Addons: get translation from main project (#10952)

* Addons: get translation from main project

Closes readthedocs/addons#218

* Addons: return original language as flyout's translation

Include the main project's language in `addons.flyout.translations` in the first
position of the list so it's shown at the beginning.
This follows the actual behavior.
However, we may want to change the ordering to be A-Z.

Closes readthedocs/addons#218

* Test: update addons flyout languages to match changes

* Test: adapt more tests

readthedocs/proxito/tests/test_hosting.py

@@ -317,6 +317,7 @@ def test_flyout_translations(self):
         assert r.status_code == 200
 
         expected = [
+            {"slug": "en", "url": "https://project.dev.readthedocs.io/en/latest/"},
             {"slug": "ja", "url": "https://project.dev.readthedocs.io/ja/latest/"},
         ]
         assert r.json()["addons"]["flyout"]["translations"] == expected
@@ -540,6 +541,10 @@ def test_flyout_subproject_urls(self):
         assert r.json()["addons"]["flyout"]["versions"] == expected_versions
 
         expected_translations = [
+            {
+                "slug": "en",
+                "url": "https://project.dev.readthedocs.io/projects/subproject/en/latest/",
+            },
             {
                 "slug": "es",
                 "url": "https://project.dev.readthedocs.io/projects/subproject/es/latest/",
@@ -673,7 +678,7 @@ def test_number_of_queries_project_version_slug(self):
                 active=True,
             )
 
-        with self.assertNumQueries(16):
+        with self.assertNumQueries(17):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -702,7 +707,7 @@ def test_number_of_queries_url(self):
                 active=True,
             )
 
-        with self.assertNumQueries(16):
+        with self.assertNumQueries(17):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -738,7 +743,7 @@ def test_number_of_queries_url_subproject(self):
                 active=True,
             )
 
-        with self.assertNumQueries(20):
+        with self.assertNumQueries(21):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -764,7 +769,7 @@ def test_number_of_queries_url_translations(self):
                 language=language,
             )
 
-        with self.assertNumQueries(20):
+        with self.assertNumQueries(21):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {

readthedocs/proxito/views/hosting.py

@@ -1,5 +1,6 @@
 """Views for hosting features."""
 
+import itertools
 from functools import lru_cache
 
 import packaging
@@ -268,9 +269,17 @@ def _v0(self, project, version, build, filename, url, user):
         if version:
             version_downloads = version.get_downloads(pretty=True).items()
 
+        main_project = project.main_language_project or project
         project_translations = (
-            project.translations.all().only("language").order_by("language")
+            main_project.translations.all().only("language").order_by("language")
         )
+        if project_translations.exists():
+            # Always prefix the list of translations with the main project's language,
+            # when there are translations present.
+            # Example: a project with Russian and Spanish translations will be showns as:
+            #     en (original), es, ru
+            project_translations = itertools.chain([main_project], project_translations)
+
         # Make one DB query here and then check on Python code
         # TODO: make usage of ``Project.addons.<name>_enabled`` to decide if enabled
         #
@@ -288,8 +297,6 @@ def _v0(self, project, version, build, filename, url, user):
                 " AND IT'S GOING TO CHANGE COMPLETELY -- DO NOT USE IT!"
             ),
             "projects": {
-                # TODO: return the "parent" project here when the "current"
-                # project is a subproject/translation.
                 "current": ProjectSerializerNoLinks(project).data,
             },
             "versions": {