src/Protocol/ActivityPub/Processor.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\Text\BBCode;
  25 use Friendica\Content\Text\HTML;
  26 use Friendica\Core\Logger;
  27 use Friendica\Core\Protocol;
  28 use Friendica\Database\DBA;
  29 use Friendica\DI;
  30 use Friendica\Model\APContact;
  31 use Friendica\Model\Contact;
  32 use Friendica\Model\Conversation;
  33 use Friendica\Model\Event;
  34 use Friendica\Model\Item;
  35 use Friendica\Model\Mail;
  36 use Friendica\Model\Term;
  37 use Friendica\Model\User;
  38 use Friendica\Protocol\Activity;
  39 use Friendica\Protocol\ActivityPub;
  40 use Friendica\Util\DateTimeFormat;
  41 use Friendica\Util\JsonLD;
  42 use Friendica\Util\Strings;
  43
  44 /**
  45  * ActivityPub Processor Protocol class
  46  */
  47 class Processor
  48 {
  49         /**
  50          * Converts mentions from Pleroma into the Friendica format
  51          *
  52          * @param string $body
  53          *
  54          * @return string converted body
  55          */
  56         private static function convertMentions($body)
  57         {
  58                 $URLSearchString = "^\[\]";
  59                 $body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
  60
  61                 return $body;
  62         }
  63
  64         /**
  65          * Replaces emojis in the body
  66          *
  67          * @param array $emojis
  68          * @param string $body
  69          *
  70          * @return string with replaced emojis
  71          */
  72         private static function replaceEmojis($body, array $emojis)
  73         {
  74                 foreach ($emojis as $emoji) {
  75                         $replace = '[class=emoji mastodon][img=' . $emoji['href'] . ']' . $emoji['name'] . '[/img][/class]';
  76                         $body = str_replace($emoji['name'], $replace, $body);
  77                 }
  78                 return $body;
  79         }
  80
  81         /**
  82          * Constructs a string with tags for a given tag array
  83          *
  84          * @param array   $tags
  85          * @param boolean $sensitive
  86          * @return string with tags
  87          */
  88         private static function constructTagString(array $tags = null, $sensitive = false)
  89         {
  90                 if (empty($tags)) {
  91                         return '';
  92                 }
  93
  94                 $tag_text = '';
  95                 foreach ($tags as $tag) {
  96                         if (in_array($tag['type'] ?? '', ['Mention', 'Hashtag'])) {
  97                                 if (!empty($tag_text)) {
  98                                         $tag_text .= ',';
  99                                 }
 100
 101                                 $tag_text .= substr($tag['name'], 0, 1) . '[url=' . $tag['href'] . ']' . substr($tag['name'], 1) . '[/url]';
 102                         }
 103                 }
 104
 105                 /// @todo add nsfw for $sensitive
 106
 107                 return $tag_text;
 108         }
 109
 110         /**
 111          * Add attachment data to the item array
 112          *
 113          * @param array   $activity
 114          * @param array   $item
 115          *
 116          * @return array array
 117          */
 118         private static function constructAttachList($activity, $item)
 119         {
 120                 if (empty($activity['attachments'])) {
 121                         return $item;
 122                 }
 123
 124                 foreach ($activity['attachments'] as $attach) {
 125                         $filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
 126                         if ($filetype == 'image') {
 127                                 if (!empty($activity['source']) && strpos($activity['source'], $attach['url'])) {
 128                                         continue;
 129                                 }
 130
 131                                 if (empty($attach['name'])) {
 132                                         $item['body'] .= "\n[img]" . $attach['url'] . '[/img]';
 133                                 } else {
 134                                         $item['body'] .= "\n[img=" . $attach['url'] . ']' . $attach['name'] . '[/img]';
 135                                 }
 136                         } else {
 137                                 if (!empty($item["attach"])) {
 138                                         $item["attach"] .= ',';
 139                                 } else {
 140                                         $item["attach"] = '';
 141                                 }
 142                                 if (!isset($attach['length'])) {
 143                                         $attach['length'] = "0";
 144                                 }
 145                                 $item["attach"] .= '[attach]href="'.$attach['url'].'" length="'.$attach['length'].'" type="'.$attach['mediaType'].'" title="'.($attach['name'] ?? '') .'"[/attach]';
 146                         }
 147                 }
 148
 149                 return $item;
 150         }
 151
 152         /**
 153          * Updates a message
 154          *
 155          * @param array $activity Activity array
 156          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 157          */
 158         public static function updateItem($activity)
 159         {
 160                 $item = Item::selectFirst(['uri', 'thr-parent', 'gravity'], ['uri' => $activity['id']]);
 161                 if (!DBA::isResult($item)) {
 162                         Logger::warning('Unknown item', ['uri' => $activity['id']]);
 163                         return;
 164                 }
 165
 166                 $item['changed'] = DateTimeFormat::utcNow();
 167                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 168
 169                 $item = self::processContent($activity, $item);
 170                 if (empty($item)) {
 171                         return;
 172                 }
 173
 174                 Item::update($item, ['uri' => $activity['id']]);
 175         }
 176
 177         /**
 178          * Prepares data for a message
 179          *
 180          * @param array $activity Activity array
 181          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 182          * @throws \ImagickException
 183          */
 184         public static function createItem($activity)
 185         {
 186                 $item = [];
 187                 $item['verb'] = Activity::POST;
 188                 $item['thr-parent'] = $activity['reply-to-id'];
 189
 190                 if ($activity['reply-to-id'] == $activity['id']) {
 191                         $item['gravity'] = GRAVITY_PARENT;
 192                         $item['object-type'] = Activity\ObjectType::NOTE;
 193                 } else {
 194                         $item['gravity'] = GRAVITY_COMMENT;
 195                         $item['object-type'] = Activity\ObjectType::COMMENT;
 196
 197                         // Ensure that the comment reaches all receivers of the referring post
 198                         $activity['receiver'] = self::addReceivers($activity);
 199                 }
 200
 201                 if (empty($activity['directmessage']) && ($activity['id'] != $activity['reply-to-id']) && !Item::exists(['uri' => $activity['reply-to-id']])) {
 202                         Logger::notice('Parent not found. Try to refetch it.', ['parent' => $activity['reply-to-id']]);
 203                         self::fetchMissingActivity($activity['reply-to-id'], $activity);
 204                 }
 205
 206                 $item['diaspora_signed_text'] = $activity['diaspora:comment'] ?? '';
 207
 208                 self::postItem($activity, $item);
 209         }
 210
 211         /**
 212          * Delete items
 213          *
 214          * @param array $activity
 215          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 216          * @throws \ImagickException
 217          */
 218         public static function deleteItem($activity)
 219         {
 220                 $owner = Contact::getIdForURL($activity['actor']);
 221
 222                 Logger::log('Deleting item ' . $activity['object_id'] . ' from ' . $owner, Logger::DEBUG);
 223                 Item::delete(['uri' => $activity['object_id'], 'owner-id' => $owner]);
 224         }
 225
 226         /**
 227          * Prepare the item array for an activity
 228          *
 229          * @param array $activity Activity array
 230          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 231          * @throws \ImagickException
 232          */
 233         public static function addTag($activity)
 234         {
 235                 if (empty($activity['object_content']) || empty($activity['object_id'])) {
 236                         return;
 237                 }
 238
 239                 foreach ($activity['receiver'] as $receiver) {
 240                         $item = Item::selectFirst(['id', 'tag', 'origin', 'author-link'], ['uri' => $activity['target_id'], 'uid' => $receiver]);
 241                         if (!DBA::isResult($item)) {
 242                                 // We don't fetch missing content for this purpose
 243                                 continue;
 244                         }
 245
 246                         if (($item['author-link'] != $activity['actor']) && !$item['origin']) {
 247                                 Logger::info('Not origin, not from the author, skipping update', ['id' => $item['id'], 'author' => $item['author-link'], 'actor' => $activity['actor']]);
 248                                 continue;
 249                         }
 250
 251                         // To-Do:
 252                         // - Check if "blocktag" is set
 253                         // - Check if actor is a contact
 254
 255                         if (!stristr($item['tag'], trim($activity['object_content']))) {
 256                                 $tag = $item['tag'] . (strlen($item['tag']) ? ',' : '') . '#[url=' . $activity['object_id'] . ']'. $activity['object_content'] . '[/url]';
 257                                 Item::update(['tag' => $tag], ['id' => $item['id']]);
 258                                 Logger::info('Tagged item', ['id' => $item['id'], 'tag' => $activity['object_content'], 'uri' => $activity['target_id'], 'actor' => $activity['actor']]);
 259                         }
 260                 }
 261         }
 262
 263         /**
 264          * Add users to the receiver list of the given public activity.
 265          * This is used to ensure that the activity will be stored in every thread.
 266          *
 267          * @param array $activity Activity array
 268          * @return array Modified receiver list
 269          */
 270         private static function addReceivers(array $activity)
 271         {
 272                 if (!in_array(0, $activity['receiver'])) {
 273                         // Private activities will not be modified
 274                         return $activity['receiver'];
 275                 }
 276
 277                 // Add all owners of the referring item to the receivers
 278                 $original = $receivers = $activity['receiver'];
 279                 $items = Item::select(['uid'], ['uri' => $activity['object_id']]);
 280                 while ($item = DBA::fetch($items)) {
 281                         $receivers['uid:' . $item['uid']] = $item['uid'];
 282                 }
 283                 DBA::close($items);
 284
 285                 if (count($original) != count($receivers)) {
 286                         Logger::info('Improved data', ['id' => $activity['id'], 'object' => $activity['object_id'], 'original' => $original, 'improved' => $receivers]);
 287                 }
 288
 289                 return $receivers;
 290         }
 291
 292         /**
 293          * Prepare the item array for an activity
 294          *
 295          * @param array  $activity Activity array
 296          * @param string $verb     Activity verb
 297          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 298          * @throws \ImagickException
 299          */
 300         public static function createActivity($activity, $verb)
 301         {
 302                 $item = [];
 303                 $item['verb'] = $verb;
 304                 $item['thr-parent'] = $activity['object_id'];
 305                 $item['gravity'] = GRAVITY_ACTIVITY;
 306                 $item['object-type'] = Activity\ObjectType::NOTE;
 307
 308                 $item['diaspora_signed_text'] = $activity['diaspora:like'] ?? '';
 309
 310                 $activity['receiver'] = self::addReceivers($activity);
 311
 312                 self::postItem($activity, $item);
 313         }
 314
 315         /**
 316          * Create an event
 317          *
 318          * @param array $activity Activity array
 319          * @param array $item
 320          * @throws \Exception
 321          */
 322         public static function createEvent($activity, $item)
 323         {
 324                 $event['summary']  = HTML::toBBCode($activity['name']);
 325                 $event['desc']     = HTML::toBBCode($activity['content']);
 326                 $event['start']    = $activity['start-time'];
 327                 $event['finish']   = $activity['end-time'];
 328                 $event['nofinish'] = empty($event['finish']);
 329                 $event['location'] = $activity['location'];
 330                 $event['adjust']   = true;
 331                 $event['cid']      = $item['contact-id'];
 332                 $event['uid']      = $item['uid'];
 333                 $event['uri']      = $item['uri'];
 334                 $event['edited']   = $item['edited'];
 335                 $event['private']  = $item['private'];
 336                 $event['guid']     = $item['guid'];
 337                 $event['plink']    = $item['plink'];
 338
 339                 $condition = ['uri' => $item['uri'], 'uid' => $item['uid']];
 340                 $ev = DBA::selectFirst('event', ['id'], $condition);
 341                 if (DBA::isResult($ev)) {
 342                         $event['id'] = $ev['id'];
 343                 }
 344
 345                 $event_id = Event::store($event);
 346                 Logger::log('Event '.$event_id.' was stored', Logger::DEBUG);
 347         }
 348
 349         /**
 350          * Process the content
 351          *
 352          * @param array $activity Activity array
 353          * @param array $item
 354          * @return array|bool Returns the item array or false if there was an unexpected occurrence
 355          * @throws \Exception
 356          */
 357         private static function processContent($activity, $item)
 358         {
 359                 $item['title'] = HTML::toBBCode($activity['name']);
 360
 361                 if (!empty($activity['source'])) {
 362                         $item['body'] = $activity['source'];
 363                 } else {
 364                         $content = HTML::toBBCode($activity['content']);
 365
 366                         if (!empty($activity['emojis'])) {
 367                                 $content = self::replaceEmojis($content, $activity['emojis']);
 368                         }
 369
 370                         $content = self::convertMentions($content);
 371
 372                         if (empty($activity['directmessage']) && ($item['thr-parent'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
 373                                 $item_private = !in_array(0, $activity['item_receiver']);
 374                                 $parent = Item::selectFirst(['id', 'private', 'author-link', 'alias'], ['uri' => $item['thr-parent']]);
 375                                 if (!DBA::isResult($parent)) {
 376                                         Logger::warning('Unknown parent item.', ['uri' => $item['thr-parent']]);
 377                                         return false;
 378                                 }
 379                                 if ($item_private && ($parent['private'] == Item::PRIVATE)) {
 380                                         Logger::warning('Item is private but the parent is not. Dropping.', ['item-uri' => $item['uri'], 'thr-parent' => $item['thr-parent']]);
 381                                         return false;
 382                                 }
 383
 384                                 $potential_implicit_mentions = self::getImplicitMentionList($parent);
 385                                 $content = self::removeImplicitMentionsFromBody($content, $potential_implicit_mentions);
 386                                 $activity['tags'] = self::convertImplicitMentionsInTags($activity['tags'], $potential_implicit_mentions);
 387                         }
 388                         $item['content-warning'] = HTML::toBBCode($activity['summary']);
 389                         $item['body'] = $content;
 390
 391                         if (($activity['object_type'] == 'as:Video') && !empty($activity['alternate-url'])) {
 392                                 $item['body'] .= "\n[video]" . $activity['alternate-url'] . '[/video]';
 393                         }
 394                 }
 395
 396                 $item['tag'] = self::constructTagString($activity['tags'], $activity['sensitive']);
 397
 398                 $item['location'] = $activity['location'];
 399
 400                 if (!empty($item['latitude']) && !empty($item['longitude'])) {
 401                         $item['coord'] = $item['latitude'] . ' ' . $item['longitude'];
 402                 }
 403
 404                 $item['app'] = $activity['generator'];
 405
 406                 return $item;
 407         }
 408
 409         /**
 410          * Generate a GUID out of an URL
 411          *
 412          * @param string $url message URL
 413          * @return string with GUID
 414          */
 415         private static function getGUIDByURL(string $url)
 416         {
 417                 $parsed = parse_url($url);
 418
 419                 $host_hash = hash('crc32', $parsed['host']);
 420
 421                 unset($parsed["scheme"]);
 422                 unset($parsed["host"]);
 423
 424                 $path = implode("/", $parsed);
 425
 426                 return $host_hash . '-'. hash('fnv164', $path) . '-'. hash('joaat', $path);
 427         }
 428
 429         /**
 430          * Creates an item post
 431          *
 432          * @param array $activity Activity data
 433          * @param array $item     item array
 434          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 435          * @throws \ImagickException
 436          */
 437         private static function postItem($activity, $item)
 438         {
 439                 /// @todo What to do with $activity['context']?
 440                 if (empty($activity['directmessage']) && ($item['gravity'] != GRAVITY_PARENT) && !Item::exists(['uri' => $item['thr-parent']])) {
 441                         Logger::info('Parent not found, message will be discarded.', ['thr-parent' => $item['thr-parent']]);
 442                         return;
 443                 }
 444
 445                 $item['network'] = Protocol::ACTIVITYPUB;
 446                 $item['author-link'] = $activity['author'];
 447                 $item['author-id'] = Contact::getIdForURL($activity['author'], 0, true);
 448                 $item['owner-link'] = $activity['actor'];
 449                 $item['owner-id'] = Contact::getIdForURL($activity['actor'], 0, true);
 450
 451                 if (in_array(0, $activity['receiver']) && !empty($activity['unlisted'])) {
 452                         $item['private'] = Item::UNLISTED;
 453                 } elseif (in_array(0, $activity['receiver'])) {
 454                         $item['private'] = Item::PUBLIC;
 455                 } else {
 456                         $item['private'] = Item::PRIVATE;
 457                 }
 458
 459                 if (!empty($activity['raw'])) {
 460                         $item['source'] = $activity['raw'];
 461                         $item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
 462                         $item['conversation-href'] = $activity['context'] ?? '';
 463                         $item['conversation-uri'] = $activity['conversation'] ?? '';
 464
 465                         if (isset($activity['push'])) {
 466                                 $item['direction'] = $activity['push'] ? Conversation::PUSH : Conversation::PULL;
 467                         }
 468                 }
 469
 470                 $isForum = false;
 471
 472                 if (!empty($activity['thread-completion'])) {
 473                         // Store the original actor in the "causer" fields to enable the check for ignored or blocked contacts
 474                         $item['causer-link'] = $item['owner-link'];
 475                         $item['causer-id'] = $item['owner-id'];
 476
 477                         Logger::info('Ignoring actor because of thread completion.', ['actor' => $item['owner-link']]);
 478                         $item['owner-link'] = $item['author-link'];
 479                         $item['owner-id'] = $item['author-id'];
 480                 } else {
 481                         $actor = APContact::getByURL($item['owner-link'], false);
 482                         $isForum = ($actor['type'] == 'Group');
 483                 }
 484
 485                 $item['uri'] = $activity['id'];
 486
 487                 $item['created'] = DateTimeFormat::utc($activity['published']);
 488                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 489                 $item['guid'] = $activity['diaspora:guid'] ?: self::getGUIDByURL($item['uri']);
 490
 491                 $item = self::processContent($activity, $item);
 492                 if (empty($item)) {
 493                         return;
 494                 }
 495
 496                 $item['plink'] = $activity['alternate-url'] ?? $item['uri'];
 497
 498                 $item = self::constructAttachList($activity, $item);
 499
 500                 $stored = false;
 501
 502                 foreach ($activity['receiver'] as $receiver) {
 503                         if ($receiver == -1) {
 504                                 continue;
 505                         }
 506
 507                         $item['uid'] = $receiver;
 508
 509                         if ($isForum) {
 510                                 $item['contact-id'] = Contact::getIdForURL($activity['actor'], $receiver, true);
 511                         } else {
 512                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver, true);
 513                         }
 514
 515                         if (($receiver != 0) && empty($item['contact-id'])) {
 516                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], 0, true);
 517                         }
 518
 519                         if (!empty($activity['directmessage'])) {
 520                                 self::postMail($activity, $item);
 521                                 continue;
 522                         }
 523
 524                         if (DI::pConfig()->get($receiver, 'system', 'accept_only_sharer', false) && ($receiver != 0) && ($item['gravity'] == GRAVITY_PARENT)) {
 525                                 $skip = !Contact::isSharingByURL($activity['author'], $receiver);
 526
 527                                 if ($skip && (($activity['type'] == 'as:Announce') || $isForum)) {
 528                                         $skip = !Contact::isSharingByURL($activity['actor'], $receiver);
 529                                 }
 530
 531                                 if ($skip) {
 532                                         Logger::info('Skipping post', ['uid' => $receiver, 'url' => $item['uri']]);
 533                                         continue;
 534                                 }
 535
 536                                 Logger::info('Accepting post', ['uid' => $receiver, 'url' => $item['uri']]);
 537                         }
 538
 539                         if ($activity['object_type'] == 'as:Event') {
 540                                 self::createEvent($activity, $item);
 541                         }
 542
 543                         $item_id = Item::insert($item);
 544                         if ($item_id) {
 545                                 Logger::info('Item insertion successful', ['user' => $item['uid'], 'item_id' => $item_id]);
 546                         } else {
 547                                 Logger::notice('Item insertion aborted', ['user' => $item['uid']]);
 548                         }
 549
 550                         if ($item['uid'] == 0) {
 551                                 $stored = $item_id;
 552                         }
 553                 }
 554
 555                 // Store send a follow request for every reshare - but only when the item had been stored
 556                 if ($stored && ($item['private'] != Item::PRIVATE) && ($item['gravity'] == GRAVITY_PARENT) && ($item['author-link'] != $item['owner-link'])) {
 557                         $author = APContact::getByURL($item['owner-link'], false);
 558                         // We send automatic follow requests for reshared messages. (We don't need though for forum posts)
 559                         if ($author['type'] != 'Group') {
 560                                 Logger::log('Send follow request for ' . $item['uri'] . ' (' . $stored . ') to ' . $item['author-link'], Logger::DEBUG);
 561                                 ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
 562                         }
 563                 }
 564         }
 565
 566         /**
 567          * Creates an mail post
 568          *
 569          * @param array $activity Activity data
 570          * @param array $item     item array
 571          * @return int|bool New mail table row id or false on error
 572          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 573          */
 574         private static function postMail($activity, $item)
 575         {
 576                 if (($item['gravity'] != GRAVITY_PARENT) && !DBA::exists('mail', ['uri' => $item['thr-parent'], 'uid' => $item['uid']])) {
 577                         Logger::info('Parent not found, mail will be discarded.', ['uid' => $item['uid'], 'uri' => $item['thr-parent']]);
 578                         return false;
 579                 }
 580
 581                 Logger::info('Direct Message', $item);
 582
 583                 $msg = [];
 584                 $msg['uid'] = $item['uid'];
 585
 586                 $msg['contact-id'] = $item['contact-id'];
 587
 588                 $contact = Contact::getById($item['contact-id'], ['name', 'url', 'photo']);
 589                 $msg['from-name'] = $contact['name'];
 590                 $msg['from-url'] = $contact['url'];
 591                 $msg['from-photo'] = $contact['photo'];
 592
 593                 $msg['uri'] = $item['uri'];
 594                 $msg['created'] = $item['created'];
 595
 596                 $parent = DBA::selectFirst('mail', ['parent-uri', 'title'], ['uri' => $item['thr-parent']]);
 597                 if (DBA::isResult($parent)) {
 598                         $msg['parent-uri'] = $parent['parent-uri'];
 599                         $msg['title'] = $parent['title'];
 600                 } else {
 601                         $msg['parent-uri'] = $item['thr-parent'];
 602
 603                         if (!empty($item['title'])) {
 604                                 $msg['title'] = $item['title'];
 605                         } elseif (!empty($item['content-warning'])) {
 606                                 $msg['title'] = $item['content-warning'];
 607                         } else {
 608                                 // Trying to generate a title out of the body
 609                                 $title = $item['body'];
 610
 611                                 while (preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $title, $matches)) {
 612                                         $title = $matches[3];
 613                                 }
 614
 615                                 $title = trim(HTML::toPlaintext(BBCode::convert($title, false, 2, true), 0));
 616
 617                                 if (strlen($title) > 20) {
 618                                         $title = substr($title, 0, 20) . '...';
 619                                 }
 620
 621                                 $msg['title'] = $title;
 622                         }
 623                 }
 624                 $msg['body'] = $item['body'];
 625
 626                 return Mail::insert($msg);
 627         }
 628
 629         /**
 630          * Fetches missing posts
 631          *
 632          * @param string $url message URL
 633          * @param array $child activity array with the child of this message
 634          * @return string fetched message URL
 635          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 636          */
 637         public static function fetchMissingActivity($url, $child = [])
 638         {
 639                 if (!empty($child['receiver'])) {
 640                         $uid = ActivityPub\Receiver::getFirstUserFromReceivers($child['receiver']);
 641                 } else {
 642                         $uid = 0;
 643                 }
 644
 645                 $object = ActivityPub::fetchContent($url, $uid);
 646                 if (empty($object)) {
 647                         Logger::log('Activity ' . $url . ' was not fetchable, aborting.');
 648                         return '';
 649                 }
 650
 651                 if (empty($object['id'])) {
 652                         Logger::log('Activity ' . $url . ' has got not id, aborting. ' . json_encode($object));
 653                         return '';
 654                 }
 655
 656                 if (!empty($child['author'])) {
 657                         $actor = $child['author'];
 658                 } elseif (!empty($object['actor'])) {
 659                         $actor = $object['actor'];
 660                 } elseif (!empty($object['attributedTo'])) {
 661                         $actor = $object['attributedTo'];
 662                 } else {
 663                         // Shouldn't happen
 664                         $actor = '';
 665                 }
 666
 667                 if (!empty($object['published'])) {
 668                         $published = $object['published'];
 669                 } elseif (!empty($child['published'])) {
 670                         $published = $child['published'];
 671                 } else {
 672                         $published = DateTimeFormat::utcNow();
 673                 }
 674
 675                 $activity = [];
 676                 $activity['@context'] = $object['@context'];
 677                 unset($object['@context']);
 678                 $activity['id'] = $object['id'];
 679                 $activity['to'] = $object['to'] ?? [];
 680                 $activity['cc'] = $object['cc'] ?? [];
 681                 $activity['actor'] = $actor;
 682                 $activity['object'] = $object;
 683                 $activity['published'] = $published;
 684                 $activity['type'] = 'Create';
 685
 686                 $ldactivity = JsonLD::compact($activity);
 687
 688                 $ldactivity['thread-completion'] = true;
 689
 690                 ActivityPub\Receiver::processActivity($ldactivity, json_encode($activity));
 691
 692                 Logger::notice('Activity had been fetched and processed.', ['url' => $url, 'object' => $activity['id']]);
 693
 694                 return $activity['id'];
 695         }
 696
 697         /**
 698          * perform a "follow" request
 699          *
 700          * @param array $activity
 701          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 702          * @throws \ImagickException
 703          */
 704         public static function followUser($activity)
 705         {
 706                 $uid = User::getIdForURL($activity['object_id']);
 707                 if (empty($uid)) {
 708                         return;
 709                 }
 710
 711                 $owner = User::getOwnerDataById($uid);
 712
 713                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 714                 if (!empty($cid)) {
 715                         self::switchContact($cid);
 716                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
 717                         $contact = DBA::selectFirst('contact', [], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
 718                 } else {
 719                         $contact = [];
 720                 }
 721
 722                 $item = ['author-id' => Contact::getIdForURL($activity['actor']),
 723                         'author-link' => $activity['actor']];
 724
 725                 $note = Strings::escapeTags(trim($activity['content'] ?? ''));
 726
 727                 // Ensure that the contact has got the right network type
 728                 self::switchContact($item['author-id']);
 729
 730                 $result = Contact::addRelationship($owner, $contact, $item, false, $note);
 731                 if ($result === true) {
 732                         ActivityPub\Transmitter::sendContactAccept($item['author-link'], $item['author-id'], $owner['uid']);
 733                 }
 734
 735                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 736                 if (empty($cid)) {
 737                         return;
 738                 }
 739
 740                 if (empty($contact)) {
 741                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
 742                 }
 743
 744                 Logger::log('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
 745         }
 746
 747         /**
 748          * Update the given profile
 749          *
 750          * @param array $activity
 751          * @throws \Exception
 752          */
 753         public static function updatePerson($activity)
 754         {
 755                 if (empty($activity['object_id'])) {
 756                         return;
 757                 }
 758
 759                 Logger::log('Updating profile for ' . $activity['object_id'], Logger::DEBUG);
 760                 Contact::updateFromProbeByURL($activity['object_id'], true);
 761         }
 762
 763         /**
 764          * Delete the given profile
 765          *
 766          * @param array $activity
 767          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 768          */
 769         public static function deletePerson($activity)
 770         {
 771                 if (empty($activity['object_id']) || empty($activity['actor'])) {
 772                         Logger::log('Empty object id or actor.', Logger::DEBUG);
 773                         return;
 774                 }
 775
 776                 if ($activity['object_id'] != $activity['actor']) {
 777                         Logger::log('Object id does not match actor.', Logger::DEBUG);
 778                         return;
 779                 }
 780
 781                 $contacts = DBA::select('contact', ['id'], ['nurl' => Strings::normaliseLink($activity['object_id'])]);
 782                 while ($contact = DBA::fetch($contacts)) {
 783                         Contact::remove($contact['id']);
 784                 }
 785                 DBA::close($contacts);
 786
 787                 Logger::log('Deleted contact ' . $activity['object_id'], Logger::DEBUG);
 788         }
 789
 790         /**
 791          * Accept a follow request
 792          *
 793          * @param array $activity
 794          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 795          * @throws \ImagickException
 796          */
 797         public static function acceptFollowUser($activity)
 798         {
 799                 $uid = User::getIdForURL($activity['object_actor']);
 800                 if (empty($uid)) {
 801                         return;
 802                 }
 803
 804                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 805                 if (empty($cid)) {
 806                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 807                         return;
 808                 }
 809
 810                 self::switchContact($cid);
 811
 812                 $fields = ['pending' => false];
 813
 814                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
 815                 if ($contact['rel'] == Contact::FOLLOWER) {
 816                         $fields['rel'] = Contact::FRIEND;
 817                 }
 818
 819                 $condition = ['id' => $cid];
 820                 DBA::update('contact', $fields, $condition);
 821                 Logger::log('Accept contact request from contact ' . $cid . ' for user ' . $uid, Logger::DEBUG);
 822         }
 823
 824         /**
 825          * Reject a follow request
 826          *
 827          * @param array $activity
 828          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 829          * @throws \ImagickException
 830          */
 831         public static function rejectFollowUser($activity)
 832         {
 833                 $uid = User::getIdForURL($activity['object_actor']);
 834                 if (empty($uid)) {
 835                         return;
 836                 }
 837
 838                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 839                 if (empty($cid)) {
 840                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 841                         return;
 842                 }
 843
 844                 self::switchContact($cid);
 845
 846                 if (DBA::exists('contact', ['id' => $cid, 'rel' => Contact::SHARING])) {
 847                         Contact::remove($cid);
 848                         Logger::log('Rejected contact request from contact ' . $cid . ' for user ' . $uid . ' - contact had been removed.', Logger::DEBUG);
 849                 } else {
 850                         Logger::log('Rejected contact request from contact ' . $cid . ' for user ' . $uid . '.', Logger::DEBUG);
 851                 }
 852         }
 853
 854         /**
 855          * Undo activity like "like" or "dislike"
 856          *
 857          * @param array $activity
 858          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 859          * @throws \ImagickException
 860          */
 861         public static function undoActivity($activity)
 862         {
 863                 if (empty($activity['object_id'])) {
 864                         return;
 865                 }
 866
 867                 if (empty($activity['object_actor'])) {
 868                         return;
 869                 }
 870
 871                 $author_id = Contact::getIdForURL($activity['object_actor']);
 872                 if (empty($author_id)) {
 873                         return;
 874                 }
 875
 876                 Item::delete(['uri' => $activity['object_id'], 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
 877         }
 878
 879         /**
 880          * Activity to remove a follower
 881          *
 882          * @param array $activity
 883          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 884          * @throws \ImagickException
 885          */
 886         public static function undoFollowUser($activity)
 887         {
 888                 $uid = User::getIdForURL($activity['object_object']);
 889                 if (empty($uid)) {
 890                         return;
 891                 }
 892
 893                 $owner = User::getOwnerDataById($uid);
 894
 895                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 896                 if (empty($cid)) {
 897                         Logger::log('No contact found for ' . $activity['actor'], Logger::DEBUG);
 898                         return;
 899                 }
 900
 901                 self::switchContact($cid);
 902
 903                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
 904                 if (!DBA::isResult($contact)) {
 905                         return;
 906                 }
 907
 908                 Contact::removeFollower($owner, $contact);
 909                 Logger::log('Undo following request from contact ' . $cid . ' for user ' . $uid, Logger::DEBUG);
 910         }
 911
 912         /**
 913          * Switches a contact to AP if needed
 914          *
 915          * @param integer $cid Contact ID
 916          * @throws \Exception
 917          */
 918         private static function switchContact($cid)
 919         {
 920                 $contact = DBA::selectFirst('contact', ['network', 'url'], ['id' => $cid]);
 921                 if (!DBA::isResult($contact) || in_array($contact['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN]) || Contact::isLocal($contact['url'])) {
 922                         return;
 923                 }
 924
 925                 Logger::info('Change existing contact', ['cid' => $cid, 'previous' => $contact['network']]);
 926                 Contact::updateFromProbe($cid);
 927         }
 928
 929         /**
 930          * Collects implicit mentions like:
 931          * - the author of the parent item
 932          * - all the mentioned conversants in the parent item
 933          *
 934          * @param array $parent Item array with at least ['id', 'author-link', 'alias']
 935          * @return array
 936          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 937          */
 938         private static function getImplicitMentionList(array $parent)
 939         {
 940                 if (DI::config()->get('system', 'disable_implicit_mentions')) {
 941                         return [];
 942                 }
 943
 944                 $parent_terms = Term::tagArrayFromItemId($parent['id'], [Term::MENTION, Term::IMPLICIT_MENTION]);
 945
 946                 $parent_author = Contact::getDetailsByURL($parent['author-link'], 0);
 947
 948                 $implicit_mentions = [];
 949                 if (empty($parent_author)) {
 950                         Logger::notice('Author public contact unknown.', ['author-link' => $parent['author-link'], 'item-id' => $parent['id']]);
 951                 } else {
 952                         $implicit_mentions[] = $parent_author['url'];
 953                         $implicit_mentions[] = $parent_author['nurl'];
 954                         $implicit_mentions[] = $parent_author['alias'];
 955                 }
 956
 957                 if (!empty($parent['alias'])) {
 958                         $implicit_mentions[] = $parent['alias'];
 959                 }
 960
 961                 foreach ($parent_terms as $term) {
 962                         $contact = Contact::getDetailsByURL($term['url'], 0);
 963                         if (!empty($contact)) {
 964                                 $implicit_mentions[] = $contact['url'];
 965                                 $implicit_mentions[] = $contact['nurl'];
 966                                 $implicit_mentions[] = $contact['alias'];
 967                         }
 968                 }
 969
 970                 return $implicit_mentions;
 971         }
 972
 973         /**
 974          * Strips from the body prepended implicit mentions
 975          *
 976          * @param string $body
 977          * @param array $potential_mentions
 978          * @return string
 979          */
 980         private static function removeImplicitMentionsFromBody($body, array $potential_mentions)
 981         {
 982                 if (DI::config()->get('system', 'disable_implicit_mentions')) {
 983                         return $body;
 984                 }
 985
 986                 $kept_mentions = [];
 987
 988                 // Extract one prepended mention at a time from the body
 989                 while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $body, $matches)) {
 990                         if (!in_array($matches[2], $potential_mentions)) {
 991                                 $kept_mentions[] = $matches[1];
 992                         }
 993
 994                         $body = $matches[3];
 995                 }
 996
 997                 // Re-appending the kept mentions to the body after extraction
 998                 $kept_mentions[] = $body;
 999
1000                 return implode('', $kept_mentions);
1001         }
1002
1003         private static function convertImplicitMentionsInTags($activity_tags, array $potential_mentions)
1004         {
1005                 if (DI::config()->get('system', 'disable_implicit_mentions')) {
1006                         return $activity_tags;
1007                 }
1008
1009                 foreach ($activity_tags as $index => $tag) {
1010                         if (in_array($tag['href'], $potential_mentions)) {
1011                                 $activity_tags[$index]['name'] = preg_replace(
1012                                         '/' . preg_quote(Term::TAG_CHARACTER[Term::MENTION], '/') . '/',
1013                                         Term::TAG_CHARACTER[Term::IMPLICIT_MENTION],
1014                                         $activity_tags[$index]['name'],
1015                                         1
1016                                 );
1017                         }
1018                 }
1019
1020                 return $activity_tags;
1021         }
1022 }