a mostly empty array out of the activity data (instead of the object).
 256                         // This way we later don't have to check for the existence of ech individual array element.
 257                         $object_data = self::processObject($activity);
 258                         $object_data['name'] = $type;
 259                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 260                         $object_data['object_id'] = $object_id;
 261                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 262                 } elseif (in_array($type, ['as:Add'])) {
 263                         $object_data = [];
 264                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 265                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 266                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 267                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 268                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 269                 } else {
 270                         $object_data = [];
 271                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 272                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 273                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 274                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 275                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 276
 277                         // An Undo is done on the object of an object, so we need that type as well
 278                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
 279                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 280                         }
 281                 }
 282
 283                 $object_data = self::addActivityFields($object_data, $activity);
 284
 285                 if (empty($object_data['object_type'])) {
 286                         $object_data['object_type'] = $object_type;
 287                 }
 288
 289                 $object_data['type'] = $type;
 290                 $object_data['actor'] = $actor;
 291                 $object_data['item_receiver'] = $receivers;
 292                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
 293
 294                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 295
 296                 return $object_data;
 297         }
 298
 299         /**
 300          * Fetches the first user id from the receiver array
 301          *
 302          * @param array $receivers Array with receivers
 303          * @return integer user id;
 304          */
 305         public static function getFirstUserFromReceivers($receivers)
 306         {
 307                 foreach ($receivers as $receiver) {
 308                         if (!empty($receiver)) {
 309                                 return $receiver;
 310                         }
 311                 }
 312                 return 0;
 313         }
 314
 315         /**
 316          * Processes the activity object
 317          *
 318          * @param array   $activity     Array with activity data
 319          * @param string  $body
 320          * @param integer $uid          User ID
 321          * @param boolean $trust_source Do we trust the source?
 322          * @param boolean $push         Message had been pushed to our system
 323          * @throws \Exception
 324          */
 325         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false, $push = false)
 326         {
 327                 $type = JsonLD::fetchElement($activity, '@type');
 328                 if (!$type) {
 329                         Logger::log('Empty type', Logger::DEBUG);
 330                         return;
 331                 }
 332
 333                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 334                         Logger::log('Empty object', Logger::DEBUG);
 335                         return;
 336                 }
 337
 338                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
 339                         Logger::log('Empty actor', Logger::DEBUG);
 340                         return;
 341                 }
 342
 343                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 344                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 345                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 346                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 347                         $trust_source = ($actor == $attributed_to);
 348                         if (!$trust_source) {
 349                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 350                         }
 351                 }
 352
 353                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 354                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 355                 if (empty($object_data)) {
 356                         Logger::log('No object data found', Logger::DEBUG);
 357                         return;
 358                 }
 359
 360                 if (!$trust_source) {
 361                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 362                         return;
 363                 }
 364
 365                 if (!empty($body) && empty($object_data['raw'])) {
 366                         $object_data['raw'] = $body;
 367                 }
 368
 369                 // Internal flag for thread completion. See Processor.php
 370                 if (!empty($activity['thread-completion'])) {
 371                         $object_data['thread-completion'] = $activity['thread-completion'];
 372                 }
 373
 374                 switch ($type) {
 375                         case 'as:Create':
 376                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 377                                         $item = ActivityPub\Processor::createItem($object_data);
 378                                         ActivityPub\Processor::postItem($object_data, $item);
 379                                 }
 380                                 break;
 381
 382                         case 'as:Add':
 383                                 if ($object_data['object_type'] == 'as:tag') {
 384                                         ActivityPub\Processor::addTag($object_data);
 385                                 }
 386                                 break;
 387
 388                         case 'as:Announce':
 389                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 390                                         $object_data['thread-completion'] = true;
 391
 392                                         $item = ActivityPub\Processor::createItem($object_data);
 393                                         ActivityPub\Processor::postItem($object_data, $item);
 394
 395                                         $announce_object_data = self::processObject($activity);
 396                                         $announce_object_data['name'] = $type;
 397                                         $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 398                                         $announce_object_data['object_id'] = $object_data['object_id'];
 399                                         $announce_object_data['object_type'] = $object_data['object_type'];
 400                                         $announce_object_data['push'] = $push;
 401
 402                                         if (!empty($body)) {
 403                                                 $announce_object_data['raw'] = $body;
 404                                         }
 405
 406                                         ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 407                                 }
 408                                 break;
 409
 410                         case 'as:Like':
 411                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 412                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 413                                 }
 414                                 break;
 415
 416                         case 'as:Dislike':
 417                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 418                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 419                                 }
 420                                 break;
 421
 422                         case 'as:TentativeAccept':
 423                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 424                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 425                                 }
 426                                 break;
 427
 428                         case 'as:Update':
 429                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 430                                         ActivityPub\Processor::updateItem($object_data);
 431                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 432                                         ActivityPub\Processor::updatePerson($object_data);
 433                                 }
 434                                 break;
 435
 436                         case 'as:Delete':
 437                                 if ($object_data['object_type'] == 'as:Tombstone') {
 438                                         ActivityPub\Processor::deleteItem($object_data);
 439                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 440                                         ActivityPub\Processor::deletePerson($object_data);
 441                                 }
 442                                 break;
 443
 444                         case 'as:Follow':
 445                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 446                                         ActivityPub\Processor::followUser($object_data);
 447                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 448                                         $object_data['reply-to-id'] = $object_data['object_id'];
 449                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 450                                 }
 451                                 break;
 452
 453                         case 'as:Accept':
 454                                 if ($object_data['object_type'] == 'as:Follow') {
 455                                         ActivityPub\Processor::acceptFollowUser($object_data);
 456                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 457                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 458                                 }
 459                                 break;
 460
 461                         case 'as:Reject':
 462                                 if ($object_data['object_type'] == 'as:Follow') {
 463                                         ActivityPub\Processor::rejectFollowUser($object_data);
 464                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 465                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 466                                 }
 467                                 break;
 468
 469                         case 'as:Undo':
 470                                 if (($object_data['object_type'] == 'as:Follow') &&
 471                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 472                                         ActivityPub\Processor::undoFollowUser($object_data);
 473                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 474                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 475                                         ActivityPub\Processor::rejectFollowUser($object_data);
 476                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 477                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 478                                         ActivityPub\Processor::undoActivity($object_data);
 479                                 }
 480                                 break;
 481
 482                         default:
 483                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 484                                 break;
 485                 }
 486         }
 487
 488         /**
 489          * Fetch the receiver list from an activity array
 490          *
 491          * @param array   $activity
 492          * @param string  $actor
 493          * @param array   $tags
 494          * @param boolean $fetch_unlisted
 495          *
 496          * @return array with receivers (user id)
 497          * @throws \Exception
 498          */
 499         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 500         {
 501                 $receivers = [];
 502
 503                 // When it is an answer, we inherite the receivers from the parent
 504                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 505                 if (!empty($replyto)) {
 506                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 507                         $fixedReplyTo = Item::getURIByLink($replyto);
 508                         $replyto = $fixedReplyTo ?: $replyto;
 509
 510                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 511                         while ($parent = Item::fetch($parents)) {
 512                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 513                         }
 514                 }
 515
 516                 if (!empty($actor)) {
 517                         $profile = APContact::getByURL($actor);
 518                         $followers = $profile['followers'] ?? '';
 519
 520                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 521                 } else {
 522                         Logger::log('Empty actor', Logger::DEBUG);
 523                         $followers = '';
 524                 }
 525
 526                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 527                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 528                         if (empty($receiver_list)) {
 529                                 continue;
 530                         }
 531
 532                         foreach ($receiver_list as $receiver) {
 533                                 if ($receiver == self::PUBLIC_COLLECTION) {
 534                                         $receivers['uid:0'] = 0;
 535                                 }
 536
 537                                 // Add receiver "-1" for unlisted posts
 538                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 539                                         $receivers['uid:-1'] = -1;
 540                                 }
 541
 542                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 543                                         // This will most likely catch all OStatus connections to Mastodon
 544                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 545                                                 , 'archive' => false, 'pending' => false];
 546                                         $contacts = DBA::select('contact', ['uid'], $condition);
 547                                         while ($contact = DBA::fetch($contacts)) {
 548                                                 if ($contact['uid'] != 0) {
 549                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 550                                                 }
 551                                         }
 552                                         DBA::close($contacts);
 553                                 }
 554
 555                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 556                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 557                                         continue;
 558                                 }
 559
 560                                 // Fetching all directly addressed receivers
 561                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 562                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 563                                 if (!DBA::isResult($contact)) {
 564                                         continue;
 565                                 }
 566
 567                                 // Check if the potential receiver is following the actor
 568                                 // Exception: The receiver is targetted via "to" or this is a comment
 569                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 570                                         $networks = Protocol::FEDERATED;
 571                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 572                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 573
 574                                         // Forum posts are only accepted from forum contacts
 575                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 576                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 577                                         }
 578
 579                                         if (!DBA::exists('contact', $condition)) {
 580                                                 continue;
 581                                         }
 582                                 }
 583
 584                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 585                         }
 586                 }
 587
 588                 self::switchContacts($receivers, $actor);
 589
 590                 return $receivers;
 591         }
 592
 593         /**
 594          * Fetch the receiver list of a given actor
 595          *
 596          * @param string $actor
 597          * @param array  $tags
 598          *
 599          * @return array with receivers (user id)
 600          * @throws \Exception
 601          */
 602         public static function getReceiverForActor($actor, $tags)
 603         {
 604                 $receivers = [];
 605                 $networks = Protocol::FEDERATED;
 606                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 607                         'network' => $networks, 'archive' => false, 'pending' => false];
 608                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 609                 while ($contact = DBA::fetch($contacts)) {
 610                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 611                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 612                         }
 613                 }
 614                 DBA::close($contacts);
 615                 return $receivers;
 616         }
 617
 618         /**
 619          * Tests if the contact is a valid receiver for this actor
 620          *
 621          * @param array  $contact
 622          * @param string $actor
 623          * @param array  $tags
 624          *
 625          * @return bool with receivers (user id)
 626          * @throws \Exception
 627          */
 628         private static function isValidReceiverForActor($contact, $actor, $tags)
 629         {
 630                 // Public contacts are no valid receiver
 631                 if ($contact['uid'] == 0) {
 632                         return false;
 633                 }
 634
 635                 // Are we following the contact? Then this is a valid receiver
 636                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 637                         return true;
 638                 }
 639
 640                 // When the possible receiver isn't a community, then it is no valid receiver
 641                 $owner = User::getOwnerDataById($contact['uid']);
 642                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 643                         return false;
 644                 }
 645
 646                 // Is the community account tagged?
 647                 foreach ($tags as $tag) {
 648                         if ($tag['type'] != 'Mention') {
 649                                 continue;
 650                         }
 651
 652                         if ($tag['href'] == $owner['url']) {
 653                                 return true;
 654                         }
 655                 }
 656
 657                 return false;
 658         }
 659
 660         /**
 661          * Switches existing contacts to ActivityPub
 662          *
 663          * @param integer $cid Contact ID
 664          * @param integer $uid User ID
 665          * @param string  $url Profile URL
 666          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 667          * @throws \ImagickException
 668          */
 669         public static function switchContact($cid, $uid, $url)
 670         {
 671                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 672                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 673                         return;
 674                 }
 675
 676                 if (Contact::updateFromProbe($cid)) {
 677                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 678                 }
 679
 680                 // Send a new follow request to be sure that the connection still exists
 681                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 682                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 683                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 684                 }
 685         }
 686
 687         /**
 688          *
 689          *
 690          * @param $receivers
 691          * @param $actor
 692          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 693          * @throws \ImagickException
 694          */
 695         private static function switchContacts($receivers, $actor)
 696         {
 697                 if (empty($actor)) {
 698                         return;
 699                 }
 700
 701                 foreach ($receivers as $receiver) {
 702                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 703                         if (DBA::isResult($contact)) {
 704                                 self::switchContact($contact['id'], $receiver, $actor);
 705                         }
 706
 707                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 708                         if (DBA::isResult($contact)) {
 709                                 self::switchContact($contact['id'], $receiver, $actor);
 710                         }
 711                 }
 712         }
 713
 714         /**
 715          *
 716          *
 717          * @param       $object_data
 718          * @param array $activity
 719          *
 720          * @return mixed
 721          */
 722         private static function addActivityFields($object_data, $activity)
 723         {
 724                 if (!empty($activity['published']) && empty($object_data['published'])) {
 725                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 726                 }
 727
 728                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 729                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 730                 }
 731
 732                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 733                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 734
 735                 if (!empty($object_data['object_id'])) {
 736                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 737                         $objectId = Item::getURIByLink($object_data['object_id']);
 738                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 739                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 740                                 $object_data['object_id'] = $objectId;
 741                         }
 742                 }
 743
 744                 return $object_data;
 745         }
 746
 747         /**
 748          * Fetches the object data from external ressources if needed
 749          *
 750          * @param string  $object_id    Object ID of the the provided object
 751          * @param array   $object       The provided object array
 752          * @param boolean $trust_source Do we trust the provided object?
 753          * @param integer $uid          User ID for the signature that we use to fetch data
 754          *
 755          * @return array|false with trusted and valid object data
 756          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 757          * @throws \ImagickException
 758          */
 759         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 760         {
 761                 // By fetching the type we check if the object is complete.
 762                 $type = JsonLD::fetchElement($object, '@type');
 763
 764                 if (!$trust_source || empty($type)) {
 765                         $data = ActivityPub::fetchContent($object_id, $uid);
 766                         if (!empty($data)) {
 767                                 $object = JsonLD::compact($data);
 768                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 769                         } else {
 770                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 771
 772                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 773                                 if (!DBA::isResult($item)) {
 774                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 775                                         return false;
 776                                 }
 777                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 778                                 $data = ActivityPub\Transmitter::createNote($item);
 779                                 $object = JsonLD::compact($data);
 780                         }
 781                 } else {
 782                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 783                 }
 784
 785                 $type = JsonLD::fetchElement($object, '@type');
 786
 787                 if (empty($type)) {
 788                         Logger::log('Empty type', Logger::DEBUG);
 789                         return false;
 790                 }
 791
 792                 if (in_array($type, self::CONTENT_TYPES)) {
 793                         $object_data = self::processObject($object);
 794
 795                         if (!empty($data)) {
 796                                 $object_data['raw'] = json_encode($data);
 797                         }
 798                         return $object_data;
 799                 }
 800
 801                 if ($type == 'as:Announce') {
 802                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 803                         if (empty($object_id) || !is_string($object_id)) {
 804                                 return false;
 805                         }
 806                         return self::fetchObject($object_id, [], false, $uid);
 807                 }
 808
 809                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 810                 return false;
 811         }
 812
 813         /**
 814          * Convert tags from JSON-LD format into a simplified format
 815          *
 816          * @param array $tags Tags in JSON-LD format
 817          *
 818          * @return array with tags in a simplified format
 819          */
 820         private static function processTags(array $tags)
 821         {
 822                 $taglist = [];
 823
 824                 foreach ($tags as $tag) {
 825                         if (empty($tag)) {
 826                                 continue;
 827                         }
 828
 829                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 830                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 831                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 832
 833                         if (empty($element['type'])) {
 834                                 continue;
 835                         }
 836
 837                         if (empty($element['href'])) {
 838                                 $element['href'] = $element['name'];
 839                         }
 840
 841                         $taglist[] = $element;
 842                 }
 843                 return $taglist;
 844         }
 845
 846         /**
 847          * Convert emojis from JSON-LD format into a simplified format
 848          *
 849          * @param array $emojis
 850          * @return array with emojis in a simplified format
 851          */
 852         private static function processEmojis(array $emojis)
 853         {
 854                 $emojilist = [];
 855
 856                 foreach ($emojis as $emoji) {
 857                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 858                                 continue;
 859                         }
 860
 861                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
 862                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
 863                                 'href' => $url];
 864
 865                         $emojilist[] = $element;
 866                 }
 867
 868                 return $emojilist;
 869         }
 870
 871         /**
 872          * Convert attachments from JSON-LD format into a simplified format
 873          *
 874          * @param array $attachments Attachments in JSON-LD format
 875          *
 876          * @return array Attachments in a simplified format
 877          */
 878         private static function processAttachments(array $attachments)
 879         {
 880                 $attachlist = [];
 881
 882                 // Removes empty values
 883                 $attachments = array_filter($attachments);
 884
 885                 foreach ($attachments as $attachment) {
 886                         switch (JsonLD::fetchElement($attachment, '@type')) {
 887                                 case 'as:Page':
 888                                         $pageUrl = null;
 889                                         $pageImage = null;
 890
 891                                         $urls = JsonLD::fetchElementArray($attachment, 'as:url');
 892                                         foreach ($urls as $url) {
 893                                                 // Single scalar URL case
 894                                                 if (is_string($url)) {
 895                                                         $pageUrl = $url;
 896                                                         continue;
 897                                                 }
 898
 899                                                 $href = JsonLD::fetchElement($url, 'as:href', '@id');
 900                                                 $mediaType = JsonLD::fetchElement($url, 'as:mediaType', '@value');
 901                                                 if (Strings::startsWith($mediaType, 'image')) {
 902                                                         $pageImage = $href;
 903                                                 } else {
 904                                                         $pageUrl = $href;
 905                                                 }
 906                                         }
 907
 908                                         $attachlist[] = [
 909                                                 'type'  => 'link',
 910                                                 'title' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 911                                                 'desc'  => JsonLD::fetchElement($attachment, 'as:summary', '@value'),
 912                                                 'url'   => $pageUrl,
 913                                                 'image' => $pageImage,
 914                                         ];
 915                                         break;
 916                                 case 'as:Link':
 917                                         $attachlist[] = [
 918                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 919                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 920                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 921                                                 'url' => JsonLD::fetchElement($attachment, 'as:href', '@id')
 922                                         ];
 923                                         break;
 924                                 case 'as:Image':
 925                                         $mediaType = JsonLD::fetchElement($attachment, 'as:mediaType', '@value');
 926                                         $imageFullUrl = JsonLD::fetchElement($attachment, 'as:url', '@id');
 927                                         $imagePreviewUrl = null;
 928                                         // Multiple URLs?
 929                                         if (!$imageFullUrl && ($urls = JsonLD::fetchElementArray($attachment, 'as:url'))) {
 930                                                 $imageVariants = [];
 931                                                 $previewVariants = [];
 932                                                 foreach ($urls as $url) {
 933                                                         // Scalar URL, no discrimination possible
 934                                                         if (is_string($url)) {
 935                                                                 $imageFullUrl = $url;
 936                                                                 continue;
 937                                                         }
 938
 939                                                         // Not sure what to do with a different Link media type than the base Image, we skip
 940                                                         if ($mediaType != JsonLD::fetchElement($url, 'as:mediaType', '@value')) {
 941                                                                 continue;
 942                                                         }
 943
 944                                                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
 945
 946                                                         // Default URL choice if no discriminating width is provided
 947                                                         $imageFullUrl = $href ?? $imageFullUrl;
 948
 949                                                         $width = intval(JsonLD::fetchElement($url, 'as:width', '@value') ?? 1);
 950
 951                                                         if ($href && $width) {
 952                                                                 $imageVariants[$width] = $href;
 953                                                                 // 632 is the ideal width for full screen frio posts, we compute the absolute distance to it
 954                                                                 $previewVariants[abs(632 - $width)] = $href;
 955                                                         }
 956                                                 }
 957
 958                                                 if ($imageVariants) {
 959                                                         // Taking the maximum size image
 960                                                         ksort($imageVariants);
 961                                                         $imageFullUrl = array_pop($imageVariants);
 962
 963                                                         // Taking the minimum number distance to the target distance
 964                                                         ksort($previewVariants);
 965                                                         $imagePreviewUrl = array_shift($previewVariants);
 966                                                 }
 967
 968                                                 unset($imageVariants);
 969                                                 unset($previewVariants);
 970                                         }
 971
 972                                         $attachlist[] = [
 973                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 974                                                 'mediaType' => $mediaType,
 975                                                 'name'  => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 976                                                 'url'   => $imageFullUrl,
 977                                                 'image' => $imagePreviewUrl !== $imageFullUrl ? $imagePreviewUrl : null,
 978                                         ];
 979                                         break;
 980                                 default:
 981                                         $attachlist[] = [
 982                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 983                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 984                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 985                                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')
 986                                         ];
 987                         }
 988                 }
 989
 990                 return $attachlist;
 991         }
 992
 993         /**
 994          * Fetch the original source or content with the "language" Markdown or HTML
 995          *
 996          * @param array $object
 997          * @param array $object_data
 998          *
 999          * @return array
1000          * @throws \Exception
1001          */
1002         private static function getSource($object, $object_data)
1003         {
1004                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
1005                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1006                 if (!empty($object_data['source'])) {
1007                         return $object_data;
1008                 }
1009
1010                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
1011                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1012                 if (!empty($object_data['source'])) {
1013                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
1014                         return $object_data;
1015                 }
1016
1017                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
1018                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1019                 if (!empty($object_data['source'])) {
1020                         $object_data['source'] = HTML::toBBCode($object_data['source']);
1021                         return $object_data;
1022                 }
1023
1024                 return $object_data;
1025         }
1026
1027         /**
1028          * Check if the "as:url" element is an array with multiple links
1029          * This is the case with audio and video posts.
1030          * Then the links are added as attachments
1031          *
1032          * @param array $object      The raw object
1033          * @param array $object_data The parsed object data for later processing
1034          * @return array the object data
1035          */
1036         private static function processAttachmentUrls(array $object, array $object_data) {
1037                 // Check if this is some url with multiple links
1038                 if (empty($object['as:url'])) {
1039                         return $object_data;
1040                 }
1041
1042                 $urls = $object['as:url'];
1043                 $keys = array_keys($urls);
1044                 if (!is_numeric(array_pop($keys))) {
1045                         return $object_data;
1046                 }
1047
1048                 $attachments = [];
1049
1050                 foreach ($urls as $url) {
1051                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1052                                 continue;
1053                         }
1054
1055                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1056                         if (empty($href)) {
1057                                 continue;
1058                         }
1059
1060                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1061                         if (empty($mediatype)) {
1062                                 continue;
1063                         }
1064
1065                         if ($mediatype == 'text/html') {
1066                                 $object_data['alternate-url'] = $href;
1067                         }
1068
1069                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
1070
1071                         if ($filetype == 'audio') {
1072                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href];
1073                         } elseif ($filetype == 'video') {
1074                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1075
1076                                 // We save bandwidth by using a moderate height
1077                                 // Peertube normally uses these heights: 240, 360, 480, 720, 1080
1078                                 if (!empty($attachments[$filetype]['height']) &&
1079                                         (($height > 480) || $height < $attachments[$filetype]['height'])) {
1080                                         continue;
1081                                 }
1082
1083                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href, 'height' => $height];
1084                         }
1085                 }
1086
1087                 foreach ($attachments as $type => $attachment) {
1088                         $object_data['attachments'][] = ['type' => $type,
1089                                 'mediaType' => $attachment['type'],
1090                                 'name' => '',
1091                                 'url' => $attachment['url']];
1092                 }
1093                 return $object_data;
1094         }
1095
1096         /**
1097          * Fetches data from the object part of an activity
1098          *
1099          * @param array $object
1100          *
1101          * @return array
1102          * @throws \Exception
1103          */
1104         private static function processObject($object)
1105         {
1106                 if (!JsonLD::fetchElement($object, '@id')) {
1107                         return false;
1108                 }
1109
1110                 $object_data = [];
1111                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1112                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1113                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1114
1115                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1116                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1117                         $object_data['reply-to-id'] = $object_data['id'];
1118                 } else {
1119                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1120                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1121                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1122                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1123                                 $object_data['reply-to-id'] = $replyToId;
1124                         }
1125                 }
1126
1127                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1128                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1129
1130                 if (empty($object_data['updated'])) {
1131                         $object_data['updated'] = $object_data['published'];
1132                 }
1133
1134                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1135                         $object_data['published'] = $object_data['updated'];
1136                 }
1137
1138                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1139                 if (empty($actor)) {
1140                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1141                 }
1142
1143                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1144                 $location = JsonLD::fetchElement($location, 'location', '@value');
1145                 if ($location) {
1146                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1147                         // down to HTML and then finally format to plaintext.
1148                         $location = Markdown::convert($location);
1149                         $location = BBCode::convert($location);
1150                         $location = HTML::toPlaintext($location);
1151                 }
1152
1153                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1154                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1155                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1156                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1157                 $object_data['actor'] = $object_data['author'] = $actor;
1158                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1159                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1160                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1161                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1162                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1163                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1164                 $object_data = self::getSource($object, $object_data);
1165                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1166                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1167                 $object_data['location'] = $location;
1168                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1169                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1170                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1171                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1172                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment') ?? []);
1173                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag') ?? []);
1174                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji') ?? []);
1175                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1176                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1177                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1178
1179                 // Special treatment for Hubzilla links
1180                 if (is_array($object_data['alternate-url'])) {
1181                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1182
1183                         if (!is_string($object_data['alternate-url'])) {
1184                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1185                         }
1186                 }
1187
1188                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1189                         $object_data = self::processAttachmentUrls($object, $object_data);
1190                 }
1191
1192                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1193                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1194                 unset($object_data['receiver']['uid:-1']);
1195
1196                 // Common object data:
1197
1198                 // Unhandled
1199                 // @context, type, actor, signature, mediaType, duration, replies, icon
1200
1201                 // Also missing: (Defined in the standard, but currently unused)
1202                 // audience, preview, endTime, startTime, image
1203
1204                 // Data in Notes:
1205
1206                 // Unhandled
1207                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1208                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1209
1210                 // Data in video:
1211
1212                 // To-Do?
1213                 // category, licence, language, commentsEnabled
1214
1215                 // Unhandled
1216                 // views, waitTranscoding, state, support, subtitleLanguage
1217                 // likes, dislikes, shares, comments
1218
1219                 return $object_data;
1220         }
1221 }