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\HTTPSignature;
  37 use Friendica\Util\JsonLD;
  38 use Friendica\Util\LDSignature;
  39 use Friendica\Util\Strings;
  40
  41 /**
  42  * ActivityPub Receiver Protocol class
  43  *
  44  * To-Do:
  45  * @todo Undo Announce
  46  *
  47  * Check what this is meant to do:
  48  * - Add
  49  * - Block
  50  * - Flag
  51  * - Remove
  52  * - Undo Block
  53  */
  54 class Receiver
  55 {
  56         const PUBLIC_COLLECTION = 'as:Public';
  57         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  58         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio'];
  59         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  60
  61         const TARGET_UNKNOWN = 0;
  62         const TARGET_TO = 1;
  63         const TARGET_CC = 2;
  64         const TARGET_BTO = 3;
  65         const TARGET_BCC = 4;
  66         const TARGET_FOLLOWER = 5;
  67         const TARGET_ANSWER = 6;
  68         const TARGET_GLOBAL = 7;
  69
  70         /**
  71          * Checks if the web request is done for the AP protocol
  72          *
  73          * @return bool is it AP?
  74          */
  75         public static function isRequest()
  76         {
  77                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
  78                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
  79         }
  80
  81         /**
  82          * Checks incoming message from the inbox
  83          *
  84          * @param         $body
  85          * @param         $header
  86          * @param integer $uid User ID
  87          * @throws \Exception
  88          */
  89         public static function processInbox($body, $header, $uid)
  90         {
  91                 $activity = json_decode($body, true);
  92                 if (empty($activity)) {
  93                         Logger::warning('Invalid body.');
  94                         return;
  95                 }
  96
  97                 $ldactivity = JsonLD::compact($activity);
  98
  99                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
 100
 101                 $apcontact = APContact::getByURL($actor);
 102                 if (!empty($apcontact) && ($apcontact['type'] == 'Application') && ($apcontact['nick'] == 'relay')) {
 103                         self::processRelayPost($ldactivity, $actor);
 104                         return;
 105                 }
 106
 107                 $http_signer = HTTPSignature::getSigner($body, $header);
 108                 if (empty($http_signer)) {
 109                         Logger::warning('Invalid HTTP signature, message will be discarded.');
 110                         return;
 111                 } else {
 112                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
 113                 }
 114
 115                 $signer = [$http_signer];
 116
 117                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 118
 119                 if (LDSignature::isSigned($activity)) {
 120                         $ld_signer = LDSignature::getSigner($activity);
 121                         if (empty($ld_signer)) {
 122                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
 123                         } elseif ($ld_signer != $http_signer) {
 124                                 $signer[] = $ld_signer;
 125                         }
 126                         if (!empty($ld_signer && ($actor == $http_signer))) {
 127                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
 128                                 $trust_source = true;
 129                         } elseif (!empty($ld_signer)) {
 130                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
 131                                 $trust_source = true;
 132                         } elseif ($actor == $http_signer) {
 133                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
 134                                 $trust_source = true;
 135                         } else {
 136                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
 137                                 $trust_source = false;
 138                         }
 139                 } elseif ($actor == $http_signer) {
 140                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 141                         $trust_source = true;
 142                 } else {
 143                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 144                         $trust_source = false;
 145                 }
 146
 147                 self::processActivity($ldactivity, $body, $uid, $trust_source, true, $signer);
 148         }
 149
 150         /**
 151          * Process incoming posts from relays
 152          *
 153          * @param array  $activity
 154          * @param string $actor
 155          * @return void
 156          */
 157         private static function processRelayPost(array $activity, string $actor)
 158         {
 159                 $type = JsonLD::fetchElement($activity, '@type');
 160                 if (!$type) {
 161                         Logger::info('Empty type', ['activity' => $activity]);
 162                         return;
 163                 }
 164
 165                 if ($type != 'as:Announce') {
 166                         Logger::info('Not an announcement', ['activity' => $activity]);
 167                         return;
 168                 }
 169
 170                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 171                 if (empty($object_id)) {
 172                         Logger::info('No object id found', ['activity' => $activity]);
 173                         return;
 174                 }
 175
 176                 Logger::info('Got relayed message id', ['id' => $object_id]);
 177
 178                 $item_id = Item::searchByLink($object_id);
 179                 if ($item_id) {
 180                         Logger::info('Relayed message already exists', ['id' => $object_id, 'item' => $item_id]);
 181                         return;
 182                 }
 183
 184                 Processor::fetchMissingActivity($object_id, [], $actor);
 185
 186                 $item_id = Item::searchByLink($object_id);
 187                 if ($item_id) {
 188                         Logger::info('Relayed message had been fetched and stored', ['id' => $object_id, 'item' => $item_id]);
 189                 } else {
 190                         Logger::notice('Relayed message had not been stored', ['id' => $object_id]);
 191                 }
 192         }
 193
 194         /**
 195          * Fetches the object type for a given object id
 196          *
 197          * @param array   $activity
 198          * @param string  $object_id Object ID of the the provided object
 199          * @param integer $uid       User ID
 200          *
 201          * @return string with object type
 202          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 203          * @throws \ImagickException
 204          */
 205         private static function fetchObjectType($activity, $object_id, $uid = 0)
 206         {
 207                 if (!empty($activity['as:object'])) {
 208                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 209                         if (!empty($object_type)) {
 210                                 return $object_type;
 211                         }
 212                 }
 213
 214                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 215                         // We just assume "note" since it doesn't make a difference for the further processing
 216                         return 'as:Note';
 217                 }
 218
 219                 $profile = APContact::getByURL($object_id);
 220                 if (!empty($profile['type'])) {
 221                         return 'as:' . $profile['type'];
 222                 }
 223
 224                 $data = ActivityPub::fetchContent($object_id, $uid);
 225                 if (!empty($data)) {
 226                         $object = JsonLD::compact($data);
 227                         $type = JsonLD::fetchElement($object, '@type');
 228                         if (!empty($type)) {
 229                                 return $type;
 230                         }
 231                 }
 232
 233                 return null;
 234         }
 235
 236         /**
 237          * Prepare the object array
 238          *
 239          * @param array   $activity     Array with activity data
 240          * @param integer $uid          User ID
 241          * @param boolean $push         Message had been pushed to our system
 242          * @param boolean $trust_source Do we trust the source?
 243          *
 244          * @return array with object data
 245          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 246          * @throws \ImagickException
 247          */
 248         public static function prepareObjectData($activity, $uid, $push, &$trust_source)
 249         {
 250                 $id = JsonLD::fetchElement($activity, '@id');
 251                 if (!empty($id) && !$trust_source) {
 252                         $fetched_activity = ActivityPub::fetchContent($id, $uid ?? 0);
 253                         if (!empty($fetched_activity)) {
 254                                 $object = JsonLD::compact($fetched_activity);
 255                                 $fetched_id = JsonLD::fetchElement($object, '@id');
 256                                 if ($fetched_id == $id) {
 257                                         Logger::info('Activity had been fetched successfully', ['id' => $id]);
 258                                         $trust_source = true;
 259                                         $activity = $object;
 260                                 } else {
 261                                         Logger::info('Activity id is not equal', ['id' => $id, 'fetched' => $fetched_id]);
 262                                 }
 263                         } else {
 264                                 Logger::info('Activity could not been fetched', ['id' => $id]);
 265                         }
 266                 }
 267
 268                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 269                 if (empty($actor)) {
 270                         Logger::info('Empty actor', ['activity' => $activity]);
 271                         return [];
 272                 }
 273
 274                 $type = JsonLD::fetchElement($activity, '@type');
 275
 276                 // Fetch all receivers from to, cc, bto and bcc
 277                 $receiverdata = self::getReceivers($activity, $actor);
 278                 $receivers = $reception_types = [];
 279                 foreach ($receiverdata as $key => $data) {
 280                         $receivers[$key] = $data['uid'];
 281                         $reception_types[$data['uid']] = $data['type'] ?? 0;
 282                 }
 283
 284                 // When it is a delivery to a personal inbox we add that user to the receivers
 285                 if (!empty($uid)) {
 286                         $additional = ['uid:' . $uid => $uid];
 287                         $receivers = array_merge($receivers, $additional);
 288                         if (empty($reception_types[$uid]) || in_array($reception_types[$uid], [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL])) {
 289                                 $reception_types[$uid] = self::TARGET_BCC;
 290                         }
 291                 } else {
 292                         // We possibly need some user to fetch private content,
 293                         // so we fetch the first out ot the list.
 294                         $uid = self::getFirstUserFromReceivers($receivers);
 295                 }
 296
 297                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 298                 if (empty($object_id)) {
 299                         Logger::log('No object found', Logger::DEBUG);
 300                         return [];
 301                 }
 302
 303                 if (!is_string($object_id)) {
 304                         Logger::info('Invalid object id', ['object' => $object_id]);
 305                         return [];
 306                 }
 307
 308                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 309
 310                 // Fetch the content only on activities where this matters
 311                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 312                         // Always fetch on "Announce"
 313                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source && ($type != 'as:Announce'), $uid);
 314                         if (empty($object_data)) {
 315                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 316                                 return [];
 317                         }
 318
 319                         $object_data['object_id'] = $object_id;
 320
 321                         if ($type == 'as:Announce') {
 322                                 $object_data['push'] = false;
 323                         } else {
 324                                 $object_data['push'] = $push;
 325                         }
 326
 327                         // Test if it is an answer to a mail
 328                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 329                                 $object_data['directmessage'] = true;
 330                         } else {
 331                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 332                         }
 333                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 334                         // Create a mostly empty array out of the activity data (instead of the object).
 335                         // This way we later don't have to check for the existence of ech individual array element.
 336                         $object_data = self::processObject($activity);
 337                         $object_data['name'] = $type;
 338                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 339                         $object_data['object_id'] = $object_id;
 340                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 341                 } elseif (in_array($type, ['as:Add'])) {
 342                         $object_data = [];
 343                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 344                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 345                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 346                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 347                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 348                 } else {
 349                         $object_data = [];
 350                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 351                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 352                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 353                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 354                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 355
 356                         // An Undo is done on the object of an object, so we need that type as well
 357                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
 358                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 359                         }
 360                 }
 361
 362                 $object_data = self::addActivityFields($object_data, $activity);
 363
 364                 if (empty($object_data['object_type'])) {
 365                         $object_data['object_type'] = $object_type;
 366                 }
 367
 368                 $object_data['type'] = $type;
 369                 $object_data['actor'] = $actor;
 370                 $object_data['item_receiver'] = $receivers;
 371                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
 372                 $object_data['reception_type'] = array_merge($object_data['reception_type'] ?? [], $reception_types);
 373
 374                 $author = $object_data['author'] ?? $actor;
 375                 if (!empty($author) && !empty($object_data['id'])) {
 376                         $author_host = parse_url($author, PHP_URL_HOST);
 377                         $id_host = parse_url($object_data['id'], PHP_URL_HOST);
 378                         if ($author_host == $id_host) {
 379                                 Logger::info('Valid hosts', ['type' => $type, 'host' => $id_host]);
 380                         } else {
 381                                 Logger::notice('Differing hosts on author and id', ['type' => $type, 'author' => $author_host, 'id' => $id_host]);
 382                                 $trust_source = false;
 383                         }
 384                 }
 385
 386                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 387
 388                 return $object_data;
 389         }
 390
 391         /**
 392          * Fetches the first user id from the receiver array
 393          *
 394          * @param array $receivers Array with receivers
 395          * @return integer user id;
 396          */
 397         public static function getFirstUserFromReceivers($receivers)
 398         {
 399                 foreach ($receivers as $receiver) {
 400                         if (!empty($receiver)) {
 401                                 return $receiver;
 402                         }
 403                 }
 404                 return 0;
 405         }
 406
 407         /**
 408          * Processes the activity object
 409          *
 410          * @param array   $activity     Array with activity data
 411          * @param string  $body
 412          * @param integer $uid          User ID
 413          * @param boolean $trust_source Do we trust the source?
 414          * @param boolean $push         Message had been pushed to our system
 415          * @throws \Exception
 416          */
 417         public static function processActivity($activity, string $body = '', int $uid = null, bool $trust_source = false, bool $push = false, array $signer = [])
 418         {
 419                 $type = JsonLD::fetchElement($activity, '@type');
 420                 if (!$type) {
 421                         Logger::info('Empty type', ['activity' => $activity]);
 422                         return;
 423                 }
 424
 425                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 426                         Logger::info('Empty object', ['activity' => $activity]);
 427                         return;
 428                 }
 429
 430                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 431                 if (empty($actor)) {
 432                         Logger::info('Empty actor', ['activity' => $activity]);
 433                         return;
 434                 }
 435
 436                 if (is_array($activity['as:object'])) {
 437                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 438                 } else {
 439                         $attributed_to = '';
 440                 }
 441
 442                 // Test the provided signatures against the actor and "attributedTo"
 443                 if ($trust_source) {
 444                         if (!empty($attributed_to) && !empty($actor)) {
 445                                 $trust_source = (in_array($actor, $signer) && in_array($attributed_to, $signer));
 446                         } else {
 447                                 $trust_source = in_array($actor, $signer);
 448                         }
 449                 }
 450
 451                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 452                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 453                 if (empty($object_data)) {
 454                         Logger::info('No object data found', ['activity' => $activity]);
 455                         return;
 456                 }
 457
 458                 if (!$trust_source) {
 459                         Logger::info('Activity trust could not be achieved.',  ['id' => $object_data['object_id'], 'type' => $type, 'signer' => $signer, 'actor' => $actor, 'attributedTo' => $attributed_to]);
 460                         return;
 461                 }
 462
 463                 if (!empty($body) && empty($object_data['raw'])) {
 464                         $object_data['raw'] = $body;
 465                 }
 466
 467                 // Internal flag for thread completion. See Processor.php
 468                 if (!empty($activity['thread-completion'])) {
 469                         $object_data['thread-completion'] = $activity['thread-completion'];
 470                 }
 471
 472                 // Internal flag for posts that arrived via relay
 473                 if (!empty($activity['from-relay'])) {
 474                         $object_data['from-relay'] = $activity['from-relay'];
 475                 }
 476
 477                 switch ($type) {
 478                         case 'as:Create':
 479                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 480                                         $item = ActivityPub\Processor::createItem($object_data);
 481                                         ActivityPub\Processor::postItem($object_data, $item);
 482                                 }
 483                                 break;
 484
 485                         case 'as:Add':
 486                                 if ($object_data['object_type'] == 'as:tag') {
 487                                         ActivityPub\Processor::addTag($object_data);
 488                                 }
 489                                 break;
 490
 491                         case 'as:Announce':
 492                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 493                                         $object_data['thread-completion'] = true;
 494
 495                                         $item = ActivityPub\Processor::createItem($object_data);
 496                                         if (empty($item)) {
 497                                                 return;
 498                                         }
 499
 500                                         $item['post-type'] = Item::PT_ANNOUNCEMENT;
 501                                         ActivityPub\Processor::postItem($object_data, $item);
 502
 503                                         $announce_object_data = self::processObject($activity);
 504                                         $announce_object_data['name'] = $type;
 505                                         $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 506                                         $announce_object_data['object_id'] = $object_data['object_id'];
 507                                         $announce_object_data['object_type'] = $object_data['object_type'];
 508                                         $announce_object_data['push'] = $push;
 509
 510                                         if (!empty($body)) {
 511                                                 $announce_object_data['raw'] = $body;
 512                                         }
 513
 514                                         ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 515                                 }
 516                                 break;
 517
 518                         case 'as:Like':
 519                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 520                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 521                                 }
 522                                 break;
 523
 524                         case 'as:Dislike':
 525                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 526                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 527                                 }
 528                                 break;
 529
 530                         case 'as:TentativeAccept':
 531                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 532                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 533                                 }
 534                                 break;
 535
 536                         case 'as:Update':
 537                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 538                                         ActivityPub\Processor::updateItem($object_data);
 539                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 540                                         ActivityPub\Processor::updatePerson($object_data);
 541                                 }
 542                                 break;
 543
 544                         case 'as:Delete':
 545                                 if ($object_data['object_type'] == 'as:Tombstone') {
 546                                         ActivityPub\Processor::deleteItem($object_data);
 547                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 548                                         ActivityPub\Processor::deletePerson($object_data);
 549                                 }
 550                                 break;
 551
 552                         case 'as:Follow':
 553                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 554                                         ActivityPub\Processor::followUser($object_data);
 555                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 556                                         $object_data['reply-to-id'] = $object_data['object_id'];
 557                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 558                                 }
 559                                 break;
 560
 561                         case 'as:Accept':
 562                                 if ($object_data['object_type'] == 'as:Follow') {
 563                                         ActivityPub\Processor::acceptFollowUser($object_data);
 564                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 565                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 566                                 }
 567                                 break;
 568
 569                         case 'as:Reject':
 570                                 if ($object_data['object_type'] == 'as:Follow') {
 571                                         ActivityPub\Processor::rejectFollowUser($object_data);
 572                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 573                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 574                                 }
 575                                 break;
 576
 577                         case 'as:Undo':
 578                                 if (($object_data['object_type'] == 'as:Follow') &&
 579                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 580                                         ActivityPub\Processor::undoFollowUser($object_data);
 581                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 582                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 583                                         ActivityPub\Processor::rejectFollowUser($object_data);
 584                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 585                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 586                                         ActivityPub\Processor::undoActivity($object_data);
 587                                 }
 588                                 break;
 589
 590                         default:
 591                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 592                                 break;
 593                 }
 594         }
 595
 596         /**
 597          * Fetch the receiver list from an activity array
 598          *
 599          * @param array   $activity
 600          * @param string  $actor
 601          * @param array   $tags
 602          * @param boolean $fetch_unlisted
 603          *
 604          * @return array with receivers (user id)
 605          * @throws \Exception
 606          */
 607         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 608         {
 609                 $reply = $receivers = [];
 610
 611                 // When it is an answer, we inherite the receivers from the parent
 612                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 613                 if (!empty($replyto)) {
 614                         $reply = [$replyto];
 615
 616                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 617                         $fixedReplyTo = Item::getURIByLink($replyto);
 618                         if (!empty($fixedReplyTo)) {
 619                                 $reply[] = $fixedReplyTo;
 620                         }
 621                 }
 622
 623                 // Fetch all posts that refer to the object id
 624                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 625                 if (!empty($object_id)) {
 626                         $reply[] = $object_id;
 627                 }
 628
 629                 if (!empty($reply)) {
 630                         $parents = Item::select(['uid'], ['uri' => $reply]);
 631                         while ($parent = Item::fetch($parents)) {
 632                                 $receivers['uid:' . $parent['uid']] = ['uid' => $parent['uid'], 'type' => self::TARGET_ANSWER];
 633                         }
 634                 }
 635
 636                 if (!empty($actor)) {
 637                         $profile = APContact::getByURL($actor);
 638                         $followers = $profile['followers'] ?? '';
 639
 640                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 641                 } else {
 642                         Logger::info('Empty actor', ['activity' => $activity]);
 643                         $followers = '';
 644                 }
 645
 646                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 647                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 648                         if (empty($receiver_list)) {
 649                                 continue;
 650                         }
 651
 652                         foreach ($receiver_list as $receiver) {
 653                                 if ($receiver == self::PUBLIC_COLLECTION) {
 654                                         $receivers['uid:0'] = ['uid' => 0, 'type' => self::TARGET_GLOBAL];
 655                                 }
 656
 657                                 // Add receiver "-1" for unlisted posts
 658                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 659                                         $receivers['uid:-1'] = ['uid' => -1, 'type' => self::TARGET_GLOBAL];
 660                                 }
 661
 662                                 // Fetch the receivers for the public and the followers collection
 663                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 664                                         $receivers = self::getReceiverForActor($actor, $tags, $receivers);
 665                                         continue;
 666                                 }
 667
 668                                 // Fetching all directly addressed receivers
 669                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 670                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 671                                 if (!DBA::isResult($contact)) {
 672                                         continue;
 673                                 }
 674
 675                                 // Check if the potential receiver is following the actor
 676                                 // Exception: The receiver is targetted via "to" or this is a comment
 677                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 678                                         $networks = Protocol::FEDERATED;
 679                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 680                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 681
 682                                         // Forum posts are only accepted from forum contacts
 683                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 684                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 685                                         }
 686
 687                                         if (!DBA::exists('contact', $condition)) {
 688                                                 continue;
 689                                         }
 690                                 }
 691
 692                                 $type = $receivers['uid:' . $contact['uid']]['type'] ?? self::TARGET_UNKNOWN;
 693                                 if (in_array($type, [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL])) {
 694                                         switch ($element) {
 695                                                 case 'as:to':
 696                                                         $type = self::TARGET_TO;
 697                                                         break;
 698                                                 case 'as:cc':
 699                                                         $type = self::TARGET_CC;
 700                                                         break;
 701                                                 case 'as:bto':
 702                                                         $type = self::TARGET_BTO;
 703                                                         break;
 704                                                 case 'as:bcc':
 705                                                         $type = self::TARGET_BCC;
 706                                                         break;
 707                                         }
 708
 709                                         $receivers['uid:' . $contact['uid']] = ['uid' => $contact['uid'], 'type' => $type];
 710                                 }
 711                         }
 712                 }
 713
 714                 self::switchContacts($receivers, $actor);
 715
 716                 return $receivers;
 717         }
 718
 719         /**
 720          * Fetch the receiver list of a given actor
 721          *
 722          * @param string $actor
 723          * @param array  $tags
 724          *
 725          * @return array with receivers (user id)
 726          * @throws \Exception
 727          */
 728         private static function getReceiverForActor($actor, $tags, $receivers)
 729         {
 730                 $basecondition = ['rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 731                         'network' => Protocol::FEDERATED, 'archive' => false, 'pending' => false];
 732
 733                 $condition = DBA::mergeConditions($basecondition, ['nurl' => Strings::normaliseLink($actor)]);
 734                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 735                 while ($contact = DBA::fetch($contacts)) {
 736                         if (empty($receivers['uid:' . $contact['uid']]) && self::isValidReceiverForActor($contact, $actor, $tags)) {
 737                                 $receivers['uid:' . $contact['uid']] = ['uid' => $contact['uid'], 'type' => self::TARGET_FOLLOWER];
 738                         }
 739                 }
 740                 DBA::close($contacts);
 741
 742                 // The queries are split because of performance issues
 743                 $condition = DBA::mergeConditions($basecondition, ["`alias` IN (?, ?)", Strings::normaliseLink($actor), $actor]);
 744                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 745                 while ($contact = DBA::fetch($contacts)) {
 746                         if (empty($receivers['uid:' . $contact['uid']]) && self::isValidReceiverForActor($contact, $actor, $tags)) {
 747                                 $receivers['uid:' . $contact['uid']] = ['uid' => $contact['uid'], 'type' => self::TARGET_FOLLOWER];
 748                         }
 749                 }
 750                 DBA::close($contacts);
 751                 return $receivers;
 752         }
 753
 754         /**
 755          * Tests if the contact is a valid receiver for this actor
 756          *
 757          * @param array  $contact
 758          * @param string $actor
 759          * @param array  $tags
 760          *
 761          * @return bool with receivers (user id)
 762          * @throws \Exception
 763          */
 764         private static function isValidReceiverForActor($contact, $actor, $tags)
 765         {
 766                 // Public contacts are no valid receiver
 767                 if ($contact['uid'] == 0) {
 768                         return false;
 769                 }
 770
 771                 // Are we following the contact? Then this is a valid receiver
 772                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 773                         return true;
 774                 }
 775
 776                 // When the possible receiver isn't a community, then it is no valid receiver
 777                 $owner = User::getOwnerDataById($contact['uid']);
 778                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 779                         return false;
 780                 }
 781
 782                 // Is the community account tagged?
 783                 foreach ($tags as $tag) {
 784                         if ($tag['type'] != 'Mention') {
 785                                 continue;
 786                         }
 787
 788                         if ($tag['href'] == $owner['url']) {
 789                                 return true;
 790                         }
 791                 }
 792
 793                 return false;
 794         }
 795
 796         /**
 797          * Switches existing contacts to ActivityPub
 798          *
 799          * @param integer $cid Contact ID
 800          * @param integer $uid User ID
 801          * @param string  $url Profile URL
 802          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 803          * @throws \ImagickException
 804          */
 805         public static function switchContact($cid, $uid, $url)
 806         {
 807                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 808                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 809                         return;
 810                 }
 811
 812                 if (Contact::updateFromProbe($cid)) {
 813                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 814                 }
 815
 816                 // Send a new follow request to be sure that the connection still exists
 817                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 818                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 819                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 820                 }
 821         }
 822
 823         /**
 824          *
 825          *
 826          * @param $receivers
 827          * @param $actor
 828          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 829          * @throws \ImagickException
 830          */
 831         private static function switchContacts($receivers, $actor)
 832         {
 833                 if (empty($actor)) {
 834                         return;
 835                 }
 836
 837                 foreach ($receivers as $receiver) {
 838                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 839                         if (DBA::isResult($contact)) {
 840                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 841                         }
 842
 843                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 844                         if (DBA::isResult($contact)) {
 845                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 846                         }
 847                 }
 848         }
 849
 850         /**
 851          *
 852          *
 853          * @param       $object_data
 854          * @param array $activity
 855          *
 856          * @return mixed
 857          */
 858         private static function addActivityFields($object_data, $activity)
 859         {
 860                 if (!empty($activity['published']) && empty($object_data['published'])) {
 861                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 862                 }
 863
 864                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 865                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 866                 }
 867
 868                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 869                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 870
 871                 if (!empty($object_data['object_id'])) {
 872                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 873                         $objectId = Item::getURIByLink($object_data['object_id']);
 874                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 875                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 876                                 $object_data['object_id'] = $objectId;
 877                         }
 878                 }
 879
 880                 return $object_data;
 881         }
 882
 883         /**
 884          * Fetches the object data from external ressources if needed
 885          *
 886          * @param string  $object_id    Object ID of the the provided object
 887          * @param array   $object       The provided object array
 888          * @param boolean $trust_source Do we trust the provided object?
 889          * @param integer $uid          User ID for the signature that we use to fetch data
 890          *
 891          * @return array|false with trusted and valid object data
 892          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 893          * @throws \ImagickException
 894          */
 895         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 896         {
 897                 // By fetching the type we check if the object is complete.
 898                 $type = JsonLD::fetchElement($object, '@type');
 899
 900                 if (!$trust_source || empty($type)) {
 901                         $data = ActivityPub::fetchContent($object_id, $uid);
 902                         if (!empty($data)) {
 903                                 $object = JsonLD::compact($data);
 904                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 905                         } else {
 906                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 907
 908                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 909                                 if (!DBA::isResult($item)) {
 910                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 911                                         return false;
 912                                 }
 913                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 914                                 $data = ActivityPub\Transmitter::createNote($item);
 915                                 $object = JsonLD::compact($data);
 916                         }
 917
 918                         $id = JsonLD::fetchElement($object, '@id');
 919                         if (empty($id)) {
 920                                 Logger::info('Empty id');
 921                                 return false;
 922                         }
 923
 924                         if ($id != $object_id) {
 925                                 Logger::info('Fetched id differs from provided id', ['provided' => $object_id, 'fetched' => $id]);
 926                                 return false;
 927                         }
 928                 } else {
 929                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 930                 }
 931
 932                 $type = JsonLD::fetchElement($object, '@type');
 933                 if (empty($type)) {
 934                         Logger::info('Empty type');
 935                         return false;
 936                 }
 937
 938                 // We currently don't handle 'pt:CacheFile', but with this step we avoid logging
 939                 if (in_array($type, self::CONTENT_TYPES) || ($type == 'pt:CacheFile')) {
 940                         $object_data = self::processObject($object);
 941
 942                         if (!empty($data)) {
 943                                 $object_data['raw'] = json_encode($data);
 944                         }
 945                         return $object_data;
 946                 }
 947
 948                 if ($type == 'as:Announce') {
 949                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 950                         if (empty($object_id) || !is_string($object_id)) {
 951                                 return false;
 952                         }
 953                         return self::fetchObject($object_id, [], false, $uid);
 954                 }
 955
 956                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 957                 return false;
 958         }
 959
 960         /**
 961          * Convert tags from JSON-LD format into a simplified format
 962          *
 963          * @param array $tags Tags in JSON-LD format
 964          *
 965          * @return array with tags in a simplified format
 966          */
 967         private static function processTags(array $tags)
 968         {
 969                 $taglist = [];
 970
 971                 foreach ($tags as $tag) {
 972                         if (empty($tag)) {
 973                                 continue;
 974                         }
 975
 976                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 977                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 978                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 979
 980                         if (empty($element['type'])) {
 981                                 continue;
 982                         }
 983
 984                         if (empty($element['href'])) {
 985                                 $element['href'] = $element['name'];
 986                         }
 987
 988                         $taglist[] = $element;
 989                 }
 990                 return $taglist;
 991         }
 992
 993         /**
 994          * Convert emojis from JSON-LD format into a simplified format
 995          *
 996          * @param array $emojis
 997          * @return array with emojis in a simplified format
 998          */
 999         private static function processEmojis(array $emojis)
1000         {
1001                 $emojilist = [];
1002
1003                 foreach ($emojis as $emoji) {
1004                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
1005                                 continue;
1006                         }
1007
1008                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
1009                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
1010                                 'href' => $url];
1011
1012                         $emojilist[] = $element;
1013                 }
1014
1015                 return $emojilist;
1016         }
1017
1018         /**
1019          * Convert attachments from JSON-LD format into a simplified format
1020          *
1021          * @param array $attachments Attachments in JSON-LD format
1022          *
1023          * @return array Attachments in a simplified format
1024          */
1025         private static function processAttachments(array $attachments)
1026         {
1027                 $attachlist = [];
1028
1029                 // Removes empty values
1030                 $attachments = array_filter($attachments);
1031
1032                 foreach ($attachments as $attachment) {
1033                         switch (JsonLD::fetchElement($attachment, '@type')) {
1034                                 case 'as:Page':
1035                                         $pageUrl = null;
1036                                         $pageImage = null;
1037
1038                                         $urls = JsonLD::fetchElementArray($attachment, 'as:url');
1039                                         foreach ($urls as $url) {
1040                                                 // Single scalar URL case
1041                                                 if (is_string($url)) {
1042                                                         $pageUrl = $url;
1043                                                         continue;
1044                                                 }
1045
1046                                                 $href = JsonLD::fetchElement($url, 'as:href', '@id');
1047                                                 $mediaType = JsonLD::fetchElement($url, 'as:mediaType', '@value');
1048                                                 if (Strings::startsWith($mediaType, 'image')) {
1049                                                         $pageImage = $href;
1050                                                 } else {
1051                                                         $pageUrl = $href;
1052                                                 }
1053                                         }
1054
1055                                         $attachlist[] = [
1056                                                 'type'  => 'link',
1057                                                 'title' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1058                                                 'desc'  => JsonLD::fetchElement($attachment, 'as:summary', '@value'),
1059                                                 'url'   => $pageUrl,
1060                                                 'image' => $pageImage,
1061                                         ];
1062                                         break;
1063                                 case 'as:Link':
1064                                         $attachlist[] = [
1065                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1066                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1067                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1068                                                 'url' => JsonLD::fetchElement($attachment, 'as:href', '@id')
1069                                         ];
1070                                         break;
1071                                 case 'as:Image':
1072                                         $mediaType = JsonLD::fetchElement($attachment, 'as:mediaType', '@value');
1073                                         $imageFullUrl = JsonLD::fetchElement($attachment, 'as:url', '@id');
1074                                         $imagePreviewUrl = null;
1075                                         // Multiple URLs?
1076                                         if (!$imageFullUrl && ($urls = JsonLD::fetchElementArray($attachment, 'as:url'))) {
1077                                                 $imageVariants = [];
1078                                                 $previewVariants = [];
1079                                                 foreach ($urls as $url) {
1080                                                         // Scalar URL, no discrimination possible
1081                                                         if (is_string($url)) {
1082                                                                 $imageFullUrl = $url;
1083                                                                 continue;
1084                                                         }
1085
1086                                                         // Not sure what to do with a different Link media type than the base Image, we skip
1087                                                         if ($mediaType != JsonLD::fetchElement($url, 'as:mediaType', '@value')) {
1088                                                                 continue;
1089                                                         }
1090
1091                                                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1092
1093                                                         // Default URL choice if no discriminating width is provided
1094                                                         $imageFullUrl = $href ?? $imageFullUrl;
1095
1096                                                         $width = intval(JsonLD::fetchElement($url, 'as:width', '@value') ?? 1);
1097
1098                                                         if ($href && $width) {
1099                                                                 $imageVariants[$width] = $href;
1100                                                                 // 632 is the ideal width for full screen frio posts, we compute the absolute distance to it
1101                                                                 $previewVariants[abs(632 - $width)] = $href;
1102                                                         }
1103                                                 }
1104
1105                                                 if ($imageVariants) {
1106                                                         // Taking the maximum size image
1107                                                         ksort($imageVariants);
1108                                                         $imageFullUrl = array_pop($imageVariants);
1109
1110                                                         // Taking the minimum number distance to the target distance
1111                                                         ksort($previewVariants);
1112                                                         $imagePreviewUrl = array_shift($previewVariants);
1113                                                 }
1114
1115                                                 unset($imageVariants);
1116                                                 unset($previewVariants);
1117                                         }
1118
1119                                         $attachlist[] = [
1120                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1121                                                 'mediaType' => $mediaType,
1122                                                 'name'  => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1123                                                 'url'   => $imageFullUrl,
1124                                                 'image' => $imagePreviewUrl !== $imageFullUrl ? $imagePreviewUrl : null,
1125                                         ];
1126                                         break;
1127                                 default:
1128                                         $attachlist[] = [
1129                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1130                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1131                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1132                                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')
1133                                         ];
1134                         }
1135                 }
1136
1137                 return $attachlist;
1138         }
1139
1140         /**
1141          * Fetch the original source or content with the "language" Markdown or HTML
1142          *
1143          * @param array $object
1144          * @param array $object_data
1145          *
1146          * @return array
1147          * @throws \Exception
1148          */
1149         private static function getSource($object, $object_data)
1150         {
1151                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
1152                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1153                 if (!empty($object_data['source'])) {
1154                         return $object_data;
1155                 }
1156
1157                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
1158                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1159                 if (!empty($object_data['source'])) {
1160                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
1161                         return $object_data;
1162                 }
1163
1164                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
1165                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1166                 if (!empty($object_data['source'])) {
1167                         $object_data['source'] = HTML::toBBCode($object_data['source']);
1168                         return $object_data;
1169                 }
1170
1171                 return $object_data;
1172         }
1173
1174         /**
1175          * Check if the "as:url" element is an array with multiple links
1176          * This is the case with audio and video posts.
1177          * Then the links are added as attachments
1178          *
1179          * @param array $object      The raw object
1180          * @param array $object_data The parsed object data for later processing
1181          * @return array the object data
1182          */
1183         private static function processAttachmentUrls(array $object, array $object_data) {
1184                 // Check if this is some url with multiple links
1185                 if (empty($object['as:url'])) {
1186                         return $object_data;
1187                 }
1188
1189                 $urls = $object['as:url'];
1190                 $keys = array_keys($urls);
1191                 if (!is_numeric(array_pop($keys))) {
1192                         return $object_data;
1193                 }
1194
1195                 $attachments = [];
1196
1197                 foreach ($urls as $url) {
1198                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1199                                 continue;
1200                         }
1201
1202                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1203                         if (empty($href)) {
1204                                 continue;
1205                         }
1206
1207                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1208                         if (empty($mediatype)) {
1209                                 continue;
1210                         }
1211
1212                         if ($mediatype == 'text/html') {
1213                                 $object_data['alternate-url'] = $href;
1214                         }
1215
1216                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
1217
1218                         if ($filetype == 'audio') {
1219                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href];
1220                         } elseif ($filetype == 'video') {
1221                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1222
1223                                 // We save bandwidth by using a moderate height
1224                                 // Peertube normally uses these heights: 240, 360, 480, 720, 1080
1225                                 if (!empty($attachments[$filetype]['height']) &&
1226                                         (($height > 480) || $height < $attachments[$filetype]['height'])) {
1227                                         continue;
1228                                 }
1229
1230                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href, 'height' => $height];
1231                         }
1232                 }
1233
1234                 foreach ($attachments as $type => $attachment) {
1235                         $object_data['attachments'][] = ['type' => $type,
1236                                 'mediaType' => $attachment['type'],
1237                                 'name' => '',
1238                                 'url' => $attachment['url']];
1239                 }
1240                 return $object_data;
1241         }
1242
1243         /**
1244          * Fetches data from the object part of an activity
1245          *
1246          * @param array $object
1247          *
1248          * @return array
1249          * @throws \Exception
1250          */
1251         private static function processObject($object)
1252         {
1253                 if (!JsonLD::fetchElement($object, '@id')) {
1254                         return false;
1255                 }
1256
1257                 $object_data = [];
1258                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1259                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1260                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1261
1262                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1263                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1264                         $object_data['reply-to-id'] = $object_data['id'];
1265                 } else {
1266                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1267                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1268                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1269                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1270                                 $object_data['reply-to-id'] = $replyToId;
1271                         }
1272                 }
1273
1274                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1275                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1276
1277                 if (empty($object_data['updated'])) {
1278                         $object_data['updated'] = $object_data['published'];
1279                 }
1280
1281                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1282                         $object_data['published'] = $object_data['updated'];
1283                 }
1284
1285                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1286                 if (empty($actor)) {
1287                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1288                 }
1289
1290                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1291                 $location = JsonLD::fetchElement($location, 'location', '@value');
1292                 if ($location) {
1293                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1294                         // down to HTML and then finally format to plaintext.
1295                         $location = Markdown::convert($location);
1296                         $location = BBCode::convert($location);
1297                         $location = HTML::toPlaintext($location);
1298                 }
1299
1300                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1301                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1302                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1303                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1304                 $object_data['actor'] = $object_data['author'] = $actor;
1305                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1306                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1307                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1308                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1309                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1310                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1311                 $object_data = self::getSource($object, $object_data);
1312                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1313                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1314                 $object_data['location'] = $location;
1315                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1316                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1317                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1318                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1319                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment') ?? []);
1320                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag') ?? []);
1321                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji') ?? []);
1322                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1323                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1324                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1325
1326                 // Special treatment for Hubzilla links
1327                 if (is_array($object_data['alternate-url'])) {
1328                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1329
1330                         if (!is_string($object_data['alternate-url'])) {
1331                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1332                         }
1333                 }
1334
1335                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1336                         $object_data = self::processAttachmentUrls($object, $object_data);
1337                 }
1338
1339                 $receiverdata = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1340                 $receivers = $reception_types = [];
1341                 foreach ($receiverdata as $key => $data) {
1342                         $receivers[$key] = $data['uid'];
1343                         $reception_types[$data['uid']] = $data['type'] ?? 0;
1344                 }
1345
1346                 $object_data['receiver'] = $receivers;
1347                 $object_data['reception_type'] = $reception_types;
1348
1349                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1350                 unset($object_data['receiver']['uid:-1']);
1351
1352                 // Common object data:
1353
1354                 // Unhandled
1355                 // @context, type, actor, signature, mediaType, duration, replies, icon
1356
1357                 // Also missing: (Defined in the standard, but currently unused)
1358                 // audience, preview, endTime, startTime, image
1359
1360                 // Data in Notes:
1361
1362                 // Unhandled
1363                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1364                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1365
1366                 // Data in video:
1367
1368                 // To-Do?
1369                 // category, licence, language, commentsEnabled
1370
1371                 // Unhandled
1372                 // views, waitTranscoding, state, support, subtitleLanguage
1373                 // likes, dislikes, shares, comments
1374
1375                 return $object_data;
1376         }
1377 }