src/Model/Contact/Relation.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2022, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Model\Contact;
  23
  24 use Exception;
  25 use Friendica\Core\Logger;
  26 use Friendica\Core\Protocol;
  27 use Friendica\Database\Database;
  28 use Friendica\Database\DBA;
  29 use Friendica\DI;
  30 use Friendica\Model\APContact;
  31 use Friendica\Model\Contact;
  32 use Friendica\Model\Profile;
  33 use Friendica\Model\User;
  34 use Friendica\Protocol\ActivityPub;
  35 use Friendica\Util\DateTimeFormat;
  36 use Friendica\Util\Strings;
  37
  38 /**
  39  * This class provides relationship information based on the `contact-relation` table.
  40  * This table is directional (cid = source, relation-cid = target), references public contacts (with uid=0) and records both
  41  * follows and the last interaction (likes/comments) on public posts.
  42  */
  43 class Relation
  44 {
  45         /**
  46          * No discovery of followers/followings
  47          */
  48         const DISCOVERY_NONE = 0;
  49         /**
  50          * Discover followers/followings of local contacts
  51          */
  52         const DISCOVERY_LOCAL = 1;
  53         /**
  54          * Discover followers/followings of local contacts and contacts that visibly interacted on the system
  55          */
  56         const DISCOVERY_INTERACTOR = 2;
  57         /**
  58          * Discover followers/followings of all contacts
  59          */
  60         const DISCOVERY_ALL = 3;
  61
  62         public static function store(int $target, int $actor, string $interaction_date)
  63         {
  64                 if ($actor == $target) {
  65                         return;
  66                 }
  67
  68                 DBA::insert('contact-relation', ['last-interaction' => $interaction_date, 'cid' => $target, 'relation-cid' => $actor], Database::INSERT_UPDATE);
  69         }
  70
  71         /**
  72          * Fetches the followers of a given profile and adds them
  73          *
  74          * @param string $url URL of a profile
  75          * @return void
  76          */
  77         public static function discoverByUrl(string $url)
  78         {
  79                 $contact = Contact::getByURL($url);
  80                 if (empty($contact)) {
  81                         Logger::info('Contact not found', ['url' => $url]);
  82                         return;
  83                 }
  84
  85                 if (!self::isDiscoverable($url, $contact)) {
  86                         Logger::info('Contact is not discoverable', ['url' => $url]);
  87                         return;
  88                 }
  89
  90                 $uid = User::getIdForURL($url);
  91                 if (!empty($uid)) {
  92                         Logger::info('Fetch the followers/followings locally', ['url' => $url]);
  93                         $followers = self::getContacts($uid, [Contact::FOLLOWER, Contact::FRIEND]);
  94                         $followings = self::getContacts($uid, [Contact::SHARING, Contact::FRIEND]);
  95                 } elseif (!Contact::isLocal($url)) {
  96                         Logger::info('Fetch the followers/followings by polling the endpoints', ['url' => $url]);
  97                         $apcontact = APContact::getByURL($url, false);
  98
  99                         if (!empty($apcontact['followers']) && is_string($apcontact['followers'])) {
 100                                 $followers = ActivityPub::fetchItems($apcontact['followers']);
 101                         } else {
 102                                 $followers = [];
 103                         }
 104
 105                         if (!empty($apcontact['following']) && is_string($apcontact['following'])) {
 106                                 $followings = ActivityPub::fetchItems($apcontact['following']);
 107                         } else {
 108                                 $followings = [];
 109                         }
 110                 } else {
 111                         Logger::warning('Contact seems to be local but could not be found here', ['url' => $url]);
 112                         $followers = [];
 113                         $followings = [];
 114                 }
 115
 116                 if (empty($followers) && empty($followings)) {
 117                         Contact::update(['last-discovery' => DateTimeFormat::utcNow()], ['id' => $contact['id']]);
 118                         Logger::info('The contact does not offer discoverable data', ['id' => $contact['id'], 'url' => $url, 'network' => $contact['network']]);
 119                         return;
 120                 }
 121
 122                 $target = $contact['id'];
 123
 124                 if (!empty($followers)) {
 125                         // Clear the follower list, since it will be recreated in the next step
 126                         DBA::update('contact-relation', ['follows' => false], ['cid' => $target]);
 127                 }
 128
 129                 $contacts = [];
 130                 foreach (array_merge($followers, $followings) as $contact) {
 131                         if (is_string($contact)) {
 132                                 $contacts[] = $contact;
 133                         } elseif (!empty($contact['url']) && is_string($contact['url'])) {
 134                                 $contacts[] = $contact['url'];
 135                         }
 136                 }
 137                 $contacts = array_unique($contacts);
 138
 139                 $follower_counter = 0;
 140                 $following_counter = 0;
 141
 142                 Logger::info('Discover contacts', ['id' => $target, 'url' => $url, 'contacts' => count($contacts)]);
 143                 foreach ($contacts as $contact) {
 144                         $actor = Contact::getIdForURL($contact);
 145                         if (!empty($actor)) {
 146                                 if (in_array($contact, $followers)) {
 147                                         $fields = ['cid' => $target, 'relation-cid' => $actor, 'follows' => true, 'follow-updated' => DateTimeFormat::utcNow()];
 148                                         DBA::insert('contact-relation', $fields, Database::INSERT_UPDATE);
 149                                         $follower_counter++;
 150                                 }
 151
 152                                 if (in_array($contact, $followings)) {
 153                                         $fields = ['cid' => $actor, 'relation-cid' => $target, 'follows' => true, 'follow-updated' => DateTimeFormat::utcNow()];
 154                                         DBA::insert('contact-relation', $fields, Database::INSERT_UPDATE);
 155                                         $following_counter++;
 156                                 }
 157                         }
 158                 }
 159
 160                 if (!empty($followers)) {
 161                         // Delete all followers that aren't followers anymore (and aren't interacting)
 162                         DBA::delete('contact-relation', ['cid' => $target, 'follows' => false, 'last-interaction' => DBA::NULL_DATETIME]);
 163                 }
 164
 165                 Contact::update(['last-discovery' => DateTimeFormat::utcNow()], ['id' => $target]);
 166                 Logger::info('Contacts discovery finished', ['id' => $target, 'url' => $url, 'follower' => $follower_counter, 'following' => $following_counter]);
 167                 return;
 168         }
 169
 170         /**
 171          * Fetch contact url list from the given local user
 172          *
 173          * @param integer $uid
 174          * @param array $rel
 175          * @return array contact list
 176          */
 177         private static function getContacts(int $uid, array $rel): array
 178         {
 179                 $list = [];
 180                 $profile = Profile::getByUID($uid);
 181                 if (!empty($profile['hide-friends'])) {
 182                         return $list;
 183                 }
 184
 185                 $condition = [
 186                         'rel' => $rel,
 187                         'uid' => $uid,
 188                         'self' => false,
 189                         'deleted' => false,
 190                         'hidden' => false,
 191                         'archive' => false,
 192                         'pending' => false,
 193                 ];
 194                 $condition = DBA::mergeConditions($condition, ["`url` IN (SELECT `url` FROM `apcontact`)"]);
 195                 $contacts = DBA::select('contact', ['url'], $condition);
 196                 while ($contact = DBA::fetch($contacts)) {
 197                         $list[] = $contact['url'];
 198                 }
 199                 DBA::close($contacts);
 200
 201                 return $list;
 202         }
 203
 204         /**
 205          * Tests if a given contact url is discoverable
 206          *
 207          * @param string $url     Contact url
 208          * @param array  $contact Contact array
 209          * @return boolean True if contact is discoverable
 210          */
 211         public static function isDiscoverable(string $url, array $contact = []): bool
 212         {
 213                 $contact_discovery = DI::config()->get('system', 'contact_discovery');
 214
 215                 if ($contact_discovery == self::DISCOVERY_NONE) {
 216                         return false;
 217                 }
 218
 219                 if (empty($contact)) {
 220                         $contact = Contact::getByURL($url, false);
 221                 }
 222
 223                 if (empty($contact)) {
 224                         return false;
 225                 }
 226
 227                 if ($contact['last-discovery'] > DateTimeFormat::utc('now - 1 month')) {
 228                         Logger::info('No discovery - Last was less than a month ago.', ['id' => $contact['id'], 'url' => $url, 'discovery' => $contact['last-discovery']]);
 229                         return false;
 230                 }
 231
 232                 if ($contact_discovery != self::DISCOVERY_ALL) {
 233                         $local = DBA::exists('contact', ["`nurl` = ? AND `uid` != ?", Strings::normaliseLink($url), 0]);
 234                         if (($contact_discovery == self::DISCOVERY_LOCAL) && !$local) {
 235                                 Logger::info('No discovery - This contact is not followed/following locally.', ['id' => $contact['id'], 'url' => $url]);
 236                                 return false;
 237                         }
 238
 239                         if ($contact_discovery == self::DISCOVERY_INTERACTOR) {
 240                                 $interactor = DBA::exists('contact-relation', ["`relation-cid` = ? AND `last-interaction` > ?", $contact['id'], DBA::NULL_DATETIME]);
 241                                 if (!$local && !$interactor) {
 242                                         Logger::info('No discovery - This contact is not interacting locally.', ['id' => $contact['id'], 'url' => $url]);
 243                                         return false;
 244                                 }
 245                         }
 246                 } elseif ($contact['created'] > DateTimeFormat::utc('now - 1 day')) {
 247                         // Newly created contacts are not discovered to avoid DDoS attacks
 248                         Logger::info('No discovery - Contact record is less than a day old.', ['id' => $contact['id'], 'url' => $url, 'discovery' => $contact['created']]);
 249                         return false;
 250                 }
 251
 252                 if (!in_array($contact['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::OSTATUS])) {
 253                         $apcontact = APContact::getByURL($url, false);
 254                         if (empty($apcontact)) {
 255                                 Logger::info('No discovery - The contact does not seem to speak ActivityPub.', ['id' => $contact['id'], 'url' => $url, 'network' => $contact['network']]);
 256                                 return false;
 257                         }
 258                 }
 259
 260                 return true;
 261         }
 262
 263         /**
 264          * Returns an array of suggested contacts for given user id
 265          *
 266          * @param int $uid   User id
 267          * @param int $start optional, default 0
 268          * @param int $limit optional, default 80
 269          * @return array
 270          */
 271         static public function getSuggestions(int $uid, int $start = 0, int $limit = 80): array
 272         {
 273                 $cid = Contact::getPublicIdByUserId($uid);
 274                 $totallimit = $start + $limit;
 275                 $contacts = [];
 276
 277                 Logger::info('Collecting suggestions', ['uid' => $uid, 'cid' => $cid, 'start' => $start, 'limit' => $limit]);
 278
 279                 $diaspora = DI::config()->get('system', 'diaspora_enabled') ? Protocol::DIASPORA : Protocol::ACTIVITYPUB;
 280                 $ostatus = !DI::config()->get('system', 'ostatus_disabled') ? Protocol::OSTATUS : Protocol::ACTIVITYPUB;
 281
 282                 // The query returns contacts where contacts interacted with whom the given user follows.
 283                 // Contacts who already are in the user's contact table are ignored.
 284                 $results = DBA::select('contact', [], ["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` IN
 285                                 (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ?)
 286                                         AND NOT `cid` IN (SELECT `id` FROM `contact` WHERE `uid` = ? AND `nurl` IN
 287                                                 (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))))
 288                         AND NOT `hidden` AND `network` IN (?, ?, ?, ?)",
 289                         $cid,
 290                         0,
 291                         $uid, Contact::FRIEND, Contact::SHARING,
 292                         Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus,
 293                         ], [
 294                                 'order' => ['last-item' => true],
 295                                 'limit' => $totallimit,
 296                         ]
 297                 );
 298
 299                 while ($contact = DBA::fetch($results)) {
 300                         $contacts[$contact['id']] = $contact;
 301                 }
 302
 303                 DBA::close($results);
 304
 305                 Logger::info('Contacts of contacts who are followed by the given user', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
 306
 307                 if (count($contacts) >= $totallimit) {
 308                         return array_slice($contacts, $start, $limit);
 309                 }
 310
 311                 // The query returns contacts where contacts interacted with whom also interacted with the given user.
 312                 // Contacts who already are in the user's contact table are ignored.
 313                 $results = DBA::select('contact', [],
 314                         ["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` IN
 315                                 (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ?)
 316                                         AND NOT `cid` IN (SELECT `id` FROM `contact` WHERE `uid` = ? AND `nurl` IN
 317                                                 (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))))
 318                         AND NOT `hidden` AND `network` IN (?, ?, ?, ?)",
 319                         $cid, 0, $uid, Contact::FRIEND, Contact::SHARING,
 320                         Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
 321                         ['order' => ['last-item' => true], 'limit' => $totallimit]
 322                 );
 323
 324                 while ($contact = DBA::fetch($results)) {
 325                         $contacts[$contact['id']] = $contact;
 326                 }
 327                 DBA::close($results);
 328
 329                 Logger::info('Contacts of contacts who are following the given user', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
 330
 331                 if (count($contacts) >= $totallimit) {
 332                         return array_slice($contacts, $start, $limit);
 333                 }
 334
 335                 // The query returns contacts that follow the given user but aren't followed by that user.
 336                 $results = DBA::select('contact', [],
 337                         ["`nurl` IN (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` = ?)
 338                         AND NOT `hidden` AND `uid` = ? AND `network` IN (?, ?, ?, ?)",
 339                         $uid, Contact::FOLLOWER, 0,
 340                         Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
 341                         ['order' => ['last-item' => true], 'limit' => $totallimit]
 342                 );
 343
 344                 while ($contact = DBA::fetch($results)) {
 345                         $contacts[$contact['id']] = $contact;
 346                 }
 347                 DBA::close($results);
 348
 349                 Logger::info('Followers that are not followed by the given user', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
 350
 351                 if (count($contacts) >= $totallimit) {
 352                         return array_slice($contacts, $start, $limit);
 353                 }
 354
 355                 // The query returns any contact that isn't followed by that user.
 356                 $results = DBA::select('contact', [],
 357                         ["NOT `nurl` IN (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))
 358                         AND NOT `hidden` AND `uid` = ? AND `network` IN (?, ?, ?, ?)",
 359                         $uid, Contact::FRIEND, Contact::SHARING, 0,
 360                         Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
 361                         ['order' => ['last-item' => true], 'limit' => $totallimit]
 362                 );
 363
 364                 while ($contact = DBA::fetch($results)) {
 365                         $contacts[$contact['id']] = $contact;
 366                 }
 367                 DBA::close($results);
 368
 369                 Logger::info('Any contact', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
 370
 371                 return array_slice($contacts, $start, $limit);
 372         }
 373
 374         /**
 375          * Counts all the known follows of the provided public contact
 376          *
 377          * @param int   $cid       Public contact id
 378          * @param array $condition Additional condition on the contact table
 379          * @return int
 380          * @throws Exception
 381          */
 382         public static function countFollows(int $cid, array $condition = []): int
 383         {
 384                 $condition = DBA::mergeConditions($condition, [
 385                         '`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)',
 386                         $cid,
 387                 ]);
 388
 389                 return DI::dba()->count('contact', $condition);
 390         }
 391
 392         /**
 393          * Returns a paginated list of contacts that are followed the provided public contact.
 394          *
 395          * @param int   $cid       Public contact id
 396          * @param array $condition Additional condition on the contact table
 397          * @param int   $count
 398          * @param int   $offset
 399          * @param bool  $shuffle
 400          * @return array
 401          * @throws Exception
 402          */
 403         public static function listFollows(int $cid, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
 404         {
 405                 $condition = DBA::mergeConditions($condition,
 406                         ['`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)',
 407                         $cid]
 408                 );
 409
 410                 return DI::dba()->selectToArray('contact', [], $condition,
 411                         ['limit' => [$offset, $count], 'order' => [$shuffle ? 'RAND()' : 'name']]
 412                 );
 413         }
 414
 415         /**
 416          * Counts all the known followers of the provided public contact
 417          *
 418          * @param int   $cid       Public contact id
 419          * @param array $condition Additional condition on the contact table
 420          * @return int
 421          * @throws Exception
 422          */
 423         public static function countFollowers(int $cid, array $condition = [])
 424         {
 425                 $condition = DBA::mergeConditions($condition,
 426                         ['`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`)',
 427                         $cid]
 428                 );
 429
 430                 return DI::dba()->count('contact', $condition);
 431         }
 432
 433         /**
 434          * Returns a paginated list of contacts that follow the provided public contact.
 435          *
 436          * @param int   $cid       Public contact id
 437          * @param array $condition Additional condition on the contact table
 438          * @param int   $count
 439          * @param int   $offset
 440          * @param bool  $shuffle
 441          * @return array
 442          * @throws Exception
 443          */
 444         public static function listFollowers(int $cid, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
 445         {
 446                 $condition = DBA::mergeConditions($condition,
 447                         ['`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`)', $cid]
 448                 );
 449
 450                 return DI::dba()->selectToArray('contact', [], $condition,
 451                         ['limit' => [$offset, $count], 'order' => [$shuffle ? 'RAND()' : 'name']]
 452                 );
 453         }
 454
 455         /**
 456          * Counts the number of contacts that are known mutuals with the provided public contact.
 457          *
 458          * @param int   $cid       Public contact id
 459          * @param array $condition Additional condition array on the contact table
 460          * @return int
 461          * @throws Exception
 462          */
 463         public static function countMutuals(int $cid, array $condition = [])
 464         {
 465                 $condition = DBA::mergeConditions($condition,
 466                         ['`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)
 467                         AND `id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`)',
 468                         $cid, $cid]
 469                 );
 470
 471                 return DI::dba()->count('contact', $condition);
 472         }
 473
 474         /**
 475          * Returns a paginated list of contacts that are known mutuals with the provided public contact.
 476          *
 477          * @param int   $cid       Public contact id
 478          * @param array $condition Additional condition on the contact table
 479          * @param int   $count
 480          * @param int   $offset
 481          * @param bool  $shuffle
 482          * @return array
 483          * @throws Exception
 484          */
 485         public static function listMutuals(int $cid, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
 486         {
 487                 $condition = DBA::mergeConditions($condition,
 488                         ['`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)
 489                         AND `id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`)',
 490                         $cid, $cid]
 491                 );
 492
 493                 return DI::dba()->selectToArray('contact', [], $condition,
 494                         ['limit' => [$offset, $count], 'order' => [$shuffle ? 'RAND()' : 'name']]
 495                 );
 496         }
 497
 498
 499         /**
 500          * Counts the number of contacts with any relationship with the provided public contact.
 501          *
 502          * @param int   $cid       Public contact id
 503          * @param array $condition Additional condition array on the contact table
 504          * @return int
 505          * @throws Exception
 506          */
 507         public static function countAll(int $cid, array $condition = [])
 508         {
 509                 $condition = DBA::mergeConditions($condition,
 510                         ['(`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)
 511                         OR `id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`))',
 512                                 $cid, $cid]
 513                 );
 514
 515                 return DI::dba()->count('contact', $condition);
 516         }
 517
 518         /**
 519          * Returns a paginated list of contacts with any relationship with the provided public contact.
 520          *
 521          * @param int   $cid       Public contact id
 522          * @param array $condition Additional condition on the contact table
 523          * @param int   $count
 524          * @param int   $offset
 525          * @param bool  $shuffle
 526          * @return array
 527          * @throws Exception
 528          */
 529         public static function listAll(int $cid, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
 530         {
 531                 $condition = DBA::mergeConditions($condition,
 532                         ['(`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)
 533                         OR `id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`))',
 534                                 $cid, $cid]
 535                 );
 536
 537                 return DI::dba()->selectToArray('contact', [], $condition,
 538                         ['limit' => [$offset, $count], 'order' => [$shuffle ? 'RAND()' : 'name']]
 539                 );
 540         }
 541
 542         /**
 543          * Counts the number of contacts that both provided public contacts have interacted with at least once.
 544          * Interactions include follows and likes and comments on public posts.
 545          *
 546          * @param int   $sourceId  Public contact id
 547          * @param int   $targetId  Public contact id
 548          * @param array $condition Additional condition array on the contact table
 549          * @return int
 550          * @throws Exception
 551          */
 552         public static function countCommon(int $sourceId, int $targetId, array $condition = [])
 553         {
 554                 $condition = DBA::mergeConditions($condition,
 555                         ['`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ?)
 556                         AND `id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ?)',
 557                         $sourceId, $targetId]
 558                 );
 559
 560                 return DI::dba()->count('contact', $condition);
 561         }
 562
 563         /**
 564          * Returns a paginated list of contacts that both provided public contacts have interacted with at least once.
 565          * Interactions include follows and likes and comments on public posts.
 566          *
 567          * @param int   $sourceId  Public contact id
 568          * @param int   $targetId  Public contact id
 569          * @param array $condition Additional condition on the contact table
 570          * @param int   $count
 571          * @param int   $offset
 572          * @param bool  $shuffle
 573          * @return array|bool Array on success, false on failure
 574          * @throws Exception
 575          */
 576         public static function listCommon(int $sourceId, int $targetId, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
 577         {
 578                 $condition = DBA::mergeConditions($condition,
 579                         ["`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ?)
 580                         AND `id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ?)",
 581                         $sourceId, $targetId]
 582                 );
 583
 584                 return DI::dba()->selectToArray('contact', [], $condition,
 585                         ['limit' => [$offset, $count], 'order' => [$shuffle ? 'RAND()' : 'name']]
 586                 );
 587         }
 588
 589         /**
 590          * Counts the number of contacts that are followed by both provided public contacts.
 591          *
 592          * @param int   $sourceId  Public contact id
 593          * @param int   $targetId  Public contact id
 594          * @param array $condition Additional condition array on the contact table
 595          * @return int
 596          * @throws Exception
 597          */
 598         public static function countCommonFollows(int $sourceId, int $targetId, array $condition = []): int
 599         {
 600                 $condition = DBA::mergeConditions($condition,
 601                         ['`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)
 602                         AND `id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)',
 603                         $sourceId, $targetId]
 604                 );
 605
 606                 return DI::dba()->count('contact', $condition);
 607         }
 608
 609         /**
 610          * Returns a paginated list of contacts that are followed by both provided public contacts.
 611          *
 612          * @param int   $sourceId  Public contact id
 613          * @param int   $targetId  Public contact id
 614          * @param array $condition Additional condition array on the contact table
 615          * @param int   $count
 616          * @param int   $offset
 617          * @param bool  $shuffle
 618          * @return array|bool Array on success, false on failure
 619          * @throws Exception
 620          */
 621         public static function listCommonFollows(int $sourceId, int $targetId, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
 622         {
 623                 $condition = DBA::mergeConditions($condition,
 624                         ["`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)
 625                         AND `id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)",
 626                         $sourceId, $targetId]
 627                 );
 628
 629                 return DI::dba()->selectToArray('contact', [], $condition,
 630                         ['limit' => [$offset, $count], 'order' => [$shuffle ? 'RAND()' : 'name']]
 631                 );
 632         }
 633
 634         /**
 635          * Counts the number of contacts that follow both provided public contacts.
 636          *
 637          * @param int   $sourceId  Public contact id
 638          * @param int   $targetId  Public contact id
 639          * @param array $condition Additional condition on the contact table
 640          * @return int
 641          * @throws Exception
 642          */
 643         public static function countCommonFollowers(int $sourceId, int $targetId, array $condition = []): int
 644         {
 645                 $condition = DBA::mergeConditions($condition,
 646                         ["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`)
 647                         AND `id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`)",
 648                         $sourceId, $targetId]
 649                 );
 650
 651                 return DI::dba()->count('contact', $condition);
 652         }
 653
 654         /**
 655          * Returns a paginated list of contacts that follow both provided public contacts.
 656          *
 657          * @param int   $sourceId  Public contact id
 658          * @param int   $targetId  Public contact id
 659          * @param array $condition Additional condition on the contact table
 660          * @param int   $count
 661          * @param int   $offset
 662          * @param bool  $shuffle
 663          * @return array|bool Array on success, false on failure
 664          * @throws Exception
 665          */
 666         public static function listCommonFollowers(int $sourceId, int $targetId, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
 667         {
 668                 $condition = DBA::mergeConditions($condition,
 669                         ["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`)
 670                         AND `id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`)",
 671                         $sourceId, $targetId]
 672                 );
 673
 674                 return DI::dba()->selectToArray('contact', [], $condition,
 675                         ['limit' => [$offset, $count],  'order' => [$shuffle ? 'RAND()' : 'name']]
 676                 );
 677         }
 678 }