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                 $urls = self::getReceiverURL($activity);
 301
 302                 // When it is a delivery to a personal inbox we add that user to the receivers
 303                 if (!empty($uid)) {
 304                         $additional = [$uid => $uid];
 305                         $receivers = array_replace($receivers, $additional);
 306                         if (empty($activity['thread-completion']) && (empty($reception_types[$uid]) || in_array($reception_types[$uid], [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL]))) {
 307                                 $reception_types[$uid] = self::TARGET_BCC;
 308                                 $owner = User::getOwnerDataById($uid);
 309                                 if (!empty($owner['url'])) {
 310                                         $urls['as:bcc'][] = $owner['url'];
 311                                 }
 312                         }
 313                 }
 314
 315                 // We possibly need some user to fetch private content,
 316                 // so we fetch one out of the receivers if no uid is provided.
 317                 $fetch_uid = $uid ?: self::getBestUserForActivity($activity);
 318
 319                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 320                 if (empty($object_id)) {
 321                         Logger::info('No object found');
 322                         return [];
 323                 }
 324
 325                 if (!is_string($object_id)) {
 326                         Logger::info('Invalid object id', ['object' => $object_id]);
 327                         return [];
 328                 }
 329
 330                 $object_type = self::fetchObjectType($activity, $object_id, $fetch_uid);
 331
 332                 // Fetch the activity on Lemmy "Announce" messages (announces of activities)
 333                 if (($type == 'as:Announce') && in_array($object_type, array_merge(self::ACTIVITY_TYPES, ['as:Delete', 'as:Undo', 'as:Update']))) {
 334                         $data = ActivityPub::fetchContent($object_id, $fetch_uid);
 335                         if (!empty($data)) {
 336                                 $type = $object_type;
 337                                 $activity = JsonLD::compact($data);
 338
 339                                 // Some variables need to be refetched since the activity changed
 340                                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 341                                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 342                                 $object_type = self::fetchObjectType($activity, $object_id, $fetch_uid);
 343                         }
 344                 }
 345
 346                 // Any activities on account types must not be altered
 347                 if (in_array($object_type, self::ACCOUNT_TYPES)) {
 348                         $object_data = [];
 349                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 350                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 351                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 352                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 353                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 354                         $object_data['push'] = $push;
 355                 } elseif (in_array($type, ['as:Create', 'as:Update', 'as:Announce']) || strpos($type, '#emojiReaction')) {
 356                 // Fetch the content only on activities where this matters
 357                 // We can receive "#emojiReaction" when fetching content from Hubzilla systems
 358                         // Always fetch on "Announce"
 359                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source && ($type != 'as:Announce'), $fetch_uid);
 360                         if (empty($object_data)) {
 361                                 Logger::info("Object data couldn't be processed");
 362                                 return [];
 363                         }
 364
 365                         $object_data['object_id'] = $object_id;
 366
 367                         if ($type == 'as:Announce') {
 368                                 $object_data['push'] = false;
 369                         } else {
 370                                 $object_data['push'] = $push;
 371                         }
 372
 373                         // Test if it is an answer to a mail
 374                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 375                                 $object_data['directmessage'] = true;
 376                         } else {
 377                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 378                         }
 379                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 380                         // Create a mostly empty array out of the activity data (instead of the object).
 381                         // This way we later don't have to check for the existence of each individual array element.
 382                         $object_data = self::processObject($activity);
 383                         $object_data['name'] = $type;
 384                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 385                         $object_data['object_id'] = $object_id;
 386                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 387                         $object_data['push'] = $push;
 388                 } elseif (in_array($type, ['as:Add'])) {
 389                         $object_data = [];
 390                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 391                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 392                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 393                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 394                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 395                         $object_data['push'] = $push;
 396                 } else {
 397                         $object_data = [];
 398                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 399                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 400                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 401                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 402                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 403                         $object_data['push'] = $push;
 404
 405                         // An Undo is done on the object of an object, so we need that type as well
 406                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
 407                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $fetch_uid);
 408                         }
 409                 }
 410
 411                 $object_data = self::addActivityFields($object_data, $activity);
 412
 413                 if (empty($object_data['object_type'])) {
 414                         $object_data['object_type'] = $object_type;
 415                 }
 416
 417                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 418                         if ((empty($object_data['receiver_urls'][$element]) || in_array($element, ['as:bto', 'as:bcc'])) && !empty($urls[$element])) {
 419                                 $object_data['receiver_urls'][$element] = array_unique(array_merge($object_data['receiver_urls'][$element] ?? [], $urls[$element]));
 420                         }
 421                 }
 422
 423                 $object_data['type'] = $type;
 424                 $object_data['actor'] = $actor;
 425                 $object_data['item_receiver'] = $receivers;
 426                 $object_data['receiver'] = array_replace($object_data['receiver'] ?? [], $receivers);
 427                 $object_data['reception_type'] = array_replace($object_data['reception_type'] ?? [], $reception_types);
 428
 429                 $author = $object_data['author'] ?? $actor;
 430                 if (!empty($author) && !empty($object_data['id'])) {
 431                         $author_host = parse_url($author, PHP_URL_HOST);
 432                         $id_host = parse_url($object_data['id'], PHP_URL_HOST);
 433                         if ($author_host == $id_host) {
 434                                 Logger::info('Valid hosts', ['type' => $type, 'host' => $id_host]);
 435                         } else {
 436                                 Logger::notice('Differing hosts on author and id', ['type' => $type, 'author' => $author_host, 'id' => $id_host]);
 437                                 $trust_source = false;
 438                         }
 439                 }
 440
 441                 Logger::info('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id']);
 442
 443                 return $object_data;
 444         }
 445
 446         /**
 447          * Fetches the first user id from the receiver array
 448          *
 449          * @param array $receivers Array with receivers
 450          * @return integer user id;
 451          */
 452         public static function getFirstUserFromReceivers($receivers)
 453         {
 454                 foreach ($receivers as $receiver) {
 455                         if (!empty($receiver)) {
 456                                 return $receiver;
 457                         }
 458                 }
 459                 return 0;
 460         }
 461
 462         /**
 463          * Processes the activity object
 464          *
 465          * @param array   $activity     Array with activity data
 466          * @param string  $body
 467          * @param integer $uid          User ID
 468          * @param boolean $trust_source Do we trust the source?
 469          * @param boolean $push         Message had been pushed to our system
 470          * @throws \Exception
 471          */
 472         public static function processActivity($activity, string $body = '', int $uid = null, bool $trust_source = false, bool $push = false, array $signer = [])
 473         {
 474                 $type = JsonLD::fetchElement($activity, '@type');
 475                 if (!$type) {
 476                         Logger::info('Empty type', ['activity' => $activity]);
 477                         return;
 478                 }
 479
 480                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 481                         Logger::info('Empty object', ['activity' => $activity]);
 482                         return;
 483                 }
 484
 485                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 486                 if (empty($actor)) {
 487                         Logger::info('Empty actor', ['activity' => $activity]);
 488                         return;
 489                 }
 490
 491                 if (is_array($activity['as:object'])) {
 492                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 493                 } else {
 494                         $attributed_to = '';
 495                 }
 496
 497                 // Test the provided signatures against the actor and "attributedTo"
 498                 if ($trust_source) {
 499                         if (!empty($attributed_to) && !empty($actor)) {
 500                                 $trust_source = (in_array($actor, $signer) && in_array($attributed_to, $signer));
 501                         } else {
 502                                 $trust_source = in_array($actor, $signer);
 503                         }
 504                 }
 505
 506                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 507                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 508                 if (empty($object_data)) {
 509                         Logger::info('No object data found', ['activity' => $activity]);
 510                         return;
 511                 }
 512
 513                 // Lemmy is announcing activities.
 514                 // We are changing the announces into regular activities.
 515                 if (($type == 'as:Announce') && in_array($object_data['type'] ?? '', array_merge(self::ACTIVITY_TYPES, ['as:Delete', 'as:Undo', 'as:Update']))) {
 516                         $type = $object_data['type'];
 517                 }
 518
 519                 if (!$trust_source) {
 520                         Logger::info('Activity trust could not be achieved.',  ['id' => $object_data['object_id'], 'type' => $type, 'signer' => $signer, 'actor' => $actor, 'attributedTo' => $attributed_to]);
 521                         return;
 522                 }
 523
 524                 if (!empty($body) && empty($object_data['raw'])) {
 525                         $object_data['raw'] = $body;
 526                 }
 527
 528                 // Internal flag for thread completion. See Processor.php
 529                 if (!empty($activity['thread-completion'])) {
 530                         $object_data['thread-completion'] = $activity['thread-completion'];
 531                 }
 532                 if (!empty($activity['thread-children-type'])) {
 533                         $object_data['thread-children-type'] = $activity['thread-children-type'];
 534                 }
 535
 536                 // Internal flag for posts that arrived via relay
 537                 if (!empty($activity['from-relay'])) {
 538                         $object_data['from-relay'] = $activity['from-relay'];
 539                 }
 540
 541                 switch ($type) {
 542                         case 'as:Create':
 543                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 544                                         $item = ActivityPub\Processor::createItem($object_data);
 545                                         ActivityPub\Processor::postItem($object_data, $item);
 546                                 }
 547                                 break;
 548
 549                         case 'as:Add':
 550                                 if ($object_data['object_type'] == 'as:tag') {
 551                                         ActivityPub\Processor::addTag($object_data);
 552                                 }
 553                                 break;
 554
 555                         case 'as:Announce':
 556                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 557                                         $object_data['thread-completion'] = Contact::getIdForURL($actor);
 558
 559                                         $item = ActivityPub\Processor::createItem($object_data);
 560                                         if (empty($item)) {
 561                                                 return;
 562                                         }
 563
 564                                         $item['post-reason'] = Item::PR_ANNOUNCEMENT;
 565                                         ActivityPub\Processor::postItem($object_data, $item);
 566
 567                                         $announce_object_data = self::processObject($activity);
 568                                         $announce_object_data['name'] = $type;
 569                                         $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 570                                         $announce_object_data['object_id'] = $object_data['object_id'];
 571                                         $announce_object_data['object_type'] = $object_data['object_type'];
 572                                         $announce_object_data['push'] = $push;
 573
 574                                         if (!empty($body)) {
 575                                                 $announce_object_data['raw'] = $body;
 576                                         }
 577
 578                                         ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 579                                 }
 580                                 break;
 581
 582                         case 'as:Like':
 583                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 584                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 585                                 }
 586                                 break;
 587
 588                         case 'as:Dislike':
 589                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 590                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 591                                 }
 592                                 break;
 593
 594                         case 'as:TentativeAccept':
 595                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 596                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 597                                 }
 598                                 break;
 599
 600                         case 'as:Update':
 601                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 602                                         ActivityPub\Processor::updateItem($object_data);
 603                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 604                                         ActivityPub\Processor::updatePerson($object_data);
 605                                 }
 606                                 break;
 607
 608                         case 'as:Delete':
 609                                 if ($object_data['object_type'] == 'as:Tombstone') {
 610                                         ActivityPub\Processor::deleteItem($object_data);
 611                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 612                                         ActivityPub\Processor::deletePerson($object_data);
 613                                 }
 614                                 break;
 615
 616                         case 'as:Follow':
 617                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 618                                         ActivityPub\Processor::followUser($object_data);
 619                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 620                                         $object_data['reply-to-id'] = $object_data['object_id'];
 621                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 622                                 }
 623                                 break;
 624
 625                         case 'as:Accept':
 626                                 if ($object_data['object_type'] == 'as:Follow') {
 627                                         ActivityPub\Processor::acceptFollowUser($object_data);
 628                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 629                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 630                                 }
 631                                 break;
 632
 633                         case 'as:Reject':
 634                                 if ($object_data['object_type'] == 'as:Follow') {
 635                                         ActivityPub\Processor::rejectFollowUser($object_data);
 636                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 637                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 638                                 }
 639                                 break;
 640
 641                         case 'as:Undo':
 642                                 if (($object_data['object_type'] == 'as:Follow') &&
 643                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 644                                         ActivityPub\Processor::undoFollowUser($object_data);
 645                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 646                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 647                                         ActivityPub\Processor::rejectFollowUser($object_data);
 648                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 649                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 650                                         ActivityPub\Processor::undoActivity($object_data);
 651                                 }
 652                                 break;
 653
 654                         default:
 655                                 Logger::info('Unknown activity: ' . $type . ' ' . $object_data['object_type']);
 656                                 break;
 657                 }
 658         }
 659
 660         /**
 661          * Fetch a user id from an activity array
 662          *
 663          * @param array  $activity
 664          * @param string $actor
 665          *
 666          * @return int   user id
 667          */
 668         public static function getBestUserForActivity(array $activity)
 669         {
 670                 $uid = 0;
 671                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id') ?? '';
 672
 673                 $receivers = self::getReceivers($activity, $actor);
 674                 foreach ($receivers as $receiver) {
 675                         if ($receiver['type'] == self::TARGET_GLOBAL) {
 676                                 return 0;
 677                         }
 678                         if (empty($uid) || ($receiver['type'] == self::TARGET_TO)) {
 679                                 $uid = $receiver['uid'];
 680                         }
 681                 }
 682
 683                 // When we haven't found any user yet, we just chose a user who most likely could have access to the content
 684                 if (empty($uid)) {
 685                         $contact = Contact::selectFirst(['uid'], ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND]]);
 686                         if (!empty($contact['uid'])) {
 687                                 $uid = $contact['uid'];
 688                         }
 689                 }
 690
 691                 return $uid;
 692         }
 693
 694         public static function getReceiverURL($activity)
 695         {
 696                 $urls = [];
 697
 698                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 699                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 700                         if (empty($receiver_list)) {
 701                                 continue;
 702                         }
 703
 704                         foreach ($receiver_list as $receiver) {
 705                                 if ($receiver == self::PUBLIC_COLLECTION) {
 706                                         $receiver = ActivityPub::PUBLIC_COLLECTION;
 707                                 }
 708                                 $urls[$element][] = $receiver;
 709                         }
 710                 }
 711
 712                 return $urls;
 713         }
 714
 715         /**
 716          * Fetch the receiver list from an activity array
 717          *
 718          * @param array   $activity
 719          * @param string  $actor
 720          * @param array   $tags
 721          * @param boolean $fetch_unlisted
 722          *
 723          * @return array with receivers (user id)
 724          * @throws \Exception
 725          */
 726         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 727         {
 728                 $reply = $receivers = [];
 729
 730                 // When it is an answer, we inherite the receivers from the parent
 731                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 732                 if (!empty($replyto)) {
 733                         $reply = [$replyto];
 734
 735                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 736                         $fixedReplyTo = Item::getURIByLink($replyto);
 737                         if (!empty($fixedReplyTo)) {
 738                                 $reply[] = $fixedReplyTo;
 739                         }
 740                 }
 741
 742                 // Fetch all posts that refer to the object id
 743                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 744                 if (!empty($object_id)) {
 745                         $reply[] = $object_id;
 746                 }
 747
 748                 if (!empty($reply)) {
 749                         $parents = Post::select(['uid'], ['uri' => $reply]);
 750                         while ($parent = Post::fetch($parents)) {
 751                                 $receivers[$parent['uid']] = ['uid' => $parent['uid'], 'type' => self::TARGET_ANSWER];
 752                         }
 753                         DBA::close($parents);
 754                 }
 755
 756                 if (!empty($actor)) {
 757                         $profile   = APContact::getByURL($actor);
 758                         $followers = $profile['followers'] ?? '';
 759                         $is_forum  = ($actor['type'] ?? '') == 'Group';
 760                         Logger::info('Got actor and followers', ['actor' => $actor, 'followers' => $followers]);
 761                 } else {
 762                         Logger::info('Empty actor', ['activity' => $activity]);
 763                         $followers = '';
 764                         $is_forum  = false;
 765                 }
 766
 767                 // We have to prevent false follower assumptions upon thread completions
 768                 $follower_target = empty($activity['thread-completion']) ? self::TARGET_FOLLOWER : self::TARGET_UNKNOWN;
 769
 770                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 771                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 772                         if (empty($receiver_list)) {
 773                                 continue;
 774                         }
 775
 776                         foreach ($receiver_list as $receiver) {
 777                                 if ($receiver == self::PUBLIC_COLLECTION) {
 778                                         $receivers[0] = ['uid' => 0, 'type' => self::TARGET_GLOBAL];
 779                                 }
 780
 781                                 // Add receiver "-1" for unlisted posts
 782                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 783                                         $receivers[-1] = ['uid' => -1, 'type' => self::TARGET_GLOBAL];
 784                                 }
 785
 786                                 // Fetch the receivers for the public and the followers collection
 787                                 if ((($receiver == $followers) || (($receiver == self::PUBLIC_COLLECTION) && !$is_forum)) && !empty($actor)) {
 788                                         $receivers = self::getReceiverForActor($actor, $tags, $receivers, $follower_target);
 789                                         continue;
 790                                 }
 791
 792                                 // Fetching all directly addressed receivers
 793                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 794                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 795                                 if (!DBA::isResult($contact)) {
 796                                         continue;
 797                                 }
 798
 799                                 // Check if the potential receiver is following the actor
 800                                 // Exception: The receiver is targetted via "to" or this is a comment
 801                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 802                                         $networks = Protocol::FEDERATED;
 803                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 804                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 805
 806                                         // Forum posts are only accepted from forum contacts
 807                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 808                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 809                                         }
 810
 811                                         if (!DBA::exists('contact', $condition)) {
 812                                                 continue;
 813                                         }
 814                                 }
 815
 816                                 $type = $receivers[$contact['uid']]['type'] ?? self::TARGET_UNKNOWN;
 817                                 if (in_array($type, [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL])) {
 818                                         switch ($element) {
 819                                                 case 'as:to':
 820                                                         $type = self::TARGET_TO;
 821                                                         break;
 822                                                 case 'as:cc':
 823                                                         $type = self::TARGET_CC;
 824                                                         break;
 825                                                 case 'as:bto':
 826                                                         $type = self::TARGET_BTO;
 827                                                         break;
 828                                                 case 'as:bcc':
 829                                                         $type = self::TARGET_BCC;
 830                                                         break;
 831                                         }
 832
 833                                         $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $type];
 834                                 }
 835                         }
 836                 }
 837
 838                 self::switchContacts($receivers, $actor);
 839
 840                 return $receivers;
 841         }
 842
 843         /**
 844          * Fetch the receiver list of a given actor
 845          *
 846          * @param string  $actor
 847          * @param array   $tags
 848          * @param array   $receivers
 849          * @param integer $target_type
 850          *
 851          * @return array with receivers (user id)
 852          * @throws \Exception
 853          */
 854         private static function getReceiverForActor($actor, $tags, $receivers, $target_type)
 855         {
 856                 $basecondition = ['rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 857                         'network' => Protocol::FEDERATED, 'archive' => false, 'pending' => false];
 858
 859                 $condition = DBA::mergeConditions($basecondition, ["`nurl` = ? AND `uid` != ?", Strings::normaliseLink($actor), 0]);
 860                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 861                 while ($contact = DBA::fetch($contacts)) {
 862                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 863                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 864                         }
 865                 }
 866                 DBA::close($contacts);
 867
 868                 // The queries are split because of performance issues
 869                 $condition = DBA::mergeConditions($basecondition, ["`alias` IN (?, ?) AND `uid` != ?", Strings::normaliseLink($actor), $actor, 0]);
 870                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 871                 while ($contact = DBA::fetch($contacts)) {
 872                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 873                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 874                         }
 875                 }
 876                 DBA::close($contacts);
 877                 return $receivers;
 878         }
 879
 880         /**
 881          * Tests if the contact is a valid receiver for this actor
 882          *
 883          * @param array  $contact
 884          * @param string $actor
 885          * @param array  $tags
 886          *
 887          * @return bool with receivers (user id)
 888          * @throws \Exception
 889          */
 890         private static function isValidReceiverForActor($contact, $tags)
 891         {
 892                 // Are we following the contact? Then this is a valid receiver
 893                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 894                         return true;
 895                 }
 896
 897                 // When the possible receiver isn't a community, then it is no valid receiver
 898                 $owner = User::getOwnerDataById($contact['uid']);
 899                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 900                         return false;
 901                 }
 902
 903                 // Is the community account tagged?
 904                 foreach ($tags as $tag) {
 905                         if ($tag['type'] != 'Mention') {
 906                                 continue;
 907                         }
 908
 909                         if (Strings::compareLink($tag['href'], $owner['url'])) {
 910                                 return true;
 911                         }
 912                 }
 913
 914                 return false;
 915         }
 916
 917         /**
 918          * Switches existing contacts to ActivityPub
 919          *
 920          * @param integer $cid Contact ID
 921          * @param integer $uid User ID
 922          * @param string  $url Profile URL
 923          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 924          * @throws \ImagickException
 925          */
 926         public static function switchContact($cid, $uid, $url)
 927         {
 928                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 929                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 930                         return;
 931                 }
 932
 933                 if (Contact::updateFromProbe($cid)) {
 934                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 935                 }
 936
 937                 // Send a new follow request to be sure that the connection still exists
 938                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 939                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 940                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 941                 }
 942         }
 943
 944         /**
 945          *
 946          *
 947          * @param $receivers
 948          * @param $actor
 949          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 950          * @throws \ImagickException
 951          */
 952         private static function switchContacts($receivers, $actor)
 953         {
 954                 if (empty($actor)) {
 955                         return;
 956                 }
 957
 958                 foreach ($receivers as $receiver) {
 959                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 960                         if (DBA::isResult($contact)) {
 961                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 962                         }
 963
 964                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 965                         if (DBA::isResult($contact)) {
 966                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 967                         }
 968                 }
 969         }
 970
 971         /**
 972          *
 973          *
 974          * @param       $object_data
 975          * @param array $activity
 976          *
 977          * @return mixed
 978          */
 979         private static function addActivityFields($object_data, $activity)
 980         {
 981                 if (!empty($activity['published']) && empty($object_data['published'])) {
 982                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 983                 }
 984
 985                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 986                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 987                 }
 988
 989                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 990                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 991
 992                 if (!empty($object_data['object_id'])) {
 993                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 994                         $objectId = Item::getURIByLink($object_data['object_id']);
 995                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 996                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 997                                 $object_data['object_id'] = $objectId;
 998                         }
 999                 }
1000
1001                 return $object_data;
1002         }
1003
1004         /**
1005          * Fetches the object data from external ressources if needed
1006          *
1007          * @param string  $object_id    Object ID of the the provided object
1008          * @param array   $object       The provided object array
1009          * @param boolean $trust_source Do we trust the provided object?
1010          * @param integer $uid          User ID for the signature that we use to fetch data
1011          *
1012          * @return array|false with trusted and valid object data
1013          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1014          * @throws \ImagickException
1015          */
1016         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
1017         {
1018                 // By fetching the type we check if the object is complete.
1019                 $type = JsonLD::fetchElement($object, '@type');
1020
1021                 if (!$trust_source || empty($type)) {
1022                         $data = ActivityPub::fetchContent($object_id, $uid);
1023                         if (!empty($data)) {
1024                                 $object = JsonLD::compact($data);
1025                                 Logger::info('Fetched content for ' . $object_id);
1026                         } else {
1027                                 Logger::info('Empty content for ' . $object_id . ', check if content is available locally.');
1028
1029                                 $item = Post::selectFirst(Item::DELIVER_FIELDLIST, ['uri' => $object_id]);
1030                                 if (!DBA::isResult($item)) {
1031                                         Logger::info('Object with url ' . $object_id . ' was not found locally.');
1032                                         return false;
1033                                 }
1034                                 Logger::info('Using already stored item for url ' . $object_id);
1035                                 $data = ActivityPub\Transmitter::createNote($item);
1036                                 $object = JsonLD::compact($data);
1037                         }
1038
1039                         $id = JsonLD::fetchElement($object, '@id');
1040                         if (empty($id)) {
1041                                 Logger::info('Empty id');
1042                                 return false;
1043                         }
1044
1045                         if ($id != $object_id) {
1046                                 Logger::info('Fetched id differs from provided id', ['provided' => $object_id, 'fetched' => $id]);
1047                                 return false;
1048                         }
1049                 } else {
1050                         Logger::info('Using original object for url ' . $object_id);
1051                 }
1052
1053                 $type = JsonLD::fetchElement($object, '@type');
1054                 if (empty($type)) {
1055                         Logger::info('Empty type');
1056                         return false;
1057                 }
1058
1059                 // Lemmy is resharing "create" activities instead of content
1060                 // We fetch the content from the activity.
1061                 if (in_array($type, ['as:Create'])) {
1062                         $object = $object['as:object'];
1063                         $type = JsonLD::fetchElement($object, '@type');
1064                         if (empty($type)) {
1065                                 Logger::info('Empty type');
1066                                 return false;
1067                         }
1068                         $object_data = self::processObject($object);
1069                 }
1070
1071                 // We currently don't handle 'pt:CacheFile', but with this step we avoid logging
1072                 if (in_array($type, self::CONTENT_TYPES) || ($type == 'pt:CacheFile')) {
1073                         $object_data = self::processObject($object);
1074
1075                         if (!empty($data)) {
1076                                 $object_data['raw'] = json_encode($data);
1077                         }
1078                         return $object_data;
1079                 }
1080
1081                 if ($type == 'as:Announce') {
1082                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
1083                         if (empty($object_id) || !is_string($object_id)) {
1084                                 return false;
1085                         }
1086                         return self::fetchObject($object_id, [], false, $uid);
1087                 }
1088
1089                 Logger::info('Unhandled object type: ' . $type);
1090                 return false;
1091         }
1092
1093         /**
1094          * Converts the language element (Used by Peertube)
1095          *
1096          * @param array $languages
1097          * @return array Languages
1098          */
1099         public static function processLanguages(array $languages)
1100         {
1101                 if (empty($languages)) {
1102                         return [];
1103                 }
1104
1105                 $language_list = [];
1106
1107                 foreach ($languages as $language) {
1108                         if (!empty($language['_:identifier']) && !empty($language['as:name'])) {
1109                                 $language_list[$language['_:identifier']] = $language['as:name'];
1110                         }
1111                 }
1112                 return $language_list;
1113         }
1114
1115         /**
1116          * Convert tags from JSON-LD format into a simplified format
1117          *
1118          * @param array $tags Tags in JSON-LD format
1119          *
1120          * @return array with tags in a simplified format
1121          */
1122         public static function processTags(array $tags)
1123         {
1124                 $taglist = [];
1125
1126                 foreach ($tags as $tag) {
1127                         if (empty($tag)) {
1128                                 continue;
1129                         }
1130
1131                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
1132                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
1133                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
1134
1135                         if (empty($element['type'])) {
1136                                 continue;
1137                         }
1138
1139                         if (empty($element['href'])) {
1140                                 $element['href'] = $element['name'];
1141                         }
1142
1143                         $taglist[] = $element;
1144                 }
1145                 return $taglist;
1146         }
1147
1148         /**
1149          * Convert emojis from JSON-LD format into a simplified format
1150          *
1151          * @param array $emojis
1152          * @return array with emojis in a simplified format
1153          */
1154         private static function processEmojis(array $emojis)
1155         {
1156                 $emojilist = [];
1157
1158                 foreach ($emojis as $emoji) {
1159                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
1160                                 continue;
1161                         }
1162
1163                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
1164                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
1165                                 'href' => $url];
1166
1167                         $emojilist[] = $element;
1168                 }
1169
1170                 return $emojilist;
1171         }
1172
1173         /**
1174          * Convert attachments from JSON-LD format into a simplified format
1175          *
1176          * @param array $attachments Attachments in JSON-LD format
1177          *
1178          * @return array Attachments in a simplified format
1179          */
1180         private static function processAttachments(array $attachments)
1181         {
1182                 $attachlist = [];
1183
1184                 // Removes empty values
1185                 $attachments = array_filter($attachments);
1186
1187                 foreach ($attachments as $attachment) {
1188                         switch (JsonLD::fetchElement($attachment, '@type')) {
1189                                 case 'as:Page':
1190                                         $pageUrl = null;
1191                                         $pageImage = null;
1192
1193                                         $urls = JsonLD::fetchElementArray($attachment, 'as:url');
1194                                         foreach ($urls as $url) {
1195                                                 // Single scalar URL case
1196                                                 if (is_string($url)) {
1197                                                         $pageUrl = $url;
1198                                                         continue;
1199                                                 }
1200
1201                                                 $href = JsonLD::fetchElement($url, 'as:href', '@id');
1202                                                 $mediaType = JsonLD::fetchElement($url, 'as:mediaType', '@value');
1203                                                 if (Strings::startsWith($mediaType, 'image')) {
1204                                                         $pageImage = $href;
1205                                                 } else {
1206                                                         $pageUrl = $href;
1207                                                 }
1208                                         }
1209
1210                                         $attachlist[] = [
1211                                                 'type'  => 'link',
1212                                                 'title' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1213                                                 'desc'  => JsonLD::fetchElement($attachment, 'as:summary', '@value'),
1214                                                 'url'   => $pageUrl,
1215                                                 'image' => $pageImage,
1216                                         ];
1217                                         break;
1218                                 case 'as:Image':
1219                                         $mediaType = JsonLD::fetchElement($attachment, 'as:mediaType', '@value');
1220                                         $imageFullUrl = JsonLD::fetchElement($attachment, 'as:url', '@id');
1221                                         $imagePreviewUrl = null;
1222                                         // Multiple URLs?
1223                                         if (!$imageFullUrl && ($urls = JsonLD::fetchElementArray($attachment, 'as:url'))) {
1224                                                 $imageVariants = [];
1225                                                 $previewVariants = [];
1226                                                 foreach ($urls as $url) {
1227                                                         // Scalar URL, no discrimination possible
1228                                                         if (is_string($url)) {
1229                                                                 $imageFullUrl = $url;
1230                                                                 continue;
1231                                                         }
1232
1233                                                         // Not sure what to do with a different Link media type than the base Image, we skip
1234                                                         if ($mediaType != JsonLD::fetchElement($url, 'as:mediaType', '@value')) {
1235                                                                 continue;
1236                                                         }
1237
1238                                                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1239
1240                                                         // Default URL choice if no discriminating width is provided
1241                                                         $imageFullUrl = $href ?? $imageFullUrl;
1242
1243                                                         $width = intval(JsonLD::fetchElement($url, 'as:width', '@value') ?? 1);
1244
1245                                                         if ($href && $width) {
1246                                                                 $imageVariants[$width] = $href;
1247                                                                 // 632 is the ideal width for full screen frio posts, we compute the absolute distance to it
1248                                                                 $previewVariants[abs(632 - $width)] = $href;
1249                                                         }
1250                                                 }
1251
1252                                                 if ($imageVariants) {
1253                                                         // Taking the maximum size image
1254                                                         ksort($imageVariants);
1255                                                         $imageFullUrl = array_pop($imageVariants);
1256
1257                                                         // Taking the minimum number distance to the target distance
1258                                                         ksort($previewVariants);
1259                                                         $imagePreviewUrl = array_shift($previewVariants);
1260                                                 }
1261
1262                                                 unset($imageVariants);
1263                                                 unset($previewVariants);
1264                                         }
1265
1266                                         $attachlist[] = [
1267                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1268                                                 'mediaType' => $mediaType,
1269                                                 'name'  => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1270                                                 'url'   => $imageFullUrl,
1271                                                 'image' => $imagePreviewUrl !== $imageFullUrl ? $imagePreviewUrl : null,
1272                                         ];
1273                                         break;
1274                                 default:
1275                                         $attachlist[] = [
1276                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1277                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1278                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1279                                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id'),
1280                                                 'height' => JsonLD::fetchElement($attachment, 'as:height', '@value'),
1281                                                 'width' => JsonLD::fetchElement($attachment, 'as:width', '@value'),
1282                                                 'image' => JsonLD::fetchElement($attachment, 'as:image', '@id')
1283                                         ];
1284                         }
1285                 }
1286
1287                 return $attachlist;
1288         }
1289
1290         /**
1291          * Fetch the original source or content with the "language" Markdown or HTML
1292          *
1293          * @param array $object
1294          * @param array $object_data
1295          *
1296          * @return array
1297          * @throws \Exception
1298          */
1299         private static function getSource($object, $object_data)
1300         {
1301                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
1302                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1303                 if (!empty($object_data['source'])) {
1304                         return $object_data;
1305                 }
1306
1307                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
1308                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1309                 if (!empty($object_data['source'])) {
1310                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
1311                         return $object_data;
1312                 }
1313
1314                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
1315                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1316                 if (!empty($object_data['source'])) {
1317                         $object_data['source'] = HTML::toBBCode($object_data['source']);
1318                         return $object_data;
1319                 }
1320
1321                 return $object_data;
1322         }
1323
1324         /**
1325          * Extracts a potential alternate URL from a list of additional URL elements
1326          *
1327          * @param array $urls
1328          * @return string
1329          */
1330         private static function extractAlternateUrl(array $urls): string
1331         {
1332                 $alternateUrl = '';
1333                 foreach ($urls as $key => $url) {
1334                         // Not a list but a single URL element
1335                         if (!is_numeric($key)) {
1336                                 continue;
1337                         }
1338
1339                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1340                                 continue;
1341                         }
1342
1343                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1344                         if (empty($href)) {
1345                                 continue;
1346                         }
1347
1348                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1349                         if (empty($mediatype)) {
1350                                 continue;
1351                         }
1352
1353                         if ($mediatype == 'text/html') {
1354                                 $alternateUrl = $href;
1355                         }
1356                 }
1357
1358                 return $alternateUrl;
1359         }
1360
1361         /**
1362          * Check if the "as:url" element is an array with multiple links
1363          * This is the case with audio and video posts.
1364          * Then the links are added as attachments
1365          *
1366          * @param array $urls The object URL list
1367          * @return array an array of attachments
1368          */
1369         private static function processAttachmentUrls(array $urls): array
1370         {
1371                 $attachments = [];
1372                 foreach ($urls as $key => $url) {
1373                         // Not a list but a single URL element
1374                         if (!is_numeric($key)) {
1375                                 continue;
1376                         }
1377
1378                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1379                                 continue;
1380                         }
1381
1382                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1383                         if (empty($href)) {
1384                                 continue;
1385                         }
1386
1387                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1388                         if (empty($mediatype)) {
1389                                 continue;
1390                         }
1391
1392                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
1393
1394                         if ($filetype == 'audio') {
1395                                 $attachments[] = ['type' => $filetype, 'mediaType' => $mediatype, 'url' => $href, 'height' => null, 'size' => null, 'name' => ''];
1396                         } elseif ($filetype == 'video') {
1397                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1398                                 // PeerTube audio-only track
1399                                 if ($height === 0) {
1400                                         continue;
1401                                 }
1402
1403                                 $size = (int)JsonLD::fetchElement($url, 'pt:size', '@value');
1404                                 $attachments[] = ['type' => $filetype, 'mediaType' => $mediatype, 'url' => $href, 'height' => $height, 'size' => $size, 'name' => ''];
1405                         } elseif (in_array($mediatype, ['application/x-bittorrent', 'application/x-bittorrent;x-scheme-handler/magnet'])) {
1406                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1407
1408                                 // For Torrent links we always store the highest resolution
1409                                 if (!empty($attachments[$mediatype]['height']) && ($height < $attachments[$mediatype]['height'])) {
1410                                         continue;
1411                                 }
1412
1413                                 $attachments[$mediatype] = ['type' => $mediatype, 'mediaType' => $mediatype, 'url' => $href, 'height' => $height, 'size' => null, 'name' => ''];
1414                         } elseif ($mediatype == 'application/x-mpegURL') {
1415                                 // PeerTube exception, actual video link is in the tags of this URL element
1416                                 $attachments = array_merge($attachments, self::processAttachmentUrls($url['as:tag']));
1417                         }
1418                 }
1419
1420                 return array_values($attachments);
1421         }
1422
1423         /**
1424          * Fetches data from the object part of an activity
1425          *
1426          * @param array $object
1427          *
1428          * @return array
1429          * @throws \Exception
1430          */
1431         private static function processObject($object)
1432         {
1433                 if (!JsonLD::fetchElement($object, '@id')) {
1434                         return false;
1435                 }
1436
1437                 $object_data = [];
1438                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1439                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1440                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1441
1442                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1443                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1444                         $object_data['reply-to-id'] = $object_data['id'];
1445
1446                         // On activities the "reply to" is the id of the object it refers to
1447                         if (in_array($object_data['object_type'], self::ACTIVITY_TYPES)) {
1448                                 $object_id = JsonLD::fetchElement($object, 'as:object', '@id');
1449                                 if (!empty($object_id)) {
1450                                         $object_data['reply-to-id'] = $object_id;
1451                                 }
1452                         }
1453                 } else {
1454                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1455                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1456                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1457                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1458                                 $object_data['reply-to-id'] = $replyToId;
1459                         }
1460                 }
1461
1462                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1463                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1464
1465                 if (empty($object_data['updated'])) {
1466                         $object_data['updated'] = $object_data['published'];
1467                 }
1468
1469                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1470                         $object_data['published'] = $object_data['updated'];
1471                 }
1472
1473                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1474                 if (empty($actor)) {
1475                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1476                 }
1477
1478                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1479                 $location = JsonLD::fetchElement($location, 'location', '@value');
1480                 if ($location) {
1481                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1482                         // down to HTML and then finally format to plaintext.
1483                         $location = Markdown::convert($location);
1484                         $location = BBCode::toPlaintext($location);
1485                 }
1486
1487                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1488                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1489                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1490                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1491                 $object_data['actor'] = $object_data['author'] = $actor;
1492                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1493                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1494                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1495                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1496                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1497                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1498                 $object_data['mediatype'] = JsonLD::fetchElement($object, 'as:mediaType', '@value');
1499                 $object_data = self::getSource($object, $object_data);
1500                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1501                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1502                 $object_data['location'] = $location;
1503                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1504                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1505                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1506                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1507                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment') ?? []);
1508                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag') ?? []);
1509                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', null, '@type', 'toot:Emoji') ?? []);
1510                 $object_data['languages'] = self::processLanguages(JsonLD::fetchElementArray($object, 'sc:inLanguage') ?? []);
1511                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1512                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1513                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1514
1515                 // Special treatment for Hubzilla links
1516                 if (is_array($object_data['alternate-url'])) {
1517                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1518
1519                         if (!is_string($object_data['alternate-url'])) {
1520                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1521                         }
1522                 }
1523
1524                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1525                         $object_data['alternate-url'] = self::extractAlternateUrl($object['as:url'] ?? []) ?: $object_data['alternate-url'];
1526                         $object_data['attachments'] = array_merge($object_data['attachments'], self::processAttachmentUrls($object['as:url'] ?? []));
1527                 }
1528
1529                 // For page types we expect that the alternate url posts to some page.
1530                 // So we add this to the attachments if it differs from the id.
1531                 // Currently only Lemmy is using the page type.
1532                 if (($object_data['object_type'] == 'as:Page') && !empty($object_data['alternate-url']) && !Strings::compareLink($object_data['alternate-url'], $object_data['id'])) {
1533                         $object_data['attachments'][] = ['url' => $object_data['alternate-url']];
1534                         $object_data['alternate-url'] = null;
1535                 }
1536
1537                 $receiverdata = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1538                 $receivers = $reception_types = [];
1539                 foreach ($receiverdata as $key => $data) {
1540                         $receivers[$key] = $data['uid'];
1541                         $reception_types[$data['uid']] = $data['type'] ?? 0;
1542                 }
1543
1544                 $object_data['receiver_urls']  = self::getReceiverURL($object);
1545                 $object_data['receiver']       = $receivers;
1546                 $object_data['reception_type'] = $reception_types;
1547
1548                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1549                 unset($object_data['receiver'][-1]);
1550                 unset($object_data['reception_type'][-1]);
1551
1552                 // Common object data:
1553
1554                 // Unhandled
1555                 // @context, type, actor, signature, mediaType, duration, replies, icon
1556
1557                 // Also missing: (Defined in the standard, but currently unused)
1558                 // audience, preview, endTime, startTime, image
1559
1560                 // Data in Notes:
1561
1562                 // Unhandled
1563                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1564                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1565
1566                 // Data in video:
1567
1568                 // To-Do?
1569                 // category, licence, language, commentsEnabled
1570
1571                 // Unhandled
1572                 // views, waitTranscoding, state, support, subtitleLanguage
1573                 // likes, dislikes, shares, comments
1574
1575                 return $object_data;
1576         }
1577 }