#2492 - Groups filtering & retrieve single endpoint (#3084)

Fixes #2492

* Added api/groups/{id} endpoint for retrieving a single group by its id
* Fixed GroupRepository incorrectly opening query to User instead of Group model
* Added filtering & paging abilities to GET api/groups endpoint
* Added test for sorting for GET api/groups endpoint

Co-authored-by: Alexander Skvortsov <38059171+askvortsov1@users.noreply.github.com>

src/Api/Controller/ListGroupsController.php

@@ -10,8 +10,10 @@
 namespace Flarum\Api\Controller;
 
 use Flarum\Api\Serializer\GroupSerializer;
-use Flarum\Group\Group;
+use Flarum\Group\Filter\GroupFilterer;
 use Flarum\Http\RequestUtil;
+use Flarum\Http\UrlGenerator;
+use Flarum\Query\QueryCriteria;
 use Psr\Http\Message\ServerRequestInterface;
 use Tobscure\JsonApi\Document;
 
@@ -22,6 +24,38 @@ class ListGroupsController extends AbstractListController
      */
     public $serializer = GroupSerializer::class;
 
+    /**
+     * {@inheritdoc}
+     */
+    public $sortFields = ['nameSingular', 'namePlural', 'isHidden'];
+
+    /**
+     * {@inheritdoc}
+     *
+     * @var int
+     */
+    public $limit = -1;
+
+    /**
+     * @var GroupFilterer
+     */
+    protected $filterer;
+
+    /**
+     * @var UrlGenerator
+     */
+    protected $url;
+
+    /**
+     * @param GroupFilterer $filterer
+     * @param UrlGenerator $url
+     */
+    public function __construct(GroupFilterer $filterer, UrlGenerator $url)
+    {
+        $this->filterer = $filterer;
+        $this->url = $url;
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -29,10 +63,25 @@ class ListGroupsController extends AbstractListController
     {
         $actor = RequestUtil::getActor($request);
 
-        $results = Group::whereVisibleTo($actor)->get();
+        $filters = $this->extractFilter($request);
+        $sort = $this->extractSort($request);
+        $sortIsDefault = $this->sortIsDefault($request);
 
-        $this->loadRelations($results, []);
+        $limit = $this->extractLimit($request);
+        $offset = $this->extractOffset($request);
 
-        return $results;
+        $criteria = new QueryCriteria($actor, $filters, $sort, $sortIsDefault);
+
+        $queryResults = $this->filterer->filter($criteria, $limit, $offset);
+
+        $document->addPaginationLinks(
+            $this->url->to('api')->route('groups.index'),
+            $request->getQueryParams(),
+            $offset,
+            $limit,
+            $queryResults->areMoreResults() ? null : 0
+        );
+
+        return $queryResults->getResults();
     }
 }

src/Api/Controller/ShowGroupController.php

@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Api\Controller;
+
+use Flarum\Api\Serializer\GroupSerializer;
+use Flarum\Group\GroupRepository;
+use Flarum\Http\RequestUtil;
+use Illuminate\Support\Arr;
+use Psr\Http\Message\ServerRequestInterface;
+use Tobscure\JsonApi\Document;
+
+class ShowGroupController extends AbstractShowController
+{
+    /**
+     * @var GroupRepository
+     */
+    protected $groups;
+
+    /**
+     * {@inheritdoc}
+     */
+    public $serializer = GroupSerializer::class;
+
+    /**
+     * @param \Flarum\Group\GroupRepository $groups
+     */
+    public function __construct(GroupRepository $groups)
+    {
+        $this->groups = $groups;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function data(ServerRequestInterface $request, Document $document)
+    {
+        $id = Arr::get($request->getQueryParams(), 'id');
+        $actor = RequestUtil::getActor($request);
+
+        $group = $this->groups->findOrFail($id, $actor);
+
+        return $group;
+    }
+}