Remove implicit mentions from incoming ActivityPub messages

- Add Processor::getImplicitMentionList and Processor::removeImplicitMentionsFromBody methods
- Rename Processor::constructTagList to Processor::constructTagString
- Add implicit mention skip in Processor::constructTagString
- Invert parameter order in Processor::replaceEmojis

diff --git a/src/Protocol/ActivityPub/Processor.php b/src/Protocol/ActivityPub/Processor.php
index fd6d70a42a2d01fac09c0501a2da35a57a03d13b..ef351f30de648a21089b52802daef4bc83736dc3 100644 (file)
--- a/src/Protocol/ActivityPub/Processor.php
+++ b/src/Protocol/ActivityPub/Processor.php
@@ -13,6 +13,7 @@ use Friendica\Model\Contact;
 use Friendica\Model\APContact;
 use Friendica\Model\Item;
 use Friendica\Model\Event;
+use Friendica\Model\Term;
 use Friendica\Model\User;
 use Friendica\Protocol\ActivityPub;
 use Friendica\Util\DateTimeFormat;
@@ -47,7 +48,7 @@ class Processor
         *
         * @return string with replaced emojis
         */
-       public static function replaceEmojis($emojis, $body)
+       public static function replaceEmojis($body, array $emojis)
        {
                foreach ($emojis as $emoji) {
                        $replace = '[class=emoji mastodon][img=' . $emoji['href'] . ']' . $emoji['name'] . '[/img][/class]';
@@ -59,12 +60,12 @@ class Processor
        /**
         * Constructs a string with tags for a given tag array
         *
-        * @param array $tags
+        * @param array   $tags
         * @param boolean $sensitive
-        *
+        * @param array   $implicit_mentions List of profile URLs to skip
         * @return string with tags
         */
-       private static function constructTagList($tags, $sensitive)
+       private static function constructTagString($tags, $sensitive, array $implicit_mentions)
        {
                if (empty($tags)) {
                        return '';
@@ -72,7 +73,7 @@ class Processor
 
                $tag_text = '';
                foreach ($tags as $tag) {
-                       if (in_array(defaults($tag, 'type', ''), ['Mention', 'Hashtag'])) {
+                       if (in_array(defaults($tag, 'type', ''), ['Mention', 'Hashtag']) && !in_array($tag['href'], $implicit_mentions)) {
                                if (!empty($tag_text)) {
                                        $tag_text .= ',';
                                }
@@ -128,14 +129,35 @@ class Processor
         */
        public static function updateItem($activity)
        {
-               $item = [];
+               $item = Item::selectFirst(['uri', 'parent-uri', 'gravity'], ['uri' => $activity['id']]);
+               if (!DBA::isResult($item)) {
+                       Logger::warning('Unknown item with uri: ' . $activity['id']);
+                       return;
+               }
+
                $item['changed'] = DateTimeFormat::utcNow();
                $item['edited'] = $activity['updated'];
                $item['title'] = HTML::toBBCode($activity['name']);
                $item['content-warning'] = HTML::toBBCode($activity['summary']);
-               $content = self::replaceEmojis($activity['emojis'], HTML::toBBCode($activity['content']));
-               $item['body'] = self::convertMentions($content);
-               $item['tag'] = self::constructTagList($activity['tags'], $activity['sensitive']);
+
+               $content = HTML::toBBCode($activity['content']);
+               $content = self::replaceEmojis($content, $activity['emojis']);
+               $content = self::convertMentions($content);
+
+               $implicit_mentions = [];
+               if (($item['parent-uri'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
+                       $parent = Item::selectFirst(['id', 'author-link', 'alias'], ['uri' => $item['parent-uri']]);
+                       if (!DBA::isResult($parent)) {
+                               Logger::warning('Unknown item parent with uri: ' . $item['parent-uri']);
+                               return;
+                       }
+
+                       $implicit_mentions = self::getImplicitMentionList($parent);
+                       $content = self::removeImplicitMentionsFromBody($content, $implicit_mentions);
+               }
+
+               $item['body'] = $content;
+               $item['tag'] = self::constructTagString($activity['tags'], $activity['sensitive'], $implicit_mentions);
 
                Item::update($item, ['uri' => $activity['id']]);
        }
@@ -273,10 +295,15 @@ class Processor
                }
 
                $item['uri'] = $activity['id'];
+               $content = HTML::toBBCode($activity['content']);
+               $content = self::replaceEmojis($content, $activity['emojis']);
+               $content = self::convertMentions($content);
+
+               $implicit_mentions = [];
 
                if (($item['parent-uri'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
                        $item_private = !in_array(0, $activity['item_receiver']);
-                       $parent = Item::selectFirst(['private'], ['uri' => $item['parent-uri']]);
+                       $parent = Item::selectFirst(['id', 'private', 'author-link', 'alias'], ['uri' => $item['parent-uri']]);
                        if (!DBA::isResult($parent)) {
                                return;
                        }
@@ -284,6 +311,9 @@ class Processor
                                Logger::log('Item ' . $item['uri'] . ' is private but the parent ' . $item['parent-uri'] . ' is not. So we drop it.');
                                return;
                        }
+
+                       $implicit_mentions = self::getImplicitMentionList($parent);
+                       $content = self::removeImplicitMentionsFromBody($content, $implicit_mentions);
                }
 
                $item['created'] = $activity['published'];
@@ -291,8 +321,7 @@ class Processor
                $item['guid'] = $activity['diaspora:guid'];
                $item['title'] = HTML::toBBCode($activity['name']);
                $item['content-warning'] = HTML::toBBCode($activity['summary']);
-               $content = self::replaceEmojis($activity['emojis'], HTML::toBBCode($activity['content']));
-               $item['body'] = self::convertMentions($content);
+               $item['body'] = $content;
 
                if (($activity['object_type'] == 'as:Video') && !empty($activity['alternate-url'])) {
                        $item['body'] .= "\n[video]" . $activity['alternate-url'] . '[/video]';
@@ -304,7 +333,7 @@ class Processor
                        $item['coord'] = $item['latitude'] . ' ' . $item['longitude'];
                }
 
-               $item['tag'] = self::constructTagList($activity['tags'], $activity['sensitive']);
+               $item['tag'] = self::constructTagString($activity['tags'], $activity['sensitive'], $implicit_mentions);
                $item['app'] = $activity['generator'];
                $item['plink'] = defaults($activity, 'alternate-url', $item['uri']);
 
@@ -610,4 +639,62 @@ class Processor
                Logger::log('Change existing contact ' . $cid . ' from ' . $contact['network'] . ' to ActivityPub.');
                Contact::updateFromProbe($cid, Protocol::ACTIVITYPUB);
        }
+
+       /**
+        * Collects implicit mentions like:
+        * - the author of the parent item
+        * - all the mentioned conversants in the parent item
+        *
+        * @param array $parent Item array with at least ['id', 'author-link', 'alias']
+        * @return array
+        * @throws \Friendica\Network\HTTPException\InternalServerErrorException
+        */
+       private static function getImplicitMentionList(array $parent)
+       {
+               $parent_terms = Term::tagArrayFromItemId($parent['id'], [TERM_MENTION]);
+
+               $implicit_mentions = [
+                       $parent['author-link']
+               ];
+
+               if ($parent['alias']) {
+                       $implicit_mentions[] = $parent['alias'];
+               }
+
+               foreach ($parent_terms as $term) {
+                       $contact = Contact::getDetailsByURL($term['url']);
+
+                       $implicit_mentions[] = $contact['url'];
+                       $implicit_mentions[] = $contact['nurl'];
+                       $implicit_mentions[] = $contact['alias'];
+               }
+
+               return $implicit_mentions;
+       }
+
+       /**
+        * Strips from the body prepended implicit mentions
+        *
+        * @param string $body
+        * @param array  $implicit_mentions List of profile URLs
+        * @return string
+        */
+       private static function removeImplicitMentionsFromBody($body, array $implicit_mentions)
+       {
+               $kept_mentions = [];
+
+               // Extract one prepended mention at a time from the body
+               while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#mi', $body, $matches)) {
+                       if (!in_array($matches[2], $implicit_mentions) ) {
+                               $kept_mentions[] = $matches[1];
+                       }
+
+                       $body = $matches[3];
+               }
+
+               // Re-appending the kept mentions to the body after extraction
+               $kept_mentions[] = $body;
+
+               return implode('', $kept_mentions);
+       }
 }