Search: refactor api view

Mainly this was done to allow us support searching on
different versions of subprojects.
Currently, we assume we search the same version for all subprojects.

- _get_all_projects_data and _get_all_projects
  were merged into just one method.
  And instead of returning a list of projects we return a dictionary of project slugs mapped to a VersionData object.
- There is some duplication in .com.
  `_has_permission` and `_get_subproject_versions_queryset`
  are overridden in .com.
- ProjectData was renamed to VersionData since it has more attributes
  related to a version than a project.

Author: stsewd

readthedocs/search/api.py

@@ -229,9 +229,16 @@ def _get_all_projects_data(self):
         )
         for project in subprojects:
             version = self._get_subproject_version(
-                version_slug=main_version,
+                version_slug=main_version.slug,
                 subproject=project,
             )
+            # Fallback to the default version of the subproject.
+            if not version and project.default_version:
+                version = self._get_subproject_version(
+                    version_slug=project.default_version,
+                    subproject=project,
+                )
+
             if version and self._has_permission(self.request.user, version):
                 url = project.get_docs_url(version_slug=version.slug)
                 projects_data[project.slug] = VersionData(
@@ -290,22 +297,20 @@ def get_queryset(self):
            calling ``search.execute().hits``. This is why an DSL search object
            is compatible with DRF's paginator.
         """
-        filters = {}
-        filters['project'] = list(self._get_all_projects_data().keys())
-        filters['version'] = self._get_version().slug
+        projects = {
+            project: version.slug
+            for project, version in self._get_all_projects_data().items()
+        }
 
-        # Check to avoid searching all projects in case these filters are empty.
-        if not filters['project']:
-            log.info('Unable to find a project to search')
-            return []
-        if not filters['version']:
+        # Check to avoid searching all projects in case it's empty.
+        if not projects:
             log.info('Unable to find a version to search')
             return []
 
         query = self.request.query_params['q']
         queryset = PageSearch(
             query=query,
-            filters=filters,
+            projects=projects,
             user=self.request.user,
             # We use a permission class to control authorization
             filter_by_user=False,