From 4e5f8dce11967b25f9ee16ded9c29949f4978e7d Mon Sep 17 00:00:00 2001
From: IanM <ian@morland.me>
Date: Wed, 6 Nov 2024 22:59:36 +0000
Subject: [PATCH] feat: add a solution filter for the posts endpoint

---
 extend.php                          |  4 +++
 src/Search/BestAnswerPostFilter.php | 40 +++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 src/Search/BestAnswerPostFilter.php

diff --git a/extend.php b/extend.php
index e2ff0b4..cb0e77d 100644
--- a/extend.php
+++ b/extend.php
@@ -23,6 +23,7 @@
 use Flarum\Discussion\Filter\DiscussionFilterer;
 use Flarum\Discussion\Search\DiscussionSearcher;
 use Flarum\Extend;
+use Flarum\Post\Filter\PostFilterer;
 use Flarum\Post\Post;
 use Flarum\Settings\Event\Saving as SettingsSaving;
 use Flarum\Tags\Api\Serializer\TagSerializer;
@@ -127,6 +128,9 @@
     (new Extend\Filter(DiscussionFilterer::class))
         ->addFilter(Search\BestAnswerFilterGambit::class),
 
+    (new Extend\Filter(PostFilterer::class))
+        ->addFilter(Search\BestAnswerPostFilter::class),
+
     (new Extend\ApiSerializer(TagSerializer::class))
         ->attributes(function (TagSerializer $serializer, Tag $tag, array $attributes) {
             $attributes['isQnA'] = (bool) $tag->is_qna;
diff --git a/src/Search/BestAnswerPostFilter.php b/src/Search/BestAnswerPostFilter.php
new file mode 100644
index 0000000..7fe2b18
--- /dev/null
+++ b/src/Search/BestAnswerPostFilter.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace FoF\BestAnswer\Search;
+
+use Flarum\Filter\FilterInterface;
+use Flarum\Filter\FilterState;
+use Flarum\User\User;
+use Illuminate\Database\Query\Builder;
+
+class BestAnswerPostFilter implements FilterInterface
+{
+    public function getFilterKey(): string
+    {
+        return 'is:solution';
+    }
+
+    public function filter(FilterState $filterState, string $filterValue, bool $negate)
+    {
+        $this->constrain($filterState->getQuery(), $filterState->getActor(), $negate);
+    }
+
+    protected function constrain(Builder $query, User $actor, bool $negate)
+    {
+        // Join the `discussions` table to access `best_answer_post_id`.
+        $query->join('discussions', 'posts.discussion_id', '=', 'discussions.id')
+            ->where('posts.type', 'comment');
+
+        if ($negate) {
+            // Exclude posts that are marked as the best answer
+            $query->where(function ($query) {
+                $query->whereNull('discussions.best_answer_post_id')
+                    ->orWhereColumn('posts.id', '!=', 'discussions.best_answer_post_id');
+            });
+        } else {
+            // Include only posts that are marked as the best answer
+            $query->whereNotNull('discussions.best_answer_post_id')
+                ->whereColumn('posts.id', '=', 'discussions.best_answer_post_id');
+        }
+    }
+}