src/Protocol/ActivityPub/Transmitter.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2020, Friendica
   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\Feature;
  25 use Friendica\Content\Text\BBCode;
  26 use Friendica\Content\Text\Plaintext;
  27 use Friendica\Core\Cache\Duration;
  28 use Friendica\Core\Logger;
  29 use Friendica\Core\Protocol;
  30 use Friendica\Core\System;
  31 use Friendica\Database\DBA;
  32 use Friendica\DI;
  33 use Friendica\Model\APContact;
  34 use Friendica\Model\Contact;
  35 use Friendica\Model\Conversation;
  36 use Friendica\Model\Item;
  37 use Friendica\Model\ItemURI;
  38 use Friendica\Model\Profile;
  39 use Friendica\Model\Photo;
  40 use Friendica\Model\Tag;
  41 use Friendica\Model\User;
  42 use Friendica\Protocol\Activity;
  43 use Friendica\Protocol\ActivityPub;
  44 use Friendica\Util\DateTimeFormat;
  45 use Friendica\Util\HTTPSignature;
  46 use Friendica\Util\Images;
  47 use Friendica\Util\JsonLD;
  48 use Friendica\Util\LDSignature;
  49 use Friendica\Util\Map;
  50 use Friendica\Util\Network;
  51 use Friendica\Util\XML;
  52
  53 require_once 'include/api.php';
  54 require_once 'mod/share.php';
  55
  56 /**
  57  * ActivityPub Transmitter Protocol class
  58  *
  59  * To-Do:
  60  * @todo Undo Announce
  61  */
  62 class Transmitter
  63 {
  64         /**
  65          * Collects a list of contacts of the given owner
  66          *
  67          * @param array     $owner  Owner array
  68          * @param int|array $rel    The relevant value(s) contact.rel should match
  69          * @param string    $module The name of the relevant AP endpoint module (followers|following)
  70          * @param integer   $page   Page number
  71          *
  72          * @return array of owners
  73          * @throws \Exception
  74          */
  75         public static function getContacts($owner, $rel, $module, $page = null)
  76         {
  77                 $parameters = [
  78                         'rel' => $rel,
  79                         'uid' => $owner['uid'],
  80                         'self' => false,
  81                         'deleted' => false,
  82                         'hidden' => false,
  83                         'archive' => false,
  84                         'pending' => false
  85                 ];
  86                 $condition = DBA::buildCondition($parameters);
  87
  88                 $sql = "SELECT COUNT(*) as `count`
  89                         FROM `contact`
  90                         JOIN `apcontact` ON `apcontact`.`url` = `contact`.`url`
  91                         " . $condition;
  92
  93                 $contacts = DBA::fetchFirst($sql, ...$parameters);
  94
  95                 $modulePath = '/' . $module . '/';
  96
  97                 $data = ['@context' => ActivityPub::CONTEXT];
  98                 $data['id'] = DI::baseUrl() . $modulePath . $owner['nickname'];
  99                 $data['type'] = 'OrderedCollection';
 100                 $data['totalItems'] = $contacts['count'];
 101
 102                 // When we hide our friends we will only show the pure number but don't allow more.
 103                 $profile = Profile::getByUID($owner['uid']);
 104                 if (!empty($profile['hide-friends'])) {
 105                         return $data;
 106                 }
 107
 108                 if (empty($page)) {
 109                         $data['first'] = DI::baseUrl() . $modulePath . $owner['nickname'] . '?page=1';
 110                 } else {
 111                         $data['type'] = 'OrderedCollectionPage';
 112                         $list = [];
 113
 114                         $sql = "SELECT `contact`.`url`
 115                                 FROM `contact`
 116                                 JOIN `apcontact` ON `apcontact`.`url` = `contact`.`url`
 117                                 " . $condition . "
 118                                 LIMIT ?, ?";
 119
 120                         $parameters[] = ($page - 1) * 100;
 121                         $parameters[] = 100;
 122
 123                         $contacts = DBA::p($sql, ...$parameters);
 124                         while ($contact = DBA::fetch($contacts)) {
 125                                 $list[] = $contact['url'];
 126                         }
 127                         DBA::close($contacts);
 128
 129                         if (!empty($list)) {
 130                                 $data['next'] = DI::baseUrl() . $modulePath . $owner['nickname'] . '?page=' . ($page + 1);
 131                         }
 132
 133                         $data['partOf'] = DI::baseUrl() . $modulePath . $owner['nickname'];
 134
 135                         $data['orderedItems'] = $list;
 136                 }
 137
 138                 return $data;
 139         }
 140
 141         /**
 142          * Public posts for the given owner
 143          *
 144          * @param array   $owner Owner array
 145          * @param integer $page  Page numbe
 146          *
 147          * @return array of posts
 148          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 149          * @throws \ImagickException
 150          */
 151         public static function getOutbox($owner, $page = null)
 152         {
 153                 $public_contact = Contact::getIdForURL($owner['url']);
 154
 155                 $condition = ['uid' => 0, 'contact-id' => $public_contact, 'author-id' => $public_contact,
 156                         'private' => [Item::PUBLIC, Item::UNLISTED], 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT],
 157                         'deleted' => false, 'visible' => true, 'moderated' => false];
 158                 $count = DBA::count('item', $condition);
 159
 160                 $data = ['@context' => ActivityPub::CONTEXT];
 161                 $data['id'] = DI::baseUrl() . '/outbox/' . $owner['nickname'];
 162                 $data['type'] = 'OrderedCollection';
 163                 $data['totalItems'] = $count;
 164
 165                 if (empty($page)) {
 166                         $data['first'] = DI::baseUrl() . '/outbox/' . $owner['nickname'] . '?page=1';
 167                 } else {
 168                         $data['type'] = 'OrderedCollectionPage';
 169                         $list = [];
 170
 171                         $condition['parent-network'] = Protocol::NATIVE_SUPPORT;
 172
 173                         $items = Item::select(['id'], $condition, ['limit' => [($page - 1) * 20, 20], 'order' => ['created' => true]]);
 174                         while ($item = Item::fetch($items)) {
 175                                 $activity = self::createActivityFromItem($item['id'], true);
 176                                 $activity['type'] = $activity['type'] == 'Update' ? 'Create' : $activity['type'];
 177
 178                                 // Only list "Create" activity objects here, no reshares
 179                                 if (!empty($activity['object']) && ($activity['type'] == 'Create')) {
 180                                         $list[] = $activity['object'];
 181                                 }
 182                         }
 183
 184                         if (!empty($list)) {
 185                                 $data['next'] = DI::baseUrl() . '/outbox/' . $owner['nickname'] . '?page=' . ($page + 1);
 186                         }
 187
 188                         $data['partOf'] = DI::baseUrl() . '/outbox/' . $owner['nickname'];
 189
 190                         $data['orderedItems'] = $list;
 191                 }
 192
 193                 return $data;
 194         }
 195
 196         /**
 197          * Return the service array containing information the used software and it's url
 198          *
 199          * @return array with service data
 200          */
 201         private static function getService()
 202         {
 203                 return ['type' => 'Service',
 204                         'name' =>  FRIENDICA_PLATFORM . " '" . FRIENDICA_CODENAME . "' " . FRIENDICA_VERSION . '-' . DB_UPDATE_VERSION,
 205                         'url' => DI::baseUrl()->get()];
 206         }
 207
 208         /**
 209          * Return the ActivityPub profile of the given user
 210          *
 211          * @param integer $uid User ID
 212          * @return array with profile data
 213          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 214          */
 215         public static function getProfile($uid)
 216         {
 217                 $condition = ['uid' => $uid, 'blocked' => false, 'account_expired' => false,
 218                         'account_removed' => false, 'verified' => true];
 219                 $fields = ['guid', 'nickname', 'pubkey', 'account-type', 'page-flags'];
 220                 $user = DBA::selectFirst('user', $fields, $condition);
 221                 if (!DBA::isResult($user)) {
 222                         return [];
 223                 }
 224
 225                 $fields = ['locality', 'region', 'country-name'];
 226                 $profile = DBA::selectFirst('profile', $fields, ['uid' => $uid]);
 227                 if (!DBA::isResult($profile)) {
 228                         return [];
 229                 }
 230
 231                 $fields = ['name', 'url', 'location', 'about', 'avatar', 'photo'];
 232                 $contact = DBA::selectFirst('contact', $fields, ['uid' => $uid, 'self' => true]);
 233                 if (!DBA::isResult($contact)) {
 234                         return [];
 235                 }
 236
 237                 $data = ['@context' => ActivityPub::CONTEXT];
 238                 $data['id'] = $contact['url'];
 239                 $data['diaspora:guid'] = $user['guid'];
 240                 $data['type'] = ActivityPub::ACCOUNT_TYPES[$user['account-type']];
 241                 $data['following'] = DI::baseUrl() . '/following/' . $user['nickname'];
 242                 $data['followers'] = DI::baseUrl() . '/followers/' . $user['nickname'];
 243                 $data['inbox'] = DI::baseUrl() . '/inbox/' . $user['nickname'];
 244                 $data['outbox'] = DI::baseUrl() . '/outbox/' . $user['nickname'];
 245                 $data['preferredUsername'] = $user['nickname'];
 246                 $data['name'] = $contact['name'];
 247                 $data['vcard:hasAddress'] = ['@type' => 'vcard:Home', 'vcard:country-name' => $profile['country-name'],
 248                         'vcard:region' => $profile['region'], 'vcard:locality' => $profile['locality']];
 249                 $data['summary'] = BBCode::convert($contact['about'], false);
 250                 $data['url'] = $contact['url'];
 251                 $data['manuallyApprovesFollowers'] = in_array($user['page-flags'], [User::PAGE_FLAGS_NORMAL, User::PAGE_FLAGS_PRVGROUP]);
 252                 $data['publicKey'] = ['id' => $contact['url'] . '#main-key',
 253                         'owner' => $contact['url'],
 254                         'publicKeyPem' => $user['pubkey']];
 255                 $data['endpoints'] = ['sharedInbox' => DI::baseUrl() . '/inbox'];
 256                 $data['icon'] = ['type' => 'Image',
 257                         'url' => $contact['photo']];
 258
 259                 $data['generator'] = self::getService();
 260
 261                 // tags: https://kitty.town/@inmysocks/100656097926961126.json
 262                 return $data;
 263         }
 264
 265         /**
 266          * @param string $username
 267          * @return array
 268          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 269          */
 270         public static function getDeletedUser($username)
 271         {
 272                 return [
 273                         '@context' => ActivityPub::CONTEXT,
 274                         'id' => DI::baseUrl() . '/profile/' . $username,
 275                         'type' => 'Tombstone',
 276                         'published' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
 277                         'updated' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
 278                         'deleted' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
 279                 ];
 280         }
 281
 282         /**
 283          * Returns an array with permissions of a given item array
 284          *
 285          * @param array $item
 286          *
 287          * @return array with permissions
 288          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 289          * @throws \ImagickException
 290          */
 291         private static function fetchPermissionBlockFromConversation($item)
 292         {
 293                 if (empty($item['thr-parent'])) {
 294                         return [];
 295                 }
 296
 297                 $condition = ['item-uri' => $item['thr-parent'], 'protocol' => Conversation::PARCEL_ACTIVITYPUB];
 298                 $conversation = DBA::selectFirst('conversation', ['source'], $condition);
 299                 if (!DBA::isResult($conversation)) {
 300                         return [];
 301                 }
 302
 303                 $activity = json_decode($conversation['source'], true);
 304
 305                 $actor = JsonLD::fetchElement($activity, 'actor', 'id');
 306                 $profile = APContact::getByURL($actor);
 307
 308                 $item_profile = APContact::getByURL($item['author-link']);
 309                 $exclude[] = $item['author-link'];
 310
 311                 if ($item['gravity'] == GRAVITY_PARENT) {
 312                         $exclude[] = $item['owner-link'];
 313                 }
 314
 315                 $permissions['to'][] = $actor;
 316
 317                 foreach (['to', 'cc', 'bto', 'bcc'] as $element) {
 318                         if (empty($activity[$element])) {
 319                                 continue;
 320                         }
 321                         if (is_string($activity[$element])) {
 322                                 $activity[$element] = [$activity[$element]];
 323                         }
 324
 325                         foreach ($activity[$element] as $receiver) {
 326                                 if (empty($receiver)) {
 327                                         continue;
 328                                 }
 329
 330                                 if (!empty($profile['followers']) && $receiver == $profile['followers'] && !empty($item_profile['followers'])) {
 331                                         $permissions[$element][] = $item_profile['followers'];
 332                                 } elseif (!in_array($receiver, $exclude)) {
 333                                         $permissions[$element][] = $receiver;
 334                                 }
 335                         }
 336                 }
 337                 return $permissions;
 338         }
 339
 340         /**
 341          * Creates an array of permissions from an item thread
 342          *
 343          * @param array   $item       Item array
 344          * @param boolean $blindcopy  addressing via "bcc" or "cc"?
 345          * @param integer $last_id    Last item id for adding receivers
 346          * @param boolean $forum_mode "true" means that we are sending content to a forum
 347          *
 348          * @return array with permission data
 349          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 350          * @throws \ImagickException
 351          */
 352         private static function createPermissionBlockForItem($item, $blindcopy, $last_id = 0, $forum_mode = false)
 353         {
 354                 if ($last_id == 0) {
 355                         $last_id = $item['id'];
 356                 }
 357
 358                 $always_bcc = false;
 359                 $isforum = false;
 360
 361                 // Check if we should always deliver our stuff via BCC
 362                 if (!empty($item['uid'])) {
 363                         $profile = User::getOwnerDataById($item['uid']);
 364                         if (!empty($profile)) {
 365                                 $always_bcc = $profile['hide-friends'];
 366                                 $isforum = $profile['account-type'] == User::ACCOUNT_TYPE_COMMUNITY;
 367                         }
 368                 }
 369
 370                 if (DI::config()->get('system', 'ap_always_bcc')) {
 371                         $always_bcc = true;
 372                 }
 373
 374                 if ((self::isAnnounce($item) && !$isforum) || DI::config()->get('debug', 'total_ap_delivery')) {
 375                         // Will be activated in a later step
 376                         $networks = Protocol::FEDERATED;
 377                 } else {
 378                         // For now only send to these contacts:
 379                         $networks = [Protocol::ACTIVITYPUB, Protocol::OSTATUS];
 380                 }
 381
 382                 $data = ['to' => [], 'cc' => [], 'bcc' => []];
 383
 384                 if ($item['gravity'] == GRAVITY_PARENT) {
 385                         $actor_profile = APContact::getByURL($item['owner-link']);
 386                 } else {
 387                         $actor_profile = APContact::getByURL($item['author-link']);
 388                 }
 389
 390                 $terms = Tag::getByURIId($item['uri-id'], [Tag::MENTION, Tag::IMPLICIT_MENTION, Tag::EXCLUSIVE_MENTION]);
 391
 392                 if ($item['private'] != Item::PRIVATE) {
 393                         // Directly mention the original author upon a quoted reshare.
 394                         // Else just ensure that the original author receives the reshare.
 395                         $announce = self::getAnnounceArray($item);
 396                         if (!empty($announce['comment'])) {
 397                                 $data['to'][] = $announce['actor']['url'];
 398                         } elseif (!empty($announce)) {
 399                                 $data['cc'][] = $announce['actor']['url'];
 400                         }
 401
 402                         $data = array_merge($data, self::fetchPermissionBlockFromConversation($item));
 403
 404                         // Check if the item is completely public or unlisted
 405                         if ($item['private'] == Item::PUBLIC) {
 406                                 $data['to'][] = ActivityPub::PUBLIC_COLLECTION;
 407                         } else {
 408                                 $data['cc'][] = ActivityPub::PUBLIC_COLLECTION;
 409                         }
 410
 411                         foreach ($terms as $term) {
 412                                 $profile = APContact::getByURL($term['url'], false);
 413                                 if (!empty($profile)) {
 414                                         $data['to'][] = $profile['url'];
 415                                 }
 416                         }
 417                 } else {
 418                         $receiver_list = Item::enumeratePermissions($item, true);
 419
 420                         foreach ($terms as $term) {
 421                                 $cid = Contact::getIdForURL($term['url'], $item['uid']);
 422                                 if (!empty($cid) && in_array($cid, $receiver_list)) {
 423                                         $contact = DBA::selectFirst('contact', ['url', 'network', 'protocol'], ['id' => $cid]);
 424                                         if (!DBA::isResult($contact) || (!in_array($contact['network'], $networks) && ($contact['protocol'] != Protocol::ACTIVITYPUB))) {
 425                                                 continue;
 426                                         }
 427
 428                                         if ($isforum && DBA::isResult($contact) && ($contact['dfrn'] == Protocol::DFRN)) {
 429                                                 continue;
 430                                         }
 431
 432                                         if (!empty($profile = APContact::getByURL($contact['url'], false))) {
 433                                                 $data['to'][] = $profile['url'];
 434                                         }
 435                                 }
 436                         }
 437
 438                         foreach ($receiver_list as $receiver) {
 439                                 $contact = DBA::selectFirst('contact', ['url', 'hidden', 'network', 'protocol'], ['id' => $receiver]);
 440                                 if (!DBA::isResult($contact) || (!in_array($contact['network'], $networks) && ($contact['protocol'] != Protocol::ACTIVITYPUB))) {
 441                                         continue;
 442                                 }
 443
 444                                 if ($isforum && DBA::isResult($contact) && ($contact['dfrn'] == Protocol::DFRN)) {
 445                                         continue;
 446                                 }
 447
 448                                 if (!empty($profile = APContact::getByURL($contact['url'], false))) {
 449                                         if ($contact['hidden'] || $always_bcc) {
 450                                                 $data['bcc'][] = $profile['url'];
 451                                         } else {
 452                                                 $data['cc'][] = $profile['url'];
 453                                         }
 454                                 }
 455                         }
 456                 }
 457
 458                 if (!empty($item['parent'])) {
 459                         $parents = Item::select(['id', 'author-link', 'owner-link', 'gravity', 'uri'], ['parent' => $item['parent']]);
 460                         while ($parent = Item::fetch($parents)) {
 461                                 if ($parent['gravity'] == GRAVITY_PARENT) {
 462                                         $profile = APContact::getByURL($parent['owner-link'], false);
 463                                         if (!empty($profile)) {
 464                                                 if ($item['gravity'] != GRAVITY_PARENT) {
 465                                                         // Comments to forums are directed to the forum
 466                                                         // But comments to forums aren't directed to the followers collection
 467                                                         // This rule is only valid when the actor isn't the forum.
 468                                                         // The forum needs to transmit their content to their followers.
 469                                                         if (($profile['type'] == 'Group') && ($profile['url'] != $actor_profile['url'])) {
 470                                                                 $data['to'][] = $profile['url'];
 471                                                         } else {
 472                                                                 $data['cc'][] = $profile['url'];
 473                                                                 if (($item['private'] != Item::PRIVATE) && !empty($actor_profile['followers'])) {
 474                                                                         $data['cc'][] = $actor_profile['followers'];
 475                                                                 }
 476                                                         }
 477                                                 } else {
 478                                                         // Public thread parent post always are directed to the followers
 479                                                         if (($item['private'] != Item::PRIVATE) && !$forum_mode) {
 480                                                                 $data['cc'][] = $actor_profile['followers'];
 481                                                         }
 482                                                 }
 483                                         }
 484                                 }
 485
 486                                 // Don't include data from future posts
 487                                 if ($parent['id'] >= $last_id) {
 488                                         continue;
 489                                 }
 490
 491                                 $profile = APContact::getByURL($parent['author-link'], false);
 492                                 if (!empty($profile)) {
 493                                         if (($profile['type'] == 'Group') || ($parent['uri'] == $item['thr-parent'])) {
 494                                                 $data['to'][] = $profile['url'];
 495                                         } else {
 496                                                 $data['cc'][] = $profile['url'];
 497                                         }
 498                                 }
 499                         }
 500                         DBA::close($parents);
 501                 }
 502
 503                 $data['to'] = array_unique($data['to']);
 504                 $data['cc'] = array_unique($data['cc']);
 505                 $data['bcc'] = array_unique($data['bcc']);
 506
 507                 if (($key = array_search($item['author-link'], $data['to'])) !== false) {
 508                         unset($data['to'][$key]);
 509                 }
 510
 511                 if (($key = array_search($item['author-link'], $data['cc'])) !== false) {
 512                         unset($data['cc'][$key]);
 513                 }
 514
 515                 if (($key = array_search($item['author-link'], $data['bcc'])) !== false) {
 516                         unset($data['bcc'][$key]);
 517                 }
 518
 519                 foreach ($data['to'] as $to) {
 520                         if (($key = array_search($to, $data['cc'])) !== false) {
 521                                 unset($data['cc'][$key]);
 522                         }
 523
 524                         if (($key = array_search($to, $data['bcc'])) !== false) {
 525                                 unset($data['bcc'][$key]);
 526                         }
 527                 }
 528
 529                 foreach ($data['cc'] as $cc) {
 530                         if (($key = array_search($cc, $data['bcc'])) !== false) {
 531                                 unset($data['bcc'][$key]);
 532                         }
 533                 }
 534
 535                 $receivers = ['to' => array_values($data['to']), 'cc' => array_values($data['cc']), 'bcc' => array_values($data['bcc'])];
 536
 537                 if (!$blindcopy) {
 538                         unset($receivers['bcc']);
 539                 }
 540
 541                 return $receivers;
 542         }
 543
 544         /**
 545          * Check if an inbox is archived
 546          *
 547          * @param string $url Inbox url
 548          *
 549          * @return boolean "true" if inbox is archived
 550          */
 551         private static function archivedInbox($url)
 552         {
 553                 return DBA::exists('inbox-status', ['url' => $url, 'archive' => true]);
 554         }
 555
 556         /**
 557          * Fetches a list of inboxes of followers of a given user
 558          *
 559          * @param integer $uid      User ID
 560          * @param boolean $personal fetch personal inboxes
 561          *
 562          * @return array of follower inboxes
 563          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 564          * @throws \ImagickException
 565          */
 566         public static function fetchTargetInboxesforUser($uid, $personal = false)
 567         {
 568                 $inboxes = [];
 569
 570                 $isforum = false;
 571
 572                 if (!empty($item['uid'])) {
 573                         $profile = User::getOwnerDataById($item['uid']);
 574                         if (!empty($profile)) {
 575                                 $isforum = $profile['account-type'] == User::ACCOUNT_TYPE_COMMUNITY;
 576                         }
 577                 }
 578
 579                 if (DI::config()->get('debug', 'total_ap_delivery')) {
 580                         // Will be activated in a later step
 581                         $networks = Protocol::FEDERATED;
 582                 } else {
 583                         // For now only send to these contacts:
 584                         $networks = [Protocol::ACTIVITYPUB, Protocol::OSTATUS];
 585                 }
 586
 587                 $condition = ['uid' => $uid, 'archive' => false, 'pending' => false];
 588
 589                 if (!empty($uid)) {
 590                         $condition['rel'] = [Contact::FOLLOWER, Contact::FRIEND];
 591                 }
 592
 593                 $contacts = DBA::select('contact', ['url', 'network', 'protocol'], $condition);
 594                 while ($contact = DBA::fetch($contacts)) {
 595                         if (Contact::isLocal($contact['url'])) {
 596                                 continue;
 597                         }
 598
 599                         if (!in_array($contact['network'], $networks) && ($contact['protocol'] != Protocol::ACTIVITYPUB)) {
 600                                 continue;
 601                         }
 602
 603                         if ($isforum && ($contact['dfrn'] == Protocol::DFRN)) {
 604                                 continue;
 605                         }
 606
 607                         if (Network::isUrlBlocked($contact['url'])) {
 608                                 continue;
 609                         }
 610
 611                         $profile = APContact::getByURL($contact['url'], false);
 612                         if (!empty($profile)) {
 613                                 if (empty($profile['sharedinbox']) || $personal) {
 614                                         $target = $profile['inbox'];
 615                                 } else {
 616                                         $target = $profile['sharedinbox'];
 617                                 }
 618                                 if (!self::archivedInbox($target)) {
 619                                         $inboxes[$target] = $target;
 620                                 }
 621                         }
 622                 }
 623                 DBA::close($contacts);
 624
 625                 return $inboxes;
 626         }
 627
 628         /**
 629          * Fetches an array of inboxes for the given item and user
 630          *
 631          * @param array   $item       Item array
 632          * @param integer $uid        User ID
 633          * @param boolean $personal   fetch personal inboxes
 634          * @param integer $last_id    Last item id for adding receivers
 635          * @param boolean $forum_mode "true" means that we are sending content to a forum
 636          * @return array with inboxes
 637          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 638          * @throws \ImagickException
 639          */
 640         public static function fetchTargetInboxes($item, $uid, $personal = false, $last_id = 0, $forum_mode = false)
 641         {
 642                 $permissions = self::createPermissionBlockForItem($item, true, $last_id, $forum_mode);
 643                 if (empty($permissions)) {
 644                         return [];
 645                 }
 646
 647                 $inboxes = [];
 648
 649                 if ($item['gravity'] == GRAVITY_ACTIVITY) {
 650                         $item_profile = APContact::getByURL($item['author-link'], false);
 651                 } else {
 652                         $item_profile = APContact::getByURL($item['owner-link'], false);
 653                 }
 654
 655                 $profile_uid = User::getIdForURL($item_profile['url']);
 656
 657                 foreach (['to', 'cc', 'bto', 'bcc'] as $element) {
 658                         if (empty($permissions[$element])) {
 659                                 continue;
 660                         }
 661
 662                         $blindcopy = in_array($element, ['bto', 'bcc']);
 663
 664                         foreach ($permissions[$element] as $receiver) {
 665                                 if (empty($receiver) || Network::isUrlBlocked($receiver)) {
 666                                         continue;
 667                                 }
 668
 669                                 if ($item_profile && ($receiver == $item_profile['followers']) && ($uid == $profile_uid)) {
 670                                         $inboxes = array_merge($inboxes, self::fetchTargetInboxesforUser($uid, $personal));
 671                                 } else {
 672                                         if (Contact::isLocal($receiver)) {
 673                                                 continue;
 674                                         }
 675
 676                                         $profile = APContact::getByURL($receiver, false);
 677                                         if (!empty($profile)) {
 678                                                 if (empty($profile['sharedinbox']) || $personal || $blindcopy) {
 679                                                         $target = $profile['inbox'];
 680                                                 } else {
 681                                                         $target = $profile['sharedinbox'];
 682                                                 }
 683                                                 if (!self::archivedInbox($target)) {
 684                                                         $inboxes[$target] = $target;
 685                                                 }
 686                                         }
 687                                 }
 688                         }
 689                 }
 690
 691                 return $inboxes;
 692         }
 693
 694         /**
 695          * Creates an array in the structure of the item table for a given mail id
 696          *
 697          * @param integer $mail_id
 698          *
 699          * @return array
 700          * @throws \Exception
 701          */
 702         public static function ItemArrayFromMail($mail_id)
 703         {
 704                 $mail = DBA::selectFirst('mail', [], ['id' => $mail_id]);
 705                 if (!DBA::isResult($mail)) {
 706                         return [];
 707                 }
 708
 709                 $mail['uri-id'] = ItemURI::insert(['uri' => $mail['uri'], 'guid' => $mail['guid']]);
 710
 711                 $reply = DBA::selectFirst('mail', ['uri'], ['parent-uri' => $mail['parent-uri'], 'reply' => false]);
 712
 713                 // Making the post more compatible for Mastodon by:
 714                 // - Making it a note and not an article (no title)
 715                 // - Moving the title into the "summary" field that is used as a "content warning"
 716                 $mail['body'] = '[abstract]' . $mail['title'] . "[/abstract]\n" . $mail['body'];
 717                 $mail['title'] = '';
 718
 719                 $mail['author-link'] = $mail['owner-link'] = $mail['from-url'];
 720                 $mail['allow_cid'] = '<'.$mail['contact-id'].'>';
 721                 $mail['allow_gid'] = '';
 722                 $mail['deny_cid'] = '';
 723                 $mail['deny_gid'] = '';
 724                 $mail['private'] = true;
 725                 $mail['deleted'] = false;
 726                 $mail['edited'] = $mail['created'];
 727                 $mail['plink'] = $mail['uri'];
 728                 $mail['thr-parent'] = $reply['uri'];
 729                 $mail['gravity'] = ($mail['reply'] ? GRAVITY_COMMENT: GRAVITY_PARENT);
 730
 731                 $mail['event-type'] = '';
 732                 $mail['attach'] = '';
 733
 734                 $mail['parent'] = 0;
 735
 736                 return $mail;
 737         }
 738
 739         /**
 740          * Creates an activity array for a given mail id
 741          *
 742          * @param integer $mail_id
 743          * @param boolean $object_mode Is the activity item is used inside another object?
 744          *
 745          * @return array of activity
 746          * @throws \Exception
 747          */
 748         public static function createActivityFromMail($mail_id, $object_mode = false)
 749         {
 750                 $mail = self::ItemArrayFromMail($mail_id);
 751                 $object = self::createNote($mail);
 752
 753                 if (!$object_mode) {
 754                         $data = ['@context' => ActivityPub::CONTEXT];
 755                 } else {
 756                         $data = [];
 757                 }
 758
 759                 $data['id'] = $mail['uri'] . '/Create';
 760                 $data['type'] = 'Create';
 761                 $data['actor'] = $mail['author-link'];
 762                 $data['published'] = DateTimeFormat::utc($mail['created'] . '+00:00', DateTimeFormat::ATOM);
 763                 $data['instrument'] = self::getService();
 764                 $data = array_merge($data, self::createPermissionBlockForItem($mail, true));
 765
 766                 if (empty($data['to']) && !empty($data['cc'])) {
 767                         $data['to'] = $data['cc'];
 768                 }
 769
 770                 if (empty($data['to']) && !empty($data['bcc'])) {
 771                         $data['to'] = $data['bcc'];
 772                 }
 773
 774                 unset($data['cc']);
 775                 unset($data['bcc']);
 776
 777                 $object['to'] = $data['to'];
 778                 $object['tag'] = [['type' => 'Mention', 'href' => $object['to'][0], 'name' => '']];
 779
 780                 unset($object['cc']);
 781                 unset($object['bcc']);
 782
 783                 $data['directMessage'] = true;
 784
 785                 $data['object'] = $object;
 786
 787                 $owner = User::getOwnerDataById($mail['uid']);
 788
 789                 if (!$object_mode && !empty($owner)) {
 790                         return LDSignature::sign($data, $owner);
 791                 } else {
 792                         return $data;
 793                 }
 794         }
 795
 796         /**
 797          * Returns the activity type of a given item
 798          *
 799          * @param array $item
 800          *
 801          * @return string with activity type
 802          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 803          * @throws \ImagickException
 804          */
 805         private static function getTypeOfItem($item)
 806         {
 807                 $reshared = false;
 808
 809                 // Only check for a reshare, if it is a real reshare and no quoted reshare
 810                 if (strpos($item['body'], "[share") === 0) {
 811                         $announce = self::getAnnounceArray($item);
 812                         $reshared = !empty($announce);
 813                 }
 814
 815                 if ($reshared) {
 816                         $type = 'Announce';
 817                 } elseif ($item['verb'] == Activity::POST) {
 818                         if ($item['created'] == $item['edited']) {
 819                                 $type = 'Create';
 820                         } else {
 821                                 $type = 'Update';
 822                         }
 823                 } elseif ($item['verb'] == Activity::LIKE) {
 824                         $type = 'Like';
 825                 } elseif ($item['verb'] == Activity::DISLIKE) {
 826                         $type = 'Dislike';
 827                 } elseif ($item['verb'] == Activity::ATTEND) {
 828                         $type = 'Accept';
 829                 } elseif ($item['verb'] == Activity::ATTENDNO) {
 830                         $type = 'Reject';
 831                 } elseif ($item['verb'] == Activity::ATTENDMAYBE) {
 832                         $type = 'TentativeAccept';
 833                 } elseif ($item['verb'] == Activity::FOLLOW) {
 834                         $type = 'Follow';
 835                 } elseif ($item['verb'] == Activity::TAG) {
 836                         $type = 'Add';
 837                 } elseif ($item['verb'] == Activity::ANNOUNCE) {
 838                         $type = 'Announce';
 839                 } else {
 840                         $type = '';
 841                 }
 842
 843                 return $type;
 844         }
 845
 846         /**
 847          * Creates the activity or fetches it from the cache
 848          *
 849          * @param integer $item_id
 850          * @param boolean $force Force new cache entry
 851          *
 852          * @return array with the activity
 853          * @throws \Exception
 854          */
 855         public static function createCachedActivityFromItem($item_id, $force = false)
 856         {
 857                 $cachekey = 'APDelivery:createActivity:' . $item_id;
 858
 859                 if (!$force) {
 860                         $data = DI::cache()->get($cachekey);
 861                         if (!is_null($data)) {
 862                                 return $data;
 863                         }
 864                 }
 865
 866                 $data = self::createActivityFromItem($item_id);
 867
 868                 DI::cache()->set($cachekey, $data, Duration::QUARTER_HOUR);
 869                 return $data;
 870         }
 871
 872         /**
 873          * Creates an activity array for a given item id
 874          *
 875          * @param integer $item_id
 876          * @param boolean $object_mode Is the activity item is used inside another object?
 877          *
 878          * @return array of activity
 879          * @throws \Exception
 880          */
 881         public static function createActivityFromItem($item_id, $object_mode = false)
 882         {
 883                 Logger::info('Fetching activity', ['item' => $item_id]);
 884                 $item = Item::selectFirst([], ['id' => $item_id, 'parent-network' => Protocol::NATIVE_SUPPORT]);
 885                 if (!DBA::isResult($item)) {
 886                         return false;
 887                 }
 888
 889                 /// @todo This code should be removed by the end of the year 2020
 890                 if ($item['wall'] && ($item['uri'] == $item['parent-uri'])) {
 891                         $owner = User::getOwnerDataById($item['uid']);
 892                         if (($owner['account-type'] == User::ACCOUNT_TYPE_COMMUNITY) && ($item['author-link'] != $owner['url'])) {
 893                                 $type = 'Announce';
 894
 895                                 // Disguise forum posts as reshares. Will later be converted to a real announce
 896                                 $item['body'] = BBCode::getShareOpeningTag($item['author-name'], $item['author-link'], $item['author-avatar'],
 897                                         $item['plink'], $item['created'], $item['guid']) . $item['body'] . '[/share]';
 898                         }
 899                 }
 900
 901                 /*
 902                 /// @todo This code should be activated by the end of the year 2020
 903                 // See also "tagDeliver";
 904                 // In case of a forum post ensure to return the original post if author and forum are on the same machine
 905                 if (!empty($item['forum_mode'])) {
 906                         $author = Contact::getById($item['author-id'], ['nurl']);
 907                         if (!empty($author['nurl'])) {
 908                                 $self = Contact::selectFirst(['uid'], ['nurl' => $author['nurl'], 'self' => true]);
 909                                 if (!empty($self['uid'])) {
 910                                         $item = Item::selectFirst([], ['uri-id' => $item['uri-id'], 'uid' => $self['uid']]);
 911                                 }
 912                         }
 913                 }
 914                 */
 915
 916                 if (empty($type)) {
 917                         $condition = ['item-uri' => $item['uri'], 'protocol' => Conversation::PARCEL_ACTIVITYPUB];
 918                         $conversation = DBA::selectFirst('conversation', ['source'], $condition);
 919                         if (DBA::isResult($conversation)) {
 920                                 $data = json_decode($conversation['source'], true);
 921                                 if (!empty($data['type'])) {
 922                                         if (in_array($data['type'], ['Create', 'Update'])) {
 923                                                 if ($object_mode) {
 924                                                         unset($data['@context']);
 925                                                         unset($data['signature']);
 926                                                 }
 927                                                 Logger::info('Return stored conversation', ['item' => $item_id]);
 928                                                 return $data;
 929                                         } elseif (in_array('as:' . $data['type'], Receiver::CONTENT_TYPES)) {
 930                                                 if (!empty($data['@context'])) {
 931                                                         $context = $data['@context'];
 932                                                         unset($data['@context']);
 933                                                 }
 934                                                 unset($data['actor']);
 935                                                 $object = $data;
 936                                         }
 937                                 }
 938                         }
 939
 940                         $type = self::getTypeOfItem($item);
 941                 }
 942
 943                 if (!$object_mode) {
 944                         $data = ['@context' => $context ?? ActivityPub::CONTEXT];
 945
 946                         if ($item['deleted'] && ($item['gravity'] == GRAVITY_ACTIVITY)) {
 947                                 $type = 'Undo';
 948                         } elseif ($item['deleted']) {
 949                                 $type = 'Delete';
 950                         }
 951                 } else {
 952                         $data = [];
 953                 }
 954
 955                 $data['id'] = $item['uri'] . '/' . $type;
 956                 $data['type'] = $type;
 957
 958                 if (($type != 'Announce') || ($item['gravity'] != GRAVITY_PARENT)) {
 959                         $data['actor'] = $item['author-link'];
 960                 } else {
 961                         $data['actor'] = $item['owner-link'];
 962                 }
 963
 964                 $data['published'] = DateTimeFormat::utc($item['created'] . '+00:00', DateTimeFormat::ATOM);
 965
 966                 $data['instrument'] = self::getService();
 967
 968                 $data = array_merge($data, self::createPermissionBlockForItem($item, false));
 969
 970                 if (in_array($data['type'], ['Create', 'Update', 'Delete'])) {
 971                         $data['object'] = $object ?? self::createNote($item);
 972                 } elseif ($data['type'] == 'Add') {
 973                         $data = self::createAddTag($item, $data);
 974                 } elseif ($data['type'] == 'Announce') {
 975                         if ($item['verb'] == ACTIVITY::ANNOUNCE) {
 976                                 $data['object'] = $item['thr-parent'];
 977                         } else {
 978                                 $data = self::createAnnounce($item, $data);
 979                         }
 980                 } elseif ($data['type'] == 'Follow') {
 981                         $data['object'] = $item['parent-uri'];
 982                 } elseif ($data['type'] == 'Undo') {
 983                         $data['object'] = self::createActivityFromItem($item_id, true);
 984                 } else {
 985                         $data['diaspora:guid'] = $item['guid'];
 986                         if (!empty($item['signed_text'])) {
 987                                 $data['diaspora:like'] = $item['signed_text'];
 988                         }
 989                         $data['object'] = $item['thr-parent'];
 990                 }
 991
 992                 if (!empty($item['contact-uid'])) {
 993                         $uid = $item['contact-uid'];
 994                 } else {
 995                         $uid = $item['uid'];
 996                 }
 997
 998                 $owner = User::getOwnerDataById($uid);
 999
1000                 Logger::info('Fetched activity', ['item' => $item_id, 'uid' => $uid]);
1001
1002                 // We don't sign if we aren't the actor. This is important for relaying content especially for forums
1003                 if (!$object_mode && !empty($owner) && ($data['actor'] == $owner['url'])) {
1004                         return LDSignature::sign($data, $owner);
1005                 } else {
1006                         return $data;
1007                 }
1008
1009                 /// @todo Create "conversation" entry
1010         }
1011
1012         /**
1013          * Creates a location entry for a given item array
1014          *
1015          * @param array $item
1016          *
1017          * @return array with location array
1018          */
1019         private static function createLocation($item)
1020         {
1021                 $location = ['type' => 'Place'];
1022
1023                 if (!empty($item['location'])) {
1024                         $location['name'] = $item['location'];
1025                 }
1026
1027                 $coord = [];
1028
1029                 if (empty($item['coord'])) {
1030                         $coord = Map::getCoordinates($item['location']);
1031                 } else {
1032                         $coords = explode(' ', $item['coord']);
1033                         if (count($coords) == 2) {
1034                                 $coord = ['lat' => $coords[0], 'lon' => $coords[1]];
1035                         }
1036                 }
1037
1038                 if (!empty($coord['lat']) && !empty($coord['lon'])) {
1039                         $location['latitude'] = $coord['lat'];
1040                         $location['longitude'] = $coord['lon'];
1041                 }
1042
1043                 return $location;
1044         }
1045
1046         /**
1047          * Returns a tag array for a given item array
1048          *
1049          * @param array $item
1050          *
1051          * @return array of tags
1052          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1053          */
1054         private static function createTagList($item)
1055         {
1056                 $tags = [];
1057
1058                 $terms = Tag::getByURIId($item['uri-id'], [Tag::HASHTAG, Tag::MENTION, Tag::IMPLICIT_MENTION, Tag::EXCLUSIVE_MENTION]);
1059                 foreach ($terms as $term) {
1060                         if ($term['type'] == Tag::HASHTAG) {
1061                                 $url = DI::baseUrl() . '/search?tag=' . urlencode($term['name']);
1062                                 $tags[] = ['type' => 'Hashtag', 'href' => $url, 'name' => '#' . $term['name']];
1063                         } else {
1064                                 $contact = Contact::getByURL($term['url'], false, ['addr']);
1065                                 if (empty($contact)) {
1066                                         continue;
1067                                 }
1068                                 if (!empty($contact['addr'])) {
1069                                         $mention = '@' . $contact['addr'];
1070                                 } else {
1071                                         $mention = '@' . $term['url'];
1072                                 }
1073
1074                                 $tags[] = ['type' => 'Mention', 'href' => $term['url'], 'name' => $mention];
1075                         }
1076                 }
1077
1078                 $announce = self::getAnnounceArray($item);
1079                 // Mention the original author upon commented reshares
1080                 if (!empty($announce['comment'])) {
1081                         $tags[] = ['type' => 'Mention', 'href' => $announce['actor']['url'], 'name' => '@' . $announce['actor']['addr']];
1082                 }
1083
1084                 return $tags;
1085         }
1086
1087         /**
1088          * Adds attachment data to the JSON document
1089          *
1090          * @param array  $item Data of the item that is to be posted
1091          * @param string $type Object type
1092          *
1093          * @return array with attachment data
1094          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1095          */
1096         private static function createAttachmentList($item, $type)
1097         {
1098                 $attachments = [];
1099
1100                 // Currently deactivated, since it creates side effects on Mastodon and Pleroma.
1101                 // It will be reactivated, once this cleared.
1102                 /*
1103                 $attach_data = BBCode::getAttachmentData($item['body']);
1104                 if (!empty($attach_data['url'])) {
1105                         $attachment = ['type' => 'Page',
1106                                 'mediaType' => 'text/html',
1107                                 'url' => $attach_data['url']];
1108
1109                         if (!empty($attach_data['title'])) {
1110                                 $attachment['name'] = $attach_data['title'];
1111                         }
1112
1113                         if (!empty($attach_data['description'])) {
1114                                 $attachment['summary'] = $attach_data['description'];
1115                         }
1116
1117                         if (!empty($attach_data['image'])) {
1118                                 $imgdata = Images::getInfoFromURLCached($attach_data['image']);
1119                                 if ($imgdata) {
1120                                         $attachment['icon'] = ['type' => 'Image',
1121                                                 'mediaType' => $imgdata['mime'],
1122                                                 'width' => $imgdata[0],
1123                                                 'height' => $imgdata[1],
1124                                                 'url' => $attach_data['image']];
1125                                 }
1126                         }
1127
1128                         $attachments[] = $attachment;
1129                 }
1130                 */
1131                 $arr = explode('[/attach],', $item['attach']);
1132                 if (count($arr)) {
1133                         foreach ($arr as $r) {
1134                                 $matches = false;
1135                                 $cnt = preg_match('|\[attach\]href=\"(.*?)\" length=\"(.*?)\" type=\"(.*?)\" title=\"(.*?)\"|', $r, $matches);
1136                                 if ($cnt) {
1137                                         $attributes = ['type' => 'Document',
1138                                                         'mediaType' => $matches[3],
1139                                                         'url' => $matches[1],
1140                                                         'name' => null];
1141
1142                                         if (trim($matches[4]) != '') {
1143                                                 $attributes['name'] = trim($matches[4]);
1144                                         }
1145
1146                                         $attachments[] = $attributes;
1147                                 }
1148                         }
1149                 }
1150
1151                 if ($type != 'Note') {
1152                         return $attachments;
1153                 }
1154
1155                 // Simplify image codes
1156                 $body = preg_replace("/\[img\=([0-9]*)x([0-9]*)\](.*?)\[\/img\]/ism", '[img]$3[/img]', $item['body']);
1157
1158                 // Grab all pictures without alternative descriptions and create attachments out of them
1159                 if (preg_match_all("/\[img\]([^\[\]]*)\[\/img\]/Usi", $body, $pictures)) {
1160                         foreach ($pictures[1] as $picture) {
1161                                 $imgdata = Images::getInfoFromURLCached($picture);
1162                                 if ($imgdata) {
1163                                         $attachments[] = ['type' => 'Document',
1164                                                 'mediaType' => $imgdata['mime'],
1165                                                 'url' => $picture,
1166                                                 'name' => null];
1167                                 }
1168                         }
1169                 }
1170
1171                 // Grab all pictures with alternative description and create attachments out of them
1172                 if (preg_match_all("/\[img=([^\[\]]*)\]([^\[\]]*)\[\/img\]/Usi", $body, $pictures, PREG_SET_ORDER)) {
1173                         foreach ($pictures as $picture) {
1174                                 $imgdata = Images::getInfoFromURLCached($picture[1]);
1175                                 if ($imgdata) {
1176                                         $attachments[] = ['type' => 'Document',
1177                                                 'mediaType' => $imgdata['mime'],
1178                                                 'url' => $picture[1],
1179                                                 'name' => $picture[2]];
1180                                 }
1181                         }
1182                 }
1183
1184                 return $attachments;
1185         }
1186
1187         /**
1188          * Callback function to replace a Friendica style mention in a mention that is used on AP
1189          *
1190          * @param array $match Matching values for the callback
1191          * @return string Replaced mention
1192          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1193          */
1194         private static function mentionCallback($match)
1195         {
1196                 if (empty($match[1])) {
1197                         return '';
1198                 }
1199
1200                 $data = Contact::getByURL($match[1], false, ['url', 'nick']);
1201                 if (empty($data['nick'])) {
1202                         return $match[0];
1203                 }
1204
1205                 return '@[url=' . $data['url'] . ']' . $data['nick'] . '[/url]';
1206         }
1207
1208         /**
1209          * Remove image elements since they are added as attachment
1210          *
1211          * @param string $body
1212          *
1213          * @return string with removed images
1214          */
1215         private static function removePictures($body)
1216         {
1217                 // Simplify image codes
1218                 $body = preg_replace("/\[img\=([0-9]*)x([0-9]*)\](.*?)\[\/img\]/ism", '[img]$3[/img]', $body);
1219                 $body = preg_replace("/\[img\=(.*?)\](.*?)\[\/img\]/ism", '[img]$1[/img]', $body);
1220
1221                 // Now remove local links
1222                 $body = preg_replace_callback(
1223                         '/\[url=([^\[\]]*)\]\[img\](.*)\[\/img\]\[\/url\]/Usi',
1224                         function ($match) {
1225                                 // We remove the link when it is a link to a local photo page
1226                                 if (Photo::isLocalPage($match[1])) {
1227                                         return '';
1228                                 }
1229                                 // otherwise we just return the link
1230                                 return '[url]' . $match[1] . '[/url]';
1231                         },
1232                         $body
1233                 );
1234
1235                 // Remove all pictures
1236                 $body = preg_replace("/\[img\]([^\[\]]*)\[\/img\]/Usi", '', $body);
1237
1238                 return $body;
1239         }
1240
1241         /**
1242          * Fetches the "context" value for a givem item array from the "conversation" table
1243          *
1244          * @param array $item
1245          *
1246          * @return string with context url
1247          * @throws \Exception
1248          */
1249         private static function fetchContextURLForItem($item)
1250         {
1251                 $conversation = DBA::selectFirst('conversation', ['conversation-href', 'conversation-uri'], ['item-uri' => $item['parent-uri']]);
1252                 if (DBA::isResult($conversation) && !empty($conversation['conversation-href'])) {
1253                         $context_uri = $conversation['conversation-href'];
1254                 } elseif (DBA::isResult($conversation) && !empty($conversation['conversation-uri'])) {
1255                         $context_uri = $conversation['conversation-uri'];
1256                 } else {
1257                         $context_uri = $item['parent-uri'] . '#context';
1258                 }
1259                 return $context_uri;
1260         }
1261
1262         /**
1263          * Returns if the post contains sensitive content ("nsfw")
1264          *
1265          * @param integer $uri_id
1266          *
1267          * @return boolean
1268          * @throws \Exception
1269          */
1270         private static function isSensitive($uri_id)
1271         {
1272                 return DBA::exists('tag-view', ['uri-id' => $uri_id, 'name' => 'nsfw']);
1273         }
1274
1275         /**
1276          * Creates event data
1277          *
1278          * @param array $item
1279          *
1280          * @return array with the event data
1281          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1282          */
1283         public static function createEvent($item)
1284         {
1285                 $event = [];
1286                 $event['name'] = $item['event-summary'];
1287                 $event['content'] = BBCode::convert($item['event-desc'], false, BBCode::ACTIVITYPUB);
1288                 $event['startTime'] = DateTimeFormat::utc($item['event-start'] . '+00:00', DateTimeFormat::ATOM);
1289
1290                 if (!$item['event-nofinish']) {
1291                         $event['endTime'] = DateTimeFormat::utc($item['event-finish'] . '+00:00', DateTimeFormat::ATOM);
1292                 }
1293
1294                 if (!empty($item['event-location'])) {
1295                         $item['location'] = $item['event-location'];
1296                         $event['location'] = self::createLocation($item);
1297                 }
1298
1299                 return $event;
1300         }
1301
1302         /**
1303          * Creates a note/article object array
1304          *
1305          * @param array $item
1306          *
1307          * @return array with the object data
1308          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1309          * @throws \ImagickException
1310          */
1311         public static function createNote($item)
1312         {
1313                 if (empty($item)) {
1314                         return [];
1315                 }
1316
1317                 if ($item['event-type'] == 'event') {
1318                         $type = 'Event';
1319                 } elseif (!empty($item['title'])) {
1320                         $type = 'Article';
1321                 } else {
1322                         $type = 'Note';
1323                 }
1324
1325                 if ($item['deleted']) {
1326                         $type = 'Tombstone';
1327                 }
1328
1329                 $data = [];
1330                 $data['id'] = $item['uri'];
1331                 $data['type'] = $type;
1332
1333                 if ($item['deleted']) {
1334                         return $data;
1335                 }
1336
1337                 $data['summary'] = BBCode::toPlaintext(BBCode::getAbstract($item['body'], Protocol::ACTIVITYPUB));
1338
1339                 if ($item['uri'] != $item['thr-parent']) {
1340                         $data['inReplyTo'] = $item['thr-parent'];
1341                 } else {
1342                         $data['inReplyTo'] = null;
1343                 }
1344
1345                 $data['diaspora:guid'] = $item['guid'];
1346                 $data['published'] = DateTimeFormat::utc($item['created'] . '+00:00', DateTimeFormat::ATOM);
1347
1348                 if ($item['created'] != $item['edited']) {
1349                         $data['updated'] = DateTimeFormat::utc($item['edited'] . '+00:00', DateTimeFormat::ATOM);
1350                 }
1351
1352                 $data['url'] = $item['plink'];
1353                 $data['attributedTo'] = $item['author-link'];
1354                 $data['sensitive'] = self::isSensitive($item['uri-id']);
1355                 $data['context'] = self::fetchContextURLForItem($item);
1356
1357                 if (!empty($item['title'])) {
1358                         $data['name'] = BBCode::toPlaintext($item['title'], false);
1359                 }
1360
1361                 $permission_block = self::createPermissionBlockForItem($item, false);
1362
1363                 $body = $item['body'];
1364
1365                 if (empty($item['uid']) || !Feature::isEnabled($item['uid'], 'explicit_mentions')) {
1366                         $body = self::prependMentions($body, $item['uri-id']);
1367                 }
1368
1369                 if ($type == 'Note') {
1370                         $body = self::removePictures($body);
1371                 } elseif (($type == 'Article') && empty($data['summary'])) {
1372                         $data['summary'] = BBCode::toPlaintext(Plaintext::shorten(self::removePictures($body), 1000));
1373                 }
1374
1375                 if ($type == 'Event') {
1376                         $data = array_merge($data, self::createEvent($item));
1377                 } else {
1378                         $regexp = "/[@!]\[url\=([^\[\]]*)\].*?\[\/url\]/ism";
1379                         $body = preg_replace_callback($regexp, ['self', 'mentionCallback'], $body);
1380
1381                         $data['content'] = BBCode::convert($body, false, BBCode::ACTIVITYPUB);
1382                 }
1383
1384                 // The regular "content" field does contain a minimized HTML. This is done since systems like
1385                 // Mastodon has got problems with - for example - embedded pictures.
1386                 // The contentMap does contain the unmodified HTML.
1387                 $language = self::getLanguage($item);
1388                 if (!empty($language)) {
1389                         $regexp = "/[@!]\[url\=([^\[\]]*)\].*?\[\/url\]/ism";
1390                         $richbody = preg_replace_callback($regexp, ['self', 'mentionCallback'], $item['body']);
1391                         $richbody = BBCode::removeAttachment($richbody);
1392
1393                         $data['contentMap'][$language] = BBCode::convert($richbody, false);
1394                 }
1395
1396                 $data['source'] = ['content' => $item['body'], 'mediaType' => "text/bbcode"];
1397
1398                 if (!empty($item['signed_text']) && ($item['uri'] != $item['thr-parent'])) {
1399                         $data['diaspora:comment'] = $item['signed_text'];
1400                 }
1401
1402                 $data['attachment'] = self::createAttachmentList($item, $type);
1403                 $data['tag'] = self::createTagList($item);
1404
1405                 if (empty($data['location']) && (!empty($item['coord']) || !empty($item['location']))) {
1406                         $data['location'] = self::createLocation($item);
1407                 }
1408
1409                 if (!empty($item['app'])) {
1410                         $data['generator'] = ['type' => 'Application', 'name' => $item['app']];
1411                 }
1412
1413                 $data = array_merge($data, $permission_block);
1414
1415                 return $data;
1416         }
1417
1418         /**
1419          * Fetches the language from the post, the user or the system.
1420          *
1421          * @param array $item
1422          *
1423          * @return string language string
1424          */
1425         private static function getLanguage(array $item)
1426         {
1427                 // Try to fetch the language from the post itself
1428                 if (!empty($item['language'])) {
1429                         $languages = array_keys(json_decode($item['language'], true));
1430                         if (!empty($languages[0])) {
1431                                 return $languages[0];
1432                         }
1433                 }
1434
1435                 // Otherwise use the user's language
1436                 if (!empty($item['uid'])) {
1437                         $user = DBA::selectFirst('user', ['language'], ['uid' => $item['uid']]);
1438                         if (!empty($user['language'])) {
1439                                 return $user['language'];
1440                         }
1441                 }
1442
1443                 // And finally just use the system language
1444                 return DI::config()->get('system', 'language');
1445         }
1446
1447         /**
1448          * Creates an an "add tag" entry
1449          *
1450          * @param array $item
1451          * @param array $data activity data
1452          *
1453          * @return array with activity data for adding tags
1454          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1455          * @throws \ImagickException
1456          */
1457         private static function createAddTag($item, $data)
1458         {
1459                 $object = XML::parseString($item['object']);
1460                 $target = XML::parseString($item["target"]);
1461
1462                 $data['diaspora:guid'] = $item['guid'];
1463                 $data['actor'] = $item['author-link'];
1464                 $data['target'] = (string)$target->id;
1465                 $data['summary'] = BBCode::toPlaintext($item['body']);
1466                 $data['object'] = ['id' => (string)$object->id, 'type' => 'tag', 'name' => (string)$object->title, 'content' => (string)$object->content];
1467
1468                 return $data;
1469         }
1470
1471         /**
1472          * Creates an announce object entry
1473          *
1474          * @param array $item
1475          * @param array $data activity data
1476          *
1477          * @return array with activity data
1478          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1479          * @throws \ImagickException
1480          */
1481         private static function createAnnounce($item, $data)
1482         {
1483                 $orig_body = $item['body'];
1484                 $announce = self::getAnnounceArray($item);
1485                 if (empty($announce)) {
1486                         $data['type'] = 'Create';
1487                         $data['object'] = self::createNote($item);
1488                         return $data;
1489                 }
1490
1491                 if (empty($announce['comment'])) {
1492                         // Pure announce, without a quote
1493                         $data['type'] = 'Announce';
1494                         $data['object'] = $announce['object']['uri'];
1495                         return $data;
1496                 }
1497
1498                 // Quote
1499                 $data['type'] = 'Create';
1500                 $item['body'] = $announce['comment'] . "\n" . $announce['object']['plink'];
1501                 $data['object'] = self::createNote($item);
1502
1503                 /// @todo Finally descide how to implement this in AP. This is a possible way:
1504                 $data['object']['attachment'][] = self::createNote($announce['object']);
1505
1506                 $data['object']['source']['content'] = $orig_body;
1507                 return $data;
1508         }
1509
1510         /**
1511          * Return announce related data if the item is an annunce
1512          *
1513          * @param array $item
1514          *
1515          * @return array
1516          */
1517         public static function getAnnounceArray($item)
1518         {
1519                 $reshared = Item::getShareArray($item);
1520                 if (empty($reshared['guid'])) {
1521                         return [];
1522                 }
1523
1524                 $reshared_item = Item::selectFirst([], ['guid' => $reshared['guid']]);
1525                 if (!DBA::isResult($reshared_item)) {
1526                         return [];
1527                 }
1528
1529                 if (!in_array($reshared_item['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN])) {
1530                         return [];
1531                 }
1532
1533                 $profile = APContact::getByURL($reshared_item['author-link'], false);
1534                 if (empty($profile)) {
1535                         return [];
1536                 }
1537
1538                 return ['object' => $reshared_item, 'actor' => $profile, 'comment' => $reshared['comment']];
1539         }
1540
1541         /**
1542          * Checks if the provided item array is an announce
1543          *
1544          * @param array $item
1545          *
1546          * @return boolean
1547          */
1548         public static function isAnnounce($item)
1549         {
1550                 if ($item['verb'] == Activity::ANNOUNCE) {
1551                         return true;
1552                 }
1553
1554                 $announce = self::getAnnounceArray($item);
1555                 if (empty($announce)) {
1556                         return false;
1557                 }
1558
1559                 return empty($announce['comment']);
1560         }
1561
1562         /**
1563          * Creates an activity id for a given contact id
1564          *
1565          * @param integer $cid Contact ID of target
1566          *
1567          * @return bool|string activity id
1568          */
1569         public static function activityIDFromContact($cid)
1570         {
1571                 $contact = DBA::selectFirst('contact', ['uid', 'id', 'created'], ['id' => $cid]);
1572                 if (!DBA::isResult($contact)) {
1573                         return false;
1574                 }
1575
1576                 $hash = hash('ripemd128', $contact['uid'].'-'.$contact['id'].'-'.$contact['created']);
1577                 $uuid = substr($hash, 0, 8). '-' . substr($hash, 8, 4) . '-' . substr($hash, 12, 4) . '-' . substr($hash, 16, 4) . '-' . substr($hash, 20, 12);
1578                 return DI::baseUrl() . '/activity/' . $uuid;
1579         }
1580
1581         /**
1582          * Transmits a contact suggestion to a given inbox
1583          *
1584          * @param integer $uid           User ID
1585          * @param string  $inbox         Target inbox
1586          * @param integer $suggestion_id Suggestion ID
1587          *
1588          * @return boolean was the transmission successful?
1589          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1590          */
1591         public static function sendContactSuggestion($uid, $inbox, $suggestion_id)
1592         {
1593                 $owner = User::getOwnerDataById($uid);
1594
1595                 $suggestion = DI::fsuggest()->getById($suggestion_id);
1596
1597                 $data = ['@context' => ActivityPub::CONTEXT,
1598                         'id' => DI::baseUrl() . '/activity/' . System::createGUID(),
1599                         'type' => 'Announce',
1600                         'actor' => $owner['url'],
1601                         'object' => $suggestion->url,
1602                         'content' => $suggestion->note,
1603                         'instrument' => self::getService(),
1604                         'to' => [ActivityPub::PUBLIC_COLLECTION],
1605                         'cc' => []];
1606
1607                 $signed = LDSignature::sign($data, $owner);
1608
1609                 Logger::log('Deliver profile deletion for user ' . $uid . ' to ' . $inbox . ' via ActivityPub', Logger::DEBUG);
1610                 return HTTPSignature::transmit($signed, $inbox, $uid);
1611         }
1612
1613         /**
1614          * Transmits a profile relocation to a given inbox
1615          *
1616          * @param integer $uid   User ID
1617          * @param string  $inbox Target inbox
1618          *
1619          * @return boolean was the transmission successful?
1620          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1621          */
1622         public static function sendProfileRelocation($uid, $inbox)
1623         {
1624                 $owner = User::getOwnerDataById($uid);
1625
1626                 $data = ['@context' => ActivityPub::CONTEXT,
1627                         'id' => DI::baseUrl() . '/activity/' . System::createGUID(),
1628                         'type' => 'dfrn:relocate',
1629                         'actor' => $owner['url'],
1630                         'object' => $owner['url'],
1631                         'published' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
1632                         'instrument' => self::getService(),
1633                         'to' => [ActivityPub::PUBLIC_COLLECTION],
1634                         'cc' => []];
1635
1636                 $signed = LDSignature::sign($data, $owner);
1637
1638                 Logger::log('Deliver profile relocation for user ' . $uid . ' to ' . $inbox . ' via ActivityPub', Logger::DEBUG);
1639                 return HTTPSignature::transmit($signed, $inbox, $uid);
1640         }
1641
1642         /**
1643          * Transmits a profile deletion to a given inbox
1644          *
1645          * @param integer $uid   User ID
1646          * @param string  $inbox Target inbox
1647          *
1648          * @return boolean was the transmission successful?
1649          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1650          */
1651         public static function sendProfileDeletion($uid, $inbox)
1652         {
1653                 $owner = User::getOwnerDataById($uid);
1654
1655                 if (empty($owner)) {
1656                         Logger::error('No owner data found, the deletion message cannot be processed.', ['user' => $uid]);
1657                         return false;
1658                 }
1659
1660                 if (empty($owner['uprvkey'])) {
1661                         Logger::error('No private key for owner found, the deletion message cannot be processed.', ['user' => $uid]);
1662                         return false;
1663                 }
1664
1665                 $data = ['@context' => ActivityPub::CONTEXT,
1666                         'id' => DI::baseUrl() . '/activity/' . System::createGUID(),
1667                         'type' => 'Delete',
1668                         'actor' => $owner['url'],
1669                         'object' => $owner['url'],
1670                         'published' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
1671                         'instrument' => self::getService(),
1672                         'to' => [ActivityPub::PUBLIC_COLLECTION],
1673                         'cc' => []];
1674
1675                 $signed = LDSignature::sign($data, $owner);
1676
1677                 Logger::log('Deliver profile deletion for user ' . $uid . ' to ' . $inbox . ' via ActivityPub', Logger::DEBUG);
1678                 return HTTPSignature::transmit($signed, $inbox, $uid);
1679         }
1680
1681         /**
1682          * Transmits a profile change to a given inbox
1683          *
1684          * @param integer $uid   User ID
1685          * @param string  $inbox Target inbox
1686          *
1687          * @return boolean was the transmission successful?
1688          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1689          * @throws \ImagickException
1690          */
1691         public static function sendProfileUpdate($uid, $inbox)
1692         {
1693                 $owner = User::getOwnerDataById($uid);
1694                 $profile = APContact::getByURL($owner['url']);
1695
1696                 $data = ['@context' => ActivityPub::CONTEXT,
1697                         'id' => DI::baseUrl() . '/activity/' . System::createGUID(),
1698                         'type' => 'Update',
1699                         'actor' => $owner['url'],
1700                         'object' => self::getProfile($uid),
1701                         'published' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
1702                         'instrument' => self::getService(),
1703                         'to' => [$profile['followers']],
1704                         'cc' => []];
1705
1706                 $signed = LDSignature::sign($data, $owner);
1707
1708                 Logger::log('Deliver profile update for user ' . $uid . ' to ' . $inbox . ' via ActivityPub', Logger::DEBUG);
1709                 return HTTPSignature::transmit($signed, $inbox, $uid);
1710         }
1711
1712         /**
1713          * Transmits a given activity to a target
1714          *
1715          * @param string  $activity Type name
1716          * @param string  $target   Target profile
1717          * @param integer $uid      User ID
1718          * @return bool
1719          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1720          * @throws \ImagickException
1721          * @throws \Exception
1722          */
1723         public static function sendActivity($activity, $target, $uid, $id = '')
1724         {
1725                 $profile = APContact::getByURL($target);
1726                 if (empty($profile['inbox'])) {
1727                         Logger::warning('No inbox found for target', ['target' => $target, 'profile' => $profile]);
1728                         return;
1729                 }
1730
1731                 $owner = User::getOwnerDataById($uid);
1732
1733                 if (empty($id)) {
1734                         $id = DI::baseUrl() . '/activity/' . System::createGUID();
1735                 }
1736
1737                 $data = ['@context' => ActivityPub::CONTEXT,
1738                         'id' => $id,
1739                         'type' => $activity,
1740                         'actor' => $owner['url'],
1741                         'object' => $profile['url'],
1742                         'instrument' => self::getService(),
1743                         'to' => [$profile['url']]];
1744
1745                 Logger::log('Sending activity ' . $activity . ' to ' . $target . ' for user ' . $uid, Logger::DEBUG);
1746
1747                 $signed = LDSignature::sign($data, $owner);
1748                 return HTTPSignature::transmit($signed, $profile['inbox'], $uid);
1749         }
1750
1751         /**
1752          * Transmits a "follow object" activity to a target
1753          * This is a preparation for sending automated "follow" requests when receiving "Announce" messages
1754          *
1755          * @param string  $object Object URL
1756          * @param string  $target Target profile
1757          * @param integer $uid    User ID
1758          * @return bool
1759          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1760          * @throws \ImagickException
1761          * @throws \Exception
1762          */
1763         public static function sendFollowObject($object, $target, $uid = 0)
1764         {
1765                 $profile = APContact::getByURL($target);
1766                 if (empty($profile['inbox'])) {
1767                         Logger::warning('No inbox found for target', ['target' => $target, 'profile' => $profile]);
1768                         return;
1769                 }
1770
1771                 if (empty($uid)) {
1772                         // Fetch the list of administrators
1773                         $admin_mail = explode(',', str_replace(' ', '', DI::config()->get('config', 'admin_email')));
1774
1775                         // We need to use some user as a sender. It doesn't care who it will send. We will use an administrator account.
1776                         $condition = ['verified' => true, 'blocked' => false, 'account_removed' => false, 'account_expired' => false, 'email' => $admin_mail];
1777                         $first_user = DBA::selectFirst('user', ['uid'], $condition);
1778                         $uid = $first_user['uid'];
1779                 }
1780
1781                 $condition = ['verb' => Activity::FOLLOW, 'uid' => 0, 'parent-uri' => $object,
1782                         'author-id' => Contact::getPublicIdByUserId($uid)];
1783                 if (Item::exists($condition)) {
1784                         Logger::log('Follow for ' . $object . ' for user ' . $uid . ' does already exist.', Logger::DEBUG);
1785                         return false;
1786                 }
1787
1788                 $owner = User::getOwnerDataById($uid);
1789
1790                 $data = ['@context' => ActivityPub::CONTEXT,
1791                         'id' => DI::baseUrl() . '/activity/' . System::createGUID(),
1792                         'type' => 'Follow',
1793                         'actor' => $owner['url'],
1794                         'object' => $object,
1795                         'instrument' => self::getService(),
1796                         'to' => [$profile['url']]];
1797
1798                 Logger::log('Sending follow ' . $object . ' to ' . $target . ' for user ' . $uid, Logger::DEBUG);
1799
1800                 $signed = LDSignature::sign($data, $owner);
1801                 return HTTPSignature::transmit($signed, $profile['inbox'], $uid);
1802         }
1803
1804         /**
1805          * Transmit a message that the contact request had been accepted
1806          *
1807          * @param string  $target Target profile
1808          * @param         $id
1809          * @param integer $uid    User ID
1810          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1811          * @throws \ImagickException
1812          */
1813         public static function sendContactAccept($target, $id, $uid)
1814         {
1815                 $profile = APContact::getByURL($target);
1816                 if (empty($profile['inbox'])) {
1817                         Logger::warning('No inbox found for target', ['target' => $target, 'profile' => $profile]);
1818                         return;
1819                 }
1820
1821                 $owner = User::getOwnerDataById($uid);
1822                 $data = ['@context' => ActivityPub::CONTEXT,
1823                         'id' => DI::baseUrl() . '/activity/' . System::createGUID(),
1824                         'type' => 'Accept',
1825                         'actor' => $owner['url'],
1826                         'object' => [
1827                                 'id' => (string)$id,
1828                                 'type' => 'Follow',
1829                                 'actor' => $profile['url'],
1830                                 'object' => $owner['url']
1831                         ],
1832                         'instrument' => self::getService(),
1833                         'to' => [$profile['url']]];
1834
1835                 Logger::debug('Sending accept to ' . $target . ' for user ' . $uid . ' with id ' . $id);
1836
1837                 $signed = LDSignature::sign($data, $owner);
1838                 HTTPSignature::transmit($signed, $profile['inbox'], $uid);
1839         }
1840
1841         /**
1842          * Reject a contact request or terminates the contact relation
1843          *
1844          * @param string  $target Target profile
1845          * @param         $id
1846          * @param integer $uid    User ID
1847          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1848          * @throws \ImagickException
1849          */
1850         public static function sendContactReject($target, $id, $uid)
1851         {
1852                 $profile = APContact::getByURL($target);
1853                 if (empty($profile['inbox'])) {
1854                         Logger::warning('No inbox found for target', ['target' => $target, 'profile' => $profile]);
1855                         return;
1856                 }
1857
1858                 $owner = User::getOwnerDataById($uid);
1859                 $data = ['@context' => ActivityPub::CONTEXT,
1860                         'id' => DI::baseUrl() . '/activity/' . System::createGUID(),
1861                         'type' => 'Reject',
1862                         'actor' => $owner['url'],
1863                         'object' => [
1864                                 'id' => (string)$id,
1865                                 'type' => 'Follow',
1866                                 'actor' => $profile['url'],
1867                                 'object' => $owner['url']
1868                         ],
1869                         'instrument' => self::getService(),
1870                         'to' => [$profile['url']]];
1871
1872                 Logger::debug('Sending reject to ' . $target . ' for user ' . $uid . ' with id ' . $id);
1873
1874                 $signed = LDSignature::sign($data, $owner);
1875                 HTTPSignature::transmit($signed, $profile['inbox'], $uid);
1876         }
1877
1878         /**
1879          * Transmits a message that we don't want to follow this contact anymore
1880          *
1881          * @param string  $target Target profile
1882          * @param integer $uid    User ID
1883          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1884          * @throws \ImagickException
1885          * @throws \Exception
1886          */
1887         public static function sendContactUndo($target, $cid, $uid)
1888         {
1889                 $profile = APContact::getByURL($target);
1890                 if (empty($profile['inbox'])) {
1891                         Logger::warning('No inbox found for target', ['target' => $target, 'profile' => $profile]);
1892                         return;
1893                 }
1894
1895                 $object_id = self::activityIDFromContact($cid);
1896                 if (empty($object_id)) {
1897                         return;
1898                 }
1899
1900                 $id = DI::baseUrl() . '/activity/' . System::createGUID();
1901
1902                 $owner = User::getOwnerDataById($uid);
1903                 $data = ['@context' => ActivityPub::CONTEXT,
1904                         'id' => $id,
1905                         'type' => 'Undo',
1906                         'actor' => $owner['url'],
1907                         'object' => ['id' => $object_id, 'type' => 'Follow',
1908                                 'actor' => $owner['url'],
1909                                 'object' => $profile['url']],
1910                         'instrument' => self::getService(),
1911                         'to' => [$profile['url']]];
1912
1913                 Logger::log('Sending undo to ' . $target . ' for user ' . $uid . ' with id ' . $id, Logger::DEBUG);
1914
1915                 $signed = LDSignature::sign($data, $owner);
1916                 HTTPSignature::transmit($signed, $profile['inbox'], $uid);
1917         }
1918
1919         private static function prependMentions($body, int $uriid)
1920         {
1921                 $mentions = [];
1922
1923                 foreach (Tag::getByURIId($uriid, [Tag::IMPLICIT_MENTION]) as $tag) {
1924                         $profile = Contact::getByURL($tag['url'], false, ['addr', 'contact-type', 'nick']);
1925                         if (!empty($profile['addr'])
1926                                 && $profile['contact-type'] != Contact::TYPE_COMMUNITY
1927                                 && !strstr($body, $profile['addr'])
1928                                 && !strstr($body, $tag['url'])
1929                         ) {
1930                                 $mentions[] = '@[url=' . $tag['url'] . ']' . $profile['nick'] . '[/url]';
1931                         }
1932                 }
1933
1934                 $mentions[] = $body;
1935
1936                 return implode(' ', $mentions);
1937         }
1938 }