HIDP-51 Add middleware to handle ui_locales

packages/hidp/hidp/translations/middleware.py

@@ -0,0 +1,64 @@
+import contextlib
+
+from django.http import HttpResponseRedirect
+from django.utils import translation
+
+
+def _get_supported_language_variant(language_code):
+    with contextlib.suppress(LookupError):
+        return translation.get_supported_language_variant(language_code)
+
+
+def _get_language_from_cookie(request):
+    language = request.COOKIES.get(UiLocalesMiddleware.LANGUAGE_COOKIE_NAME)
+    if language and _get_supported_language_variant(language):
+        return language
+    return None
+
+
+def _get_language_from_ui_locales(request):
+    ui_locales = request.GET.get("ui_locales", "").strip()
+    for ui_locale in ui_locales.split():
+        if language := _get_supported_language_variant(ui_locale):
+            return language
+    return None
+
+
+class UiLocalesMiddleware:
+    """
+    Middleware that sets a cookie and activated the language based on the 'ui_locales'
+    query parameter.
+
+    As a workaround for a bug in Django Oauth Toolkit, the middleware also makes sure
+    that the 'ui_locales' query parameter is removed from the URL.
+    """
+
+    LANGUAGE_COOKIE_NAME = "hidp_language"
+
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        if "ui_locales" in request.GET:
+            # Remove the ui_locales query parameter from the URL.
+            # This is a workaround for a bug in Django OAuth Toolkit:
+            # https://github.com/jazzband/django-oauth-toolkit/issues/1468
+            query = request.GET.copy()
+            query.pop("ui_locales")
+            request.META["QUERY_STRING"] = query.urlencode()
+            response = HttpResponseRedirect(request.build_absolute_uri())
+
+            # Set the language cookie if the language is supported.
+            if language := _get_language_from_ui_locales(request):
+                # Set the language cookie.
+                response.set_cookie(
+                    self.LANGUAGE_COOKIE_NAME,
+                    language,
+                )
+
+            return response
+
+        if language := _get_language_from_cookie(request):
+            translation.activate(language)
+
+        return self.get_response(request)

packages/hidp/tests/test_settings.py

@@ -56,6 +56,7 @@
     "django.contrib.auth.middleware.AuthenticationMiddleware",
     "django.contrib.messages.middleware.MessageMiddleware",
     "hidp.rate_limit.middleware.RateLimitMiddleware",
+    "hidp.translations.middleware.UiLocalesMiddleware",
 ]
 
 USE_TZ = True

packages/hidp/tests/unit_tests/test_translations/test_middleware.py

@@ -0,0 +1,115 @@
+from unittest import mock
+
+from django.test import RequestFactory, TestCase, override_settings
+from django.utils import translation
+
+from hidp.translations.middleware import UiLocalesMiddleware
+
+
+@override_settings(LANGUAGES=[("en", "English"), ("fr", "French")])
+class TestUiLocalesMiddleware(TestCase):
+    client_class = RequestFactory
+
+    def setUp(self):
+        self.get_response = mock.Mock()
+        self.middleware = UiLocalesMiddleware(self.get_response)
+
+    def test_no_preference(self):
+        """
+        Do nothing if there is no language preference.
+        """
+        active_language = translation.get_language()
+        response = self.middleware(self.client.get("/"))
+        self.assertEqual(
+            response,
+            self.get_response.return_value,
+        )
+        self.assertEqual(active_language, translation.get_language())
+
+    def test_drops_ui_locales_param(self):
+        """
+        Removes the 'ui_locales' query parameter, keeps the rest.
+        """
+        # This is a workaround for a bug in Django OAuth Toolkit:
+        # https://github.com/jazzband/django-oauth-toolkit/issues/1468
+        request = self.client.get("/?ui_locales=fr&foo=bar")
+        response = self.middleware(request)
+        # Does not call get_response
+        self.get_response.assert_not_called()
+        # Redirects to the same URL without the 'ui_locales' query parameter.
+        self.assertEqual(
+            response.status_code,
+            302,
+        )
+        self.assertEqual(
+            response.url,
+            f'http://{request.META["SERVER_NAME"]}/?foo=bar',
+        )
+
+    def test_sets_cookie_for_supported_langauge(self):
+        """
+        Sets the language cookie if 'ui_locales' is present,
+        and the language is supported
+        """
+        request = self.client.get("/?ui_locales=fr")
+        response = self.middleware(request)
+        # Sets the language cookie.
+        self.assertEqual(
+            response.cookies["hidp_language"].value,
+            "fr",
+        )
+
+    def test_picks_first_supported_language(self):
+        """
+        Picks the first supported language if multiple are provided.
+        """
+        request = self.client.get("/?ui_locales=de fr-be en")
+        response = self.middleware(request)
+        # Sets the language cookie.
+        self.assertEqual(
+            response.cookies["hidp_language"].value,
+            # 'de' is not supported, 'fr-be' is a variant of 'fr', so 'fr' is picked.
+            "fr",
+        )
+
+    def test_ignores_unsupported_language(self):
+        """
+        Does not set the language cookie if the language is not supported.
+        """
+        request = self.client.get("/?ui_locales=de")
+        response = self.middleware(request)
+        # Does not set the language cookie.
+        self.assertNotIn(
+            "hidp_language",
+            response.cookies,
+        )
+
+    def test_activates_language(self):
+        """
+        Activates the language if it is supported.
+        """
+        request = self.client.get("/", HTTP_COOKIE="hidp_language=fr")
+        response = self.middleware(request)
+        self.assertEqual(
+            response,
+            self.get_response.return_value,
+        )
+        self.assertEqual(
+            translation.get_language(),
+            "fr",
+        )
+
+    def test_does_not_activate_unsupported_language(self):
+        """
+        Does not activate the language if it is not supported.
+        """
+        request = self.client.get("/", HTTP_COOKIE="hidp_language=de")
+        response = self.middleware(request)
+        self.assertEqual(
+            response,
+            self.get_response.return_value,
+        )
+        self.assertNotEqual(
+            translation.get_language(),
+            "de",
+        )

project/hidp_sandbox/settings.py

@@ -92,6 +92,7 @@
     "django.contrib.messages.middleware.MessageMiddleware",
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
     "hidp.rate_limit.middleware.RateLimitMiddleware",
+    "hidp.translations.middleware.UiLocalesMiddleware",
 ]
 
 ROOT_URLCONF = "hidp_sandbox.urls"
@@ -176,6 +177,10 @@
 # https://docs.djangoproject.com/en/4.2/topics/i18n/
 
 LANGUAGE_CODE = "nl-nl"
+LANGUAGES = [
+    ("nl", "Nederlands"),
+    ("en", "English"),
+]
 
 TIME_ZONE = "Europe/Amsterdam"