src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2022, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Protocol\ActivityPub;
  23
  24 use Friendica\Content\Text\BBCode;
  25 use Friendica\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', 'as:Page', 'as:Question'];
  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 incoming message from the inbox
  73          *
  74          * @param         $body
  75          * @param         $header
  76          * @param integer $uid User ID
  77          * @throws \Exception
  78          */
  79         public static function processInbox($body, $header, $uid)
  80         {
  81                 $activity = json_decode($body, true);
  82                 if (empty($activity)) {
  83                         Logger::warning('Invalid body.');
  84                         return;
  85                 }
  86
  87                 $ldactivity = JsonLD::compact($activity);
  88
  89                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
  90
  91                 $apcontact = APContact::getByURL($actor);
  92                 if (empty($apcontact)) {
  93                         Logger::notice('Unable to retrieve AP contact for actor - message is discarded', ['actor' => $actor]);
  94                         return;
  95                 } elseif ($apcontact['type'] == 'Application' && $apcontact['nick'] == 'relay') {
  96                         self::processRelayPost($ldactivity, $actor);
  97                         return;
  98                 } else {
  99                         APContact::unmarkForArchival($apcontact);
 100                 }
 101
 102                 $http_signer = HTTPSignature::getSigner($body, $header);
 103                 if ($http_signer === false) {
 104                         Logger::warning('Invalid HTTP signature, message will be discarded.');
 105                         return;
 106                 } elseif (empty($http_signer)) {
 107                         Logger::info('Signer is a tombstone. The message will be discarded, the signer account is deleted.');
 108                         return;
 109                 } else {
 110                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
 111                 }
 112
 113                 $signer = [$http_signer];
 114
 115                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 116
 117                 if (LDSignature::isSigned($activity)) {
 118                         $ld_signer = LDSignature::getSigner($activity);
 119                         if (empty($ld_signer)) {
 120                                 Logger::info('Invalid JSON-LD signature from ' . $actor);
 121                         } elseif ($ld_signer != $http_signer) {
 122                                 $signer[] = $ld_signer;
 123                         }
 124                         if (!empty($ld_signer && ($actor == $http_signer))) {
 125                                 Logger::info('The HTTP and the JSON-LD signature belong to ' . $ld_signer);
 126                                 $trust_source = true;
 127                         } elseif (!empty($ld_signer)) {
 128                                 Logger::info('JSON-LD signature is signed by ' . $ld_signer);
 129                                 $trust_source = true;
 130                         } elseif ($actor == $http_signer) {
 131                                 Logger::info('Bad JSON-LD signature, but HTTP signer fits the actor.');
 132                                 $trust_source = true;
 133                         } else {
 134                                 Logger::info('Invalid JSON-LD signature and the HTTP signer is different.');
 135                                 $trust_source = false;
 136                         }
 137                 } elseif ($actor == $http_signer) {
 138                         Logger::info('Trusting post without JSON-LD signature, The actor fits the HTTP signer.');
 139                         $trust_source = true;
 140                 } else {
 141                         Logger::info('No JSON-LD signature, different actor.');
 142                         $trust_source = false;
 143                 }
 144
 145                 self::processActivity($ldactivity, $body, $uid, $trust_source, true, $signer);
 146         }
 147
 148         /**
 149          * Process incoming posts from relays
 150          *
 151          * @param array  $activity
 152          * @param string $actor
 153          * @return void
 154          */
 155         private static function processRelayPost(array $activity, string $actor)
 156         {
 157                 $type = JsonLD::fetchElement($activity, '@type');
 158                 if (!$type) {
 159                         Logger::info('Empty type', ['activity' => $activity]);
 160                         return;
 161                 }
 162
 163                 if ($type != 'as:Announce') {
 164                         Logger::info('Not an announcement', ['activity' => $activity]);
 165                         return;
 166                 }
 167
 168                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 169                 if (empty($object_id)) {
 170                         Logger::info('No object id found', ['activity' => $activity]);
 171                         return;
 172                 }
 173
 174                 $contact = Contact::getByURL($actor);
 175                 if (empty($contact)) {
 176                         Logger::info('Relay contact not found', ['actor' => $actor]);
 177                         return;
 178                 }
 179
 180                 if (!in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 181                         Logger::notice('Relay is no sharer', ['actor' => $actor]);
 182                         return;
 183                 }
 184
 185                 Logger::info('Got relayed message id', ['id' => $object_id]);
 186
 187                 $item_id = Item::searchByLink($object_id);
 188                 if ($item_id) {
 189                         Logger::info('Relayed message already exists', ['id' => $object_id, 'item' => $item_id]);
 190                         return;
 191                 }
 192
 193                 $id = Processor::fetchMissingActivity($object_id, [], $actor);
 194                 if (empty($id)) {
 195                         Logger::notice('Relayed message had not been fetched', ['id' => $object_id]);
 196                         return;
 197                 }
 198
 199                 $item_id = Item::searchByLink($object_id);
 200                 if ($item_id) {
 201                         Logger::info('Relayed message had been fetched and stored', ['id' => $object_id, 'item' => $item_id]);
 202                 } else {
 203                         Logger::notice('Relayed message had not been stored', ['id' => $object_id]);
 204                 }
 205         }
 206
 207         /**
 208          * Fetches the object type for a given object id
 209          *
 210          * @param array   $activity
 211          * @param string  $object_id Object ID of the the provided object
 212          * @param integer $uid       User ID
 213          *
 214          * @return string with object type
 215          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 216          * @throws \ImagickException
 217          */
 218         private static function fetchObjectType($activity, $object_id, $uid = 0)
 219         {
 220                 if (!empty($activity['as:object'])) {
 221                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 222                         if (!empty($object_type)) {
 223                                 return $object_type;
 224                         }
 225                 }
 226
 227                 if (Post::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 228                         // We just assume "note" since it doesn't make a difference for the further processing
 229                         return 'as:Note';
 230                 }
 231
 232                 $profile = APContact::getByURL($object_id);
 233                 if (!empty($profile['type'])) {
 234                         APContact::unmarkForArchival($profile);
 235                         return 'as:' . $profile['type'];
 236                 }
 237
 238                 $data = ActivityPub::fetchContent($object_id, $uid);
 239                 if (!empty($data)) {
 240                         $object = JsonLD::compact($data);
 241                         $type = JsonLD::fetchElement($object, '@type');
 242                         if (!empty($type)) {
 243                                 return $type;
 244                         }
 245                 }
 246
 247                 return null;
 248         }
 249
 250         /**
 251          * Prepare the object array
 252          *
 253          * @param array   $activity     Array with activity data
 254          * @param integer $uid          User ID
 255          * @param boolean $push         Message had been pushed to our system
 256          * @param boolean $trust_source Do we trust the source?
 257          *
 258          * @return array with object data
 259          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 260          * @throws \ImagickException
 261          */
 262         public static function prepareObjectData($activity, $uid, $push, &$trust_source)
 263         {
 264                 $id = JsonLD::fetchElement($activity, '@id');
 265                 if (!empty($id) && !$trust_source) {
 266                         $fetch_uid = $uid ?: self::getBestUserForActivity($activity);
 267
 268                         $fetched_activity = ActivityPub::fetchContent($id, $fetch_uid);
 269                         if (!empty($fetched_activity)) {
 270                                 $object = JsonLD::compact($fetched_activity);
 271                                 $fetched_id = JsonLD::fetchElement($object, '@id');
 272                                 if ($fetched_id == $id) {
 273                                         Logger::info('Activity had been fetched successfully', ['id' => $id]);
 274                                         $trust_source = true;
 275                                         $activity = $object;
 276                                 } else {
 277                                         Logger::info('Activity id is not equal', ['id' => $id, 'fetched' => $fetched_id]);
 278                                 }
 279                         } else {
 280                                 Logger::info('Activity could not been fetched', ['id' => $id]);
 281                         }
 282                 }
 283
 284                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 285                 if (empty($actor)) {
 286                         Logger::info('Empty actor', ['activity' => $activity]);
 287                         return [];
 288                 }
 289
 290                 $type = JsonLD::fetchElement($activity, '@type');
 291
 292                 // Fetch all receivers from to, cc, bto and bcc
 293                 $receiverdata = self::getReceivers($activity, $actor);
 294                 $receivers = $reception_types = [];
 295                 foreach ($receiverdata as $key => $data) {
 296                         $receivers[$key] = $data['uid'];
 297                         $reception_types[$data['uid']] = $data['type'] ?? self::TARGET_UNKNOWN;
 298                 }
 299
 300                 // When it is a delivery to a personal inbox we add that user to the receivers
 301                 if (!empty($uid)) {
 302                         $additional = [$uid => $uid];
 303                         $receivers = array_replace($receivers, $additional);
 304                         if (empty($activity['thread-completion']) && (empty($reception_types[$uid]) || in_array($reception_types[$uid], [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL]))) {
 305                                 $reception_types[$uid] = self::TARGET_BCC;
 306                         }
 307                 }
 308
 309                 // We possibly need some user to fetch private content,
 310                 // so we fetch one out of the receivers if no uid is provided.
 311                 $fetch_uid = $uid ?: self::getBestUserForActivity($activity);
 312
 313                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 314                 if (empty($object_id)) {
 315                         Logger::info('No object found');
 316                         return [];
 317                 }
 318
 319                 if (!is_string($object_id)) {
 320                         Logger::info('Invalid object id', ['object' => $object_id]);
 321                         return [];
 322                 }
 323
 324                 $object_type = self::fetchObjectType($activity, $object_id, $fetch_uid);
 325
 326                 // Fetch the activity on Lemmy "Announce" messages (announces of activities)
 327                 if (($type == 'as:Announce') && in_array($object_type, array_merge(self::ACTIVITY_TYPES, ['as:Delete', 'as:Undo', 'as:Update']))) {
 328                         $data = ActivityPub::fetchContent($object_id, $fetch_uid);
 329                         if (!empty($data)) {
 330                                 $type = $object_type;
 331                                 $activity = JsonLD::compact($data);
 332
 333                                 // Some variables need to be refetched since the activity changed
 334                                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 335                                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 336                                 $object_type = self::fetchObjectType($activity, $object_id, $fetch_uid);
 337                         }
 338                 }
 339
 340                 // Any activities on account types must not be altered
 341                 if (in_array($object_type, self::ACCOUNT_TYPES)) {
 342                         $object_data = [];
 343                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 344                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 345                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 346                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 347                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 348                         $object_data['push'] = $push;
 349                 } elseif (in_array($type, ['as:Create', 'as:Update', 'as:Announce']) || strpos($type, '#emojiReaction')) {
 350                 // Fetch the content only on activities where this matters
 351                 // We can receive "#emojiReaction" when fetching content from Hubzilla systems
 352                         // Always fetch on "Announce"
 353                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source && ($type != 'as:Announce'), $fetch_uid);
 354                         if (empty($object_data)) {
 355                                 Logger::info("Object data couldn't be processed");
 356                                 return [];
 357                         }
 358
 359                         $object_data['object_id'] = $object_id;
 360
 361                         if ($type == 'as:Announce') {
 362                                 $object_data['push'] = false;
 363                         } else {
 364                                 $object_data['push'] = $push;
 365                         }
 366
 367                         // Test if it is an answer to a mail
 368                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 369                                 $object_data['directmessage'] = true;
 370                         } else {
 371                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 372                         }
 373                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 374                         // Create a mostly empty array out of the activity data (instead of the object).
 375                         // This way we later don't have to check for the existence of each individual array element.
 376                         $object_data = self::processObject($activity);
 377                         $object_data['name'] = $type;
 378                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 379                         $object_data['object_id'] = $object_id;
 380                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 381                         $object_data['push'] = $push;
 382                 } elseif (in_array($type, ['as:Add'])) {
 383                         $object_data = [];
 384                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 385                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 386                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 387                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 388                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 389                         $object_data['push'] = $push;
 390                 } else {
 391                         $object_data = [];
 392                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 393                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 394                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 395                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 396                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 397                         $object_data['push'] = $push;
 398
 399                         // An Undo is done on the object of an object, so we need that type as well
 400                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
 401                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $fetch_uid);
 402                         }
 403                 }
 404
 405                 $object_data = self::addActivityFields($object_data, $activity);
 406
 407                 if (empty($object_data['object_type'])) {
 408                         $object_data['object_type'] = $object_type;
 409                 }
 410
 411                 $object_data['type'] = $type;
 412                 $object_data['actor'] = $actor;
 413                 $object_data['item_receiver'] = $receivers;
 414                 $object_data['receiver'] = array_replace($object_data['receiver'] ?? [], $receivers);
 415                 $object_data['reception_type'] = array_replace($object_data['reception_type'] ?? [], $reception_types);
 416
 417                 $author = $object_data['author'] ?? $actor;
 418                 if (!empty($author) && !empty($object_data['id'])) {
 419                         $author_host = parse_url($author, PHP_URL_HOST);
 420                         $id_host = parse_url($object_data['id'], PHP_URL_HOST);
 421                         if ($author_host == $id_host) {
 422                                 Logger::info('Valid hosts', ['type' => $type, 'host' => $id_host]);
 423                         } else {
 424                                 Logger::notice('Differing hosts on author and id', ['type' => $type, 'author' => $author_host, 'id' => $id_host]);
 425                                 $trust_source = false;
 426                         }
 427                 }
 428
 429                 Logger::info('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id']);
 430
 431                 return $object_data;
 432         }
 433
 434         /**
 435          * Fetches the first user id from the receiver array
 436          *
 437          * @param array $receivers Array with receivers
 438          * @return integer user id;
 439          */
 440         public static function getFirstUserFromReceivers($receivers)
 441         {
 442                 foreach ($receivers as $receiver) {
 443                         if (!empty($receiver)) {
 444                                 return $receiver;
 445                         }
 446                 }
 447                 return 0;
 448         }
 449
 450         /**
 451          * Processes the activity object
 452          *
 453          * @param array   $activity     Array with activity data
 454          * @param string  $body
 455          * @param integer $uid          User ID
 456          * @param boolean $trust_source Do we trust the source?
 457          * @param boolean $push         Message had been pushed to our system
 458          * @throws \Exception
 459          */
 460         public static function processActivity($activity, string $body = '', int $uid = null, bool $trust_source = false, bool $push = false, array $signer = [])
 461         {
 462                 $type = JsonLD::fetchElement($activity, '@type');
 463                 if (!$type) {
 464                         Logger::info('Empty type', ['activity' => $activity]);
 465                         return;
 466                 }
 467
 468                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 469                         Logger::info('Empty object', ['activity' => $activity]);
 470                         return;
 471                 }
 472
 473                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 474                 if (empty($actor)) {
 475                         Logger::info('Empty actor', ['activity' => $activity]);
 476                         return;
 477                 }
 478
 479                 if (is_array($activity['as:object'])) {
 480                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 481                 } else {
 482                         $attributed_to = '';
 483                 }
 484
 485                 // Test the provided signatures against the actor and "attributedTo"
 486                 if ($trust_source) {
 487                         if (!empty($attributed_to) && !empty($actor)) {
 488                                 $trust_source = (in_array($actor, $signer) && in_array($attributed_to, $signer));
 489                         } else {
 490                                 $trust_source = in_array($actor, $signer);
 491                         }
 492                 }
 493
 494                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 495                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 496                 if (empty($object_data)) {
 497                         Logger::info('No object data found', ['activity' => $activity]);
 498                         return;
 499                 }
 500
 501                 // Lemmy is announcing activities.
 502                 // We are changing the announces into regular activities.
 503                 if (($type == 'as:Announce') && in_array($object_data['type'] ?? '', array_merge(self::ACTIVITY_TYPES, ['as:Delete', 'as:Undo', 'as:Update']))) {
 504                         $type = $object_data['type'];
 505                 }
 506
 507                 if (!$trust_source) {
 508                         Logger::info('Activity trust could not be achieved.',  ['id' => $object_data['object_id'], 'type' => $type, 'signer' => $signer, 'actor' => $actor, 'attributedTo' => $attributed_to]);
 509                         return;
 510                 }
 511
 512                 if (!empty($body) && empty($object_data['raw'])) {
 513                         $object_data['raw'] = $body;
 514                 }
 515
 516                 // Internal flag for thread completion. See Processor.php
 517                 if (!empty($activity['thread-completion'])) {
 518                         $object_data['thread-completion'] = $activity['thread-completion'];
 519                 }
 520                 if (!empty($activity['thread-children-type'])) {
 521                         $object_data['thread-children-type'] = $activity['thread-children-type'];
 522                 }
 523
 524                 // Internal flag for posts that arrived via relay
 525                 if (!empty($activity['from-relay'])) {
 526                         $object_data['from-relay'] = $activity['from-relay'];
 527                 }
 528
 529                 switch ($type) {
 530                         case 'as:Create':
 531                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 532                                         $item = ActivityPub\Processor::createItem($object_data);
 533                                         ActivityPub\Processor::postItem($object_data, $item);
 534                                 }
 535                                 break;
 536
 537                         case 'as:Add':
 538                                 if ($object_data['object_type'] == 'as:tag') {
 539                                         ActivityPub\Processor::addTag($object_data);
 540                                 }
 541                                 break;
 542
 543                         case 'as:Announce':
 544                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 545                                         $object_data['thread-completion'] = Contact::getIdForURL($actor);
 546
 547                                         $item = ActivityPub\Processor::createItem($object_data);
 548                                         if (empty($item)) {
 549                                                 return;
 550                                         }
 551
 552                                         $item['post-reason'] = Item::PR_ANNOUNCEMENT;
 553                                         ActivityPub\Processor::postItem($object_data, $item);
 554
 555                                         $announce_object_data = self::processObject($activity);
 556                                         $announce_object_data['name'] = $type;
 557                                         $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 558                                         $announce_object_data['object_id'] = $object_data['object_id'];
 559                                         $announce_object_data['object_type'] = $object_data['object_type'];
 560                                         $announce_object_data['push'] = $push;
 561
 562                                         if (!empty($body)) {
 563                                                 $announce_object_data['raw'] = $body;
 564                                         }
 565
 566                                         ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 567                                 }
 568                                 break;
 569
 570                         case 'as:Like':
 571                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 572                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 573                                 }
 574                                 break;
 575
 576                         case 'as:Dislike':
 577                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 578                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 579                                 }
 580                                 break;
 581
 582                         case 'as:TentativeAccept':
 583                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 584                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 585                                 }
 586                                 break;
 587
 588                         case 'as:Update':
 589                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 590                                         ActivityPub\Processor::updateItem($object_data);
 591                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 592                                         ActivityPub\Processor::updatePerson($object_data);
 593                                 }
 594                                 break;
 595
 596                         case 'as:Delete':
 597                                 if ($object_data['object_type'] == 'as:Tombstone') {
 598                                         ActivityPub\Processor::deleteItem($object_data);
 599                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 600                                         ActivityPub\Processor::deletePerson($object_data);
 601                                 }
 602                                 break;
 603
 604                         case 'as:Follow':
 605                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 606                                         ActivityPub\Processor::followUser($object_data);
 607                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 608                                         $object_data['reply-to-id'] = $object_data['object_id'];
 609                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 610                                 }
 611                                 break;
 612
 613                         case 'as:Accept':
 614                                 if ($object_data['object_type'] == 'as:Follow') {
 615                                         ActivityPub\Processor::acceptFollowUser($object_data);
 616                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 617                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 618                                 }
 619                                 break;
 620
 621                         case 'as:Reject':
 622                                 if ($object_data['object_type'] == 'as:Follow') {
 623                                         ActivityPub\Processor::rejectFollowUser($object_data);
 624                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 625                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 626                                 }
 627                                 break;
 628
 629                         case 'as:Undo':
 630                                 if (($object_data['object_type'] == 'as:Follow') &&
 631                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 632                                         ActivityPub\Processor::undoFollowUser($object_data);
 633                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 634                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 635                                         ActivityPub\Processor::rejectFollowUser($object_data);
 636                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 637                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 638                                         ActivityPub\Processor::undoActivity($object_data);
 639                                 }
 640                                 break;
 641
 642                         default:
 643                                 Logger::info('Unknown activity: ' . $type . ' ' . $object_data['object_type']);
 644                                 break;
 645                 }
 646         }
 647
 648         /**
 649          * Fetch a user id from an activity array
 650          *
 651          * @param array  $activity
 652          * @param string $actor
 653          *
 654          * @return int   user id
 655          */
 656         public static function getBestUserForActivity(array $activity)
 657         {
 658                 $uid = 0;
 659                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id') ?? '';
 660
 661                 $receivers = self::getReceivers($activity, $actor);
 662                 foreach ($receivers as $receiver) {
 663                         if ($receiver['type'] == self::TARGET_GLOBAL) {
 664                                 return 0;
 665                         }
 666                         if (empty($uid) || ($receiver['type'] == self::TARGET_TO)) {
 667                                 $uid = $receiver['uid'];
 668                         }
 669                 }
 670                 return $uid;
 671         }
 672
 673         /**
 674          * Fetch the receiver list from an activity array
 675          *
 676          * @param array   $activity
 677          * @param string  $actor
 678          * @param array   $tags
 679          * @param boolean $fetch_unlisted
 680          *
 681          * @return array with receivers (user id)
 682          * @throws \Exception
 683          */
 684         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 685         {
 686                 $reply = $receivers = [];
 687
 688                 // When it is an answer, we inherite the receivers from the parent
 689                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 690                 if (!empty($replyto)) {
 691                         $reply = [$replyto];
 692
 693                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 694                         $fixedReplyTo = Item::getURIByLink($replyto);
 695                         if (!empty($fixedReplyTo)) {
 696                                 $reply[] = $fixedReplyTo;
 697                         }
 698                 }
 699
 700                 // Fetch all posts that refer to the object id
 701                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 702                 if (!empty($object_id)) {
 703                         $reply[] = $object_id;
 704                 }
 705
 706                 if (!empty($reply)) {
 707                         $parents = Post::select(['uid'], ['uri' => $reply]);
 708                         while ($parent = Post::fetch($parents)) {
 709                                 $receivers[$parent['uid']] = ['uid' => $parent['uid'], 'type' => self::TARGET_ANSWER];
 710                         }
 711                         DBA::close($parents);
 712                 }
 713
 714                 if (!empty($actor)) {
 715                         $profile   = APContact::getByURL($actor);
 716                         $followers = $profile['followers'] ?? '';
 717                         $is_forum  = ($actor['type'] ?? '') == 'Group';
 718                         Logger::info('Got actor and followers', ['actor' => $actor, 'followers' => $followers]);
 719                 } else {
 720                         Logger::info('Empty actor', ['activity' => $activity]);
 721                         $followers = '';
 722                         $is_forum  = false;
 723                 }
 724
 725                 // We have to prevent false follower assumptions upon thread completions
 726                 $follower_target = empty($activity['thread-completion']) ? self::TARGET_FOLLOWER : self::TARGET_UNKNOWN;
 727
 728                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 729                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 730                         if (empty($receiver_list)) {
 731                                 continue;
 732                         }
 733
 734                         foreach ($receiver_list as $receiver) {
 735                                 if ($receiver == self::PUBLIC_COLLECTION) {
 736                                         $receivers[0] = ['uid' => 0, 'type' => self::TARGET_GLOBAL];
 737                                 }
 738
 739                                 // Add receiver "-1" for unlisted posts
 740                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 741                                         $receivers[-1] = ['uid' => -1, 'type' => self::TARGET_GLOBAL];
 742                                 }
 743
 744                                 // Fetch the receivers for the public and the followers collection
 745                                 if ((($receiver == $followers) || (($receiver == self::PUBLIC_COLLECTION) && !$is_forum)) && !empty($actor)) {
 746                                         $receivers = self::getReceiverForActor($actor, $tags, $receivers, $follower_target);
 747                                         continue;
 748                                 }
 749
 750                                 // Fetching all directly addressed receivers
 751                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 752                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 753                                 if (!DBA::isResult($contact)) {
 754                                         continue;
 755                                 }
 756
 757                                 // Check if the potential receiver is following the actor
 758                                 // Exception: The receiver is targetted via "to" or this is a comment
 759                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 760                                         $networks = Protocol::FEDERATED;
 761                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 762                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 763
 764                                         // Forum posts are only accepted from forum contacts
 765                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 766                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 767                                         }
 768
 769                                         if (!DBA::exists('contact', $condition)) {
 770                                                 continue;
 771                                         }
 772                                 }
 773
 774                                 $type = $receivers[$contact['uid']]['type'] ?? self::TARGET_UNKNOWN;
 775                                 if (in_array($type, [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL])) {
 776                                         switch ($element) {
 777                                                 case 'as:to':
 778                                                         $type = self::TARGET_TO;
 779                                                         break;
 780                                                 case 'as:cc':
 781                                                         $type = self::TARGET_CC;
 782                                                         break;
 783                                                 case 'as:bto':
 784                                                         $type = self::TARGET_BTO;
 785                                                         break;
 786                                                 case 'as:bcc':
 787                                                         $type = self::TARGET_BCC;
 788                                                         break;
 789                                         }
 790
 791                                         $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $type];
 792                                 }
 793                         }
 794                 }
 795
 796                 self::switchContacts($receivers, $actor);
 797
 798                 return $receivers;
 799         }
 800
 801         /**
 802          * Fetch the receiver list of a given actor
 803          *
 804          * @param string  $actor
 805          * @param array   $tags
 806          * @param array   $receivers
 807          * @param integer $target_type
 808          *
 809          * @return array with receivers (user id)
 810          * @throws \Exception
 811          */
 812         private static function getReceiverForActor($actor, $tags, $receivers, $target_type)
 813         {
 814                 $basecondition = ['rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 815                         'network' => Protocol::FEDERATED, 'archive' => false, 'pending' => false];
 816
 817                 $condition = DBA::mergeConditions($basecondition, ["`nurl` = ? AND `uid` != ?", Strings::normaliseLink($actor), 0]);
 818                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 819                 while ($contact = DBA::fetch($contacts)) {
 820                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 821                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 822                         }
 823                 }
 824                 DBA::close($contacts);
 825
 826                 // The queries are split because of performance issues
 827                 $condition = DBA::mergeConditions($basecondition, ["`alias` IN (?, ?) AND `uid` != ?", Strings::normaliseLink($actor), $actor, 0]);
 828                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 829                 while ($contact = DBA::fetch($contacts)) {
 830                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 831                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 832                         }
 833                 }
 834                 DBA::close($contacts);
 835                 return $receivers;
 836         }
 837
 838         /**
 839          * Tests if the contact is a valid receiver for this actor
 840          *
 841          * @param array  $contact
 842          * @param string $actor
 843          * @param array  $tags
 844          *
 845          * @return bool with receivers (user id)
 846          * @throws \Exception
 847          */
 848         private static function isValidReceiverForActor($contact, $tags)
 849         {
 850                 // Are we following the contact? Then this is a valid receiver
 851                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 852                         return true;
 853                 }
 854
 855                 // When the possible receiver isn't a community, then it is no valid receiver
 856                 $owner = User::getOwnerDataById($contact['uid']);
 857                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 858                         return false;
 859                 }
 860
 861                 // Is the community account tagged?
 862                 foreach ($tags as $tag) {
 863                         if ($tag['type'] != 'Mention') {
 864                                 continue;
 865                         }
 866
 867                         if (Strings::compareLink($tag['href'], $owner['url'])) {
 868                                 return true;
 869                         }
 870                 }
 871
 872                 return false;
 873         }
 874
 875         /**
 876          * Switches existing contacts to ActivityPub
 877          *
 878          * @param integer $cid Contact ID
 879          * @param integer $uid User ID
 880          * @param string  $url Profile URL
 881          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 882          * @throws \ImagickException
 883          */
 884         public static function switchContact($cid, $uid, $url)
 885         {
 886                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 887                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 888                         return;
 889                 }
 890
 891                 if (Contact::updateFromProbe($cid)) {
 892                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 893                 }
 894
 895                 // Send a new follow request to be sure that the connection still exists
 896                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 897                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 898                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 899                 }
 900         }
 901
 902         /**
 903          *
 904          *
 905          * @param $receivers
 906          * @param $actor
 907          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 908          * @throws \ImagickException
 909          */
 910         private static function switchContacts($receivers, $actor)
 911         {
 912                 if (empty($actor)) {
 913                         return;
 914                 }
 915
 916                 foreach ($receivers as $receiver) {
 917                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 918                         if (DBA::isResult($contact)) {
 919                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 920                         }
 921
 922                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 923                         if (DBA::isResult($contact)) {
 924                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 925                         }
 926                 }
 927         }
 928
 929         /**
 930          *
 931          *
 932          * @param       $object_data
 933          * @param array $activity
 934          *
 935          * @return mixed
 936          */
 937         private static function addActivityFields($object_data, $activity)
 938         {
 939                 if (!empty($activity['published']) && empty($object_data['published'])) {
 940                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 941                 }
 942
 943                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 944                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 945                 }
 946
 947                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 948                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 949
 950                 if (!empty($object_data['object_id'])) {
 951                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 952                         $objectId = Item::getURIByLink($object_data['object_id']);
 953                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 954                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 955                                 $object_data['object_id'] = $objectId;
 956                         }
 957                 }
 958
 959                 return $object_data;
 960         }
 961
 962         /**
 963          * Fetches the object data from external ressources if needed
 964          *
 965          * @param string  $object_id    Object ID of the the provided object
 966          * @param array   $object       The provided object array
 967          * @param boolean $trust_source Do we trust the provided object?
 968          * @param integer $uid          User ID for the signature that we use to fetch data
 969          *
 970          * @return array|false with trusted and valid object data
 971          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 972          * @throws \ImagickException
 973          */
 974         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 975         {
 976                 // By fetching the type we check if the object is complete.
 977                 $type = JsonLD::fetchElement($object, '@type');
 978
 979                 if (!$trust_source || empty($type)) {
 980                         $data = ActivityPub::fetchContent($object_id, $uid);
 981                         if (!empty($data)) {
 982                                 $object = JsonLD::compact($data);
 983                                 Logger::info('Fetched content for ' . $object_id);
 984                         } else {
 985                                 Logger::info('Empty content for ' . $object_id . ', check if content is available locally.');
 986
 987                                 $item = Post::selectFirst(Item::DELIVER_FIELDLIST, ['uri' => $object_id]);
 988                                 if (!DBA::isResult($item)) {
 989                                         Logger::info('Object with url ' . $object_id . ' was not found locally.');
 990                                         return false;
 991                                 }
 992                                 Logger::info('Using already stored item for url ' . $object_id);
 993                                 $data = ActivityPub\Transmitter::createNote($item);
 994                                 $object = JsonLD::compact($data);
 995                         }
 996
 997                         $id = JsonLD::fetchElement($object, '@id');
 998                         if (empty($id)) {
 999                                 Logger::info('Empty id');
1000                                 return false;
1001                         }
1002
1003                         if ($id != $object_id) {
1004                                 Logger::info('Fetched id differs from provided id', ['provided' => $object_id, 'fetched' => $id]);
1005                                 return false;
1006                         }
1007                 } else {
1008                         Logger::info('Using original object for url ' . $object_id);
1009                 }
1010
1011                 $type = JsonLD::fetchElement($object, '@type');
1012                 if (empty($type)) {
1013                         Logger::info('Empty type');
1014                         return false;
1015                 }
1016
1017                 // Lemmy is resharing "create" activities instead of content
1018                 // We fetch the content from the activity.
1019                 if (in_array($type, ['as:Create'])) {
1020                         $object = $object['as:object'];
1021                         $type = JsonLD::fetchElement($object, '@type');
1022                         if (empty($type)) {
1023                                 Logger::info('Empty type');
1024                                 return false;
1025                         }
1026                         $object_data = self::processObject($object);
1027                 }
1028
1029                 // We currently don't handle 'pt:CacheFile', but with this step we avoid logging
1030                 if (in_array($type, self::CONTENT_TYPES) || ($type == 'pt:CacheFile')) {
1031                         $object_data = self::processObject($object);
1032
1033                         if (!empty($data)) {
1034                                 $object_data['raw'] = json_encode($data);
1035                         }
1036                         return $object_data;
1037                 }
1038
1039                 if ($type == 'as:Announce') {
1040                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
1041                         if (empty($object_id) || !is_string($object_id)) {
1042                                 return false;
1043                         }
1044                         return self::fetchObject($object_id, [], false, $uid);
1045                 }
1046
1047                 Logger::info('Unhandled object type: ' . $type);
1048                 return false;
1049         }
1050
1051         /**
1052          * Converts the language element (Used by Peertube)
1053          *
1054          * @param array $languages
1055          * @return array Languages
1056          */
1057         public static function processLanguages(array $languages)
1058         {
1059                 if (empty($languages)) {
1060                         return [];
1061                 }
1062
1063                 $language_list = [];
1064
1065                 foreach ($languages as $language) {
1066                         if (!empty($language['_:identifier']) && !empty($language['as:name'])) {
1067                                 $language_list[$language['_:identifier']] = $language['as:name'];
1068                         }
1069                 }
1070                 return $language_list;
1071         }
1072
1073         /**
1074          * Convert tags from JSON-LD format into a simplified format
1075          *
1076          * @param array $tags Tags in JSON-LD format
1077          *
1078          * @return array with tags in a simplified format
1079          */
1080         public static function processTags(array $tags)
1081         {
1082                 $taglist = [];
1083
1084                 foreach ($tags as $tag) {
1085                         if (empty($tag)) {
1086                                 continue;
1087                         }
1088
1089                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
1090                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
1091                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
1092
1093                         if (empty($element['type'])) {
1094                                 continue;
1095                         }
1096
1097                         if (empty($element['href'])) {
1098                                 $element['href'] = $element['name'];
1099                         }
1100
1101                         $taglist[] = $element;
1102                 }
1103                 return $taglist;
1104         }
1105
1106         /**
1107          * Convert emojis from JSON-LD format into a simplified format
1108          *
1109          * @param array $emojis
1110          * @return array with emojis in a simplified format
1111          */
1112         private static function processEmojis(array $emojis)
1113         {
1114                 $emojilist = [];
1115
1116                 foreach ($emojis as $emoji) {
1117                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
1118                                 continue;
1119                         }
1120
1121                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
1122                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
1123                                 'href' => $url];
1124
1125                         $emojilist[] = $element;
1126                 }
1127
1128                 return $emojilist;
1129         }
1130
1131         /**
1132          * Convert attachments from JSON-LD format into a simplified format
1133          *
1134          * @param array $attachments Attachments in JSON-LD format
1135          *
1136          * @return array Attachments in a simplified format
1137          */
1138         private static function processAttachments(array $attachments)
1139         {
1140                 $attachlist = [];
1141
1142                 // Removes empty values
1143                 $attachments = array_filter($attachments);
1144
1145                 foreach ($attachments as $attachment) {
1146                         switch (JsonLD::fetchElement($attachment, '@type')) {
1147                                 case 'as:Page':
1148                                         $pageUrl = null;
1149                                         $pageImage = null;
1150
1151                                         $urls = JsonLD::fetchElementArray($attachment, 'as:url');
1152                                         foreach ($urls as $url) {
1153                                                 // Single scalar URL case
1154                                                 if (is_string($url)) {
1155                                                         $pageUrl = $url;
1156                                                         continue;
1157                                                 }
1158
1159                                                 $href = JsonLD::fetchElement($url, 'as:href', '@id');
1160                                                 $mediaType = JsonLD::fetchElement($url, 'as:mediaType', '@value');
1161                                                 if (Strings::startsWith($mediaType, 'image')) {
1162                                                         $pageImage = $href;
1163                                                 } else {
1164                                                         $pageUrl = $href;
1165                                                 }
1166                                         }
1167
1168                                         $attachlist[] = [
1169                                                 'type'  => 'link',
1170                                                 'title' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1171                                                 'desc'  => JsonLD::fetchElement($attachment, 'as:summary', '@value'),
1172                                                 'url'   => $pageUrl,
1173                                                 'image' => $pageImage,
1174                                         ];
1175                                         break;
1176                                 case 'as:Image':
1177                                         $mediaType = JsonLD::fetchElement($attachment, 'as:mediaType', '@value');
1178                                         $imageFullUrl = JsonLD::fetchElement($attachment, 'as:url', '@id');
1179                                         $imagePreviewUrl = null;
1180                                         // Multiple URLs?
1181                                         if (!$imageFullUrl && ($urls = JsonLD::fetchElementArray($attachment, 'as:url'))) {
1182                                                 $imageVariants = [];
1183                                                 $previewVariants = [];
1184                                                 foreach ($urls as $url) {
1185                                                         // Scalar URL, no discrimination possible
1186                                                         if (is_string($url)) {
1187                                                                 $imageFullUrl = $url;
1188                                                                 continue;
1189                                                         }
1190
1191                                                         // Not sure what to do with a different Link media type than the base Image, we skip
1192                                                         if ($mediaType != JsonLD::fetchElement($url, 'as:mediaType', '@value')) {
1193                                                                 continue;
1194                                                         }
1195
1196                                                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1197
1198                                                         // Default URL choice if no discriminating width is provided
1199                                                         $imageFullUrl = $href ?? $imageFullUrl;
1200
1201                                                         $width = intval(JsonLD::fetchElement($url, 'as:width', '@value') ?? 1);
1202
1203                                                         if ($href && $width) {
1204                                                                 $imageVariants[$width] = $href;
1205                                                                 // 632 is the ideal width for full screen frio posts, we compute the absolute distance to it
1206                                                                 $previewVariants[abs(632 - $width)] = $href;
1207                                                         }
1208                                                 }
1209
1210                                                 if ($imageVariants) {
1211                                                         // Taking the maximum size image
1212                                                         ksort($imageVariants);
1213                                                         $imageFullUrl = array_pop($imageVariants);
1214
1215                                                         // Taking the minimum number distance to the target distance
1216                                                         ksort($previewVariants);
1217                                                         $imagePreviewUrl = array_shift($previewVariants);
1218                                                 }
1219
1220                                                 unset($imageVariants);
1221                                                 unset($previewVariants);
1222                                         }
1223
1224                                         $attachlist[] = [
1225                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1226                                                 'mediaType' => $mediaType,
1227                                                 'name'  => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1228                                                 'url'   => $imageFullUrl,
1229                                                 'image' => $imagePreviewUrl !== $imageFullUrl ? $imagePreviewUrl : null,
1230                                         ];
1231                                         break;
1232                                 default:
1233                                         $attachlist[] = [
1234                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1235                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1236                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1237                                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id'),
1238                                                 'height' => JsonLD::fetchElement($attachment, 'as:height', '@value'),
1239                                                 'width' => JsonLD::fetchElement($attachment, 'as:width', '@value'),
1240                                                 'image' => JsonLD::fetchElement($attachment, 'as:image', '@id')
1241                                         ];
1242                         }
1243                 }
1244
1245                 return $attachlist;
1246         }
1247
1248         /**
1249          * Fetch the original source or content with the "language" Markdown or HTML
1250          *
1251          * @param array $object
1252          * @param array $object_data
1253          *
1254          * @return array
1255          * @throws \Exception
1256          */
1257         private static function getSource($object, $object_data)
1258         {
1259                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
1260                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1261                 if (!empty($object_data['source'])) {
1262                         return $object_data;
1263                 }
1264
1265                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
1266                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1267                 if (!empty($object_data['source'])) {
1268                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
1269                         return $object_data;
1270                 }
1271
1272                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
1273                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1274                 if (!empty($object_data['source'])) {
1275                         $object_data['source'] = HTML::toBBCode($object_data['source']);
1276                         return $object_data;
1277                 }
1278
1279                 return $object_data;
1280         }
1281
1282         /**
1283          * Extracts a potential alternate URL from a list of additional URL elements
1284          *
1285          * @param array $urls
1286          * @return string
1287          */
1288         private static function extractAlternateUrl(array $urls): string
1289         {
1290                 $alternateUrl = '';
1291                 foreach ($urls as $key => $url) {
1292                         // Not a list but a single URL element
1293                         if (!is_numeric($key)) {
1294                                 continue;
1295                         }
1296
1297                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1298                                 continue;
1299                         }
1300
1301                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1302                         if (empty($href)) {
1303                                 continue;
1304                         }
1305
1306                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1307                         if (empty($mediatype)) {
1308                                 continue;
1309                         }
1310
1311                         if ($mediatype == 'text/html') {
1312                                 $alternateUrl = $href;
1313                         }
1314                 }
1315
1316                 return $alternateUrl;
1317         }
1318
1319         /**
1320          * Check if the "as:url" element is an array with multiple links
1321          * This is the case with audio and video posts.
1322          * Then the links are added as attachments
1323          *
1324          * @param array $urls The object URL list
1325          * @return array an array of attachments
1326          */
1327         private static function processAttachmentUrls(array $urls): array
1328         {
1329                 $attachments = [];
1330                 foreach ($urls as $key => $url) {
1331                         // Not a list but a single URL element
1332                         if (!is_numeric($key)) {
1333                                 continue;
1334                         }
1335
1336                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1337                                 continue;
1338                         }
1339
1340                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1341                         if (empty($href)) {
1342                                 continue;
1343                         }
1344
1345                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1346                         if (empty($mediatype)) {
1347                                 continue;
1348                         }
1349
1350                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
1351
1352                         if ($filetype == 'audio') {
1353                                 $attachments[] = ['type' => $filetype, 'mediaType' => $mediatype, 'url' => $href, 'height' => null, 'size' => null, 'name' => ''];
1354                         } elseif ($filetype == 'video') {
1355                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1356                                 // PeerTube audio-only track
1357                                 if ($height === 0) {
1358                                         continue;
1359                                 }
1360
1361                                 $size = (int)JsonLD::fetchElement($url, 'pt:size', '@value');
1362                                 $attachments[] = ['type' => $filetype, 'mediaType' => $mediatype, 'url' => $href, 'height' => $height, 'size' => $size, 'name' => ''];
1363                         } elseif (in_array($mediatype, ['application/x-bittorrent', 'application/x-bittorrent;x-scheme-handler/magnet'])) {
1364                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1365
1366                                 // For Torrent links we always store the highest resolution
1367                                 if (!empty($attachments[$mediatype]['height']) && ($height < $attachments[$mediatype]['height'])) {
1368                                         continue;
1369                                 }
1370
1371                                 $attachments[$mediatype] = ['type' => $mediatype, 'mediaType' => $mediatype, 'url' => $href, 'height' => $height, 'size' => null, 'name' => ''];
1372                         } elseif ($mediatype == 'application/x-mpegURL') {
1373                                 // PeerTube exception, actual video link is in the tags of this URL element
1374                                 $attachments = array_merge($attachments, self::processAttachmentUrls($url['as:tag']));
1375                         }
1376                 }
1377
1378                 return array_values($attachments);
1379         }
1380
1381         /**
1382          * Fetches data from the object part of an activity
1383          *
1384          * @param array $object
1385          *
1386          * @return array
1387          * @throws \Exception
1388          */
1389         private static function processObject($object)
1390         {
1391                 if (!JsonLD::fetchElement($object, '@id')) {
1392                         return false;
1393                 }
1394
1395                 $object_data = [];
1396                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1397                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1398                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1399
1400                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1401                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1402                         $object_data['reply-to-id'] = $object_data['id'];
1403
1404                         // On activities the "reply to" is the id of the object it refers to
1405                         if (in_array($object_data['object_type'], self::ACTIVITY_TYPES)) {
1406                                 $object_id = JsonLD::fetchElement($object, 'as:object', '@id');
1407                                 if (!empty($object_id)) {
1408                                         $object_data['reply-to-id'] = $object_id;
1409                                 }
1410                         }
1411                 } else {
1412                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1413                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1414                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1415                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1416                                 $object_data['reply-to-id'] = $replyToId;
1417                         }
1418                 }
1419
1420                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1421                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1422
1423                 if (empty($object_data['updated'])) {
1424                         $object_data['updated'] = $object_data['published'];
1425                 }
1426
1427                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1428                         $object_data['published'] = $object_data['updated'];
1429                 }
1430
1431                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1432                 if (empty($actor)) {
1433                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1434                 }
1435
1436                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1437                 $location = JsonLD::fetchElement($location, 'location', '@value');
1438                 if ($location) {
1439                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1440                         // down to HTML and then finally format to plaintext.
1441                         $location = Markdown::convert($location);
1442                         $location = BBCode::toPlaintext($location);
1443                 }
1444
1445                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1446                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1447                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1448                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1449                 $object_data['actor'] = $object_data['author'] = $actor;
1450                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1451                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1452                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1453                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1454                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1455                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1456                 $object_data['mediatype'] = JsonLD::fetchElement($object, 'as:mediaType', '@value');
1457                 $object_data = self::getSource($object, $object_data);
1458                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1459                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1460                 $object_data['location'] = $location;
1461                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1462                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1463                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1464                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1465                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment') ?? []);
1466                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag') ?? []);
1467                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', null, '@type', 'toot:Emoji') ?? []);
1468                 $object_data['languages'] = self::processLanguages(JsonLD::fetchElementArray($object, 'sc:inLanguage') ?? []);
1469                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1470                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1471                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1472
1473                 // Special treatment for Hubzilla links
1474                 if (is_array($object_data['alternate-url'])) {
1475                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1476
1477                         if (!is_string($object_data['alternate-url'])) {
1478                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1479                         }
1480                 }
1481
1482                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1483                         $object_data['alternate-url'] = self::extractAlternateUrl($object['as:url'] ?? []) ?: $object_data['alternate-url'];
1484                         $object_data['attachments'] = array_merge($object_data['attachments'], self::processAttachmentUrls($object['as:url'] ?? []));
1485                 }
1486
1487                 // For page types we expect that the alternate url posts to some page.
1488                 // So we add this to the attachments if it differs from the id.
1489                 // Currently only Lemmy is using the page type.
1490                 if (($object_data['object_type'] == 'as:Page') && !empty($object_data['alternate-url']) && !Strings::compareLink($object_data['alternate-url'], $object_data['id'])) {
1491                         $object_data['attachments'][] = ['url' => $object_data['alternate-url']];
1492                         $object_data['alternate-url'] = null;
1493                 }
1494
1495                 $receiverdata = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1496                 $receivers = $reception_types = [];
1497                 foreach ($receiverdata as $key => $data) {
1498                         $receivers[$key] = $data['uid'];
1499                         $reception_types[$data['uid']] = $data['type'] ?? 0;
1500                 }
1501
1502                 $object_data['receiver'] = $receivers;
1503                 $object_data['reception_type'] = $reception_types;
1504
1505                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1506                 unset($object_data['receiver'][-1]);
1507                 unset($object_data['reception_type'][-1]);
1508
1509                 // Common object data:
1510
1511                 // Unhandled
1512                 // @context, type, actor, signature, mediaType, duration, replies, icon
1513
1514                 // Also missing: (Defined in the standard, but currently unused)
1515                 // audience, preview, endTime, startTime, image
1516
1517                 // Data in Notes:
1518
1519                 // Unhandled
1520                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1521                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1522
1523                 // Data in video:
1524
1525                 // To-Do?
1526                 // category, licence, language, commentsEnabled
1527
1528                 // Unhandled
1529                 // views, waitTranscoding, state, support, subtitleLanguage
1530                 // likes, dislikes, shares, comments
1531
1532                 return $object_data;
1533         }
1534 }