♻️(backend) allow global search in sub documents

The global search endpoint filtering by title in the database was not
searching for accessible sub documents. We change the how global search
is made: it is now returning accessible sub documents matching the
title query.

src/backend/core/api/viewsets.py

@@ -1502,10 +1502,47 @@ class DocumentViewSet(
         Fallback search method when no indexer is configured.
         Only searches in the title field of documents.
         """
-        if not validated_data.get("path"):
-            return self.list(request, *args, **kwargs)
 
-        return self._list_descendants(request, validated_data)
+        if validated_data.get("path"):
+            return self._list_descendants(request, validated_data)
+
+        top_level_documents = self.get_queryset()
+        queryset = self.queryset
+        user = request.user
+
+        filterset = DocumentFilter(request.GET, queryset=queryset, request=request)
+        if not filterset.is_valid():
+            raise drf.exceptions.ValidationError(filterset.errors)
+
+        # Among the results, we may have documents that are ancestors/descendants
+        # of each other. In this case we want to keep only the highest ancestors.
+        root_paths = utils.filter_root_paths(
+            top_level_documents.order_by("path").values_list("path", flat=True),
+            skip_sorting=True,
+        )
+
+        if not root_paths:
+            return self.get_response_for_queryset(top_level_documents.none())
+
+        path_list = db.Q()
+        for top_level_document in root_paths:
+            path_list |= db.Q(path__startswith=top_level_document)
+
+        queryset = (
+            queryset.filter(path_list)
+            .filter(ancestors_deleted_at__isnull=True)
+            .annotate_user_roles(user)
+            .annotate_is_favorite(user)
+        )
+
+        queryset = filterset.filter_queryset(queryset)
+
+        # Apply ordering only now that everything is filtered and annotated
+        queryset = filters.OrderingFilter().filter_queryset(
+            self.request, queryset, self
+        )
+
+        return self._get_response_for_search_queryset(queryset)
 
     def _list_descendants(self, request, validated_data):
         """