Adds a 'language' dropdown field to the system configuration

- The language choice is stored with the session, not persistently
- This removes confirmation messages if nothing was changed

plinth/__main__.py

@@ -213,6 +213,17 @@ def configure_django():
     if cfg.secure_proxy_ssl_header:
         secure_proxy_ssl_header = (cfg.secure_proxy_ssl_header, 'https')
 
+    # Read translated languages from the 'locale' directory
+    languages = [('en', 'English')]
+    locale_dir = os.path.join(os.path.dirname(__file__), 'locale')
+    if os.path.isdir(locale_dir):
+        translated_language_codes = next(os.walk(locale_dir))[1]
+        all_languages = dict(django.conf.global_settings.LANGUAGES)
+        for code in translated_language_codes:
+            if code in all_languages:
+                languages.append((code, all_languages[code]))
+        languages = sorted(languages, key=lambda tup: tup[1])
+
     django.conf.settings.configure(
         ALLOWED_HOSTS=['*'],
         CACHES={'default':
@@ -222,6 +233,7 @@ def configure_django():
                     'NAME': cfg.store_file}},
         DEBUG=cfg.debug,
         INSTALLED_APPS=applications,
+        LANGUAGES=languages,
         LOGGING=logging_configuration,
         LOGIN_URL='users:login',
         LOGIN_REDIRECT_URL='apps:index',

plinth/modules/config/config.py

@@ -23,7 +23,9 @@ from django import forms
 from django.contrib import messages
 from django.core import validators
 from django.core.exceptions import ValidationError
+from django.conf import settings
 from django.template.response import TemplateResponse
+from django.utils import translation
 from django.utils.translation import ugettext as _, ugettext_lazy
 import logging
 import re
@@ -51,6 +53,16 @@ def get_domainname():
     return '.'.join(fqdn.split('.')[1:])
 
 
+def get_language(request):
+    """Return the current language setting"""
+    # TODO: Store the language per user in kvstore,
+    # taking care of setting language on login, and adapting kvstore when
+    # renaming/deleting users
+
+    # The session contains more accurate information than request.LANGUAGE_CODE
+    return request.session[translation.LANGUAGE_SESSION_KEY]
+
+
 class TrimmedCharField(forms.CharField):
     """Trim the contents of a CharField"""
     def clean(self, value):
@@ -104,6 +116,14 @@ class ConfigurationForm(forms.Form):
                 ugettext_lazy('Invalid domain name')),
             domain_label_validator])
 
+    language = forms.ChoiceField(
+        label=ugettext_lazy('Language'),
+        help_text=\
+        ugettext_lazy('Language for this freedombox web administration '
+                      'interface'),
+        required=False,
+        choices=settings.LANGUAGES)
+
 
 def init():
     """Initialize the module"""
@@ -114,7 +134,7 @@ def init():
 
 def index(request):
     """Serve the configuration form"""
-    status = get_status()
+    status = get_status(request)
 
     form = None
 
@@ -124,7 +144,7 @@ def index(request):
         # pylint: disable-msg=E1101
         if form.is_valid():
             _apply_changes(request, status, form.cleaned_data)
-            status = get_status()
+            status = get_status(request)
             form = ConfigurationForm(initial=status,
                                      prefix='configuration')
     else:
@@ -135,10 +155,11 @@ def index(request):
                              'form': form})
 
 
-def get_status():
+def get_status(request):
     """Return the current status"""
     return {'hostname': get_hostname(),
-            'domainname': get_domainname()}
+            'domainname': get_domainname(),
+            'language': get_language(request)}
 
 
 def _apply_changes(request, old_status, new_status):
@@ -151,8 +172,6 @@ def _apply_changes(request, old_status, new_status):
                            .format(exception=exception))
         else:
             messages.success(request, _('Hostname set'))
-    else:
-        messages.info(request, _('Hostname is unchanged'))
 
     if old_status['domainname'] != new_status['domainname']:
         try:
@@ -162,8 +181,17 @@ def _apply_changes(request, old_status, new_status):
                            .format(exception=exception))
         else:
             messages.success(request, _('Domain name set'))
-    else:
-        messages.info(request, _('Domain name is unchanged'))
+
+    if old_status['language'] != new_status['language']:
+        language = new_status['language']
+        try:
+            translation.activate(language)
+            request.session[translation.LANGUAGE_SESSION_KEY] = language
+        except Exception as exception:
+            messages.error(request, _('Error setting language: {exception}')
+                            .format(exception=exception))
+        else:
+            messages.success(request, _('Language changed'))
 
 
 def set_hostname(hostname):

plinth/modules/config/tests/test_config.py

@@ -19,8 +19,11 @@
 Tests for config module.
 """
 
+import os
 import unittest
 
+from plinth import __main__ as plinth_main
+
 from ..config import ConfigurationForm
 
 
@@ -65,3 +68,12 @@ class TestConfig(unittest.TestCase):
             form = ConfigurationForm({'hostname': 'example',
                                       'domainname': domainname})
             self.assertFalse(form.is_valid())
+
+    def test_locale_path(self):
+        """
+        Test that the 'locale' directory is in the same folder as __main__.py.
+        This is required for detecting translated languages.
+        """
+        plinth_dir = os.path.dirname(plinth_main.__file__)
+        locale_dir = os.path.join(plinth_dir, 'locale')
+        self.assertTrue(os.path.isdir(locale_dir))