fix: unread filter gambit does not return results when > 999 read dis…

…cussions for a user (#3295)

src/Discussion/DiscussionRepository.php

@@ -42,16 +42,29 @@ public function findOrFail($id, User $user = null)
     /**
      * Get the IDs of discussions which a user has read completely.
      *
+     * @deprecated 1.3 Use `getReadIdsQuery` instead
+     *
      * @param User $user
      * @return array
      */
     public function getReadIds(User $user)
+    {
+        return $this->getReadIdsQuery($user)
+            ->all();
+    }
+
+    /**
+     * Get a query containing the IDs of discussions which a user has read completely.
+     *
+     * @param User $user
+     * @return Builder
+     */
+    public function getReadIdsQuery(User $user): Builder
     {
         return Discussion::leftJoin('discussion_user', 'discussion_user.discussion_id', '=', 'discussions.id')
             ->where('discussion_user.user_id', $user->id)
             ->whereColumn('last_read_post_number', '>=', 'last_post_number')
-            ->pluck('id')
-            ->all();
+            ->select('id');
     }
 
     /**

src/Discussion/Query/UnreadFilterGambit.php

@@ -61,7 +61,7 @@ public function filter(FilterState $filterState, string $filterValue, bool $nega
     protected function constrain(Builder $query, User $actor, bool $negate)
     {
         if ($actor->exists) {
-            $readIds = $this->discussions->getReadIds($actor);
+            $readIds = $this->discussions->getReadIdsQuery($actor);
 
             $query->where(function ($query) use ($readIds, $negate, $actor) {
                 if (! $negate) {