Revert "Remove locale selector/translation support"

This reverts commit ea29db1.

CHANGELOG.md

@@ -1,6 +1,7 @@
 ### 6.0.1
 
 * Revert: "Fix a DeprecationWarning from pythonjsonlogger" which actually broke things
+* Revert: "Removes `locale_selector` module, which has now been lifted directly into `pre-award-frontend` (and modified to support `host_matching` mode)." because this is still used by pre-award-stores
 
 ### 6.0.0
 

README.md

@@ -208,6 +208,57 @@ Where
 - `bool` is a True or False whether the check was successful
 - `str` is a message to display in the result JSON, typically `OK` or `Fail`
 
+## Translations
+Multiple language support is provided by `flask-babel`. Docs here: https://python-babel.github.io/flask-babel/#
+
+### Python Setup
+The python setup relies on 2 methods and an initialisation. In `create_app` we initialise `babel` on our app:
+
+    from fsd_utils.locale_selector.get_lang import get_lang
+
+    babel = Babel(flask_app)
+    babel.locale_selector_func = get_lang
+    LanguageSelector(flask_app)
+
+The `get_lang()` function reads the user-selected language from a cookie (if set by `LanguageSelector` - see below), or if that is not present uses a built-in function of babel to negotiate the language based on the request headers and the supported languages.
+
+`LanguageSelector` creates an additional route `/language/<language>` that sets the user's selected language in a cookie. Used the cookie rather than the session so it can be shared across the microservices.
+
+Set `COOKIE_DOMAIN` on the app to the domain you want to set the cookie on.
+
+### Creating Translations
+1. Add `trans` tags around items in your jinja html file that you want to translate. What's contained in the `trans` tag should be the english version of this text. eg:
+
+        A greeting is: {% trans %}Good Morning{% endtrans %}
+
+1. Generate a new translations template file (`messages.pot`)
+
+        pybabel extract -F babel.cfg -o messages.pot .
+
+1. If initialising a new set of translations for a new repo or adding a new language, use `init`. *This will override any changes already made in the `translations` directory!*
+
+        # Initialise a welsh translations file in app/translations
+        pybabel init -i messages.pot -d app/translations -l cy
+    The directory supplied to `-d` (eg. `app/translations`) must sit at the same level as the `templates` folder, in our case within the `app` directory. This command generates a new `messages.po` file in `translations/cy/LC_MESSAGES/` Where `cy` is the language code. (cy = Welsh/Cymraeg)
+
+1. If you've added new strings to an existing template, or added new templates after running `init`, use `update`:
+
+        pybabel update -i messages.pot -d app/translations
+
+    This will append new strings to the existing `messages.po` file, preserving any translations you already have in there.
+
+1. To add translations for strings, edit the `messages.po` file.
+
+        #: app/templates/index.html:10
+        msgid "Good Morning"
+        msgstr "Bore da"
+
+    where `msgid` is the english version of the string from the original template file, and `msgstr` is the translation of the string.
+
+1. Once the translations are ready, use `compile` to generate the binary for use at runtime:
+
+        pybabel compile -d app/translations
+
 ## Sentry
 Enables Sentry integration.
 

fsd_utils/__init__.py

@@ -3,6 +3,7 @@
 from fsd_utils.config.configclass import configclass  # noqa
 from fsd_utils.config.notify_constants import NotifyConstants  # noqa
 from fsd_utils.decision.evaluate_response_against_schema import Decision, evaluate_response
+from fsd_utils.locale_selector.set_lang import LanguageSelector
 from fsd_utils.mapping.application.application_utils import generate_text_of_application
 from fsd_utils.mapping.application.qa_mapping import (
     extract_questions_and_answers,
@@ -18,6 +19,7 @@
     CommonConfig,
     NotifyConstants,
     healthchecks,
+    LanguageSelector,
     init_sentry,
     clear_sentry,
     date_utils,

fsd_utils/locale_selector/__init__.py

@@ -0,0 +1,2 @@
+from . import get_lang  # noqa
+from . import set_lang  # noqa

fsd_utils/locale_selector/get_lang.py

@@ -0,0 +1,29 @@
+from babel import negotiate_locale
+from flask import request
+
+from fsd_utils import CommonConfig
+
+
+def get_lang():
+    # get lang if lang query arg is set
+    language_from_query_args = request.args.get("lang")
+    if language_from_query_args:
+        if language_from_query_args not in ["cy", "en"]:
+            return "en"
+        return language_from_query_args
+
+    # get locale from cookie if set
+    locale_from_cookie = request.cookies.get(CommonConfig.FSD_LANG_COOKIE_NAME)
+    if locale_from_cookie:
+        if locale_from_cookie not in ["cy", "en"]:
+            return "en"
+        return locale_from_cookie
+
+    # otherwise guess preference based on user accept header
+    preferred = [accept_language.replace("-", "_") for accept_language in request.accept_languages.values()]
+    negotiated_locale = negotiate_locale(preferred, ["en", "cy"])
+    if negotiated_locale:
+        return negotiated_locale
+
+    # default is to return english
+    return "en"

fsd_utils/locale_selector/set_lang.py

@@ -0,0 +1,33 @@
+from flask import Response, current_app, make_response, redirect, request
+
+from fsd_utils import CommonConfig
+
+
+class LanguageSelector:
+    @staticmethod
+    def get_cookie_domain(cookie_domain):
+        if not cookie_domain:
+            return None
+        else:
+            return cookie_domain
+
+    @staticmethod
+    def set_language_cookie(locale: str, response: Response):
+        response.set_cookie(
+            CommonConfig.FSD_LANG_COOKIE_NAME,
+            locale,
+            domain=LanguageSelector.get_cookie_domain(current_app.config["COOKIE_DOMAIN"]),
+            max_age=86400 * 30,  # 30 days
+        )
+
+    def __init__(self, app):
+        self.flask_app = app
+        self.flask_app.add_url_rule("/language/<locale>", view_func=self.select_language)
+
+    @staticmethod
+    def select_language(locale):
+        # TODO: Perform additional validation on referrer
+        response = make_response(redirect(request.referrer or "/", 302))
+        LanguageSelector.set_language_cookie(locale, response)
+
+        return response

tests/test_get_lang.py

@@ -0,0 +1,33 @@
+from fsd_utils.locale_selector.get_lang import get_lang
+
+
+class TestGetLang:
+    def test_get_lang_query_arg_valid(self, flask_test_client):
+        with flask_test_client.application.test_request_context("/?lang=cy"):
+            assert get_lang() == "cy"
+
+    def test_get_lang_query_arg_invalid(self, flask_test_client):
+        with flask_test_client.application.test_request_context("/?lang=fr"):
+            assert get_lang() == "en"
+
+    def test_get_lang_cookie_preference(self, flask_test_client):
+        with flask_test_client.application.test_request_context("/", headers={"Cookie": "language=cy"}):
+            assert get_lang() == "cy"
+
+    def test_get_lang_cookie_preference_for_non_en_cy_language(self, flask_test_client):
+        with flask_test_client.application.test_request_context("/", headers={"Cookie": "language=de"}):
+            assert get_lang() == "en"
+
+    def test_get_lang_accept_language_preference_en(self, flask_test_client):
+        with flask_test_client.application.test_request_context(
+            "/",
+            headers={"Accept-Language": "en,en-GB;q=0.9,cy;q=0.8,en-US;q=0.7"},
+        ):
+            assert get_lang() == "en"
+
+    def test_get_lang_accept_language_preference_cy(self, flask_test_client):
+        with flask_test_client.application.test_request_context(
+            "/",
+            headers={"Accept-Language": "cy,en;q=0.9,en-GB;q=0.8,en-US;q=0.7"},  # noqa: E501
+        ):
+            assert get_lang() == "cy"

tests/test_set_lang.py

@@ -0,0 +1,14 @@
+from unittest.mock import ANY, Mock
+
+from fsd_utils.locale_selector.set_lang import LanguageSelector
+
+
+def test_set_lang(flask_test_client):
+    mock_app = Mock()
+    set_lang = LanguageSelector(mock_app)
+    mock_app.add_url_rule.assert_called_with("/language/<locale>", view_func=ANY)
+    with flask_test_client.application.test_request_context():
+        response = set_lang.select_language("cy")
+        response_cookie = response.headers.get("Set-Cookie")
+        assert response_cookie is not None, "No cookie set for language"
+        assert response_cookie.split(";")[0] == ("language" + "=cy")