src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @file src/Protocol/ActivityPub/Receiver.php
   4  */
   5 namespace Friendica\Protocol\ActivityPub;
   6
   7 use Friendica\Database\DBA;
   8 use Friendica\Util\HTTPSignature;
   9 use Friendica\Core\Protocol;
  10 use Friendica\Model\Contact;
  11 use Friendica\Model\APContact;
  12 use Friendica\Model\Item;
  13 use Friendica\Model\User;
  14 use Friendica\Util\JsonLD;
  15 use Friendica\Util\LDSignature;
  16 use Friendica\Protocol\ActivityPub;
  17 use Friendica\Model\Conversation;
  18 use Friendica\Util\DateTimeFormat;
  19
  20 /**
  21  * @brief ActivityPub Receiver Protocol class
  22  *
  23  * To-Do:
  24  * - Update (Image, Video, Article, Note)
  25  * - Event
  26  * - Undo Announce
  27  *
  28  * Check what this is meant to do:
  29  * - Add
  30  * - Block
  31  * - Flag
  32  * - Remove
  33  * - Undo Block
  34  * - Undo Accept (Problem: This could invert a contact accept or an event accept)
  35  */
  36 class Receiver
  37 {
  38         const PUBLIC_COLLECTION = 'as:Public';
  39         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  40         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image'];
  41         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  42
  43         /**
  44          * Checks if the web request is done for the AP protocol
  45          *
  46          * @return is it AP?
  47          */
  48         public static function isRequest()
  49         {
  50                 return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
  51                         stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
  52         }
  53
  54         /**
  55          * Checks incoming message from the inbox
  56          *
  57          * @param $body
  58          * @param $header
  59          * @param integer $uid User ID
  60          */
  61         public static function processInbox($body, $header, $uid)
  62         {
  63                 $http_signer = HTTPSignature::getSigner($body, $header);
  64                 if (empty($http_signer)) {
  65                         logger('Invalid HTTP signature, message will be discarded.', LOGGER_DEBUG);
  66                         return;
  67                 } else {
  68                         logger('HTTP signature is signed by ' . $http_signer, LOGGER_DEBUG);
  69                 }
  70
  71                 $activity = json_decode($body, true);
  72
  73                 if (empty($activity)) {
  74                         logger('Invalid body.', LOGGER_DEBUG);
  75                         return;
  76                 }
  77
  78                 $ldactivity = JsonLD::compact($activity);
  79
  80                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor');
  81
  82                 logger('Message for user ' . $uid . ' is from actor ' . $actor, LOGGER_DEBUG);
  83
  84                 if (LDSignature::isSigned($activity)) {
  85                         $ld_signer = LDSignature::getSigner($activity);
  86                         if (empty($ld_signer)) {
  87                                 logger('Invalid JSON-LD signature from ' . $actor, LOGGER_DEBUG);
  88                         }
  89                         if (!empty($ld_signer && ($actor == $http_signer))) {
  90                                 logger('The HTTP and the JSON-LD signature belong to ' . $ld_signer, LOGGER_DEBUG);
  91                                 $trust_source = true;
  92                         } elseif (!empty($ld_signer)) {
  93                                 logger('JSON-LD signature is signed by ' . $ld_signer, LOGGER_DEBUG);
  94                                 $trust_source = true;
  95                         } elseif ($actor == $http_signer) {
  96                                 logger('Bad JSON-LD signature, but HTTP signer fits the actor.', LOGGER_DEBUG);
  97                                 $trust_source = true;
  98                         } else {
  99                                 logger('Invalid JSON-LD signature and the HTTP signer is different.', LOGGER_DEBUG);
 100                                 $trust_source = false;
 101                         }
 102                 } elseif ($actor == $http_signer) {
 103                         logger('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', LOGGER_DEBUG);
 104                         $trust_source = true;
 105                 } else {
 106                         logger('No JSON-LD signature, different actor.', LOGGER_DEBUG);
 107                         $trust_source = false;
 108                 }
 109
 110                 self::processActivity($ldactivity, $body, $uid, $trust_source);
 111         }
 112
 113         /**
 114          * Fetches the object type for a given object id
 115          *
 116          * @param array  $activity
 117          * @param string $object_id Object ID of the the provided object
 118          *
 119          * @return string with object type
 120          */
 121         private static function fetchObjectType($activity, $object_id)
 122         {
 123
 124                 $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 125                 if (!empty($object_type)) {
 126                         return $object_type;
 127                 }
 128
 129                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 130                         // We just assume "note" since it doesn't make a difference for the further processing
 131                         return 'as:Note';
 132                 }
 133
 134                 $profile = APContact::getByURL($object_id);
 135                 if (!empty($profile['type'])) {
 136                         return 'as:' . $profile['type'];
 137                 }
 138
 139                 $data = ActivityPub::fetchContent($object_id);
 140                 if (!empty($data)) {
 141                         $object = JsonLD::compact($data);
 142                         $type = JsonLD::fetchElement($object, '@type');
 143                         if (!empty($type)) {
 144                                 return $type;
 145                         }
 146                 }
 147
 148                 return null;
 149         }
 150
 151         /**
 152          * Prepare the object array
 153          *
 154          * @param array $activity
 155          * @param integer $uid User ID
 156          * @param $trust_source
 157          *
 158          * @return array with object data
 159          */
 160         private static function prepareObjectData($activity, $uid, &$trust_source)
 161         {
 162                 $actor = JsonLD::fetchElement($activity, 'as:actor');
 163                 if (empty($actor)) {
 164                         logger('Empty actor', LOGGER_DEBUG);
 165                         return [];
 166                 }
 167
 168                 $type = JsonLD::fetchElement($activity, '@type');
 169
 170                 // Fetch all receivers from to, cc, bto and bcc
 171                 $receivers = self::getReceivers($activity, $actor);
 172
 173                 // When it is a delivery to a personal inbox we add that user to the receivers
 174                 if (!empty($uid)) {
 175                         $owner = User::getOwnerDataById($uid);
 176                         $additional = ['uid:' . $uid => $uid];
 177                         $receivers = array_merge($receivers, $additional);
 178                 }
 179
 180                 logger('Receivers: ' . json_encode($receivers), LOGGER_DEBUG);
 181
 182                 $object_id = JsonLD::fetchElement($activity, 'as:object');
 183                 if (empty($object_id)) {
 184                         logger('No object found', LOGGER_DEBUG);
 185                         return [];
 186                 }
 187
 188                 $object_type = self::fetchObjectType($activity, $object_id);
 189
 190                 // Fetch the content only on activities where this matters
 191                 if (in_array($type, ['as:Create', 'as:Announce'])) {
 192                         if ($type == 'as:Announce') {
 193                                 $trust_source = false;
 194                         }
 195                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source);
 196                         if (empty($object_data)) {
 197                                 logger("Object data couldn't be processed", LOGGER_DEBUG);
 198                                 return [];
 199                         }
 200                         // We had been able to retrieve the object data - so we can trust the source
 201                         $trust_source = true;
 202                 } elseif (in_array($type, ['as:Like', 'as:Dislike'])) {
 203                         // Create a mostly empty array out of the activity data (instead of the object).
 204                         // This way we later don't have to check for the existence of ech individual array element.
 205                         $object_data = self::processObject($activity);
 206                         $object_data['name'] = $type;
 207                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor');
 208                         $object_data['object_id'] = $object_id;
 209                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 210                 } else {
 211                         $object_data = [];
 212                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 213                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object');
 214                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor');
 215                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 216                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 217                 }
 218
 219                 $object_data = self::addActivityFields($object_data, $activity);
 220
 221                 if (empty($object_data['object_type'])) {
 222                         $object_data['object_type'] = $object_type;
 223                 }
 224
 225                 $object_data['type'] = $type;
 226                 $object_data['actor'] = $actor;
 227                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 228
 229                 logger('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], LOGGER_DEBUG);
 230
 231                 return $object_data;
 232         }
 233
 234         /**
 235          * Store the unprocessed data into the conversation table
 236          * This has to be done outside the regular function,
 237          * since we store everything - not only item posts.
 238          *
 239          * @param array  $activity Array with activity data
 240          * @param string $body     The raw message
 241          */
 242         private static function storeConversation($activity, $body)
 243         {
 244                 if (empty($body) || empty($activity['id'])) {
 245                         return;
 246                 }
 247
 248                 $conversation = [
 249                         'protocol' => Conversation::PARCEL_ACTIVITYPUB,
 250                         'item-uri' => $activity['id'],
 251                         'reply-to-uri' => defaults($activity, 'reply-to-id', ''),
 252                         'conversation-href' => defaults($activity, 'context', ''),
 253                         'conversation-uri' => defaults($activity, 'conversation', ''),
 254                         'source' => $body,
 255                         'received' => DateTimeFormat::utcNow()];
 256
 257                 DBA::insert('conversation', $conversation, true);
 258         }
 259
 260         /**
 261          * Processes the activity object
 262          *
 263          * @param array   $activity     Array with activity data
 264          * @param string  $body
 265          * @param integer $uid          User ID
 266          * @param boolean $trust_source Do we trust the source?
 267          */
 268         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
 269         {
 270                 $type = JsonLD::fetchElement($activity, '@type');
 271                 if (!$type) {
 272                         logger('Empty type', LOGGER_DEBUG);
 273                         return;
 274                 }
 275
 276                 if (!JsonLD::fetchElement($activity, 'as:object')) {
 277                         logger('Empty object', LOGGER_DEBUG);
 278                         return;
 279                 }
 280
 281                 if (!JsonLD::fetchElement($activity, 'as:actor')) {
 282                         logger('Empty actor', LOGGER_DEBUG);
 283                         return;
 284
 285                 }
 286
 287                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 288                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
 289                 if (empty($object_data)) {
 290                         logger('No object data found', LOGGER_DEBUG);
 291                         return;
 292                 }
 293
 294                 if (!$trust_source) {
 295                         logger('No trust for activity type "' . $type . '", so we quit now.', LOGGER_DEBUG);
 296                         return;
 297                 }
 298
 299                 self::storeConversation($object_data, $body);
 300
 301                 // Internal flag for thread completion. See Processor.php
 302                 if (!empty($activity['thread-completion'])) {
 303                         $object_data['thread-completion'] = $activity['thread-completion'];
 304                 }
 305
 306                 switch ($type) {
 307                         case 'as:Create':
 308                         case 'as:Announce':
 309                                 ActivityPub\Processor::createItem($object_data);
 310                                 break;
 311
 312                         case 'as:Like':
 313                                 ActivityPub\Processor::likeItem($object_data);
 314                                 break;
 315
 316                         case 'as:Dislike':
 317                                 ActivityPub\Processor::dislikeItem($object_data);
 318                                 break;
 319
 320                         case 'as:Update':
 321                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 322                                         /// @todo
 323                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 324                                         ActivityPub\Processor::updatePerson($object_data, $body);
 325                                 }
 326                                 break;
 327
 328                         case 'as:Delete':
 329                                 if ($object_data['object_type'] == 'as:Tombstone') {
 330                                         ActivityPub\Processor::deleteItem($object_data, $body);
 331                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 332                                         ActivityPub\Processor::deletePerson($object_data, $body);
 333                                 }
 334                                 break;
 335
 336                         case 'as:Follow':
 337                                 ActivityPub\Processor::followUser($object_data);
 338                                 break;
 339
 340                         case 'as:Accept':
 341                                 if ($object_data['object_type'] == 'as:Follow') {
 342                                         ActivityPub\Processor::acceptFollowUser($object_data);
 343                                 }
 344                                 break;
 345
 346                         case 'as:Reject':
 347                                 if ($object_data['object_type'] == 'as:Follow') {
 348                                         ActivityPub\Processor::rejectFollowUser($object_data);
 349                                 }
 350                                 break;
 351
 352                         case 'as:Undo':
 353                                 if ($object_data['object_type'] == 'as:Follow') {
 354                                         ActivityPub\Processor::undoFollowUser($object_data);
 355                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES)) {
 356                                         ActivityPub\Processor::undoActivity($object_data);
 357                                 }
 358                                 break;
 359
 360                         default:
 361                                 logger('Unknown activity: ' . $type, LOGGER_DEBUG);
 362                                 break;
 363                 }
 364         }
 365
 366         /**
 367          * Fetch the receiver list from an activity array
 368          *
 369          * @param array $activity
 370          * @param string $actor
 371          *
 372          * @return array with receivers (user id)
 373          */
 374         private static function getReceivers($activity, $actor)
 375         {
 376                 $receivers = [];
 377
 378                 // When it is an answer, we inherite the receivers from the parent
 379                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo');
 380                 if (!empty($replyto)) {
 381                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 382                         while ($parent = Item::fetch($parents)) {
 383                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 384                         }
 385                 }
 386
 387                 if (!empty($actor)) {
 388                         $profile = APContact::getByURL($actor);
 389                         $followers = defaults($profile, 'followers', '');
 390
 391                         logger('Actor: ' . $actor . ' - Followers: ' . $followers, LOGGER_DEBUG);
 392                 } else {
 393                         logger('Empty actor', LOGGER_DEBUG);
 394                         $followers = '';
 395                 }
 396
 397                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 398                         $receiver_list = JsonLD::fetchElementArray($activity, $element);
 399                         if (empty($receiver_list)) {
 400                                 continue;
 401                         }
 402
 403                         foreach ($receiver_list as $receiver) {
 404                                 if ($receiver == self::PUBLIC_COLLECTION) {
 405                                         $receivers['uid:0'] = 0;
 406                                 }
 407
 408                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 409                                         // This will most likely catch all OStatus connections to Mastodon
 410                                         $condition = ['alias' => [$actor, normalise_link($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 411                                                 , 'archive' => false, 'pending' => false];
 412                                         $contacts = DBA::select('contact', ['uid'], $condition);
 413                                         while ($contact = DBA::fetch($contacts)) {
 414                                                 if ($contact['uid'] != 0) {
 415                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 416                                                 }
 417                                         }
 418                                         DBA::close($contacts);
 419                                 }
 420
 421                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 422                                         $condition = ['nurl' => normalise_link($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 423                                                 'network' => Protocol::ACTIVITYPUB, 'archive' => false, 'pending' => false];
 424                                         $contacts = DBA::select('contact', ['uid'], $condition);
 425                                         while ($contact = DBA::fetch($contacts)) {
 426                                                 if ($contact['uid'] != 0) {
 427                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 428                                                 }
 429                                         }
 430                                         DBA::close($contacts);
 431                                         continue;
 432                                 }
 433
 434                                 $condition = ['self' => true, 'nurl' => normalise_link($receiver)];
 435                                 $contact = DBA::selectFirst('contact', ['uid'], $condition);
 436                                 if (!DBA::isResult($contact)) {
 437                                         continue;
 438                                 }
 439                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 440                         }
 441                 }
 442
 443                 self::switchContacts($receivers, $actor);
 444
 445                 return $receivers;
 446         }
 447
 448         /**
 449          * Switches existing contacts to ActivityPub
 450          *
 451          * @param integer $cid Contact ID
 452          * @param integer $uid User ID
 453          * @param string $url Profile URL
 454          */
 455         public static function switchContact($cid, $uid, $url)
 456         {
 457                 $profile = ActivityPub::probeProfile($url);
 458                 if (empty($profile)) {
 459                         return;
 460                 }
 461
 462                 logger('Switch contact ' . $cid . ' (' . $profile['url'] . ') for user ' . $uid . ' to ActivityPub');
 463
 464                 $photo = $profile['photo'];
 465                 unset($profile['photo']);
 466                 unset($profile['baseurl']);
 467
 468                 $profile['nurl'] = normalise_link($profile['url']);
 469                 DBA::update('contact', $profile, ['id' => $cid]);
 470
 471                 Contact::updateAvatar($photo, $uid, $cid);
 472
 473                 // Send a new follow request to be sure that the connection still exists
 474                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND]])) {
 475                         ActivityPub\Transmitter::sendActivity('Follow', $profile['url'], $uid);
 476                         logger('Send a new follow request to ' . $profile['url'] . ' for user ' . $uid, LOGGER_DEBUG);
 477                 }
 478         }
 479
 480         /**
 481          *
 482          *
 483          * @param $receivers
 484          * @param $actor
 485          */
 486         private static function switchContacts($receivers, $actor)
 487         {
 488                 if (empty($actor)) {
 489                         return;
 490                 }
 491
 492                 foreach ($receivers as $receiver) {
 493                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => normalise_link($actor)]);
 494                         if (DBA::isResult($contact)) {
 495                                 self::switchContact($contact['id'], $receiver, $actor);
 496                         }
 497
 498                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [normalise_link($actor), $actor]]);
 499                         if (DBA::isResult($contact)) {
 500                                 self::switchContact($contact['id'], $receiver, $actor);
 501                         }
 502                 }
 503         }
 504
 505         /**
 506          *
 507          *
 508          * @param $object_data
 509          * @param array $activity
 510          *
 511          * @return
 512          */
 513         private static function addActivityFields($object_data, $activity)
 514         {
 515                 if (!empty($activity['published']) && empty($object_data['published'])) {
 516                         $object_data['published'] = JsonLD::fetchElement($activity, 'published', '@value');
 517                 }
 518
 519                 if (!empty($activity['updated']) && empty($object_data['updated'])) {
 520                         $object_data['updated'] = JsonLD::fetchElement($activity, 'updated', '@value');
 521                 }
 522
 523                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 524                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid');
 525                 }
 526
 527                 if (!empty($activity['inReplyTo']) && empty($object_data['parent-uri'])) {
 528                         $object_data['parent-uri'] = JsonLD::fetchElement($activity, 'inReplyTo');
 529                 }
 530
 531                 if (!empty($activity['instrument'])) {
 532                         $object_data['service'] = JsonLD::fetchElement($activity, 'instrument', 'name', 'type', 'Service');
 533                 }
 534                 return $object_data;
 535         }
 536
 537         /**
 538          * Fetches the object data from external ressources if needed
 539          *
 540          * @param string  $object_id    Object ID of the the provided object
 541          * @param array   $object       The provided object array
 542          * @param boolean $trust_source Do we trust the provided object?
 543          *
 544          * @return array with trusted and valid object data
 545          */
 546         private static function fetchObject($object_id, $object = [], $trust_source = false)
 547         {
 548                 // By fetching the type we check if the object is complete.
 549                 $type = JsonLD::fetchElement($object, '@type');
 550
 551                 if (!$trust_source || empty($type)) {
 552                         $data = ActivityPub::fetchContent($object_id);
 553                         if (!empty($data)) {
 554                                 $object = JsonLD::compact($data);
 555                                 logger('Fetched content for ' . $object_id, LOGGER_DEBUG);
 556                         } else {
 557                                 logger('Empty content for ' . $object_id . ', check if content is available locally.', LOGGER_DEBUG);
 558
 559                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 560                                 if (!DBA::isResult($item)) {
 561                                         logger('Object with url ' . $object_id . ' was not found locally.', LOGGER_DEBUG);
 562                                         return false;
 563                                 }
 564                                 logger('Using already stored item for url ' . $object_id, LOGGER_DEBUG);
 565                                 $data = ActivityPub\Transmitter::createNote($item);
 566                                 $object = JsonLD::compact($data);
 567                         }
 568                 } else {
 569                         logger('Using original object for url ' . $object_id, LOGGER_DEBUG);
 570                 }
 571
 572                 $type = JsonLD::fetchElement($object, '@type');
 573
 574                 if (empty($type)) {
 575                         logger('Empty type', LOGGER_DEBUG);
 576                         return false;
 577                 }
 578
 579                 if (in_array($type, self::CONTENT_TYPES)) {
 580                         return self::processObject($object);
 581                 }
 582
 583                 if ($type == 'as:Announce') {
 584                         $object_id = JsonLD::fetchElement($object, 'object');
 585                         if (empty($object_id)) {
 586                                 return false;
 587                         }
 588                         return self::fetchObject($object_id);
 589                 }
 590
 591                 logger('Unhandled object type: ' . $type, LOGGER_DEBUG);
 592         }
 593
 594         /**
 595          * Convert tags from JSON-LD format into a simplified format
 596          *
 597          * @param array $tags Tags in JSON-LD format
 598          *
 599          * @return array with tags in a simplified format
 600          */
 601         private static function processTags($tags)
 602         {
 603                 $taglist = [];
 604
 605                 if (empty($tags)) {
 606                         return [];
 607                 }
 608
 609                 foreach ($tags as $tag) {
 610                         if (empty($tag)) {
 611                                 continue;
 612                         }
 613
 614                         $taglist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 615                                 'href' => JsonLD::fetchElement($tag, 'as:href'),
 616                                 'name' => JsonLD::fetchElement($tag, 'as:name')];
 617                 }
 618                 return $taglist;
 619         }
 620
 621         /**
 622          * Convert attachments from JSON-LD format into a simplified format
 623          *
 624          * @param array $attachments Attachments in JSON-LD format
 625          *
 626          * @return array with attachmants in a simplified format
 627          */
 628         private static function processAttachments($attachments)
 629         {
 630                 $attachlist = [];
 631
 632                 if (empty($attachments)) {
 633                         return [];
 634                 }
 635
 636                 foreach ($attachments as $attachment) {
 637                         if (empty($attachment)) {
 638                                 continue;
 639                         }
 640
 641                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 642                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType'),
 643                                 'name' => JsonLD::fetchElement($attachment, 'as:name'),
 644                                 'url' => JsonLD::fetchElement($attachment, 'as:url')];
 645                 }
 646                 return $attachlist;
 647         }
 648
 649         /**
 650          * Fetches data from the object part of an activity
 651          *
 652          * @param array $object
 653          *
 654          * @return array
 655          */
 656         private static function processObject($object)
 657         {
 658                 if (!JsonLD::fetchElement($object, '@id')) {
 659                         return false;
 660                 }
 661
 662                 $object_data = [];
 663                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 664                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 665
 666                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo');
 667
 668                 if (empty($object_data['reply-to-id'])) {
 669                         $object_data['reply-to-id'] = $object_data['id'];
 670                 }
 671
 672                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 673                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 674
 675                 if (empty($object_data['updated'])) {
 676                         $object_data['updated'] = $object_data['published'];
 677                 }
 678
 679                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 680                         $object_data['published'] = $object_data['updated'];
 681                 }
 682
 683                 $actor = JsonLD::fetchElement($object, 'as:attributedTo');
 684                 if (empty($actor)) {
 685                         $actor = JsonLD::fetchElement($object, 'as:actor');
 686                 }
 687
 688                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid');
 689                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment');
 690                 $object_data['actor'] = $object_data['author'] = $actor;
 691                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context');
 692                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation');
 693                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 694                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name');
 695                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary');
 696                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content');
 697                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 698                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 699                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 700                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 701 //              $object_data['service'] = JsonLD::fetchElement($object, 'instrument', 'name', 'type', 'Service'); // todo
 702                 $object_data['service'] = null;
 703                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url');
 704
 705                 // Special treatment for Hubzilla links
 706                 if (is_array($object_data['alternate-url'])) {
 707                         if (!empty($object['as:url'])) {
 708                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href');
 709                         } else {
 710                                 $object_data['alternate-url'] = null;
 711                         }
 712                 }
 713
 714                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor']);
 715
 716                 // Common object data:
 717
 718                 // Unhandled
 719                 // @context, type, actor, signature, mediaType, duration, replies, icon
 720
 721                 // Also missing: (Defined in the standard, but currently unused)
 722                 // audience, preview, endTime, startTime, generator, image
 723
 724                 // Data in Notes:
 725
 726                 // Unhandled
 727                 // contentMap, announcement_count, announcements, context_id, likes, like_count
 728                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
 729
 730                 // Data in video:
 731
 732                 // To-Do?
 733                 // category, licence, language, commentsEnabled
 734
 735                 // Unhandled
 736                 // views, waitTranscoding, state, support, subtitleLanguage
 737                 // likes, dislikes, shares, comments
 738
 739                 return $object_data;
 740         }
 741 }