+ /**
+ * Returns an array of suggested contacts for given user id
+ *
+ * @param int $uid User id
+ * @param int $start optional, default 0
+ * @param int $limit optional, default 80
+ * @return array
+ */
+ static public function getSuggestions(int $uid, int $start = 0, int $limit = 80): array
+ {
+ $cid = Contact::getPublicIdByUserId($uid);
+ $totallimit = $start + $limit;
+ $contacts = [];
+
+ Logger::info('Collecting suggestions', ['uid' => $uid, 'cid' => $cid, 'start' => $start, 'limit' => $limit]);
+
+ $diaspora = DI::config()->get('system', 'diaspora_enabled') ? Protocol::DIASPORA : Protocol::ACTIVITYPUB;
+ $ostatus = !DI::config()->get('system', 'ostatus_disabled') ? Protocol::OSTATUS : Protocol::ACTIVITYPUB;
+
+ // The query returns contacts where contacts interacted with whom the given user follows.
+ // Contacts who already are in the user's contact table are ignored.
+ $results = DBA::select('contact', [], ["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` IN
+ (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ?)
+ AND NOT `cid` IN (SELECT `id` FROM `contact` WHERE `uid` = ? AND `nurl` IN
+ (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))))
+ AND NOT `hidden` AND `network` IN (?, ?, ?, ?)",
+ $cid,
+ 0,
+ $uid, Contact::FRIEND, Contact::SHARING,
+ Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus,
+ ], [
+ 'order' => ['last-item' => true],
+ 'limit' => $totallimit,
+ ]
+ );
+
+ while ($contact = DBA::fetch($results)) {
+ $contacts[$contact['id']] = $contact;
+ }
+
+ DBA::close($results);
+
+ Logger::info('Contacts of contacts who are followed by the given user', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
+
+ if (count($contacts) >= $totallimit) {
+ return array_slice($contacts, $start, $limit);
+ }
+
+ // The query returns contacts where contacts interacted with whom also interacted with the given user.
+ // Contacts who already are in the user's contact table are ignored.
+ $results = DBA::select('contact', [],
+ ["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` IN
+ (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ?)
+ AND NOT `cid` IN (SELECT `id` FROM `contact` WHERE `uid` = ? AND `nurl` IN
+ (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))))
+ AND NOT `hidden` AND `network` IN (?, ?, ?, ?)",
+ $cid, 0, $uid, Contact::FRIEND, Contact::SHARING,
+ Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
+ ['order' => ['last-item' => true], 'limit' => $totallimit]
+ );
+
+ while ($contact = DBA::fetch($results)) {
+ $contacts[$contact['id']] = $contact;
+ }
+ DBA::close($results);
+
+ Logger::info('Contacts of contacts who are following the given user', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
+
+ if (count($contacts) >= $totallimit) {
+ return array_slice($contacts, $start, $limit);
+ }
+
+ // The query returns contacts that follow the given user but aren't followed by that user.
+ $results = DBA::select('contact', [],
+ ["`nurl` IN (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` = ?)
+ AND NOT `hidden` AND `uid` = ? AND `network` IN (?, ?, ?, ?)",
+ $uid, Contact::FOLLOWER, 0,
+ Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
+ ['order' => ['last-item' => true], 'limit' => $totallimit]
+ );
+
+ while ($contact = DBA::fetch($results)) {
+ $contacts[$contact['id']] = $contact;
+ }
+ DBA::close($results);
+
+ Logger::info('Followers that are not followed by the given user', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
+
+ if (count($contacts) >= $totallimit) {
+ return array_slice($contacts, $start, $limit);
+ }
+
+ // The query returns any contact that isn't followed by that user.
+ $results = DBA::select('contact', [],
+ ["NOT `nurl` IN (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))
+ AND NOT `hidden` AND `uid` = ? AND `network` IN (?, ?, ?, ?)",
+ $uid, Contact::FRIEND, Contact::SHARING, 0,
+ Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
+ ['order' => ['last-item' => true], 'limit' => $totallimit]
+ );
+
+ while ($contact = DBA::fetch($results)) {
+ $contacts[$contact['id']] = $contact;
+ }
+ DBA::close($results);
+
+ Logger::info('Any contact', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
+
+ return array_slice($contacts, $start, $limit);
+ }
+