Fix relevance sort (#2773)

- Adds a field to QueryCriteria that determines whether the sort provided is the controller's default sort
- Set this field to true iff sort not in query params. Default it to false
- Override $sort if a new default sort has been set on search state, and the param is true.
- Add tests!

src/Api/Controller/AbstractSerializeController.php

@@ -12,6 +12,7 @@ namespace Flarum\Api\Controller;
 use Flarum\Api\JsonApiResponse;
 use Illuminate\Contracts\Container\Container;
 use Illuminate\Database\Eloquent\Collection;
+use Illuminate\Support\Arr;
 use Illuminate\Support\Str;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
@@ -255,6 +256,11 @@ abstract class AbstractSerializeController implements RequestHandlerInterface
         return new Parameters($request->getQueryParams());
     }
 
+    protected function sortIsDefault(ServerRequestInterface $request): bool
+    {
+        return ! Arr::get($request->getQueryParams(), 'sort');
+    }
+
     /**
      * Set the serializer that will serialize data for the endpoint.
      *

src/Api/Controller/ListDiscussionsController.php

@@ -89,12 +89,13 @@ class ListDiscussionsController extends AbstractListController
         $actor = RequestUtil::getActor($request);
         $filters = $this->extractFilter($request);
         $sort = $this->extractSort($request);
+        $sortIsDefault = $this->sortIsDefault($request);
 
         $limit = $this->extractLimit($request);
         $offset = $this->extractOffset($request);
         $include = array_merge($this->extractInclude($request), ['state']);
 
-        $criteria = new QueryCriteria($actor, $filters, $sort);
+        $criteria = new QueryCriteria($actor, $filters, $sort, $sortIsDefault);
         if (array_key_exists('q', $filters)) {
             $results = $this->searcher->search($criteria, $limit, $offset);
         } else {

src/Api/Controller/ListPostsController.php

@@ -79,12 +79,13 @@ class ListPostsController extends AbstractListController
 
         $filters = $this->extractFilter($request);
         $sort = $this->extractSort($request);
+        $sortIsDefault = $this->sortIsDefault($request);
 
         $limit = $this->extractLimit($request);
         $offset = $this->extractOffset($request);
         $include = $this->extractInclude($request);
 
-        $results = $this->filterer->filter(new QueryCriteria($actor, $filters, $sort), $limit, $offset);
+        $results = $this->filterer->filter(new QueryCriteria($actor, $filters, $sort, $sortIsDefault), $limit, $offset);
 
         $document->addPaginationLinks(
             $this->url->to('api')->route('posts.index'),

src/Api/Controller/ListUsersController.php

@@ -86,12 +86,13 @@ class ListUsersController extends AbstractListController
 
         $filters = $this->extractFilter($request);
         $sort = $this->extractSort($request);
+        $sortIsDefault = $this->sortIsDefault($request);
 
         $limit = $this->extractLimit($request);
         $offset = $this->extractOffset($request);
         $include = $this->extractInclude($request);
 
-        $criteria = new QueryCriteria($actor, $filters, $sort);
+        $criteria = new QueryCriteria($actor, $filters, $sort, $sortIsDefault);
         if (array_key_exists('q', $filters)) {
             $results = $this->searcher->search($criteria, $limit, $offset);
         } else {