src/Protocol/ActivityPub.php

   1 <?php
   2 /**
   3  * @file src/Protocol/ActivityPub.php
   4  */
   5 namespace Friendica\Protocol;
   6
   7 use Friendica\Database\DBA;
   8 use Friendica\Core\System;
   9 use Friendica\BaseObject;
  10 use Friendica\Util\Network;
  11 use Friendica\Util\HTTPSignature;
  12 use Friendica\Core\Protocol;
  13 use Friendica\Model\Conversation;
  14 use Friendica\Model\Contact;
  15 use Friendica\Model\Item;
  16 use Friendica\Model\Term;
  17 use Friendica\Model\User;
  18 use Friendica\Util\DateTimeFormat;
  19 use Friendica\Util\Crypto;
  20 use Friendica\Content\Text\BBCode;
  21 use Friendica\Content\Text\HTML;
  22 use Friendica\Util\JsonLD;
  23 use Friendica\Util\LDSignature;
  24
  25 /**
  26  * @brief ActivityPub Protocol class
  27  * The ActivityPub Protocol is a message exchange protocol defined by the W3C.
  28  * https://www.w3.org/TR/activitypub/
  29  * https://www.w3.org/TR/activitystreams-core/
  30  * https://www.w3.org/TR/activitystreams-vocabulary/
  31  *
  32  * https://blog.joinmastodon.org/2018/06/how-to-implement-a-basic-activitypub-server/
  33  * https://blog.joinmastodon.org/2018/07/how-to-make-friends-and-verify-requests/
  34  *
  35  * Digest: https://tools.ietf.org/html/rfc5843
  36  * https://tools.ietf.org/html/draft-cavage-http-signatures-10#ref-15
  37  * https://github.com/digitalbazaar/php-json-ld
  38  *
  39  * Part of the code for HTTP signing is taken from the Osada project.
  40  * https://framagit.org/macgirvin/osada
  41  *
  42  * To-do:
  43  *
  44  * Receiver:
  45  * - Activities: Update, Delete
  46  * - Object Types: Person, Tombstome
  47  *
  48  * Transmitter:
  49  * - Activities: Announce
  50  * - Object Tyoes: Person, Tombstone
  51  *
  52  * General:
  53  * - Endpoints: Outbox, Follower, Following
  54  * - General cleanup
  55  * - Queueing unsucessful deliveries
  56  */
  57 class ActivityPub
  58 {
  59         const PUBLIC = 'https://www.w3.org/ns/activitystreams#Public';
  60
  61         public static function isRequest()
  62         {
  63                 return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
  64                         stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
  65         }
  66
  67         /**
  68          * Return the ActivityPub profile of the given user
  69          *
  70          * @param integer $uid User ID
  71          * @return array
  72          */
  73         public static function profile($uid)
  74         {
  75                 $accounttype = ['Person', 'Organization', 'Service', 'Group', 'Application'];
  76                 $condition = ['uid' => $uid, 'blocked' => false, 'account_expired' => false,
  77                         'account_removed' => false, 'verified' => true];
  78                 $fields = ['guid', 'nickname', 'pubkey', 'account-type', 'page-flags'];
  79                 $user = DBA::selectFirst('user', $fields, $condition);
  80                 if (!DBA::isResult($user)) {
  81                         return [];
  82                 }
  83
  84                 $fields = ['locality', 'region', 'country-name'];
  85                 $profile = DBA::selectFirst('profile', $fields, ['uid' => $uid, 'is-default' => true]);
  86                 if (!DBA::isResult($profile)) {
  87                         return [];
  88                 }
  89
  90                 $fields = ['name', 'url', 'location', 'about', 'avatar'];
  91                 $contact = DBA::selectFirst('contact', $fields, ['uid' => $uid, 'self' => true]);
  92                 if (!DBA::isResult($contact)) {
  93                         return [];
  94                 }
  95
  96                 $data = ['@context' => ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1',
  97                         ['vcard' => 'http://www.w3.org/2006/vcard/ns#', 'uuid' => 'http://schema.org/identifier',
  98                         'sensitive' => 'as:sensitive', 'manuallyApprovesFollowers' => 'as:manuallyApprovesFollowers']]];
  99
 100                 $data['id'] = $contact['url'];
 101                 $data['uuid'] = $user['guid'];
 102                 $data['type'] = $accounttype[$user['account-type']];
 103                 $data['following'] = System::baseUrl() . '/following/' . $user['nickname'];
 104                 $data['followers'] = System::baseUrl() . '/followers/' . $user['nickname'];
 105                 $data['inbox'] = System::baseUrl() . '/inbox/' . $user['nickname'];
 106                 $data['outbox'] = System::baseUrl() . '/outbox/' . $user['nickname'];
 107                 $data['preferredUsername'] = $user['nickname'];
 108                 $data['name'] = $contact['name'];
 109                 $data['vcard:hasAddress'] = ['@type' => 'vcard:Home', 'vcard:country-name' => $profile['country-name'],
 110                         'vcard:region' => $profile['region'], 'vcard:locality' => $profile['locality']];
 111                 $data['summary'] = $contact['about'];
 112                 $data['url'] = $contact['url'];
 113                 $data['manuallyApprovesFollowers'] = in_array($user['page-flags'], [Contact::PAGE_NORMAL, Contact::PAGE_PRVGROUP]);
 114                 $data['publicKey'] = ['id' => $contact['url'] . '#main-key',
 115                         'owner' => $contact['url'],
 116                         'publicKeyPem' => $user['pubkey']];
 117                 $data['endpoints'] = ['sharedInbox' => System::baseUrl() . '/inbox'];
 118                 $data['icon'] = ['type' => 'Image',
 119                         'url' => $contact['avatar']];
 120
 121                 // tags: https://kitty.town/@inmysocks/100656097926961126.json
 122                 return $data;
 123         }
 124
 125         private static function fetchPermissionBlockFromConversation($item)
 126         {
 127                 if (empty($item['thr-parent'])) {
 128                         return [];
 129                 }
 130
 131                 $condition = ['item-uri' => $item['thr-parent'], 'protocol' => Conversation::PARCEL_ACTIVITYPUB];
 132                 $conversation = DBA::selectFirst('conversation', ['source'], $condition);
 133                 if (!DBA::isResult($conversation)) {
 134                         return [];
 135                 }
 136
 137                 $activity = json_decode($conversation['source'], true);
 138
 139                 $actor = JsonLD::fetchElement($activity, 'actor', 'id');
 140                 $profile = ActivityPub::fetchprofile($actor);
 141
 142                 $item_profile = ActivityPub::fetchprofile($item['owner-link']);
 143
 144                 $permissions = [];
 145
 146                 $elements = ['to', 'cc', 'bto', 'bcc'];
 147                 foreach ($elements as $element) {
 148                         if (empty($activity[$element])) {
 149                                 continue;
 150                         }
 151                         if (is_string($activity[$element])) {
 152                                 $activity[$element] = [$activity[$element]];
 153                         }
 154                         foreach ($activity[$element] as $receiver) {
 155                                 if ($receiver == $profile['followers'] && !empty($item_profile['followers'])) {
 156                                         $receiver = $item_profile['followers'];
 157                                 }
 158                                 if ($receiver != $item['owner-link']) {
 159                                         $permissions[$element][] = $receiver;
 160                                 }
 161                         }
 162                 }
 163                 return $permissions;
 164         }
 165
 166         public static function createPermissionBlockForItem($item)
 167         {
 168                 $data = ['to' => [], 'cc' => []];
 169
 170                 $data = array_merge($data, self::fetchPermissionBlockFromConversation($item));
 171
 172                 $actor_profile = ActivityPub::fetchprofile($item['author-link']);
 173
 174                 $terms = Term::tagArrayFromItemId($item['id']);
 175
 176                 $contacts[$item['author-link']] = $item['author-link'];
 177
 178                 if (!$item['private']) {
 179                         $data['to'][] = self::PUBLIC;
 180                         if (!empty($actor_profile['followers'])) {
 181                                 $data['cc'][] = $actor_profile['followers'];
 182                         }
 183
 184                         foreach ($terms as $term) {
 185                                 if ($term['type'] != TERM_MENTION) {
 186                                         continue;
 187                                 }
 188                                 $profile = self::fetchprofile($term['url']);
 189                                 if (!empty($profile) && empty($contacts[$profile['url']])) {
 190                                         $data['cc'][] = $profile['url'];
 191                                         $contacts[$profile['url']] = $profile['url'];
 192                                 }
 193                         }
 194                 } else {
 195                         $receiver_list = Item::enumeratePermissions($item);
 196
 197                         $mentioned = [];
 198
 199                         foreach ($terms as $term) {
 200                                 if ($term['type'] != TERM_MENTION) {
 201                                         continue;
 202                                 }
 203                                 $cid = Contact::getIdForURL($term['url'], $item['uid']);
 204                                 if (!empty($cid) && in_array($cid, $receiver_list)) {
 205                                         $contact = DBA::selectFirst('contact', ['url'], ['id' => $cid, 'network' => Protocol::ACTIVITYPUB]);
 206                                         $data['to'][] = $contact['url'];
 207                                         $contacts[$contact['url']] = $contact['url'];
 208                                 }
 209                         }
 210
 211                         foreach ($receiver_list as $receiver) {
 212                                 $contact = DBA::selectFirst('contact', ['url'], ['id' => $receiver, 'network' => Protocol::ACTIVITYPUB]);
 213                                 if (empty($contacts[$contact['url']])) {
 214                                         $data['cc'][] = $contact['url'];
 215                                         $contacts[$contact['url']] = $contact['url'];
 216                                 }
 217                         }
 218                 }
 219
 220                 $parents = Item::select(['author-link', 'owner-link'], ['parent' => $item['parent']]);
 221                 while ($parent = Item::fetch($parents)) {
 222                         $profile = self::fetchprofile($parent['author-link']);
 223                         if (!empty($profile) && empty($contacts[$profile['url']])) {
 224                                 $data['cc'][] = $profile['url'];
 225                                 $contacts[$profile['url']] = $profile['url'];
 226                         }
 227
 228                         $profile = self::fetchprofile($parent['owner-link']);
 229                         if (!empty($profile) && empty($contacts[$profile['url']])) {
 230                                 $data['cc'][] = $profile['url'];
 231                                 $contacts[$profile['url']] = $profile['url'];
 232                         }
 233                 }
 234                 DBA::close($parents);
 235
 236                 if (empty($data['to'])) {
 237                         $data['to'] = $data['cc'];
 238                         $data['cc'] = [];
 239                 }
 240
 241                 return $data;
 242         }
 243
 244         public static function fetchTargetInboxes($item, $uid)
 245         {
 246                 $permissions = self::createPermissionBlockForItem($item);
 247                 if (empty($permissions)) {
 248                         return [];
 249                 }
 250
 251                 $inboxes = [];
 252
 253                 $item_profile = ActivityPub::fetchprofile($item['owner-link']);
 254
 255                 $elements = ['to', 'cc', 'bto', 'bcc'];
 256                 foreach ($elements as $element) {
 257                         if (empty($permissions[$element])) {
 258                                 continue;
 259                         }
 260                         foreach ($permissions[$element] as $receiver) {
 261                                 if ($receiver == $item_profile['followers']) {
 262                                         $contacts = DBA::select('contact', ['notify', 'batch'], ['uid' => $uid,
 263                                                 'rel' => [Contact::FOLLOWER, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB]);
 264                                         while ($contact = DBA::fetch($contacts)) {
 265                                                 $contact = defaults($contact, 'batch', $contact['notify']);
 266                                                 $inboxes[$contact] = $contact;
 267                                         }
 268                                         DBA::close($contacts);
 269                                 } else {
 270                                         $profile = self::fetchprofile($receiver);
 271                                         if (!empty($profile)) {
 272                                                 $target = defaults($profile, 'sharedinbox', $profile['inbox']);
 273                                                 $inboxes[$target] = $target;
 274                                         }
 275                                 }
 276                         }
 277                 }
 278
 279                 if (!empty($item_profile['sharedinbox'])) {
 280                         unset($inboxes[$item_profile['sharedinbox']]);
 281                 }
 282
 283                 if (!empty($item_profile['inbox'])) {
 284                         unset($inboxes[$item_profile['inbox']]);
 285                 }
 286
 287                 return $inboxes;
 288         }
 289
 290         public static function getTypeOfItem($item)
 291         {
 292                 if ($item['verb'] == ACTIVITY_POST) {
 293                         if ($item['created'] == $item['edited']) {
 294                                 $type = 'Create';
 295                         } else {
 296                                 $type = 'Update';
 297                         }
 298                 } elseif ($item['verb'] == ACTIVITY_LIKE) {
 299                         $type = 'Like';
 300                 } elseif ($item['verb'] == ACTIVITY_DISLIKE) {
 301                         $type = 'Dislike';
 302                 } elseif ($item['verb'] == ACTIVITY_ATTEND) {
 303                         $type = 'Accept';
 304                 } elseif ($item['verb'] == ACTIVITY_ATTENDNO) {
 305                         $type = 'Reject';
 306                 } elseif ($item['verb'] == ACTIVITY_ATTENDMAYBE) {
 307                         $type = 'TentativeAccept';
 308                 }
 309
 310                 if ($item['deleted']) {
 311                         $type = 'Delete';
 312                 }
 313
 314                 return $type;
 315         }
 316
 317         public static function createActivityFromItem($item_id)
 318         {
 319                 $item = Item::selectFirst([], ['id' => $item_id]);
 320
 321                 if (!DBA::isResult($item)) {
 322                         return false;
 323                 }
 324
 325                 $condition = ['item-uri' => $item['uri'], 'protocol' => Conversation::PARCEL_ACTIVITYPUB];
 326                 $conversation = DBA::selectFirst('conversation', ['source'], $condition);
 327                 if (DBA::isResult($conversation)) {
 328                         $data = json_decode($conversation['source']);
 329                         if (!empty($data)) {
 330                                 return $data;
 331                         }
 332                 }
 333
 334                 $data = ['@context' => ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1',
 335                         ['ostatus' => 'http://ostatus.org#', 'uuid' => 'http://schema.org/identifier',
 336                         'sensitive' => 'as:sensitive', 'Hashtag' => 'as:Hashtag',
 337                         'atomUri' => 'ostatus:atomUri', 'conversation' => 'ostatus:conversation',
 338                         'inReplyToAtomUri' => 'ostatus:inReplyToAtomUri']]];
 339
 340                 $data['id'] = $item['uri'] . '#activity';
 341                 $data['type'] = self::getTypeOfItem($item);;
 342                 $data['actor'] = $item['author-link'];
 343
 344                 $data['published'] = DateTimeFormat::utc($item["created"]."+00:00", DateTimeFormat::ATOM);
 345
 346                 if ($item["created"] != $item["edited"]) {
 347                         $data['updated'] = DateTimeFormat::utc($item["edited"]."+00:00", DateTimeFormat::ATOM);
 348                 }
 349
 350                 $data['context_id'] = $item['parent'];
 351                 $data['context'] = self::createConversationURLFromItem($item);
 352
 353                 $data = array_merge($data, ActivityPub::createPermissionBlockForItem($item));
 354
 355                 if (in_array($data['type'], ['Create', 'Update', 'Announce'])) {
 356                         $data['object'] = self::CreateNote($item);
 357                 } else {
 358                         $data['object'] = $item['thr-parent'];
 359                 }
 360
 361                 $owner = User::getOwnerDataById($item['uid']);
 362
 363                 return LDSignature::sign($data, $owner);
 364         }
 365
 366         public static function createObjectFromItemID($item_id)
 367         {
 368                 $item = Item::selectFirst([], ['id' => $item_id]);
 369
 370                 if (!DBA::isResult($item)) {
 371                         return false;
 372                 }
 373
 374                 $data = ['@context' => ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1',
 375                         ['ostatus' => 'http://ostatus.org#', 'uuid' => 'http://schema.org/identifier',
 376                         'sensitive' => 'as:sensitive', 'Hashtag' => 'as:Hashtag',
 377                         'atomUri' => 'ostatus:atomUri', 'conversation' => 'ostatus:conversation',
 378                         'inReplyToAtomUri' => 'ostatus:inReplyToAtomUri']]];
 379
 380                 $data = array_merge($data, self::CreateNote($item));
 381
 382
 383                 return $data;
 384         }
 385
 386         private static function createTagList($item)
 387         {
 388                 $tags = [];
 389
 390                 $terms = Term::tagArrayFromItemId($item['id']);
 391                 foreach ($terms as $term) {
 392                         if ($term['type'] == TERM_MENTION) {
 393                                 $contact = Contact::getDetailsByURL($term['url']);
 394                                 if (!empty($contact['addr'])) {
 395                                         $mention = '@' . $contact['addr'];
 396                                 } else {
 397                                         $mention = '@' . $term['url'];
 398                                 }
 399
 400                                 $tags[] = ['type' => 'Mention', 'href' => $term['url'], 'name' => $mention];
 401                         }
 402                 }
 403                 return $tags;
 404         }
 405
 406         private static function createConversationURLFromItem($item)
 407         {
 408                 $conversation = DBA::selectFirst('conversation', ['conversation-uri'], ['item-uri' => $item['parent-uri']]);
 409                 if (DBA::isResult($conversation) && !empty($conversation['conversation-uri'])) {
 410                         $conversation_uri = $conversation['conversation-uri'];
 411                 } else {
 412                         $conversation_uri = $item['parent-uri'];
 413                 }
 414                 return $conversation_uri;
 415         }
 416
 417         private static function CreateNote($item)
 418         {
 419                 if (!empty($item['title'])) {
 420                         $type = 'Article';
 421                 } else {
 422                         $type = 'Note';
 423                 }
 424
 425                 $data = [];
 426                 $data['id'] = $item['uri'];
 427                 $data['type'] = $type;
 428                 $data['summary'] = null; // Ignore by now
 429
 430                 if ($item['uri'] != $item['thr-parent']) {
 431                         $data['inReplyTo'] = $item['thr-parent'];
 432                 } else {
 433                         $data['inReplyTo'] = null;
 434                 }
 435
 436                 $data['uuid'] = $item['guid'];
 437                 $data['published'] = DateTimeFormat::utc($item["created"]."+00:00", DateTimeFormat::ATOM);
 438
 439                 if ($item["created"] != $item["edited"]) {
 440                         $data['updated'] = DateTimeFormat::utc($item["edited"]."+00:00", DateTimeFormat::ATOM);
 441                 }
 442
 443                 $data['url'] = $item['plink'];
 444                 $data['attributedTo'] = $item['author-link'];
 445                 $data['actor'] = $item['author-link'];
 446                 $data['sensitive'] = false; // - Query NSFW
 447                 $data['context_id'] = $item['parent'];
 448                 $data['conversation'] = $data['context'] = self::createConversationURLFromItem($item);
 449
 450                 if (!empty($item['title'])) {
 451                         $data['name'] = BBCode::convert($item['title'], false, 7);
 452                 }
 453
 454                 $data['content'] = BBCode::convert($item['body'], false, 7);
 455                 $data['source'] = ['content' => $item['body'], 'mediaType' => "text/bbcode"];
 456                 $data['attachment'] = []; // @ToDo
 457                 $data['tag'] = self::createTagList($item);
 458                 $data = array_merge($data, ActivityPub::createPermissionBlockForItem($item));
 459
 460                 //$data['emoji'] = []; // Ignore by now
 461                 return $data;
 462         }
 463
 464         public static function transmitActivity($activity, $target, $uid)
 465         {
 466                 $profile = self::fetchprofile($target);
 467
 468                 $owner = User::getOwnerDataById($uid);
 469
 470                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 471                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 472                         'type' => $activity,
 473                         'actor' => $owner['url'],
 474                         'object' => $profile['url'],
 475                         'to' => $profile['url']];
 476
 477                 logger('Sending activity ' . $activity . ' to ' . $target . ' for user ' . $uid, LOGGER_DEBUG);
 478
 479                 $signed = LDSignature::sign($data, $owner);
 480                 return HTTPSignature::transmit($signed, $profile['inbox'], $uid);
 481         }
 482
 483         public static function transmitContactAccept($target, $id, $uid)
 484         {
 485                 $profile = self::fetchprofile($target);
 486
 487                 $owner = User::getOwnerDataById($uid);
 488                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 489                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 490                         'type' => 'Accept',
 491                         'actor' => $owner['url'],
 492                         'object' => ['id' => $id, 'type' => 'Follow',
 493                                 'actor' => $profile['url'],
 494                                 'object' => $owner['url']],
 495                         'to' => $profile['url']];
 496
 497                 logger('Sending accept to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 498
 499                 $signed = LDSignature::sign($data, $owner);
 500                 return HTTPSignature::transmit($signed, $profile['inbox'], $uid);
 501         }
 502
 503         public static function transmitContactReject($target, $id, $uid)
 504         {
 505                 $profile = self::fetchprofile($target);
 506
 507                 $owner = User::getOwnerDataById($uid);
 508                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 509                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 510                         'type' => 'Reject',
 511                         'actor' => $owner['url'],
 512                         'object' => ['id' => $id, 'type' => 'Follow',
 513                                 'actor' => $profile['url'],
 514                                 'object' => $owner['url']],
 515                         'to' => $profile['url']];
 516
 517                 logger('Sending reject to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 518
 519                 $signed = LDSignature::sign($data, $owner);
 520                 return HTTPSignature::transmit($signed, $profile['inbox'], $uid);
 521         }
 522
 523         public static function transmitContactUndo($target, $uid)
 524         {
 525                 $profile = self::fetchprofile($target);
 526
 527                 $id = System::baseUrl() . '/activity/' . System::createGUID();
 528
 529                 $owner = User::getOwnerDataById($uid);
 530                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 531                         'id' => $id,
 532                         'type' => 'Undo',
 533                         'actor' => $owner['url'],
 534                         'object' => ['id' => $id, 'type' => 'Follow',
 535                                 'actor' => $owner['url'],
 536                                 'object' => $profile['url']],
 537                         'to' => $profile['url']];
 538
 539                 logger('Sending undo to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 540
 541                 $signed = LDSignature::sign($data, $owner);
 542                 return HTTPSignature::transmit($signed, $profile['inbox'], $uid);
 543         }
 544
 545         /**
 546          * Fetches ActivityPub content from the given url
 547          *
 548          * @param string $url content url
 549          * @return array
 550          */
 551         public static function fetchContent($url)
 552         {
 553                 $ret = Network::curl($url, false, $redirects, ['accept_content' => 'application/activity+json, application/ld+json']);
 554                 if (!$ret['success'] || empty($ret['body'])) {
 555                         return;
 556                 }
 557
 558                 return json_decode($ret['body'], true);
 559         }
 560
 561         /**
 562          * Resolves the profile url from the address by using webfinger
 563          *
 564          * @param string $addr profile address (user@domain.tld)
 565          * @return string url
 566          */
 567         private static function addrToUrl($addr)
 568         {
 569                 $addr_parts = explode('@', $addr);
 570                 if (count($addr_parts) != 2) {
 571                         return false;
 572                 }
 573
 574                 $webfinger = 'https://' . $addr_parts[1] . '/.well-known/webfinger?resource=acct:' . urlencode($addr);
 575
 576                 $ret = Network::curl($webfinger, false, $redirects, ['accept_content' => 'application/jrd+json,application/json']);
 577                 if (!$ret['success'] || empty($ret['body'])) {
 578                         return false;
 579                 }
 580
 581                 $data = json_decode($ret['body'], true);
 582
 583                 if (empty($data['links'])) {
 584                         return false;
 585                 }
 586
 587                 foreach ($data['links'] as $link) {
 588                         if (empty($link['href']) || empty($link['rel']) || empty($link['type'])) {
 589                                 continue;
 590                         }
 591
 592                         if (($link['rel'] == 'self') && ($link['type'] == 'application/activity+json')) {
 593                                 return $link['href'];
 594                         }
 595                 }
 596
 597                 return false;
 598         }
 599
 600         public static function fetchprofile($url, $update = false)
 601         {
 602                 if (empty($url)) {
 603                         return false;
 604                 }
 605
 606                 if (!$update) {
 607                         $apcontact = DBA::selectFirst('apcontact', [], ['url' => $url]);
 608                         if (DBA::isResult($apcontact)) {
 609                                 return $apcontact;
 610                         }
 611
 612                         $apcontact = DBA::selectFirst('apcontact', [], ['alias' => $url]);
 613                         if (DBA::isResult($apcontact)) {
 614                                 return $apcontact;
 615                         }
 616
 617                         $apcontact = DBA::selectFirst('apcontact', [], ['addr' => $url]);
 618                         if (DBA::isResult($apcontact)) {
 619                                 return $apcontact;
 620                         }
 621                 }
 622
 623                 if (empty(parse_url($url, PHP_URL_SCHEME))) {
 624                         $url = self::addrToUrl($url);
 625                         if (empty($url)) {
 626                                 return false;
 627                         }
 628                 }
 629
 630                 $data = self::fetchContent($url);
 631
 632                 if (empty($data) || empty($data['id']) || empty($data['inbox'])) {
 633                         return false;
 634                 }
 635
 636                 $apcontact = [];
 637                 $apcontact['url'] = $data['id'];
 638                 $apcontact['uuid'] = defaults($data, 'uuid', null);
 639                 $apcontact['type'] = defaults($data, 'type', null);
 640                 $apcontact['following'] = defaults($data, 'following', null);
 641                 $apcontact['followers'] = defaults($data, 'followers', null);
 642                 $apcontact['inbox'] = defaults($data, 'inbox', null);
 643                 $apcontact['outbox'] = defaults($data, 'outbox', null);
 644                 $apcontact['sharedinbox'] = JsonLD::fetchElement($data, 'endpoints', 'sharedInbox');
 645                 $apcontact['nick'] = defaults($data, 'preferredUsername', null);
 646                 $apcontact['name'] = defaults($data, 'name', $apcontact['nick']);
 647                 $apcontact['about'] = defaults($data, 'summary', '');
 648                 $apcontact['photo'] = JsonLD::fetchElement($data, 'icon', 'url');
 649                 $apcontact['alias'] = JsonLD::fetchElement($data, 'url', 'href');
 650
 651                 $parts = parse_url($apcontact['url']);
 652                 unset($parts['scheme']);
 653                 unset($parts['path']);
 654                 $apcontact['addr'] = $apcontact['nick'] . '@' . str_replace('//', '', Network::unparseURL($parts));
 655
 656                 $apcontact['pubkey'] = trim(JsonLD::fetchElement($data, 'publicKey', 'publicKeyPem'));
 657
 658                 // To-Do
 659                 // manuallyApprovesFollowers
 660
 661                 // Unhandled
 662                 // @context, tag, attachment, image, nomadicLocations, signature, following, followers, featured, movedTo, liked
 663
 664                 // Unhandled from Misskey
 665                 // sharedInbox, isCat
 666
 667                 // Unhandled from Kroeg
 668                 // kroeg:blocks, updated
 669
 670                 // Check if the address is resolvable
 671                 if (self::addrToUrl($apcontact['addr']) == $apcontact['url']) {
 672                         $parts = parse_url($apcontact['url']);
 673                         unset($parts['path']);
 674                         $apcontact['baseurl'] = Network::unparseURL($parts);
 675                 } else {
 676                         $apcontact['addr'] = null;
 677                 }
 678
 679                 if ($apcontact['url'] == $apcontact['alias']) {
 680                         $apcontact['alias'] = null;
 681                 }
 682
 683                 $apcontact['updated'] = DateTimeFormat::utcNow();
 684
 685                 DBA::update('apcontact', $apcontact, ['url' => $url], true);
 686
 687                 return $apcontact;
 688         }
 689
 690         /**
 691          * Fetches a profile from the given url into an array that is compatible to Probe::uri
 692          *
 693          * @param string $url profile url
 694          * @return array
 695          */
 696         public static function probeProfile($url)
 697         {
 698                 $apcontact = self::fetchprofile($url, true);
 699                 if (empty($apcontact)) {
 700                         return false;
 701                 }
 702
 703                 $profile = ['network' => Protocol::ACTIVITYPUB];
 704                 $profile['nick'] = $apcontact['nick'];
 705                 $profile['name'] = $apcontact['name'];
 706                 $profile['guid'] = $apcontact['uuid'];
 707                 $profile['url'] = $apcontact['url'];
 708                 $profile['addr'] = $apcontact['addr'];
 709                 $profile['alias'] = $apcontact['alias'];
 710                 $profile['photo'] = $apcontact['photo'];
 711                 // $profile['community']
 712                 // $profile['keywords']
 713                 // $profile['location']
 714                 $profile['about'] = $apcontact['about'];
 715                 $profile['batch'] = $apcontact['sharedinbox'];
 716                 $profile['notify'] = $apcontact['inbox'];
 717                 $profile['poll'] = $apcontact['outbox'];
 718                 $profile['pubkey'] = $apcontact['pubkey'];
 719                 $profile['baseurl'] = $apcontact['baseurl'];
 720
 721                 // Remove all "null" fields
 722                 foreach ($profile as $field => $content) {
 723                         if (is_null($content)) {
 724                                 unset($profile[$field]);
 725                         }
 726                 }
 727
 728                 return $profile;
 729         }
 730
 731         public static function processInbox($body, $header, $uid)
 732         {
 733                 $http_signer = HTTPSignature::getSigner($body, $header);
 734                 if (empty($http_signer)) {
 735                         logger('Invalid HTTP signature, message will be discarded.', LOGGER_DEBUG);
 736                         return;
 737                 } else {
 738                         logger('HTTP signature is signed by ' . $http_signer, LOGGER_DEBUG);
 739                 }
 740
 741                 $activity = json_decode($body, true);
 742
 743                 $actor = JsonLD::fetchElement($activity, 'actor', 'id');
 744                 logger('Message for user ' . $uid . ' is from actor ' . $actor, LOGGER_DEBUG);
 745
 746                 if (empty($activity)) {
 747                         logger('Invalid body.', LOGGER_DEBUG);
 748                         return;
 749                 }
 750
 751                 if (LDSignature::isSigned($activity)) {
 752                         $ld_signer = LDSignature::getSigner($activity);
 753                         if (!empty($ld_signer && ($actor == $http_signer))) {
 754                                 logger('The HTTP and the JSON-LD signature belong to ' . $ld_signer, LOGGER_DEBUG);
 755                                 $trust_source = true;
 756                         } elseif (!empty($ld_signer)) {
 757                                 logger('JSON-LD signature is signed by ' . $ld_signer, LOGGER_DEBUG);
 758                                 $trust_source = true;
 759                         } elseif ($actor == $http_signer) {
 760                                 logger('Bad JSON-LD signature, but HTTP signer fits the actor.', LOGGER_DEBUG);
 761                                 $trust_source = true;
 762                         } else {
 763                                 logger('Invalid JSON-LD signature and the HTTP signer is different.', LOGGER_DEBUG);
 764                                 $trust_source = false;
 765                         }
 766                 } elseif ($actor == $http_signer) {
 767                         logger('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', LOGGER_DEBUG);
 768                         $trust_source = true;
 769                 } else {
 770                         logger('No JSON-LD signature, different actor.', LOGGER_DEBUG);
 771                         $trust_source = false;
 772                 }
 773
 774                 self::processActivity($activity, $body, $uid, $trust_source);
 775         }
 776
 777         public static function fetchOutbox($url, $uid)
 778         {
 779                 $data = self::fetchContent($url);
 780                 if (empty($data)) {
 781                         return;
 782                 }
 783
 784                 if (!empty($data['orderedItems'])) {
 785                         $items = $data['orderedItems'];
 786                 } elseif (!empty($data['first']['orderedItems'])) {
 787                         $items = $data['first']['orderedItems'];
 788                 } elseif (!empty($data['first'])) {
 789                         self::fetchOutbox($data['first'], $uid);
 790                         return;
 791                 } else {
 792                         $items = [];
 793                 }
 794
 795                 foreach ($items as $activity) {
 796                         self::processActivity($activity, '', $uid, true);
 797                 }
 798         }
 799
 800         private static function prepareObjectData($activity, $uid, $trust_source)
 801         {
 802                 $actor = JsonLD::fetchElement($activity, 'actor', 'id');
 803                 if (empty($actor)) {
 804                         logger('Empty actor', LOGGER_DEBUG);
 805                         return [];
 806                 }
 807
 808                 // Fetch all receivers from to, cc, bto and bcc
 809                 $receivers = self::getReceivers($activity, $actor);
 810
 811                 // When it is a delivery to a personal inbox we add that user to the receivers
 812                 if (!empty($uid)) {
 813                         $owner = User::getOwnerDataById($uid);
 814                         $additional = ['uid:' . $uid => $uid];
 815                         $receivers = array_merge($receivers, $additional);
 816                 }
 817
 818                 logger('Receivers: ' . json_encode($receivers), LOGGER_DEBUG);
 819
 820                 if (is_string($activity['object'])) {
 821                         $object_url = $activity['object'];
 822                 } elseif (!empty($activity['object']['id'])) {
 823                         $object_url = $activity['object']['id'];
 824                 } else {
 825                         logger('No object found', LOGGER_DEBUG);
 826                         return [];
 827                 }
 828
 829                 // Fetch the content only on activities where this matters
 830                 if (in_array($activity['type'], ['Create', 'Update', 'Announce'])) {
 831                         $object_data = self::fetchObject($object_url, $activity['object'], $trust_source);
 832                         if (empty($object_data)) {
 833                                 logger("Object data couldn't be processed", LOGGER_DEBUG);
 834                                 return [];
 835                         }
 836                 } elseif ($activity['type'] == 'Accept') {
 837                         $object_data = [];
 838                         $object_data['object_type'] = JsonLD::fetchElement($activity, 'object', 'type');
 839                         $object_data['object'] = JsonLD::fetchElement($activity, 'object', 'actor');
 840                 } elseif ($activity['type'] == 'Undo') {
 841                         $object_data = [];
 842                         $object_data['object_type'] = JsonLD::fetchElement($activity, 'object', 'type');
 843                         $object_data['object'] = JsonLD::fetchElement($activity, 'object', 'object');
 844                 } elseif (in_array($activity['type'], ['Like', 'Dislike'])) {
 845                         // Create a mostly empty array out of the activity data (instead of the object).
 846                         // This way we later don't have to check for the existence of ech individual array element.
 847                         $object_data = self::processCommonData($activity);
 848                         $object_data['name'] = $activity['type'];
 849                         $object_data['author'] = $activity['actor'];
 850                         $object_data['object'] = $object_url;
 851                 } elseif ($activity['type'] == 'Follow') {
 852                         $object_data['id'] = $activity['id'];
 853                         $object_data['object'] = $object_url;
 854                 } else {
 855                         $object_data = [];
 856                 }
 857
 858                 $object_data = self::addActivityFields($object_data, $activity);
 859
 860                 $object_data['type'] = $activity['type'];
 861                 $object_data['owner'] = $actor;
 862                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 863
 864                 return $object_data;
 865         }
 866
 867         private static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
 868         {
 869                 if (empty($activity['type'])) {
 870                         logger('Empty type', LOGGER_DEBUG);
 871                         return;
 872                 }
 873
 874                 if (empty($activity['object'])) {
 875                         logger('Empty object', LOGGER_DEBUG);
 876                         return;
 877                 }
 878
 879                 if (empty($activity['actor'])) {
 880                         logger('Empty actor', LOGGER_DEBUG);
 881                         return;
 882
 883                 }
 884
 885                 // Non standard
 886                 // title, atomUri, context_id, statusnetConversationId
 887
 888                 // To-Do?
 889                 // context, location, signature;
 890
 891                 logger('Processing activity: ' . $activity['type'], LOGGER_DEBUG);
 892
 893                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
 894                 if (empty($object_data)) {
 895                         logger('No object data found', LOGGER_DEBUG);
 896                         return;
 897                 }
 898
 899                 switch ($activity['type']) {
 900                         case 'Create':
 901                         case 'Announce':
 902                                 self::createItem($object_data, $body);
 903                                 break;
 904
 905                         case 'Like':
 906                                 self::likeItem($object_data, $body);
 907                                 break;
 908
 909                         case 'Dislike':
 910                                 self::dislikeItem($object_data, $body);
 911                                 break;
 912
 913                         case 'Update':
 914                                 break;
 915
 916                         case 'Delete':
 917                                 break;
 918
 919                         case 'Follow':
 920                                 self::followUser($object_data);
 921                                 break;
 922
 923                         case 'Accept':
 924                                 if ($object_data['object_type'] == 'Follow') {
 925                                         self::acceptFollowUser($object_data);
 926                                 }
 927                                 break;
 928
 929                         case 'Undo':
 930                                 if ($object_data['object_type'] == 'Follow') {
 931                                         self::undoFollowUser($object_data);
 932                                 }
 933                                 break;
 934
 935                         default:
 936                                 logger('Unknown activity: ' . $activity['type'], LOGGER_DEBUG);
 937                                 break;
 938                 }
 939         }
 940
 941         private static function getReceivers($activity, $actor)
 942         {
 943                 $receivers = [];
 944
 945                 // When it is an answer, we inherite the receivers from the parent
 946                 $replyto = JsonLD::fetchElement($activity, 'inReplyTo', 'id');
 947                 if (!empty($replyto)) {
 948                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 949                         while ($parent = Item::fetch($parents)) {
 950                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 951                         }
 952                 }
 953
 954                 if (!empty($actor)) {
 955                         $profile = self::fetchprofile($actor);
 956                         $followers = defaults($profile, 'followers', '');
 957
 958                         logger('Actor: ' . $actor . ' - Followers: ' . $followers, LOGGER_DEBUG);
 959                 } else {
 960                         logger('Empty actor', LOGGER_DEBUG);
 961                         $followers = '';
 962                 }
 963
 964                 $elements = ['to', 'cc', 'bto', 'bcc'];
 965                 foreach ($elements as $element) {
 966                         if (empty($activity[$element])) {
 967                                 continue;
 968                         }
 969
 970                         // The receiver can be an arror or a string
 971                         if (is_string($activity[$element])) {
 972                                 $activity[$element] = [$activity[$element]];
 973                         }
 974
 975                         foreach ($activity[$element] as $receiver) {
 976                                 if ($receiver == self::PUBLIC) {
 977                                         $receivers['uid:0'] = 0;
 978                                 }
 979
 980                                 if (($receiver == self::PUBLIC) && !empty($actor)) {
 981                                         // This will most likely catch all OStatus connections to Mastodon
 982                                         $condition = ['alias' => [$actor, normalise_link($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]];
 983                                         $contacts = DBA::select('contact', ['uid'], $condition);
 984                                         while ($contact = DBA::fetch($contacts)) {
 985                                                 if ($contact['uid'] != 0) {
 986                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 987                                                 }
 988                                         }
 989                                         DBA::close($contacts);
 990                                 }
 991
 992                                 if (in_array($receiver, [$followers, self::PUBLIC]) && !empty($actor)) {
 993                                         $condition = ['nurl' => normalise_link($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 994                                                 'network' => Protocol::ACTIVITYPUB];
 995                                         $contacts = DBA::select('contact', ['uid'], $condition);
 996                                         while ($contact = DBA::fetch($contacts)) {
 997                                                 if ($contact['uid'] != 0) {
 998                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 999                                                 }
1000                                         }
1001                                         DBA::close($contacts);
1002                                         continue;
1003                                 }
1004
1005                                 $condition = ['self' => true, 'nurl' => normalise_link($receiver)];
1006                                 $contact = DBA::selectFirst('contact', ['uid'], $condition);
1007                                 if (!DBA::isResult($contact)) {
1008                                         continue;
1009                                 }
1010                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
1011                         }
1012                 }
1013                 return $receivers;
1014         }
1015
1016         private static function addActivityFields($object_data, $activity)
1017         {
1018                 if (!empty($activity['published']) && empty($object_data['published'])) {
1019                         $object_data['published'] = $activity['published'];
1020                 }
1021
1022                 if (!empty($activity['updated']) && empty($object_data['updated'])) {
1023                         $object_data['updated'] = $activity['updated'];
1024                 }
1025
1026                 if (!empty($activity['inReplyTo']) && empty($object_data['parent-uri'])) {
1027                         $object_data['parent-uri'] = JsonLD::fetchElement($activity, 'inReplyTo', 'id');
1028                 }
1029
1030                 if (!empty($activity['instrument'])) {
1031                         $object_data['service'] = JsonLD::fetchElement($activity, 'instrument', 'name', 'type', 'Service');
1032                 }
1033                 return $object_data;
1034         }
1035
1036         private static function fetchObject($object_url, $object = [], $trust_source = false)
1037         {
1038                 if (!$trust_source || is_string($object)) {
1039                         $data = self::fetchContent($object_url);
1040                         if (empty($data)) {
1041                                 logger('Empty content for ' . $object_url . ', check if content is available locally.', LOGGER_DEBUG);
1042                                 $data = $object_url;
1043                         } else {
1044                                 logger('Fetched content for ' . $object_url, LOGGER_DEBUG);
1045                         }
1046                 } else {
1047                         logger('Using original object for url ' . $object_url, LOGGER_DEBUG);
1048                         $data = $object;
1049                 }
1050
1051                 if (is_string($data)) {
1052                         $item = Item::selectFirst([], ['uri' => $data]);
1053                         if (!DBA::isResult($item)) {
1054                                 logger('Object with url ' . $data . ' was not found locally.', LOGGER_DEBUG);
1055                                 return false;
1056                         }
1057                         logger('Using already stored item for url ' . $object_url, LOGGER_DEBUG);
1058                         $data = self::CreateNote($item);
1059                 }
1060
1061                 if (empty($data['type'])) {
1062                         logger('Empty type', LOGGER_DEBUG);
1063                         return false;
1064                 } else {
1065                         $type = $data['type'];
1066                         logger('Type ' . $type, LOGGER_DEBUG);
1067                 }
1068
1069                 if (in_array($type, ['Note', 'Article', 'Video'])) {
1070                         $common = self::processCommonData($data);
1071                 }
1072
1073                 switch ($type) {
1074                         case 'Note':
1075                                 return array_merge($common, self::processNote($data));
1076                         case 'Article':
1077                                 return array_merge($common, self::processArticle($data));
1078                         case 'Video':
1079                                 return array_merge($common, self::processVideo($data));
1080
1081                         case 'Announce':
1082                                 if (empty($data['object'])) {
1083                                         return false;
1084                                 }
1085                                 return self::fetchObject($data['object']);
1086
1087                         case 'Person':
1088                         case 'Tombstone':
1089                                 break;
1090
1091                         default:
1092                                 logger('Unknown object type: ' . $data['type'], LOGGER_DEBUG);
1093                                 break;
1094                 }
1095         }
1096
1097         private static function processCommonData(&$object)
1098         {
1099                 if (empty($object['id'])) {
1100                         return false;
1101                 }
1102
1103                 $object_data = [];
1104                 $object_data['type'] = $object['type'];
1105                 $object_data['uri'] = $object['id'];
1106
1107                 if (!empty($object['inReplyTo'])) {
1108                         $object_data['reply-to-uri'] = JsonLD::fetchElement($object, 'inReplyTo', 'id');
1109                 } else {
1110                         $object_data['reply-to-uri'] = $object_data['uri'];
1111                 }
1112
1113                 $object_data['published'] = defaults($object, 'published', null);
1114                 $object_data['updated'] = defaults($object, 'updated', $object_data['published']);
1115
1116                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1117                         $object_data['published'] = $object_data['updated'];
1118                 }
1119
1120                 $object_data['uuid'] = defaults($object, 'uuid', null);
1121                 $object_data['owner'] = $object_data['author'] = JsonLD::fetchElement($object, 'attributedTo', 'id');
1122                 $object_data['context'] = defaults($object, 'context', null);
1123                 $object_data['conversation'] = defaults($object, 'conversation', null);
1124                 $object_data['sensitive'] = defaults($object, 'sensitive', null);
1125                 $object_data['name'] = defaults($object, 'title', null);
1126                 $object_data['name'] = defaults($object, 'name', $object_data['name']);
1127                 $object_data['summary'] = defaults($object, 'summary', null);
1128                 $object_data['content'] = defaults($object, 'content', null);
1129                 $object_data['source'] = defaults($object, 'source', null);
1130                 $object_data['location'] = JsonLD::fetchElement($object, 'location', 'name', 'type', 'Place');
1131                 $object_data['attachments'] = defaults($object, 'attachment', null);
1132                 $object_data['tags'] = defaults($object, 'tag', null);
1133                 $object_data['service'] = JsonLD::fetchElement($object, 'instrument', 'name', 'type', 'Service');
1134                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'url', 'href');
1135                 $object_data['receiver'] = self::getReceivers($object, $object_data['owner']);
1136
1137                 // Unhandled
1138                 // @context, type, actor, signature, mediaType, duration, replies, icon
1139
1140                 // Also missing: (Defined in the standard, but currently unused)
1141                 // audience, preview, endTime, startTime, generator, image
1142
1143                 return $object_data;
1144         }
1145
1146         private static function processNote($object)
1147         {
1148                 $object_data = [];
1149
1150                 // To-Do?
1151                 // emoji, atomUri, inReplyToAtomUri
1152
1153                 // Unhandled
1154                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1155                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1156
1157                 return $object_data;
1158         }
1159
1160         private static function processArticle($object)
1161         {
1162                 $object_data = [];
1163
1164                 return $object_data;
1165         }
1166
1167         private static function processVideo($object)
1168         {
1169                 $object_data = [];
1170
1171                 // To-Do?
1172                 // category, licence, language, commentsEnabled
1173
1174                 // Unhandled
1175                 // views, waitTranscoding, state, support, subtitleLanguage
1176                 // likes, dislikes, shares, comments
1177
1178                 return $object_data;
1179         }
1180
1181         private static function convertMentions($body)
1182         {
1183                 $URLSearchString = "^\[\]";
1184                 $body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
1185
1186                 return $body;
1187         }
1188
1189         private static function constructTagList($tags, $sensitive)
1190         {
1191                 if (empty($tags)) {
1192                         return '';
1193                 }
1194
1195                 $tag_text = '';
1196                 foreach ($tags as $tag) {
1197                         if (in_array($tag['type'], ['Mention', 'Hashtag'])) {
1198                                 if (!empty($tag_text)) {
1199                                         $tag_text .= ',';
1200                                 }
1201
1202                                 if (empty($tag['href'])) {
1203                                         //$tag['href']
1204                                         logger('Blubb!');
1205                                 }
1206
1207                                 $tag_text .= substr($tag['name'], 0, 1) . '[url=' . $tag['href'] . ']' . substr($tag['name'], 1) . '[/url]';
1208                         }
1209                 }
1210
1211                 /// @todo add nsfw for $sensitive
1212
1213                 return $tag_text;
1214         }
1215
1216         private static function constructAttachList($attachments, $item)
1217         {
1218                 if (empty($attachments)) {
1219                         return $item;
1220                 }
1221
1222                 foreach ($attachments as $attach) {
1223                         $filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
1224                         if ($filetype == 'image') {
1225                                 $item['body'] .= "\n[img]".$attach['url'].'[/img]';
1226                         } else {
1227                                 if (!empty($item["attach"])) {
1228                                         $item["attach"] .= ',';
1229                                 } else {
1230                                         $item["attach"] = '';
1231                                 }
1232                                 if (!isset($attach['length'])) {
1233                                         $attach['length'] = "0";
1234                                 }
1235                                 $item["attach"] .= '[attach]href="'.$attach['url'].'" length="'.$attach['length'].'" type="'.$attach['mediaType'].'" title="'.defaults($attach, 'name', '').'"[/attach]';
1236                         }
1237                 }
1238
1239                 return $item;
1240         }
1241
1242         private static function createItem($activity, $body)
1243         {
1244                 $item = [];
1245                 $item['verb'] = ACTIVITY_POST;
1246                 $item['parent-uri'] = $activity['reply-to-uri'];
1247
1248                 if ($activity['reply-to-uri'] == $activity['uri']) {
1249                         $item['gravity'] = GRAVITY_PARENT;
1250                         $item['object-type'] = ACTIVITY_OBJ_NOTE;
1251                 } else {
1252                         $item['gravity'] = GRAVITY_COMMENT;
1253                         $item['object-type'] = ACTIVITY_OBJ_COMMENT;
1254                 }
1255
1256                 if (($activity['uri'] != $activity['reply-to-uri']) && !Item::exists(['uri' => $activity['reply-to-uri']])) {
1257                         logger('Parent ' . $activity['reply-to-uri'] . ' not found. Try to refetch it.');
1258                         self::fetchMissingActivity($activity['reply-to-uri'], $activity);
1259                 }
1260
1261                 self::postItem($activity, $item, $body);
1262         }
1263
1264         private static function likeItem($activity, $body)
1265         {
1266                 $item = [];
1267                 $item['verb'] = ACTIVITY_LIKE;
1268                 $item['parent-uri'] = $activity['object'];
1269                 $item['gravity'] = GRAVITY_ACTIVITY;
1270                 $item['object-type'] = ACTIVITY_OBJ_NOTE;
1271
1272                 self::postItem($activity, $item, $body);
1273         }
1274
1275         private static function dislikeItem($activity, $body)
1276         {
1277                 $item = [];
1278                 $item['verb'] = ACTIVITY_DISLIKE;
1279                 $item['parent-uri'] = $activity['object'];
1280                 $item['gravity'] = GRAVITY_ACTIVITY;
1281                 $item['object-type'] = ACTIVITY_OBJ_NOTE;
1282
1283                 self::postItem($activity, $item, $body);
1284         }
1285
1286         private static function postItem($activity, $item, $body)
1287         {
1288                 /// @todo What to do with $activity['context']?
1289
1290                 $item['network'] = Protocol::ACTIVITYPUB;
1291                 $item['private'] = !in_array(0, $activity['receiver']);
1292                 $item['author-id'] = Contact::getIdForURL($activity['author'], 0, true);
1293                 $item['owner-id'] = Contact::getIdForURL($activity['owner'], 0, true);
1294                 $item['uri'] = $activity['uri'];
1295                 $item['created'] = $activity['published'];
1296                 $item['edited'] = $activity['updated'];
1297                 $item['guid'] = $activity['uuid'];
1298                 $item['title'] = HTML::toBBCode($activity['name']);
1299                 $item['content-warning'] = HTML::toBBCode($activity['summary']);
1300                 $item['body'] = self::convertMentions(HTML::toBBCode($activity['content']));
1301                 $item['location'] = $activity['location'];
1302                 $item['tag'] = self::constructTagList($activity['tags'], $activity['sensitive']);
1303                 $item['app'] = $activity['service'];
1304                 $item['plink'] = defaults($activity, 'alternate-url', $item['uri']);
1305
1306                 $item = self::constructAttachList($activity['attachments'], $item);
1307
1308                 $source = JsonLD::fetchElement($activity, 'source', 'content', 'mediaType', 'text/bbcode');
1309                 if (!empty($source)) {
1310                         $item['body'] = $source;
1311                 }
1312
1313                 $item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
1314                 $item['source'] = $body;
1315                 $item['conversation-uri'] = $activity['conversation'];
1316
1317                 foreach ($activity['receiver'] as $receiver) {
1318                         $item['uid'] = $receiver;
1319                         $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver, true);
1320
1321                         if (($receiver != 0) && empty($item['contact-id'])) {
1322                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], 0, true);
1323                         }
1324
1325                         $item_id = Item::insert($item);
1326                         logger('Storing for user ' . $item['uid'] . ': ' . $item_id);
1327                 }
1328         }
1329
1330         private static function fetchMissingActivity($url, $child)
1331         {
1332                 $object = ActivityPub::fetchContent($url);
1333                 if (empty($object)) {
1334                         logger('Activity ' . $url . ' was not fetchable, aborting.');
1335                         return;
1336                 }
1337
1338                 $activity = [];
1339                 $activity['@context'] = $object['@context'];
1340                 unset($object['@context']);
1341                 $activity['id'] = $object['id'];
1342                 $activity['to'] = defaults($object, 'to', []);
1343                 $activity['cc'] = defaults($object, 'cc', []);
1344                 $activity['actor'] = $child['author'];
1345                 $activity['object'] = $object;
1346                 $activity['published'] = $object['published'];
1347                 $activity['type'] = 'Create';
1348
1349                 self::processActivity($activity);
1350                 logger('Activity ' . $url . ' had been fetched and processed.');
1351         }
1352
1353         private static function getUserOfObject($object)
1354         {
1355                 $self = DBA::selectFirst('contact', ['uid'], ['nurl' => normalise_link($object), 'self' => true]);
1356                 if (!DBA::isResult($self)) {
1357                         return false;
1358                 } else {
1359                         return $self['uid'];
1360                 }
1361         }
1362
1363         private static function followUser($activity)
1364         {
1365                 $uid = self::getUserOfObject($activity['object']);
1366                 if (empty($uid)) {
1367                         return;
1368                 }
1369
1370                 $owner = User::getOwnerDataById($uid);
1371
1372                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1373                 if (!empty($cid)) {
1374                         $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1375                 } else {
1376                         $contact = false;
1377                 }
1378
1379                 $item = ['author-id' => Contact::getIdForURL($activity['owner']),
1380                         'author-link' => $activity['owner']];
1381
1382                 Contact::addRelationship($owner, $contact, $item);
1383                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1384                 if (empty($cid)) {
1385                         return;
1386                 }
1387
1388                 $contact = DBA::selectFirst('contact', ['network'], ['id' => $cid]);
1389                 if ($contact['network'] != Protocol::ACTIVITYPUB) {
1390                         Contact::updateFromProbe($cid, Protocol::ACTIVITYPUB);
1391                 }
1392
1393                 DBA::update('contact', ['hub-verify' => $activity['id']], ['id' => $cid]);
1394                 logger('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
1395         }
1396
1397         private static function acceptFollowUser($activity)
1398         {
1399                 $uid = self::getUserOfObject($activity['object']);
1400                 if (empty($uid)) {
1401                         return;
1402                 }
1403
1404                 $owner = User::getOwnerDataById($uid);
1405
1406                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1407                 if (empty($cid)) {
1408                         logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
1409                         return;
1410                 }
1411
1412                 $fields = ['pending' => false];
1413
1414                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
1415                 if ($contact['rel'] == Contact::FOLLOWER) {
1416                         $fields['rel'] = Contact::FRIEND;
1417                 }
1418
1419                 $condition = ['id' => $cid];
1420                 DBA::update('contact', $fields, $condition);
1421                 logger('Accept contact request from contact ' . $cid . ' for user ' . $uid, LOGGER_DEBUG);
1422         }
1423
1424         private static function undoFollowUser($activity)
1425         {
1426                 $uid = self::getUserOfObject($activity['object']);
1427                 if (empty($uid)) {
1428                         return;
1429                 }
1430
1431                 $owner = User::getOwnerDataById($uid);
1432
1433                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1434                 if (empty($cid)) {
1435                         logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
1436                         return;
1437                 }
1438
1439                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1440                 if (!DBA::isResult($contact)) {
1441                         return;
1442                 }
1443
1444                 Contact::removeFollower($owner, $contact);
1445                 logger('Undo following request from contact ' . $cid . ' for user ' . $uid, LOGGER_DEBUG);
1446         }
1447 }