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