src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2021, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Protocol\ActivityPub;
  23
  24 use Friendica\Content\Text\BBCode;
  25 use Friendica\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\Post;
  34 use Friendica\Model\User;
  35 use Friendica\Protocol\Activity;
  36 use Friendica\Protocol\ActivityPub;
  37 use Friendica\Util\HTTPSignature;
  38 use Friendica\Util\JsonLD;
  39 use Friendica\Util\LDSignature;
  40 use Friendica\Util\Strings;
  41
  42 /**
  43  * ActivityPub Receiver Protocol class
  44  *
  45  * To-Do:
  46  * @todo Undo Announce
  47  *
  48  * Check what this is meant to do:
  49  * - Add
  50  * - Block
  51  * - Flag
  52  * - Remove
  53  * - Undo Block
  54  */
  55 class Receiver
  56 {
  57         const PUBLIC_COLLECTION = 'as:Public';
  58         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  59         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio'];
  60         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  61
  62         const TARGET_UNKNOWN = 0;
  63         const TARGET_TO = 1;
  64         const TARGET_CC = 2;
  65         const TARGET_BTO = 3;
  66         const TARGET_BCC = 4;
  67         const TARGET_FOLLOWER = 5;
  68         const TARGET_ANSWER = 6;
  69         const TARGET_GLOBAL = 7;
  70
  71         /**
  72          * Checks if the web request is done for the AP protocol
  73          *
  74          * @return bool is it AP?
  75          */
  76         public static function isRequest()
  77         {
  78                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
  79                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
  80         }
  81
  82         /**
  83          * Checks incoming message from the inbox
  84          *
  85          * @param         $body
  86          * @param         $header
  87          * @param integer $uid User ID
  88          * @throws \Exception
  89          */
  90         public static function processInbox($body, $header, $uid)
  91         {
  92                 $activity = json_decode($body, true);
  93                 if (empty($activity)) {
  94                         Logger::warning('Invalid body.');
  95                         return;
  96                 }
  97
  98                 $ldactivity = JsonLD::compact($activity);
  99
 100                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
 101
 102                 $apcontact = APContact::getByURL($actor);
 103                 if (empty($apcontact)) {
 104                         Logger::notice('Unable to retrieve AP contact for actor - message is discarded', ['actor' => $actor]);
 105                         return;
 106                 } elseif ($apcontact['type'] == 'Application' && $apcontact['nick'] == 'relay') {
 107                         self::processRelayPost($ldactivity, $actor);
 108                         return;
 109                 } else {
 110                         APContact::unmarkForArchival($apcontact);
 111                 }
 112
 113                 $http_signer = HTTPSignature::getSigner($body, $header);
 114                 if (empty($http_signer)) {
 115                         Logger::warning('Invalid HTTP signature, message will be discarded.');
 116                         return;
 117                 } else {
 118                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
 119                 }
 120
 121                 $signer = [$http_signer];
 122
 123                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 124
 125                 if (LDSignature::isSigned($activity)) {
 126                         $ld_signer = LDSignature::getSigner($activity);
 127                         if (empty($ld_signer)) {
 128                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
 129                         } elseif ($ld_signer != $http_signer) {
 130                                 $signer[] = $ld_signer;
 131                         }
 132                         if (!empty($ld_signer && ($actor == $http_signer))) {
 133                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
 134                                 $trust_source = true;
 135                         } elseif (!empty($ld_signer)) {
 136                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
 137                                 $trust_source = true;
 138                         } elseif ($actor == $http_signer) {
 139                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
 140                                 $trust_source = true;
 141                         } else {
 142                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
 143                                 $trust_source = false;
 144                         }
 145                 } elseif ($actor == $http_signer) {
 146                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 147                         $trust_source = true;
 148                 } else {
 149                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 150                         $trust_source = false;
 151                 }
 152
 153                 self::processActivity($ldactivity, $body, $uid, $trust_source, true, $signer);
 154         }
 155
 156         /**
 157          * Process incoming posts from relays
 158          *
 159          * @param array  $activity
 160          * @param string $actor
 161          * @return void
 162          */
 163         private static function processRelayPost(array $activity, string $actor)
 164         {
 165                 $type = JsonLD::fetchElement($activity, '@type');
 166                 if (!$type) {
 167                         Logger::info('Empty type', ['activity' => $activity]);
 168                         return;
 169                 }
 170
 171                 if ($type != 'as:Announce') {
 172                         Logger::info('Not an announcement', ['activity' => $activity]);
 173                         return;
 174                 }
 175
 176                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 177                 if (empty($object_id)) {
 178                         Logger::info('No object id found', ['activity' => $activity]);
 179                         return;
 180                 }
 181
 182                 $contact = Contact::getByURL($actor);
 183                 if (empty($contact)) {
 184                         Logger::info('Relay contact not found', ['actor' => $actor]);
 185                         return;
 186                 }
 187
 188                 if (!in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 189                         Logger::notice('Relay is no sharer', ['actor' => $actor]);
 190                         return;
 191                 }
 192
 193                 Logger::info('Got relayed message id', ['id' => $object_id]);
 194
 195                 $item_id = Item::searchByLink($object_id);
 196                 if ($item_id) {
 197                         Logger::info('Relayed message already exists', ['id' => $object_id, 'item' => $item_id]);
 198                         return;
 199                 }
 200
 201                 $id = Processor::fetchMissingActivity($object_id, [], $actor);
 202                 if (empty($id)) {
 203                         Logger::notice('Relayed message had not been fetched', ['id' => $object_id]);
 204                         return;
 205                 }
 206
 207                 $item_id = Item::searchByLink($object_id);
 208                 if ($item_id) {
 209                         Logger::info('Relayed message had been fetched and stored', ['id' => $object_id, 'item' => $item_id]);
 210                 } else {
 211                         Logger::notice('Relayed message had not been stored', ['id' => $object_id]);
 212                 }
 213         }
 214
 215         /**
 216          * Fetches the object type for a given object id
 217          *
 218          * @param array   $activity
 219          * @param string  $object_id Object ID of the the provided object
 220          * @param integer $uid       User ID
 221          *
 222          * @return string with object type
 223          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 224          * @throws \ImagickException
 225          */
 226         private static function fetchObjectType($activity, $object_id, $uid = 0)
 227         {
 228                 if (!empty($activity['as:object'])) {
 229                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 230                         if (!empty($object_type)) {
 231                                 return $object_type;
 232                         }
 233                 }
 234
 235                 if (Post::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 236                         // We just assume "note" since it doesn't make a difference for the further processing
 237                         return 'as:Note';
 238                 }
 239
 240                 $profile = APContact::getByURL($object_id);
 241                 if (!empty($profile['type'])) {
 242                         APContact::unmarkForArchival($profile);
 243                         return 'as:' . $profile['type'];
 244                 }
 245
 246                 $data = ActivityPub::fetchContent($object_id, $uid);
 247                 if (!empty($data)) {
 248                         $object = JsonLD::compact($data);
 249                         $type = JsonLD::fetchElement($object, '@type');
 250                         if (!empty($type)) {
 251                                 return $type;
 252                         }
 253                 }
 254
 255                 return null;
 256         }
 257
 258         /**
 259          * Prepare the object array
 260          *
 261          * @param array   $activity     Array with activity data
 262          * @param integer $uid          User ID
 263          * @param boolean $push         Message had been pushed to our system
 264          * @param boolean $trust_source Do we trust the source?
 265          *
 266          * @return array with object data
 267          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 268          * @throws \ImagickException
 269          */
 270         public static function prepareObjectData($activity, $uid, $push, &$trust_source)
 271         {
 272                 $id = JsonLD::fetchElement($activity, '@id');
 273                 if (!empty($id) && !$trust_source) {
 274                         $fetched_activity = ActivityPub::fetchContent($id, $uid ?? 0);
 275                         if (!empty($fetched_activity)) {
 276                                 $object = JsonLD::compact($fetched_activity);
 277                                 $fetched_id = JsonLD::fetchElement($object, '@id');
 278                                 if ($fetched_id == $id) {
 279                                         Logger::info('Activity had been fetched successfully', ['id' => $id]);
 280                                         $trust_source = true;
 281                                         $activity = $object;
 282                                 } else {
 283                                         Logger::info('Activity id is not equal', ['id' => $id, 'fetched' => $fetched_id]);
 284                                 }
 285                         } else {
 286                                 Logger::info('Activity could not been fetched', ['id' => $id]);
 287                         }
 288                 }
 289
 290                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 291                 if (empty($actor)) {
 292                         Logger::info('Empty actor', ['activity' => $activity]);
 293                         return [];
 294                 }
 295
 296                 $type = JsonLD::fetchElement($activity, '@type');
 297
 298                 // Fetch all receivers from to, cc, bto and bcc
 299                 $receiverdata = self::getReceivers($activity, $actor);
 300                 $receivers = $reception_types = [];
 301                 foreach ($receiverdata as $key => $data) {
 302                         $receivers[$key] = $data['uid'];
 303                         $reception_types[$data['uid']] = $data['type'] ?? self::TARGET_UNKNOWN;
 304                 }
 305
 306                 // When it is a delivery to a personal inbox we add that user to the receivers
 307                 if (!empty($uid)) {
 308                         $additional = [$uid => $uid];
 309                         $receivers = array_replace($receivers, $additional);
 310                         if (empty($activity['thread-completion']) && (empty($reception_types[$uid]) || in_array($reception_types[$uid], [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL]))) {
 311                                 $reception_types[$uid] = self::TARGET_BCC;
 312                         }
 313                 } else {
 314                         // We possibly need some user to fetch private content,
 315                         // so we fetch the first out ot the list.
 316                         $uid = self::getFirstUserFromReceivers($receivers);
 317                 }
 318
 319                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 320                 if (empty($object_id)) {
 321                         Logger::log('No object found', Logger::DEBUG);
 322                         return [];
 323                 }
 324
 325                 if (!is_string($object_id)) {
 326                         Logger::info('Invalid object id', ['object' => $object_id]);
 327                         return [];
 328                 }
 329
 330                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 331
 332                 // Fetch the content only on activities where this matters
 333                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 334                         // Always fetch on "Announce"
 335                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source && ($type != 'as:Announce'), $uid);
 336                         if (empty($object_data)) {
 337                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 338                                 return [];
 339                         }
 340
 341                         $object_data['object_id'] = $object_id;
 342
 343                         if ($type == 'as:Announce') {
 344                                 $object_data['push'] = false;
 345                         } else {
 346                                 $object_data['push'] = $push;
 347                         }
 348
 349                         // Test if it is an answer to a mail
 350                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 351                                 $object_data['directmessage'] = true;
 352                         } else {
 353                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 354                         }
 355                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 356                         // Create a mostly empty array out of the activity data (instead of the object).
 357                         // This way we later don't have to check for the existence of ech individual array element.
 358                         $object_data = self::processObject($activity);
 359                         $object_data['name'] = $type;
 360                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 361                         $object_data['object_id'] = $object_id;
 362                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 363                         $object_data['push'] = $push;
 364                 } elseif (in_array($type, ['as:Add'])) {
 365                         $object_data = [];
 366                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 367                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 368                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 369                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 370                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 371                         $object_data['push'] = $push;
 372                 } else {
 373                         $object_data = [];
 374                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 375                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 376                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 377                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 378                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 379                         $object_data['push'] = $push;
 380
 381                         // An Undo is done on the object of an object, so we need that type as well
 382                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
 383                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 384                         }
 385                 }
 386
 387                 $object_data = self::addActivityFields($object_data, $activity);
 388
 389                 if (empty($object_data['object_type'])) {
 390                         $object_data['object_type'] = $object_type;
 391                 }
 392
 393                 $object_data['type'] = $type;
 394                 $object_data['actor'] = $actor;
 395                 $object_data['item_receiver'] = $receivers;
 396                 $object_data['receiver'] = array_replace($object_data['receiver'] ?? [], $receivers);
 397                 $object_data['reception_type'] = array_replace($object_data['reception_type'] ?? [], $reception_types);
 398
 399                 $author = $object_data['author'] ?? $actor;
 400                 if (!empty($author) && !empty($object_data['id'])) {
 401                         $author_host = parse_url($author, PHP_URL_HOST);
 402                         $id_host = parse_url($object_data['id'], PHP_URL_HOST);
 403                         if ($author_host == $id_host) {
 404                                 Logger::info('Valid hosts', ['type' => $type, 'host' => $id_host]);
 405                         } else {
 406                                 Logger::notice('Differing hosts on author and id', ['type' => $type, 'author' => $author_host, 'id' => $id_host]);
 407                                 $trust_source = false;
 408                         }
 409                 }
 410
 411                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 412
 413                 return $object_data;
 414         }
 415
 416         /**
 417          * Fetches the first user id from the receiver array
 418          *
 419          * @param array $receivers Array with receivers
 420          * @return integer user id;
 421          */
 422         public static function getFirstUserFromReceivers($receivers)
 423         {
 424                 foreach ($receivers as $receiver) {
 425                         if (!empty($receiver)) {
 426                                 return $receiver;
 427                         }
 428                 }
 429                 return 0;
 430         }
 431
 432         /**
 433          * Processes the activity object
 434          *
 435          * @param array   $activity     Array with activity data
 436          * @param string  $body
 437          * @param integer $uid          User ID
 438          * @param boolean $trust_source Do we trust the source?
 439          * @param boolean $push         Message had been pushed to our system
 440          * @throws \Exception
 441          */
 442         public static function processActivity($activity, string $body = '', int $uid = null, bool $trust_source = false, bool $push = false, array $signer = [])
 443         {
 444                 $type = JsonLD::fetchElement($activity, '@type');
 445                 if (!$type) {
 446                         Logger::info('Empty type', ['activity' => $activity]);
 447                         return;
 448                 }
 449
 450                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 451                         Logger::info('Empty object', ['activity' => $activity]);
 452                         return;
 453                 }
 454
 455                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 456                 if (empty($actor)) {
 457                         Logger::info('Empty actor', ['activity' => $activity]);
 458                         return;
 459                 }
 460
 461                 if (is_array($activity['as:object'])) {
 462                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 463                 } else {
 464                         $attributed_to = '';
 465                 }
 466
 467                 // Test the provided signatures against the actor and "attributedTo"
 468                 if ($trust_source) {
 469                         if (!empty($attributed_to) && !empty($actor)) {
 470                                 $trust_source = (in_array($actor, $signer) && in_array($attributed_to, $signer));
 471                         } else {
 472                                 $trust_source = in_array($actor, $signer);
 473                         }
 474                 }
 475
 476                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 477                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 478                 if (empty($object_data)) {
 479                         Logger::info('No object data found', ['activity' => $activity]);
 480                         return;
 481                 }
 482
 483                 if (!$trust_source) {
 484                         Logger::info('Activity trust could not be achieved.',  ['id' => $object_data['object_id'], 'type' => $type, 'signer' => $signer, 'actor' => $actor, 'attributedTo' => $attributed_to]);
 485                         return;
 486                 }
 487
 488                 if (!empty($body) && empty($object_data['raw'])) {
 489                         $object_data['raw'] = $body;
 490                 }
 491
 492                 // Internal flag for thread completion. See Processor.php
 493                 if (!empty($activity['thread-completion'])) {
 494                         $object_data['thread-completion'] = $activity['thread-completion'];
 495                 }
 496
 497                 // Internal flag for posts that arrived via relay
 498                 if (!empty($activity['from-relay'])) {
 499                         $object_data['from-relay'] = $activity['from-relay'];
 500                 }
 501
 502                 switch ($type) {
 503                         case 'as:Create':
 504                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 505                                         $item = ActivityPub\Processor::createItem($object_data);
 506                                         ActivityPub\Processor::postItem($object_data, $item);
 507                                 }
 508                                 break;
 509
 510                         case 'as:Add':
 511                                 if ($object_data['object_type'] == 'as:tag') {
 512                                         ActivityPub\Processor::addTag($object_data);
 513                                 }
 514                                 break;
 515
 516                         case 'as:Announce':
 517                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 518                                         $object_data['thread-completion'] = Contact::getIdForURL($actor);
 519
 520                                         $item = ActivityPub\Processor::createItem($object_data);
 521                                         if (empty($item)) {
 522                                                 return;
 523                                         }
 524
 525                                         $item['post-type'] = Item::PT_ANNOUNCEMENT;
 526                                         ActivityPub\Processor::postItem($object_data, $item);
 527
 528                                         $announce_object_data = self::processObject($activity);
 529                                         $announce_object_data['name'] = $type;
 530                                         $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 531                                         $announce_object_data['object_id'] = $object_data['object_id'];
 532                                         $announce_object_data['object_type'] = $object_data['object_type'];
 533                                         $announce_object_data['push'] = $push;
 534
 535                                         if (!empty($body)) {
 536                                                 $announce_object_data['raw'] = $body;
 537                                         }
 538
 539                                         ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 540                                 }
 541                                 break;
 542
 543                         case 'as:Like':
 544                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 545                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 546                                 }
 547                                 break;
 548
 549                         case 'as:Dislike':
 550                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 551                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 552                                 }
 553                                 break;
 554
 555                         case 'as:TentativeAccept':
 556                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 557                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 558                                 }
 559                                 break;
 560
 561                         case 'as:Update':
 562                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 563                                         ActivityPub\Processor::updateItem($object_data);
 564                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 565                                         ActivityPub\Processor::updatePerson($object_data);
 566                                 }
 567                                 break;
 568
 569                         case 'as:Delete':
 570                                 if ($object_data['object_type'] == 'as:Tombstone') {
 571                                         ActivityPub\Processor::deleteItem($object_data);
 572                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 573                                         ActivityPub\Processor::deletePerson($object_data);
 574                                 }
 575                                 break;
 576
 577                         case 'as:Follow':
 578                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 579                                         ActivityPub\Processor::followUser($object_data);
 580                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 581                                         $object_data['reply-to-id'] = $object_data['object_id'];
 582                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 583                                 }
 584                                 break;
 585
 586                         case 'as:Accept':
 587                                 if ($object_data['object_type'] == 'as:Follow') {
 588                                         ActivityPub\Processor::acceptFollowUser($object_data);
 589                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 590                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 591                                 }
 592                                 break;
 593
 594                         case 'as:Reject':
 595                                 if ($object_data['object_type'] == 'as:Follow') {
 596                                         ActivityPub\Processor::rejectFollowUser($object_data);
 597                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 598                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 599                                 }
 600                                 break;
 601
 602                         case 'as:Undo':
 603                                 if (($object_data['object_type'] == 'as:Follow') &&
 604                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 605                                         ActivityPub\Processor::undoFollowUser($object_data);
 606                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 607                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 608                                         ActivityPub\Processor::rejectFollowUser($object_data);
 609                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 610                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 611                                         ActivityPub\Processor::undoActivity($object_data);
 612                                 }
 613                                 break;
 614
 615                         default:
 616                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 617                                 break;
 618                 }
 619         }
 620
 621         /**
 622          * Fetch the receiver list from an activity array
 623          *
 624          * @param array   $activity
 625          * @param string  $actor
 626          * @param array   $tags
 627          * @param boolean $fetch_unlisted
 628          *
 629          * @return array with receivers (user id)
 630          * @throws \Exception
 631          */
 632         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 633         {
 634                 $reply = $receivers = [];
 635
 636                 // When it is an answer, we inherite the receivers from the parent
 637                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 638                 if (!empty($replyto)) {
 639                         $reply = [$replyto];
 640
 641                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 642                         $fixedReplyTo = Item::getURIByLink($replyto);
 643                         if (!empty($fixedReplyTo)) {
 644                                 $reply[] = $fixedReplyTo;
 645                         }
 646                 }
 647
 648                 // Fetch all posts that refer to the object id
 649                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 650                 if (!empty($object_id)) {
 651                         $reply[] = $object_id;
 652                 }
 653
 654                 if (!empty($reply)) {
 655                         $parents = Post::select(['uid'], ['uri' => $reply]);
 656                         while ($parent = Post::fetch($parents)) {
 657                                 $receivers[$parent['uid']] = ['uid' => $parent['uid'], 'type' => self::TARGET_ANSWER];
 658                         }
 659                         DBA::close($parents);
 660                 }
 661
 662                 if (!empty($actor)) {
 663                         $profile = APContact::getByURL($actor);
 664                         $followers = $profile['followers'] ?? '';
 665
 666                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 667                 } else {
 668                         Logger::info('Empty actor', ['activity' => $activity]);
 669                         $followers = '';
 670                 }
 671
 672                 // We have to prevent false follower assumptions upon thread completions
 673                 $follower_target = empty($activity['thread-completion']) ? self::TARGET_FOLLOWER : self::TARGET_UNKNOWN;
 674
 675                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 676                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 677                         if (empty($receiver_list)) {
 678                                 continue;
 679                         }
 680
 681                         foreach ($receiver_list as $receiver) {
 682                                 if ($receiver == self::PUBLIC_COLLECTION) {
 683                                         $receivers[0] = ['uid' => 0, 'type' => self::TARGET_GLOBAL];
 684                                 }
 685
 686                                 // Add receiver "-1" for unlisted posts
 687                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 688                                         $receivers[-1] = ['uid' => -1, 'type' => self::TARGET_GLOBAL];
 689                                 }
 690
 691                                 // Fetch the receivers for the public and the followers collection
 692                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 693                                         $receivers = self::getReceiverForActor($actor, $tags, $receivers, $follower_target);
 694                                         continue;
 695                                 }
 696
 697                                 // Fetching all directly addressed receivers
 698                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 699                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 700                                 if (!DBA::isResult($contact)) {
 701                                         continue;
 702                                 }
 703
 704                                 // Check if the potential receiver is following the actor
 705                                 // Exception: The receiver is targetted via "to" or this is a comment
 706                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 707                                         $networks = Protocol::FEDERATED;
 708                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 709                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 710
 711                                         // Forum posts are only accepted from forum contacts
 712                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 713                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 714                                         }
 715
 716                                         if (!DBA::exists('contact', $condition)) {
 717                                                 continue;
 718                                         }
 719                                 }
 720
 721                                 $type = $receivers[$contact['uid']]['type'] ?? self::TARGET_UNKNOWN;
 722                                 if (in_array($type, [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL])) {
 723                                         switch ($element) {
 724                                                 case 'as:to':
 725                                                         $type = self::TARGET_TO;
 726                                                         break;
 727                                                 case 'as:cc':
 728                                                         $type = self::TARGET_CC;
 729                                                         break;
 730                                                 case 'as:bto':
 731                                                         $type = self::TARGET_BTO;
 732                                                         break;
 733                                                 case 'as:bcc':
 734                                                         $type = self::TARGET_BCC;
 735                                                         break;
 736                                         }
 737
 738                                         $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $type];
 739                                 }
 740                         }
 741                 }
 742
 743                 self::switchContacts($receivers, $actor);
 744
 745                 return $receivers;
 746         }
 747
 748         /**
 749          * Fetch the receiver list of a given actor
 750          *
 751          * @param string  $actor
 752          * @param array   $tags
 753          * @param array   $receivers
 754          * @param integer $target_type
 755          *
 756          * @return array with receivers (user id)
 757          * @throws \Exception
 758          */
 759         private static function getReceiverForActor($actor, $tags, $receivers, $target_type)
 760         {
 761                 $basecondition = ['rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 762                         'network' => Protocol::FEDERATED, 'archive' => false, 'pending' => false];
 763
 764                 $condition = DBA::mergeConditions($basecondition, ["`nurl` = ? AND `uid` != ?", Strings::normaliseLink($actor), 0]);
 765                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 766                 while ($contact = DBA::fetch($contacts)) {
 767                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 768                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 769                         }
 770                 }
 771                 DBA::close($contacts);
 772
 773                 // The queries are split because of performance issues
 774                 $condition = DBA::mergeConditions($basecondition, ["`alias` IN (?, ?) AND `uid` != ?", Strings::normaliseLink($actor), $actor, 0]);
 775                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 776                 while ($contact = DBA::fetch($contacts)) {
 777                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 778                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 779                         }
 780                 }
 781                 DBA::close($contacts);
 782                 return $receivers;
 783         }
 784
 785         /**
 786          * Tests if the contact is a valid receiver for this actor
 787          *
 788          * @param array  $contact
 789          * @param string $actor
 790          * @param array  $tags
 791          *
 792          * @return bool with receivers (user id)
 793          * @throws \Exception
 794          */
 795         private static function isValidReceiverForActor($contact, $tags)
 796         {
 797                 // Are we following the contact? Then this is a valid receiver
 798                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 799                         return true;
 800                 }
 801
 802                 // When the possible receiver isn't a community, then it is no valid receiver
 803                 $owner = User::getOwnerDataById($contact['uid']);
 804                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 805                         return false;
 806                 }
 807
 808                 // Is the community account tagged?
 809                 foreach ($tags as $tag) {
 810                         if ($tag['type'] != 'Mention') {
 811                                 continue;
 812                         }
 813
 814                         if (Strings::compareLink($tag['href'], $owner['url'])) {
 815                                 return true;
 816                         }
 817                 }
 818
 819                 return false;
 820         }
 821
 822         /**
 823          * Switches existing contacts to ActivityPub
 824          *
 825          * @param integer $cid Contact ID
 826          * @param integer $uid User ID
 827          * @param string  $url Profile URL
 828          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 829          * @throws \ImagickException
 830          */
 831         public static function switchContact($cid, $uid, $url)
 832         {
 833                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 834                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 835                         return;
 836                 }
 837
 838                 if (Contact::updateFromProbe($cid)) {
 839                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 840                 }
 841
 842                 // Send a new follow request to be sure that the connection still exists
 843                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 844                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 845                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 846                 }
 847         }
 848
 849         /**
 850          *
 851          *
 852          * @param $receivers
 853          * @param $actor
 854          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 855          * @throws \ImagickException
 856          */
 857         private static function switchContacts($receivers, $actor)
 858         {
 859                 if (empty($actor)) {
 860                         return;
 861                 }
 862
 863                 foreach ($receivers as $receiver) {
 864                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 865                         if (DBA::isResult($contact)) {
 866                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 867                         }
 868
 869                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 870                         if (DBA::isResult($contact)) {
 871                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 872                         }
 873                 }
 874         }
 875
 876         /**
 877          *
 878          *
 879          * @param       $object_data
 880          * @param array $activity
 881          *
 882          * @return mixed
 883          */
 884         private static function addActivityFields($object_data, $activity)
 885         {
 886                 if (!empty($activity['published']) && empty($object_data['published'])) {
 887                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 888                 }
 889
 890                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 891                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 892                 }
 893
 894                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 895                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 896
 897                 if (!empty($object_data['object_id'])) {
 898                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 899                         $objectId = Item::getURIByLink($object_data['object_id']);
 900                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 901                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 902                                 $object_data['object_id'] = $objectId;
 903                         }
 904                 }
 905
 906                 return $object_data;
 907         }
 908
 909         /**
 910          * Fetches the object data from external ressources if needed
 911          *
 912          * @param string  $object_id    Object ID of the the provided object
 913          * @param array   $object       The provided object array
 914          * @param boolean $trust_source Do we trust the provided object?
 915          * @param integer $uid          User ID for the signature that we use to fetch data
 916          *
 917          * @return array|false with trusted and valid object data
 918          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 919          * @throws \ImagickException
 920          */
 921         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 922         {
 923                 // By fetching the type we check if the object is complete.
 924                 $type = JsonLD::fetchElement($object, '@type');
 925
 926                 if (!$trust_source || empty($type)) {
 927                         $data = ActivityPub::fetchContent($object_id, $uid);
 928                         if (!empty($data)) {
 929                                 $object = JsonLD::compact($data);
 930                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 931                         } else {
 932                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 933
 934                                 $item = Post::selectFirst(Item::DELIVER_FIELDLIST, ['uri' => $object_id]);
 935                                 if (!DBA::isResult($item)) {
 936                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 937                                         return false;
 938                                 }
 939                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 940                                 $data = ActivityPub\Transmitter::createNote($item);
 941                                 $object = JsonLD::compact($data);
 942                         }
 943
 944                         $id = JsonLD::fetchElement($object, '@id');
 945                         if (empty($id)) {
 946                                 Logger::info('Empty id');
 947                                 return false;
 948                         }
 949
 950                         if ($id != $object_id) {
 951                                 Logger::info('Fetched id differs from provided id', ['provided' => $object_id, 'fetched' => $id]);
 952                                 return false;
 953                         }
 954                 } else {
 955                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 956                 }
 957
 958                 $type = JsonLD::fetchElement($object, '@type');
 959                 if (empty($type)) {
 960                         Logger::info('Empty type');
 961                         return false;
 962                 }
 963
 964                 // We currently don't handle 'pt:CacheFile', but with this step we avoid logging
 965                 if (in_array($type, self::CONTENT_TYPES) || ($type == 'pt:CacheFile')) {
 966                         $object_data = self::processObject($object);
 967
 968                         if (!empty($data)) {
 969                                 $object_data['raw'] = json_encode($data);
 970                         }
 971                         return $object_data;
 972                 }
 973
 974                 if ($type == 'as:Announce') {
 975                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 976                         if (empty($object_id) || !is_string($object_id)) {
 977                                 return false;
 978                         }
 979                         return self::fetchObject($object_id, [], false, $uid);
 980                 }
 981
 982                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 983                 return false;
 984         }
 985
 986         /**
 987          * Converts the language element (Used by Peertube)
 988          *
 989          * @param array $languages
 990          * @return array Languages
 991          */
 992         public static function processLanguages(array $languages)
 993         {
 994                 if (empty($languages)) {
 995                         return [];
 996                 }
 997
 998                 $language_list = [];
 999
1000                 foreach ($languages as $language) {
1001                         if (!empty($language['_:identifier']) && !empty($language['as:name'])) {
1002                                 $language_list[$language['_:identifier']] = $language['as:name'];
1003                         }
1004                 }
1005                 return $language_list;
1006         }
1007
1008         /**
1009          * Convert tags from JSON-LD format into a simplified format
1010          *
1011          * @param array $tags Tags in JSON-LD format
1012          *
1013          * @return array with tags in a simplified format
1014          */
1015         public static function processTags(array $tags)
1016         {
1017                 $taglist = [];
1018
1019                 foreach ($tags as $tag) {
1020                         if (empty($tag)) {
1021                                 continue;
1022                         }
1023
1024                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
1025                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
1026                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
1027
1028                         if (empty($element['type'])) {
1029                                 continue;
1030                         }
1031
1032                         if (empty($element['href'])) {
1033                                 $element['href'] = $element['name'];
1034                         }
1035
1036                         $taglist[] = $element;
1037                 }
1038                 return $taglist;
1039         }
1040
1041         /**
1042          * Convert emojis from JSON-LD format into a simplified format
1043          *
1044          * @param array $emojis
1045          * @return array with emojis in a simplified format
1046          */
1047         private static function processEmojis(array $emojis)
1048         {
1049                 $emojilist = [];
1050
1051                 foreach ($emojis as $emoji) {
1052                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
1053                                 continue;
1054                         }
1055
1056                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
1057                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
1058                                 'href' => $url];
1059
1060                         $emojilist[] = $element;
1061                 }
1062
1063                 return $emojilist;
1064         }
1065
1066         /**
1067          * Convert attachments from JSON-LD format into a simplified format
1068          *
1069          * @param array $attachments Attachments in JSON-LD format
1070          *
1071          * @return array Attachments in a simplified format
1072          */
1073         private static function processAttachments(array $attachments)
1074         {
1075                 $attachlist = [];
1076
1077                 // Removes empty values
1078                 $attachments = array_filter($attachments);
1079
1080                 foreach ($attachments as $attachment) {
1081                         switch (JsonLD::fetchElement($attachment, '@type')) {
1082                                 case 'as:Page':
1083                                         $pageUrl = null;
1084                                         $pageImage = null;
1085
1086                                         $urls = JsonLD::fetchElementArray($attachment, 'as:url');
1087                                         foreach ($urls as $url) {
1088                                                 // Single scalar URL case
1089                                                 if (is_string($url)) {
1090                                                         $pageUrl = $url;
1091                                                         continue;
1092                                                 }
1093
1094                                                 $href = JsonLD::fetchElement($url, 'as:href', '@id');
1095                                                 $mediaType = JsonLD::fetchElement($url, 'as:mediaType', '@value');
1096                                                 if (Strings::startsWith($mediaType, 'image')) {
1097                                                         $pageImage = $href;
1098                                                 } else {
1099                                                         $pageUrl = $href;
1100                                                 }
1101                                         }
1102
1103                                         $attachlist[] = [
1104                                                 'type'  => 'link',
1105                                                 'title' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1106                                                 'desc'  => JsonLD::fetchElement($attachment, 'as:summary', '@value'),
1107                                                 'url'   => $pageUrl,
1108                                                 'image' => $pageImage,
1109                                         ];
1110                                         break;
1111                                 case 'as:Link':
1112                                         $attachlist[] = [
1113                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1114                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1115                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1116                                                 'url' => JsonLD::fetchElement($attachment, 'as:href', '@id')
1117                                         ];
1118                                         break;
1119                                 case 'as:Image':
1120                                         $mediaType = JsonLD::fetchElement($attachment, 'as:mediaType', '@value');
1121                                         $imageFullUrl = JsonLD::fetchElement($attachment, 'as:url', '@id');
1122                                         $imagePreviewUrl = null;
1123                                         // Multiple URLs?
1124                                         if (!$imageFullUrl && ($urls = JsonLD::fetchElementArray($attachment, 'as:url'))) {
1125                                                 $imageVariants = [];
1126                                                 $previewVariants = [];
1127                                                 foreach ($urls as $url) {
1128                                                         // Scalar URL, no discrimination possible
1129                                                         if (is_string($url)) {
1130                                                                 $imageFullUrl = $url;
1131                                                                 continue;
1132                                                         }
1133
1134                                                         // Not sure what to do with a different Link media type than the base Image, we skip
1135                                                         if ($mediaType != JsonLD::fetchElement($url, 'as:mediaType', '@value')) {
1136                                                                 continue;
1137                                                         }
1138
1139                                                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1140
1141                                                         // Default URL choice if no discriminating width is provided
1142                                                         $imageFullUrl = $href ?? $imageFullUrl;
1143
1144                                                         $width = intval(JsonLD::fetchElement($url, 'as:width', '@value') ?? 1);
1145
1146                                                         if ($href && $width) {
1147                                                                 $imageVariants[$width] = $href;
1148                                                                 // 632 is the ideal width for full screen frio posts, we compute the absolute distance to it
1149                                                                 $previewVariants[abs(632 - $width)] = $href;
1150                                                         }
1151                                                 }
1152
1153                                                 if ($imageVariants) {
1154                                                         // Taking the maximum size image
1155                                                         ksort($imageVariants);
1156                                                         $imageFullUrl = array_pop($imageVariants);
1157
1158                                                         // Taking the minimum number distance to the target distance
1159                                                         ksort($previewVariants);
1160                                                         $imagePreviewUrl = array_shift($previewVariants);
1161                                                 }
1162
1163                                                 unset($imageVariants);
1164                                                 unset($previewVariants);
1165                                         }
1166
1167                                         $attachlist[] = [
1168                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1169                                                 'mediaType' => $mediaType,
1170                                                 'name'  => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1171                                                 'url'   => $imageFullUrl,
1172                                                 'image' => $imagePreviewUrl !== $imageFullUrl ? $imagePreviewUrl : null,
1173                                         ];
1174                                         break;
1175                                 default:
1176                                         $attachlist[] = [
1177                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1178                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1179                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1180                                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')
1181                                         ];
1182                         }
1183                 }
1184
1185                 return $attachlist;
1186         }
1187
1188         /**
1189          * Fetch the original source or content with the "language" Markdown or HTML
1190          *
1191          * @param array $object
1192          * @param array $object_data
1193          *
1194          * @return array
1195          * @throws \Exception
1196          */
1197         private static function getSource($object, $object_data)
1198         {
1199                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
1200                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1201                 if (!empty($object_data['source'])) {
1202                         return $object_data;
1203                 }
1204
1205                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
1206                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1207                 if (!empty($object_data['source'])) {
1208                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
1209                         return $object_data;
1210                 }
1211
1212                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
1213                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1214                 if (!empty($object_data['source'])) {
1215                         $object_data['source'] = HTML::toBBCode($object_data['source']);
1216                         return $object_data;
1217                 }
1218
1219                 return $object_data;
1220         }
1221
1222         /**
1223          * Check if the "as:url" element is an array with multiple links
1224          * This is the case with audio and video posts.
1225          * Then the links are added as attachments
1226          *
1227          * @param array $object      The raw object
1228          * @param array $object_data The parsed object data for later processing
1229          * @return array the object data
1230          */
1231         private static function processAttachmentUrls(array $object, array $object_data) {
1232                 // Check if this is some url with multiple links
1233                 if (empty($object['as:url'])) {
1234                         return $object_data;
1235                 }
1236
1237                 $urls = $object['as:url'];
1238                 $keys = array_keys($urls);
1239                 if (!is_numeric(array_pop($keys))) {
1240                         return $object_data;
1241                 }
1242
1243                 $attachments = [];
1244
1245                 foreach ($urls as $url) {
1246                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1247                                 continue;
1248                         }
1249
1250                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1251                         if (empty($href)) {
1252                                 continue;
1253                         }
1254
1255                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1256                         if (empty($mediatype)) {
1257                                 continue;
1258                         }
1259
1260                         if ($mediatype == 'text/html') {
1261                                 $object_data['alternate-url'] = $href;
1262                         }
1263
1264                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
1265
1266                         if ($filetype == 'audio') {
1267                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href, 'height' => null, 'size' => null];
1268                         } elseif ($filetype == 'video') {
1269                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1270                                 $size = (int)JsonLD::fetchElement($url, 'pt:size', '@value');
1271
1272                                 // We save bandwidth by using a moderate height (alt least 480 pixel height)
1273                                 // Peertube normally uses these heights: 240, 360, 480, 720, 1080
1274                                 if (!empty($attachments[$filetype]['height']) &&
1275                                         ($height > $attachments[$filetype]['height']) && ($attachments[$filetype]['height'] >= 480)) {
1276                                         continue;
1277                                 }
1278
1279                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href, 'height' => $height, 'size' => $size];
1280                         } elseif (in_array($mediatype, ['application/x-bittorrent', 'application/x-bittorrent;x-scheme-handler/magnet'])) {
1281                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1282
1283                                 // For Torrent links we always store the highest resolution
1284                                 if (!empty($attachments[$mediatype]['height']) && ($height < $attachments[$mediatype]['height'])) {
1285                                         continue;
1286                                 }
1287
1288                                 $attachments[$mediatype] = ['type' => $mediatype, 'url' => $href, 'height' => $height, 'size' => null];
1289                         }
1290                 }
1291
1292                 foreach ($attachments as $type => $attachment) {
1293                         $object_data['attachments'][] = ['type' => $type,
1294                                 'mediaType' => $attachment['type'],
1295                                 'height' => $attachment['height'],
1296                                 'size' => $attachment['size'],
1297                                 'name' => '',
1298                                 'url' => $attachment['url']];
1299                 }
1300                 return $object_data;
1301         }
1302
1303         /**
1304          * Fetches data from the object part of an activity
1305          *
1306          * @param array $object
1307          *
1308          * @return array
1309          * @throws \Exception
1310          */
1311         private static function processObject($object)
1312         {
1313                 if (!JsonLD::fetchElement($object, '@id')) {
1314                         return false;
1315                 }
1316
1317                 $object_data = [];
1318                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1319                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1320                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1321
1322                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1323                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1324                         $object_data['reply-to-id'] = $object_data['id'];
1325                 } else {
1326                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1327                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1328                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1329                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1330                                 $object_data['reply-to-id'] = $replyToId;
1331                         }
1332                 }
1333
1334                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1335                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1336
1337                 if (empty($object_data['updated'])) {
1338                         $object_data['updated'] = $object_data['published'];
1339                 }
1340
1341                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1342                         $object_data['published'] = $object_data['updated'];
1343                 }
1344
1345                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1346                 if (empty($actor)) {
1347                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1348                 }
1349
1350                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1351                 $location = JsonLD::fetchElement($location, 'location', '@value');
1352                 if ($location) {
1353                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1354                         // down to HTML and then finally format to plaintext.
1355                         $location = Markdown::convert($location);
1356                         $location = BBCode::convert($location);
1357                         $location = HTML::toPlaintext($location);
1358                 }
1359
1360                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1361                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1362                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1363                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1364                 $object_data['actor'] = $object_data['author'] = $actor;
1365                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1366                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1367                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1368                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1369                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1370                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1371                 $object_data['mediatype'] = JsonLD::fetchElement($object, 'as:mediaType', '@value');
1372                 $object_data = self::getSource($object, $object_data);
1373                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1374                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1375                 $object_data['location'] = $location;
1376                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1377                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1378                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1379                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1380                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment') ?? []);
1381                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag') ?? []);
1382                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', null, '@type', 'toot:Emoji') ?? []);
1383                 $object_data['languages'] = self::processLanguages(JsonLD::fetchElementArray($object, 'sc:inLanguage') ?? []);
1384                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1385                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1386                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1387
1388                 // Special treatment for Hubzilla links
1389                 if (is_array($object_data['alternate-url'])) {
1390                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1391
1392                         if (!is_string($object_data['alternate-url'])) {
1393                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1394                         }
1395                 }
1396
1397                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1398                         $object_data = self::processAttachmentUrls($object, $object_data);
1399                 }
1400
1401                 $receiverdata = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1402                 $receivers = $reception_types = [];
1403                 foreach ($receiverdata as $key => $data) {
1404                         $receivers[$key] = $data['uid'];
1405                         $reception_types[$data['uid']] = $data['type'] ?? 0;
1406                 }
1407
1408                 $object_data['receiver'] = $receivers;
1409                 $object_data['reception_type'] = $reception_types;
1410
1411                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1412                 unset($object_data['receiver'][-1]);
1413                 unset($object_data['reception_type'][-1]);
1414
1415                 // Common object data:
1416
1417                 // Unhandled
1418                 // @context, type, actor, signature, mediaType, duration, replies, icon
1419
1420                 // Also missing: (Defined in the standard, but currently unused)
1421                 // audience, preview, endTime, startTime, image
1422
1423                 // Data in Notes:
1424
1425                 // Unhandled
1426                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1427                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1428
1429                 // Data in video:
1430
1431                 // To-Do?
1432                 // category, licence, language, commentsEnabled
1433
1434                 // Unhandled
1435                 // views, waitTranscoding, state, support, subtitleLanguage
1436                 // likes, dislikes, shares, comments
1437
1438                 return $object_data;
1439         }
1440 }