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\Network;
  41 use Friendica\Util\Strings;
  42
  43 /**
  44  * ActivityPub Receiver Protocol class
  45  *
  46  * To-Do:
  47  * @todo Undo Announce
  48  *
  49  * Check what this is meant to do:
  50  * - Add
  51  * - Block
  52  * - Flag
  53  * - Remove
  54  * - Undo Block
  55  */
  56 class Receiver
  57 {
  58         const PUBLIC_COLLECTION = 'as:Public';
  59         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  60         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio', 'as:Page', 'as:Question'];
  61         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  62
  63         const TARGET_UNKNOWN = 0;
  64         const TARGET_TO = 1;
  65         const TARGET_CC = 2;
  66         const TARGET_BTO = 3;
  67         const TARGET_BCC = 4;
  68         const TARGET_FOLLOWER = 5;
  69         const TARGET_ANSWER = 6;
  70         const TARGET_GLOBAL = 7;
  71
  72         const COMPLETION_NONE    = 0;
  73         const COMPLETION_ANNOUCE = 1;
  74         const COMPLETION_RELAY   = 2;
  75         const COMPLETION_MANUAL  = 3;
  76         const COMPLETION_AUTO    = 4;
  77
  78         /**
  79          * Checks incoming message from the inbox
  80          *
  81          * @param         $body
  82          * @param         $header
  83          * @param integer $uid User ID
  84          * @throws \Exception
  85          */
  86         public static function processInbox($body, $header, $uid)
  87         {
  88                 $activity = json_decode($body, true);
  89                 if (empty($activity)) {
  90                         Logger::warning('Invalid body.');
  91                         return;
  92                 }
  93
  94                 $ldactivity = JsonLD::compact($activity);
  95
  96                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
  97
  98                 $apcontact = APContact::getByURL($actor);
  99                 if (empty($apcontact)) {
 100                         Logger::notice('Unable to retrieve AP contact for actor - message is discarded', ['actor' => $actor]);
 101                         return;
 102                 } elseif ($apcontact['type'] == 'Application' && $apcontact['nick'] == 'relay') {
 103                         self::processRelayPost($ldactivity, $actor);
 104                         return;
 105                 } else {
 106                         APContact::unmarkForArchival($apcontact);
 107                 }
 108
 109                 $http_signer = HTTPSignature::getSigner($body, $header);
 110                 if ($http_signer === false) {
 111                         Logger::warning('Invalid HTTP signature, message will be discarded.');
 112                         return;
 113                 } elseif (empty($http_signer)) {
 114                         Logger::info('Signer is a tombstone. The message will be discarded, the signer account is deleted.');
 115                         return;
 116                 } else {
 117                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
 118                 }
 119
 120                 $signer = [$http_signer];
 121
 122                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 123
 124                 if (LDSignature::isSigned($activity)) {
 125                         $ld_signer = LDSignature::getSigner($activity);
 126                         if (empty($ld_signer)) {
 127                                 Logger::info('Invalid JSON-LD signature from ' . $actor);
 128                         } elseif ($ld_signer != $http_signer) {
 129                                 $signer[] = $ld_signer;
 130                         }
 131                         if (!empty($ld_signer && ($actor == $http_signer))) {
 132                                 Logger::info('The HTTP and the JSON-LD signature belong to ' . $ld_signer);
 133                                 $trust_source = true;
 134                         } elseif (!empty($ld_signer)) {
 135                                 Logger::info('JSON-LD signature is signed by ' . $ld_signer);
 136                                 $trust_source = true;
 137                         } elseif ($actor == $http_signer) {
 138                                 Logger::info('Bad JSON-LD signature, but HTTP signer fits the actor.');
 139                                 $trust_source = true;
 140                         } else {
 141                                 Logger::info('Invalid JSON-LD signature and the HTTP signer is different.');
 142                                 $trust_source = false;
 143                         }
 144                 } elseif ($actor == $http_signer) {
 145                         Logger::info('Trusting post without JSON-LD signature, The actor fits the HTTP signer.');
 146                         $trust_source = true;
 147                 } else {
 148                         Logger::info('No JSON-LD signature, different actor.');
 149                         $trust_source = false;
 150                 }
 151
 152                 self::processActivity($ldactivity, $body, $uid, $trust_source, true, $signer);
 153         }
 154
 155         /**
 156          * Process incoming posts from relays
 157          *
 158          * @param array  $activity
 159          * @param string $actor
 160          * @return void
 161          */
 162         private static function processRelayPost(array $activity, string $actor)
 163         {
 164                 $type = JsonLD::fetchElement($activity, '@type');
 165                 if (!$type) {
 166                         Logger::info('Empty type', ['activity' => $activity]);
 167                         return;
 168                 }
 169
 170                 if ($type != 'as:Announce') {
 171                         Logger::info('Not an announcement', ['activity' => $activity]);
 172                         return;
 173                 }
 174
 175                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 176                 if (empty($object_id)) {
 177                         Logger::info('No object id found', ['activity' => $activity]);
 178                         return;
 179                 }
 180
 181                 $contact = Contact::getByURL($actor);
 182                 if (empty($contact)) {
 183                         Logger::info('Relay contact not found', ['actor' => $actor]);
 184                         return;
 185                 }
 186
 187                 if (!in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 188                         Logger::notice('Relay is no sharer', ['actor' => $actor]);
 189                         return;
 190                 }
 191
 192                 Logger::info('Got relayed message id', ['id' => $object_id]);
 193
 194                 $item_id = Item::searchByLink($object_id);
 195                 if ($item_id) {
 196                         Logger::info('Relayed message already exists', ['id' => $object_id, 'item' => $item_id]);
 197                         return;
 198                 }
 199
 200                 $id = Processor::fetchMissingActivity($object_id, [], $actor, self::COMPLETION_RELAY);
 201                 if (empty($id)) {
 202                         Logger::notice('Relayed message had not been fetched', ['id' => $object_id]);
 203                         return;
 204                 }
 205
 206                 $item_id = Item::searchByLink($object_id);
 207                 if ($item_id) {
 208                         Logger::info('Relayed message had been fetched and stored', ['id' => $object_id, 'item' => $item_id]);
 209                 } else {
 210                         Logger::notice('Relayed message had not been stored', ['id' => $object_id]);
 211                 }
 212         }
 213
 214         /**
 215          * Fetches the object type for a given object id
 216          *
 217          * @param array   $activity
 218          * @param string  $object_id Object ID of the the provided object
 219          * @param integer $uid       User ID
 220          *
 221          * @return string with object type
 222          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 223          * @throws \ImagickException
 224          */
 225         private static function fetchObjectType($activity, $object_id, $uid = 0)
 226         {
 227                 if (!empty($activity['as:object'])) {
 228                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 229                         if (!empty($object_type)) {
 230                                 return $object_type;
 231                         }
 232                 }
 233
 234                 if (Post::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 235                         // We just assume "note" since it doesn't make a difference for the further processing
 236                         return 'as:Note';
 237                 }
 238
 239                 $profile = APContact::getByURL($object_id);
 240                 if (!empty($profile['type'])) {
 241                         APContact::unmarkForArchival($profile);
 242                         return 'as:' . $profile['type'];
 243                 }
 244
 245                 $data = ActivityPub::fetchContent($object_id, $uid);
 246                 if (!empty($data)) {
 247                         $object = JsonLD::compact($data);
 248                         $type = JsonLD::fetchElement($object, '@type');
 249                         if (!empty($type)) {
 250                                 return $type;
 251                         }
 252                 }
 253
 254                 return null;
 255         }
 256
 257         /**
 258          * Prepare the object array
 259          *
 260          * @param array   $activity     Array with activity data
 261          * @param integer $uid          User ID
 262          * @param boolean $push         Message had been pushed to our system
 263          * @param boolean $trust_source Do we trust the source?
 264          *
 265          * @return array with object data
 266          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 267          * @throws \ImagickException
 268          */
 269         public static function prepareObjectData($activity, $uid, $push, &$trust_source)
 270         {
 271                 $id = JsonLD::fetchElement($activity, '@id');
 272                 if (!empty($id) && !$trust_source) {
 273                         $fetch_uid = $uid ?: self::getBestUserForActivity($activity);
 274
 275                         $fetched_activity = ActivityPub::fetchContent($id, $fetch_uid);
 276                         if (!empty($fetched_activity)) {
 277                                 $object = JsonLD::compact($fetched_activity);
 278                                 $fetched_id = JsonLD::fetchElement($object, '@id');
 279                                 if ($fetched_id == $id) {
 280                                         Logger::info('Activity had been fetched successfully', ['id' => $id]);
 281                                         $trust_source = true;
 282                                         $activity = $object;
 283                                 } else {
 284                                         Logger::info('Activity id is not equal', ['id' => $id, 'fetched' => $fetched_id]);
 285                                 }
 286                         } else {
 287                                 Logger::info('Activity could not been fetched', ['id' => $id]);
 288                         }
 289                 }
 290
 291                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 292                 if (empty($actor)) {
 293                         Logger::info('Empty actor', ['activity' => $activity]);
 294                         return [];
 295                 }
 296
 297                 $type = JsonLD::fetchElement($activity, '@type');
 298
 299                 // Fetch all receivers from to, cc, bto and bcc
 300                 $receiverdata = self::getReceivers($activity, $actor);
 301                 $receivers = $reception_types = [];
 302                 foreach ($receiverdata as $key => $data) {
 303                         $receivers[$key] = $data['uid'];
 304                         $reception_types[$data['uid']] = $data['type'] ?? self::TARGET_UNKNOWN;
 305                 }
 306
 307                 $urls = self::getReceiverURL($activity);
 308
 309                 // When it is a delivery to a personal inbox we add that user to the receivers
 310                 if (!empty($uid)) {
 311                         $additional = [$uid => $uid];
 312                         $receivers = array_replace($receivers, $additional);
 313                         if (empty($activity['thread-completion']) && (empty($reception_types[$uid]) || in_array($reception_types[$uid], [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL]))) {
 314                                 $reception_types[$uid] = self::TARGET_BCC;
 315                                 $owner = User::getOwnerDataById($uid);
 316                                 if (!empty($owner['url'])) {
 317                                         $urls['as:bcc'][] = $owner['url'];
 318                                 }
 319                         }
 320                 }
 321
 322                 // We possibly need some user to fetch private content,
 323                 // so we fetch one out of the receivers if no uid is provided.
 324                 $fetch_uid = $uid ?: self::getBestUserForActivity($activity);
 325
 326                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 327                 if (empty($object_id)) {
 328                         Logger::info('No object found');
 329                         return [];
 330                 }
 331
 332                 if (!is_string($object_id)) {
 333                         Logger::info('Invalid object id', ['object' => $object_id]);
 334                         return [];
 335                 }
 336
 337                 $object_type = self::fetchObjectType($activity, $object_id, $fetch_uid);
 338
 339                 // Fetch the activity on Lemmy "Announce" messages (announces of activities)
 340                 if (($type == 'as:Announce') && in_array($object_type, array_merge(self::ACTIVITY_TYPES, ['as:Delete', 'as:Undo', 'as:Update']))) {
 341                         $data = ActivityPub::fetchContent($object_id, $fetch_uid);
 342                         if (!empty($data)) {
 343                                 $type = $object_type;
 344                                 $activity = JsonLD::compact($data);
 345
 346                                 // Some variables need to be refetched since the activity changed
 347                                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 348                                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 349                                 $object_type = self::fetchObjectType($activity, $object_id, $fetch_uid);
 350                         }
 351                 }
 352
 353                 // Any activities on account types must not be altered
 354                 if (in_array($object_type, self::ACCOUNT_TYPES)) {
 355                         $object_data = [];
 356                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 357                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 358                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 359                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 360                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 361                         $object_data['push'] = $push;
 362                 } elseif (in_array($type, ['as:Create', 'as:Update', 'as:Announce']) || strpos($type, '#emojiReaction')) {
 363                 // Fetch the content only on activities where this matters
 364                 // We can receive "#emojiReaction" when fetching content from Hubzilla systems
 365                         // Always fetch on "Announce"
 366                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source && ($type != 'as:Announce'), $fetch_uid);
 367                         if (empty($object_data)) {
 368                                 Logger::info("Object data couldn't be processed");
 369                                 return [];
 370                         }
 371
 372                         $object_data['object_id'] = $object_id;
 373
 374                         if ($type == 'as:Announce') {
 375                                 $object_data['push'] = false;
 376                         } else {
 377                                 $object_data['push'] = $push;
 378                         }
 379
 380                         // Test if it is an answer to a mail
 381                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 382                                 $object_data['directmessage'] = true;
 383                         } else {
 384                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 385                         }
 386                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 387                         // Create a mostly empty array out of the activity data (instead of the object).
 388                         // This way we later don't have to check for the existence of each individual array element.
 389                         $object_data = self::processObject($activity);
 390                         $object_data['name'] = $type;
 391                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 392                         $object_data['object_id'] = $object_id;
 393                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 394                         $object_data['push'] = $push;
 395                 } elseif (in_array($type, ['as:Add'])) {
 396                         $object_data = [];
 397                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 398                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 399                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 400                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 401                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 402                         $object_data['push'] = $push;
 403                 } else {
 404                         $object_data = [];
 405                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 406                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 407                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 408                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 409                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 410                         $object_data['push'] = $push;
 411
 412                         // An Undo is done on the object of an object, so we need that type as well
 413                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
 414                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $fetch_uid);
 415                         }
 416                 }
 417
 418                 $object_data = self::addActivityFields($object_data, $activity);
 419
 420                 if (empty($object_data['object_type'])) {
 421                         $object_data['object_type'] = $object_type;
 422                 }
 423
 424                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 425                         if ((empty($object_data['receiver_urls'][$element]) || in_array($element, ['as:bto', 'as:bcc'])) && !empty($urls[$element])) {
 426                                 $object_data['receiver_urls'][$element] = array_unique(array_merge($object_data['receiver_urls'][$element] ?? [], $urls[$element]));
 427                         }
 428                 }
 429
 430                 $object_data['type'] = $type;
 431                 $object_data['actor'] = $actor;
 432                 $object_data['item_receiver'] = $receivers;
 433                 $object_data['receiver'] = array_replace($object_data['receiver'] ?? [], $receivers);
 434                 $object_data['reception_type'] = array_replace($object_data['reception_type'] ?? [], $reception_types);
 435
 436                 $author = $object_data['author'] ?? $actor;
 437                 if (!empty($author) && !empty($object_data['id'])) {
 438                         $author_host = parse_url($author, PHP_URL_HOST);
 439                         $id_host = parse_url($object_data['id'], PHP_URL_HOST);
 440                         if ($author_host == $id_host) {
 441                                 Logger::info('Valid hosts', ['type' => $type, 'host' => $id_host]);
 442                         } else {
 443                                 Logger::notice('Differing hosts on author and id', ['type' => $type, 'author' => $author_host, 'id' => $id_host]);
 444                                 $trust_source = false;
 445                         }
 446                 }
 447
 448                 Logger::info('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id']);
 449
 450                 return $object_data;
 451         }
 452
 453         /**
 454          * Fetches the first user id from the receiver array
 455          *
 456          * @param array $receivers Array with receivers
 457          * @return integer user id;
 458          */
 459         public static function getFirstUserFromReceivers($receivers)
 460         {
 461                 foreach ($receivers as $receiver) {
 462                         if (!empty($receiver)) {
 463                                 return $receiver;
 464                         }
 465                 }
 466                 return 0;
 467         }
 468
 469         /**
 470          * Processes the activity object
 471          *
 472          * @param array   $activity     Array with activity data
 473          * @param string  $body
 474          * @param integer $uid          User ID
 475          * @param boolean $trust_source Do we trust the source?
 476          * @param boolean $push         Message had been pushed to our system
 477          * @throws \Exception
 478          */
 479         public static function processActivity($activity, string $body = '', int $uid = null, bool $trust_source = false, bool $push = false, array $signer = [])
 480         {
 481                 $type = JsonLD::fetchElement($activity, '@type');
 482                 if (!$type) {
 483                         Logger::info('Empty type', ['activity' => $activity]);
 484                         return;
 485                 }
 486
 487                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 488                         Logger::info('Empty object', ['activity' => $activity]);
 489                         return;
 490                 }
 491
 492                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 493                 if (empty($actor)) {
 494                         Logger::info('Empty actor', ['activity' => $activity]);
 495                         return;
 496                 }
 497
 498                 if (is_array($activity['as:object'])) {
 499                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 500                 } else {
 501                         $attributed_to = '';
 502                 }
 503
 504                 // Test the provided signatures against the actor and "attributedTo"
 505                 if ($trust_source) {
 506                         if (!empty($attributed_to) && !empty($actor)) {
 507                                 $trust_source = (in_array($actor, $signer) && in_array($attributed_to, $signer));
 508                         } else {
 509                                 $trust_source = in_array($actor, $signer);
 510                         }
 511                 }
 512
 513                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 514                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 515                 if (empty($object_data)) {
 516                         Logger::info('No object data found', ['activity' => $activity]);
 517                         return;
 518                 }
 519
 520                 // Lemmy is announcing activities.
 521                 // We are changing the announces into regular activities.
 522                 if (($type == 'as:Announce') && in_array($object_data['type'] ?? '', array_merge(self::ACTIVITY_TYPES, ['as:Delete', 'as:Undo', 'as:Update']))) {
 523                         $type = $object_data['type'];
 524                 }
 525
 526                 if (!$trust_source) {
 527                         Logger::info('Activity trust could not be achieved.',  ['id' => $object_data['object_id'], 'type' => $type, 'signer' => $signer, 'actor' => $actor, 'attributedTo' => $attributed_to]);
 528                         return;
 529                 }
 530
 531                 if (!empty($body) && empty($object_data['raw'])) {
 532                         $object_data['raw'] = $body;
 533                 }
 534
 535                 // Internal flag for thread completion. See Processor.php
 536                 if (!empty($activity['thread-completion'])) {
 537                         $object_data['thread-completion'] = $activity['thread-completion'];
 538                 }
 539
 540                 if (!empty($activity['completion-mode'])) {
 541                         $object_data['completion-mode'] = $activity['completion-mode'];
 542                 }
 543
 544                 if (!empty($activity['thread-children-type'])) {
 545                         $object_data['thread-children-type'] = $activity['thread-children-type'];
 546                 }
 547
 548                 // Internal flag for posts that arrived via relay
 549                 if (!empty($activity['from-relay'])) {
 550                         $object_data['from-relay'] = $activity['from-relay'];
 551                 }
 552
 553                 switch ($type) {
 554                         case 'as:Create':
 555                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 556                                         $item = ActivityPub\Processor::createItem($object_data);
 557                                         ActivityPub\Processor::postItem($object_data, $item);
 558                                 }
 559                                 break;
 560
 561                         case 'as:Add':
 562                                 if ($object_data['object_type'] == 'as:tag') {
 563                                         ActivityPub\Processor::addTag($object_data);
 564                                 }
 565                                 break;
 566
 567                         case 'as:Announce':
 568                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 569                                         $object_data['thread-completion'] = Contact::getIdForURL($actor);
 570                                         $object_data['completion-mode']   = self::COMPLETION_ANNOUCE;
 571
 572                                         $item = ActivityPub\Processor::createItem($object_data);
 573                                         if (empty($item)) {
 574                                                 return;
 575                                         }
 576
 577                                         $item['post-reason'] = Item::PR_ANNOUNCEMENT;
 578                                         ActivityPub\Processor::postItem($object_data, $item);
 579
 580                                         $announce_object_data = self::processObject($activity);
 581                                         $announce_object_data['name'] = $type;
 582                                         $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 583                                         $announce_object_data['object_id'] = $object_data['object_id'];
 584                                         $announce_object_data['object_type'] = $object_data['object_type'];
 585                                         $announce_object_data['push'] = $push;
 586
 587                                         if (!empty($body)) {
 588                                                 $announce_object_data['raw'] = $body;
 589                                         }
 590
 591                                         ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 592                                 }
 593                                 break;
 594
 595                         case 'as:Like':
 596                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 597                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 598                                 }
 599                                 break;
 600
 601                         case 'as:Dislike':
 602                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 603                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 604                                 }
 605                                 break;
 606
 607                         case 'as:TentativeAccept':
 608                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 609                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 610                                 }
 611                                 break;
 612
 613                         case 'as:Update':
 614                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 615                                         ActivityPub\Processor::updateItem($object_data);
 616                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 617                                         ActivityPub\Processor::updatePerson($object_data);
 618                                 }
 619                                 break;
 620
 621                         case 'as:Delete':
 622                                 if ($object_data['object_type'] == 'as:Tombstone') {
 623                                         ActivityPub\Processor::deleteItem($object_data);
 624                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 625                                         ActivityPub\Processor::deletePerson($object_data);
 626                                 }
 627                                 break;
 628
 629                         case 'as:Follow':
 630                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 631                                         ActivityPub\Processor::followUser($object_data);
 632                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 633                                         $object_data['reply-to-id'] = $object_data['object_id'];
 634                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 635                                 }
 636                                 break;
 637
 638                         case 'as:Accept':
 639                                 if ($object_data['object_type'] == 'as:Follow') {
 640                                         ActivityPub\Processor::acceptFollowUser($object_data);
 641                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 642                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 643                                 }
 644                                 break;
 645
 646                         case 'as:Reject':
 647                                 if ($object_data['object_type'] == 'as:Follow') {
 648                                         ActivityPub\Processor::rejectFollowUser($object_data);
 649                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 650                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 651                                 }
 652                                 break;
 653
 654                         case 'as:Undo':
 655                                 if (($object_data['object_type'] == 'as:Follow') &&
 656                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 657                                         ActivityPub\Processor::undoFollowUser($object_data);
 658                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 659                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 660                                         ActivityPub\Processor::rejectFollowUser($object_data);
 661                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 662                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 663                                         ActivityPub\Processor::undoActivity($object_data);
 664                                 }
 665                                 break;
 666
 667                         default:
 668                                 Logger::info('Unknown activity: ' . $type . ' ' . $object_data['object_type']);
 669                                 break;
 670                 }
 671         }
 672
 673         /**
 674          * Fetch a user id from an activity array
 675          *
 676          * @param array  $activity
 677          * @param string $actor
 678          *
 679          * @return int   user id
 680          */
 681         public static function getBestUserForActivity(array $activity)
 682         {
 683                 $uid = 0;
 684                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id') ?? '';
 685
 686                 $receivers = self::getReceivers($activity, $actor);
 687                 foreach ($receivers as $receiver) {
 688                         if ($receiver['type'] == self::TARGET_GLOBAL) {
 689                                 return 0;
 690                         }
 691                         if (empty($uid) || ($receiver['type'] == self::TARGET_TO)) {
 692                                 $uid = $receiver['uid'];
 693                         }
 694                 }
 695
 696                 // When we haven't found any user yet, we just chose a user who most likely could have access to the content
 697                 if (empty($uid)) {
 698                         $contact = Contact::selectFirst(['uid'], ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND]]);
 699                         if (!empty($contact['uid'])) {
 700                                 $uid = $contact['uid'];
 701                         }
 702                 }
 703
 704                 return $uid;
 705         }
 706
 707         public static function getReceiverURL($activity)
 708         {
 709                 $urls = [];
 710
 711                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 712                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 713                         if (empty($receiver_list)) {
 714                                 continue;
 715                         }
 716
 717                         foreach ($receiver_list as $receiver) {
 718                                 if ($receiver == self::PUBLIC_COLLECTION) {
 719                                         $receiver = ActivityPub::PUBLIC_COLLECTION;
 720                                 }
 721                                 $urls[$element][] = $receiver;
 722                         }
 723                 }
 724
 725                 return $urls;
 726         }
 727
 728         /**
 729          * Fetch the receiver list from an activity array
 730          *
 731          * @param array   $activity
 732          * @param string  $actor
 733          * @param array   $tags
 734          * @param boolean $fetch_unlisted
 735          *
 736          * @return array with receivers (user id)
 737          * @throws \Exception
 738          */
 739         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 740         {
 741                 $reply = $receivers = [];
 742
 743                 // When it is an answer, we inherite the receivers from the parent
 744                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 745                 if (!empty($replyto)) {
 746                         $reply = [$replyto];
 747
 748                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 749                         $fixedReplyTo = Item::getURIByLink($replyto);
 750                         if (!empty($fixedReplyTo)) {
 751                                 $reply[] = $fixedReplyTo;
 752                         }
 753                 }
 754
 755                 // Fetch all posts that refer to the object id
 756                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 757                 if (!empty($object_id)) {
 758                         $reply[] = $object_id;
 759                 }
 760
 761                 if (!empty($reply)) {
 762                         $parents = Post::select(['uid'], ['uri' => $reply]);
 763                         while ($parent = Post::fetch($parents)) {
 764                                 $receivers[$parent['uid']] = ['uid' => $parent['uid'], 'type' => self::TARGET_ANSWER];
 765                         }
 766                         DBA::close($parents);
 767                 }
 768
 769                 if (!empty($actor)) {
 770                         $profile   = APContact::getByURL($actor);
 771                         $followers = $profile['followers'] ?? '';
 772                         $is_forum  = ($actor['type'] ?? '') == 'Group';
 773                         Logger::info('Got actor and followers', ['actor' => $actor, 'followers' => $followers]);
 774                 } else {
 775                         Logger::info('Empty actor', ['activity' => $activity]);
 776                         $followers = '';
 777                         $is_forum  = false;
 778                 }
 779
 780                 // We have to prevent false follower assumptions upon thread completions
 781                 $follower_target = empty($activity['thread-completion']) ? self::TARGET_FOLLOWER : self::TARGET_UNKNOWN;
 782
 783                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 784                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 785                         if (empty($receiver_list)) {
 786                                 continue;
 787                         }
 788
 789                         foreach ($receiver_list as $receiver) {
 790                                 if ($receiver == self::PUBLIC_COLLECTION) {
 791                                         $receivers[0] = ['uid' => 0, 'type' => self::TARGET_GLOBAL];
 792                                 }
 793
 794                                 // Add receiver "-1" for unlisted posts
 795                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 796                                         $receivers[-1] = ['uid' => -1, 'type' => self::TARGET_GLOBAL];
 797                                 }
 798
 799                                 // Fetch the receivers for the public and the followers collection
 800                                 if ((($receiver == $followers) || (($receiver == self::PUBLIC_COLLECTION) && !$is_forum)) && !empty($actor)) {
 801                                         $receivers = self::getReceiverForActor($actor, $tags, $receivers, $follower_target);
 802                                         continue;
 803                                 }
 804
 805                                 // Fetching all directly addressed receivers
 806                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 807                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 808                                 if (!DBA::isResult($contact)) {
 809                                         continue;
 810                                 }
 811
 812                                 // Check if the potential receiver is following the actor
 813                                 // Exception: The receiver is targetted via "to" or this is a comment
 814                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 815                                         $networks = Protocol::FEDERATED;
 816                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 817                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 818
 819                                         // Forum posts are only accepted from forum contacts
 820                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 821                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 822                                         }
 823
 824                                         if (!DBA::exists('contact', $condition)) {
 825                                                 continue;
 826                                         }
 827                                 }
 828
 829                                 $type = $receivers[$contact['uid']]['type'] ?? self::TARGET_UNKNOWN;
 830                                 if (in_array($type, [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL])) {
 831                                         switch ($element) {
 832                                                 case 'as:to':
 833                                                         $type = self::TARGET_TO;
 834                                                         break;
 835                                                 case 'as:cc':
 836                                                         $type = self::TARGET_CC;
 837                                                         break;
 838                                                 case 'as:bto':
 839                                                         $type = self::TARGET_BTO;
 840                                                         break;
 841                                                 case 'as:bcc':
 842                                                         $type = self::TARGET_BCC;
 843                                                         break;
 844                                         }
 845
 846                                         $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $type];
 847                                 }
 848                         }
 849                 }
 850
 851                 self::switchContacts($receivers, $actor);
 852
 853                 return $receivers;
 854         }
 855
 856         /**
 857          * Fetch the receiver list of a given actor
 858          *
 859          * @param string  $actor
 860          * @param array   $tags
 861          * @param array   $receivers
 862          * @param integer $target_type
 863          *
 864          * @return array with receivers (user id)
 865          * @throws \Exception
 866          */
 867         private static function getReceiverForActor($actor, $tags, $receivers, $target_type)
 868         {
 869                 $basecondition = ['rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 870                         'network' => Protocol::FEDERATED, 'archive' => false, 'pending' => false];
 871
 872                 $condition = DBA::mergeConditions($basecondition, ["`nurl` = ? AND `uid` != ?", Strings::normaliseLink($actor), 0]);
 873                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 874                 while ($contact = DBA::fetch($contacts)) {
 875                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 876                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 877                         }
 878                 }
 879                 DBA::close($contacts);
 880
 881                 // The queries are split because of performance issues
 882                 $condition = DBA::mergeConditions($basecondition, ["`alias` IN (?, ?) AND `uid` != ?", Strings::normaliseLink($actor), $actor, 0]);
 883                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 884                 while ($contact = DBA::fetch($contacts)) {
 885                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 886                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 887                         }
 888                 }
 889                 DBA::close($contacts);
 890                 return $receivers;
 891         }
 892
 893         /**
 894          * Tests if the contact is a valid receiver for this actor
 895          *
 896          * @param array  $contact
 897          * @param string $actor
 898          * @param array  $tags
 899          *
 900          * @return bool with receivers (user id)
 901          * @throws \Exception
 902          */
 903         private static function isValidReceiverForActor($contact, $tags)
 904         {
 905                 // Are we following the contact? Then this is a valid receiver
 906                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 907                         return true;
 908                 }
 909
 910                 // When the possible receiver isn't a community, then it is no valid receiver
 911                 $owner = User::getOwnerDataById($contact['uid']);
 912                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 913                         return false;
 914                 }
 915
 916                 // Is the community account tagged?
 917                 foreach ($tags as $tag) {
 918                         if ($tag['type'] != 'Mention') {
 919                                 continue;
 920                         }
 921
 922                         if (Strings::compareLink($tag['href'], $owner['url'])) {
 923                                 return true;
 924                         }
 925                 }
 926
 927                 return false;
 928         }
 929
 930         /**
 931          * Switches existing contacts to ActivityPub
 932          *
 933          * @param integer $cid Contact ID
 934          * @param integer $uid User ID
 935          * @param string  $url Profile URL
 936          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 937          * @throws \ImagickException
 938          */
 939         public static function switchContact($cid, $uid, $url)
 940         {
 941                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 942                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 943                         return;
 944                 }
 945
 946                 if (Contact::updateFromProbe($cid)) {
 947                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 948                 }
 949
 950                 // Send a new follow request to be sure that the connection still exists
 951                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 952                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 953                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 954                 }
 955         }
 956
 957         /**
 958          *
 959          *
 960          * @param $receivers
 961          * @param $actor
 962          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 963          * @throws \ImagickException
 964          */
 965         private static function switchContacts($receivers, $actor)
 966         {
 967                 if (empty($actor)) {
 968                         return;
 969                 }
 970
 971                 foreach ($receivers as $receiver) {
 972                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 973                         if (DBA::isResult($contact)) {
 974                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 975                         }
 976
 977                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 978                         if (DBA::isResult($contact)) {
 979                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 980                         }
 981                 }
 982         }
 983
 984         /**
 985          *
 986          *
 987          * @param       $object_data
 988          * @param array $activity
 989          *
 990          * @return mixed
 991          */
 992         private static function addActivityFields($object_data, $activity)
 993         {
 994                 if (!empty($activity['published']) && empty($object_data['published'])) {
 995                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 996                 }
 997
 998                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 999                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
1000                 }
1001
1002                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
1003                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
1004
1005                 if (!empty($object_data['object_id'])) {
1006                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1007                         $objectId = Item::getURIByLink($object_data['object_id']);
1008                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
1009                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
1010                                 $object_data['object_id'] = $objectId;
1011                         }
1012                 }
1013
1014                 return $object_data;
1015         }
1016
1017         /**
1018          * Fetches the object data from external ressources if needed
1019          *
1020          * @param string  $object_id    Object ID of the the provided object
1021          * @param array   $object       The provided object array
1022          * @param boolean $trust_source Do we trust the provided object?
1023          * @param integer $uid          User ID for the signature that we use to fetch data
1024          *
1025          * @return array|false with trusted and valid object data
1026          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1027          * @throws \ImagickException
1028          */
1029         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
1030         {
1031                 // By fetching the type we check if the object is complete.
1032                 $type = JsonLD::fetchElement($object, '@type');
1033
1034                 if (!$trust_source || empty($type)) {
1035                         $data = ActivityPub::fetchContent($object_id, $uid);
1036                         if (!empty($data)) {
1037                                 $object = JsonLD::compact($data);
1038                                 Logger::info('Fetched content for ' . $object_id);
1039                         } else {
1040                                 Logger::info('Empty content for ' . $object_id . ', check if content is available locally.');
1041
1042                                 $item = Post::selectFirst(Item::DELIVER_FIELDLIST, ['uri' => $object_id]);
1043                                 if (!DBA::isResult($item)) {
1044                                         Logger::info('Object with url ' . $object_id . ' was not found locally.');
1045                                         return false;
1046                                 }
1047                                 Logger::info('Using already stored item for url ' . $object_id);
1048                                 $data = ActivityPub\Transmitter::createNote($item);
1049                                 $object = JsonLD::compact($data);
1050                         }
1051
1052                         $id = JsonLD::fetchElement($object, '@id');
1053                         if (empty($id)) {
1054                                 Logger::info('Empty id');
1055                                 return false;
1056                         }
1057
1058                         if ($id != $object_id) {
1059                                 Logger::info('Fetched id differs from provided id', ['provided' => $object_id, 'fetched' => $id]);
1060                                 return false;
1061                         }
1062                 } else {
1063                         Logger::info('Using original object for url ' . $object_id);
1064                 }
1065
1066                 $type = JsonLD::fetchElement($object, '@type');
1067                 if (empty($type)) {
1068                         Logger::info('Empty type');
1069                         return false;
1070                 }
1071
1072                 // Lemmy is resharing "create" activities instead of content
1073                 // We fetch the content from the activity.
1074                 if (in_array($type, ['as:Create'])) {
1075                         $object = $object['as:object'];
1076                         $type = JsonLD::fetchElement($object, '@type');
1077                         if (empty($type)) {
1078                                 Logger::info('Empty type');
1079                                 return false;
1080                         }
1081                         $object_data = self::processObject($object);
1082                 }
1083
1084                 // We currently don't handle 'pt:CacheFile', but with this step we avoid logging
1085                 if (in_array($type, self::CONTENT_TYPES) || ($type == 'pt:CacheFile')) {
1086                         $object_data = self::processObject($object);
1087
1088                         if (!empty($data)) {
1089                                 $object_data['raw'] = json_encode($data);
1090                         }
1091                         return $object_data;
1092                 }
1093
1094                 if ($type == 'as:Announce') {
1095                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
1096                         if (empty($object_id) || !is_string($object_id)) {
1097                                 return false;
1098                         }
1099                         return self::fetchObject($object_id, [], false, $uid);
1100                 }
1101
1102                 Logger::info('Unhandled object type: ' . $type);
1103                 return false;
1104         }
1105
1106         /**
1107          * Converts the language element (Used by Peertube)
1108          *
1109          * @param array $languages
1110          * @return array Languages
1111          */
1112         public static function processLanguages(array $languages)
1113         {
1114                 if (empty($languages)) {
1115                         return [];
1116                 }
1117
1118                 $language_list = [];
1119
1120                 foreach ($languages as $language) {
1121                         if (!empty($language['_:identifier']) && !empty($language['as:name'])) {
1122                                 $language_list[$language['_:identifier']] = $language['as:name'];
1123                         }
1124                 }
1125                 return $language_list;
1126         }
1127
1128         /**
1129          * Convert tags from JSON-LD format into a simplified format
1130          *
1131          * @param array $tags Tags in JSON-LD format
1132          *
1133          * @return array with tags in a simplified format
1134          */
1135         public static function processTags(array $tags)
1136         {
1137                 $taglist = [];
1138
1139                 foreach ($tags as $tag) {
1140                         if (empty($tag)) {
1141                                 continue;
1142                         }
1143
1144                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
1145                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
1146                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
1147
1148                         if (empty($element['type'])) {
1149                                 continue;
1150                         }
1151
1152                         if (empty($element['href'])) {
1153                                 $element['href'] = $element['name'];
1154                         }
1155
1156                         $taglist[] = $element;
1157                 }
1158                 return $taglist;
1159         }
1160
1161         /**
1162          * Convert emojis from JSON-LD format into a simplified format
1163          *
1164          * @param array $emojis
1165          * @return array with emojis in a simplified format
1166          */
1167         private static function processEmojis(array $emojis)
1168         {
1169                 $emojilist = [];
1170
1171                 foreach ($emojis as $emoji) {
1172                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
1173                                 continue;
1174                         }
1175
1176                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
1177                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
1178                                 'href' => $url];
1179
1180                         $emojilist[] = $element;
1181                 }
1182
1183                 return $emojilist;
1184         }
1185
1186         /**
1187          * Convert attachments from JSON-LD format into a simplified format
1188          *
1189          * @param array $attachments Attachments in JSON-LD format
1190          *
1191          * @return array Attachments in a simplified format
1192          */
1193         private static function processAttachments(array $attachments)
1194         {
1195                 $attachlist = [];
1196
1197                 // Removes empty values
1198                 $attachments = array_filter($attachments);
1199
1200                 foreach ($attachments as $attachment) {
1201                         switch (JsonLD::fetchElement($attachment, '@type')) {
1202                                 case 'as:Page':
1203                                         $pageUrl = null;
1204                                         $pageImage = null;
1205
1206                                         $urls = JsonLD::fetchElementArray($attachment, 'as:url');
1207                                         foreach ($urls as $url) {
1208                                                 // Single scalar URL case
1209                                                 if (is_string($url)) {
1210                                                         $pageUrl = $url;
1211                                                         continue;
1212                                                 }
1213
1214                                                 $href = JsonLD::fetchElement($url, 'as:href', '@id');
1215                                                 $mediaType = JsonLD::fetchElement($url, 'as:mediaType', '@value');
1216                                                 if (Strings::startsWith($mediaType, 'image')) {
1217                                                         $pageImage = $href;
1218                                                 } else {
1219                                                         $pageUrl = $href;
1220                                                 }
1221                                         }
1222
1223                                         $attachlist[] = [
1224                                                 'type'  => 'link',
1225                                                 'title' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1226                                                 'desc'  => JsonLD::fetchElement($attachment, 'as:summary', '@value'),
1227                                                 'url'   => $pageUrl,
1228                                                 'image' => $pageImage,
1229                                         ];
1230                                         break;
1231                                 case 'as:Image':
1232                                         $mediaType = JsonLD::fetchElement($attachment, 'as:mediaType', '@value');
1233                                         $imageFullUrl = JsonLD::fetchElement($attachment, 'as:url', '@id');
1234                                         $imagePreviewUrl = null;
1235                                         // Multiple URLs?
1236                                         if (!$imageFullUrl && ($urls = JsonLD::fetchElementArray($attachment, 'as:url'))) {
1237                                                 $imageVariants = [];
1238                                                 $previewVariants = [];
1239                                                 foreach ($urls as $url) {
1240                                                         // Scalar URL, no discrimination possible
1241                                                         if (is_string($url)) {
1242                                                                 $imageFullUrl = $url;
1243                                                                 continue;
1244                                                         }
1245
1246                                                         // Not sure what to do with a different Link media type than the base Image, we skip
1247                                                         if ($mediaType != JsonLD::fetchElement($url, 'as:mediaType', '@value')) {
1248                                                                 continue;
1249                                                         }
1250
1251                                                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1252
1253                                                         // Default URL choice if no discriminating width is provided
1254                                                         $imageFullUrl = $href ?? $imageFullUrl;
1255
1256                                                         $width = intval(JsonLD::fetchElement($url, 'as:width', '@value') ?? 1);
1257
1258                                                         if ($href && $width) {
1259                                                                 $imageVariants[$width] = $href;
1260                                                                 // 632 is the ideal width for full screen frio posts, we compute the absolute distance to it
1261                                                                 $previewVariants[abs(632 - $width)] = $href;
1262                                                         }
1263                                                 }
1264
1265                                                 if ($imageVariants) {
1266                                                         // Taking the maximum size image
1267                                                         ksort($imageVariants);
1268                                                         $imageFullUrl = array_pop($imageVariants);
1269
1270                                                         // Taking the minimum number distance to the target distance
1271                                                         ksort($previewVariants);
1272                                                         $imagePreviewUrl = array_shift($previewVariants);
1273                                                 }
1274
1275                                                 unset($imageVariants);
1276                                                 unset($previewVariants);
1277                                         }
1278
1279                                         $attachlist[] = [
1280                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1281                                                 'mediaType' => $mediaType,
1282                                                 'name'  => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1283                                                 'url'   => $imageFullUrl,
1284                                                 'image' => $imagePreviewUrl !== $imageFullUrl ? $imagePreviewUrl : null,
1285                                         ];
1286                                         break;
1287                                 default:
1288                                         $attachlist[] = [
1289                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1290                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1291                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1292                                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id'),
1293                                                 'height' => JsonLD::fetchElement($attachment, 'as:height', '@value'),
1294                                                 'width' => JsonLD::fetchElement($attachment, 'as:width', '@value'),
1295                                                 'image' => JsonLD::fetchElement($attachment, 'as:image', '@id')
1296                                         ];
1297                         }
1298                 }
1299
1300                 return $attachlist;
1301         }
1302
1303         /**
1304          * Fetch the original source or content with the "language" Markdown or HTML
1305          *
1306          * @param array $object
1307          * @param array $object_data
1308          *
1309          * @return array
1310          * @throws \Exception
1311          */
1312         private static function getSource($object, $object_data)
1313         {
1314                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
1315                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1316                 if (!empty($object_data['source'])) {
1317                         return $object_data;
1318                 }
1319
1320                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
1321                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1322                 if (!empty($object_data['source'])) {
1323                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
1324                         return $object_data;
1325                 }
1326
1327                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
1328                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1329                 if (!empty($object_data['source'])) {
1330                         $object_data['source'] = HTML::toBBCode($object_data['source']);
1331                         return $object_data;
1332                 }
1333
1334                 return $object_data;
1335         }
1336
1337         /**
1338          * Extracts a potential alternate URL from a list of additional URL elements
1339          *
1340          * @param array $urls
1341          * @return string
1342          */
1343         private static function extractAlternateUrl(array $urls): string
1344         {
1345                 $alternateUrl = '';
1346                 foreach ($urls as $key => $url) {
1347                         // Not a list but a single URL element
1348                         if (!is_numeric($key)) {
1349                                 continue;
1350                         }
1351
1352                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1353                                 continue;
1354                         }
1355
1356                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1357                         if (empty($href)) {
1358                                 continue;
1359                         }
1360
1361                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1362                         if (empty($mediatype)) {
1363                                 continue;
1364                         }
1365
1366                         if ($mediatype == 'text/html') {
1367                                 $alternateUrl = $href;
1368                         }
1369                 }
1370
1371                 return $alternateUrl;
1372         }
1373
1374         /**
1375          * Check if the "as:url" element is an array with multiple links
1376          * This is the case with audio and video posts.
1377          * Then the links are added as attachments
1378          *
1379          * @param array $urls The object URL list
1380          * @return array an array of attachments
1381          */
1382         private static function processAttachmentUrls(array $urls): array
1383         {
1384                 $attachments = [];
1385                 foreach ($urls as $key => $url) {
1386                         // Not a list but a single URL element
1387                         if (!is_numeric($key)) {
1388                                 continue;
1389                         }
1390
1391                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1392                                 continue;
1393                         }
1394
1395                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1396                         if (empty($href)) {
1397                                 continue;
1398                         }
1399
1400                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1401                         if (empty($mediatype)) {
1402                                 continue;
1403                         }
1404
1405                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
1406
1407                         if ($filetype == 'audio') {
1408                                 $attachments[] = ['type' => $filetype, 'mediaType' => $mediatype, 'url' => $href, 'height' => null, 'size' => null, 'name' => ''];
1409                         } elseif ($filetype == 'video') {
1410                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1411                                 // PeerTube audio-only track
1412                                 if ($height === 0) {
1413                                         continue;
1414                                 }
1415
1416                                 $size = (int)JsonLD::fetchElement($url, 'pt:size', '@value');
1417                                 $attachments[] = ['type' => $filetype, 'mediaType' => $mediatype, 'url' => $href, 'height' => $height, 'size' => $size, 'name' => ''];
1418                         } elseif (in_array($mediatype, ['application/x-bittorrent', 'application/x-bittorrent;x-scheme-handler/magnet'])) {
1419                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1420
1421                                 // For Torrent links we always store the highest resolution
1422                                 if (!empty($attachments[$mediatype]['height']) && ($height < $attachments[$mediatype]['height'])) {
1423                                         continue;
1424                                 }
1425
1426                                 $attachments[$mediatype] = ['type' => $mediatype, 'mediaType' => $mediatype, 'url' => $href, 'height' => $height, 'size' => null, 'name' => ''];
1427                         } elseif ($mediatype == 'application/x-mpegURL') {
1428                                 // PeerTube exception, actual video link is in the tags of this URL element
1429                                 $attachments = array_merge($attachments, self::processAttachmentUrls($url['as:tag']));
1430                         }
1431                 }
1432
1433                 return array_values($attachments);
1434         }
1435
1436         /**
1437          * Fetches data from the object part of an activity
1438          *
1439          * @param array $object
1440          *
1441          * @return array
1442          * @throws \Exception
1443          */
1444         private static function processObject($object)
1445         {
1446                 if (!JsonLD::fetchElement($object, '@id')) {
1447                         return false;
1448                 }
1449
1450                 $object_data = [];
1451                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1452                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1453                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1454
1455                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1456                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1457                         $object_data['reply-to-id'] = $object_data['id'];
1458
1459                         // On activities the "reply to" is the id of the object it refers to
1460                         if (in_array($object_data['object_type'], self::ACTIVITY_TYPES)) {
1461                                 $object_id = JsonLD::fetchElement($object, 'as:object', '@id');
1462                                 if (!empty($object_id)) {
1463                                         $object_data['reply-to-id'] = $object_id;
1464                                 }
1465                         }
1466                 } else {
1467                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1468                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1469                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1470                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1471                                 $object_data['reply-to-id'] = $replyToId;
1472                         }
1473                 }
1474
1475                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1476                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1477
1478                 if (empty($object_data['updated'])) {
1479                         $object_data['updated'] = $object_data['published'];
1480                 }
1481
1482                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1483                         $object_data['published'] = $object_data['updated'];
1484                 }
1485
1486                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1487                 if (empty($actor)) {
1488                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1489                 }
1490
1491                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1492                 $location = JsonLD::fetchElement($location, 'location', '@value');
1493                 if ($location) {
1494                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1495                         // down to HTML and then finally format to plaintext.
1496                         $location = Markdown::convert($location);
1497                         $location = BBCode::toPlaintext($location);
1498                 }
1499
1500                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1501                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1502                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1503                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1504                 $object_data['actor'] = $object_data['author'] = $actor;
1505                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1506                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1507                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1508                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1509                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1510                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1511                 $object_data['mediatype'] = JsonLD::fetchElement($object, 'as:mediaType', '@value');
1512                 $object_data = self::getSource($object, $object_data);
1513                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1514                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1515                 $object_data['location'] = $location;
1516                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1517                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1518                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1519                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1520                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment') ?? []);
1521                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag') ?? []);
1522                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', null, '@type', 'toot:Emoji') ?? []);
1523                 $object_data['languages'] = self::processLanguages(JsonLD::fetchElementArray($object, 'sc:inLanguage') ?? []);
1524                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1525                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1526                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1527
1528                 // Special treatment for Hubzilla links
1529                 if (is_array($object_data['alternate-url'])) {
1530                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1531
1532                         if (!is_string($object_data['alternate-url'])) {
1533                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1534                         }
1535                 }
1536
1537                 if (!empty($object_data['alternate-url']) && !Network::isValidHttpUrl($object_data['alternate-url'])) {
1538                         $object_data['alternate-url'] = null;
1539                 }
1540
1541                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1542                         $object_data['alternate-url'] = self::extractAlternateUrl($object['as:url'] ?? []) ?: $object_data['alternate-url'];
1543                         $object_data['attachments'] = array_merge($object_data['attachments'], self::processAttachmentUrls($object['as:url'] ?? []));
1544                 }
1545
1546                 // For page types we expect that the alternate url posts to some page.
1547                 // So we add this to the attachments if it differs from the id.
1548                 // Currently only Lemmy is using the page type.
1549                 if (($object_data['object_type'] == 'as:Page') && !empty($object_data['alternate-url']) && !Strings::compareLink($object_data['alternate-url'], $object_data['id'])) {
1550                         $object_data['attachments'][] = ['url' => $object_data['alternate-url']];
1551                         $object_data['alternate-url'] = null;
1552                 }
1553
1554                 $receiverdata = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1555                 $receivers = $reception_types = [];
1556                 foreach ($receiverdata as $key => $data) {
1557                         $receivers[$key] = $data['uid'];
1558                         $reception_types[$data['uid']] = $data['type'] ?? 0;
1559                 }
1560
1561                 $object_data['receiver_urls']  = self::getReceiverURL($object);
1562                 $object_data['receiver']       = $receivers;
1563                 $object_data['reception_type'] = $reception_types;
1564
1565                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1566                 unset($object_data['receiver'][-1]);
1567                 unset($object_data['reception_type'][-1]);
1568
1569                 // Common object data:
1570
1571                 // Unhandled
1572                 // @context, type, actor, signature, mediaType, duration, replies, icon
1573
1574                 // Also missing: (Defined in the standard, but currently unused)
1575                 // audience, preview, endTime, startTime, image
1576
1577                 // Data in Notes:
1578
1579                 // Unhandled
1580                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1581                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1582
1583                 // Data in video:
1584
1585                 // To-Do?
1586                 // category, licence, language, commentsEnabled
1587
1588                 // Unhandled
1589                 // views, waitTranscoding, state, support, subtitleLanguage
1590                 // likes, dislikes, shares, comments
1591
1592                 return $object_data;
1593         }
1594 }