allow tagging custom locales

fixes CNVS-28111

test plan:
 * edit config/locales.yml, and add `custom: true` under one of the
   locales (such as japanese:
ja:
  locales:
    ja: Custom Japanese!
  custom: true
 * load up Canvas (be sure you're using RAILS_LOAD_ALL_LOCALES=1),
   and Japanese should no longer show up in the account or users
   pages to select
 * go to /plugins/i18n, and enable the plugin, and check the custom
   locale (it will be the only one listed), and save
 * the "custom" locale should show up in dropdowns again

Change-Id: Iae6c923b50262b27a25487a0d8458b2627809630
Reviewed-on: https://gerrit.instructure.com/74795
Tested-by: Jenkins
Reviewed-by: Simon Williams <simon@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>

Author: ccutrer

app/views/plugins/_i18n_settings.html.erb

@@ -0,0 +1,10 @@
+<%= fields_for :settings, OpenObject.new(settings) do |f| %>
+    <table style="width: 500px;" class="formtable">
+      <% LocaleSelection.custom_locales.each do |locale| %>
+          <tr>
+            <td><%= f.blabel locale, I18n.send(:t, :locales, :locale => locale)[locale] %></td>
+            <td><%= f.check_box locale, :enabled => settings[locale] %></td>
+          </tr>
+      <% end %>
+    </table>
+<% end %>

lib/canvas/plugins/default_plugins.rb

@@ -244,6 +244,16 @@
                  :success_timeout => "600",
                  :format_type => "instructure_csv" }
 })
+Canvas::Plugin.register('i18n', nil, {
+    :name => lambda{ t :name, 'I18n' },
+    :description => lambda{ t :description, 'Custom Locales' },
+    :website => 'https://www.instructure.com',
+    :author => 'Instructure',
+    :author_website => 'http://www.instructure.com',
+    :version => '1.0.0',
+    :settings_partial => 'plugins/i18n_settings',
+    :validator => 'I18nValidator'
+})
 Canvas::Plugin.register('sis_import', :sis, {
   :name => lambda{ t :name, 'SIS Import' },
   :description => lambda{ t :description, 'Import SIS Data' },

lib/canvas/plugins/validators/i18n_validator.rb

@@ -0,0 +1,26 @@
+#
+# Copyright (C) 2016 Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+module Canvas::Plugins::Validators::I18nValidator
+  def self.validate(settings, plugin_setting)
+    settings.inject({}) do |result, (i18n, enabled)|
+      result[i18n] = true if Canvas::Plugin::value_to_boolean(enabled)
+      result
+    end
+  end
+end

lib/locale_selection.rb

@@ -86,11 +86,20 @@ def infer_browser_locale(accept_language, supported_locales)
   # if the locale name is not yet translated, it won't be included (even if
   # there are other translations for that locale)
   def available_locales
-    I18n.available_locales.inject({}) do |hash, locale|
+    result = {}
+    settings = Canvas::Plugin.find(:i18n).settings || {}
+    enabled_custom_locales = settings.select { |locale, enabled| enabled }.map(&:first).map(&:to_sym)
+    I18n.available_locales.each do |locale|
       name = I18n.send(:t, :locales, :locale => locale)[locale]
-      hash[locale.to_s] = name if name
-      hash
+      custom = I18n.send(:t, :custom, locale: locale) == true
+      next if custom && !enabled_custom_locales.include?(locale)
+      result[locale.to_s] = name if name
     end
+    result
+  end
+
+  def self.custom_locales
+    @custom_locales ||= I18n.available_locales.select{ |locale| I18n.send(:t, :custom, :locale => locale) == true }.sort
   end
 
   def crowdsourced_locales

spec/lib/locale_selection_spec.rb

@@ -185,4 +185,18 @@ def ls
       expect(ls.infer_locale(:accept_language => "it", :root_account => @root_account, :context => @account, :user => @user, :session_locale => 'zh')).to eql('de')
     end
   end
+
+  describe "available_locales" do
+    it "does not include custom locales" do
+      I18n.stubs(:available_locales).returns([:en, :ja])
+      I18n.stubs(:t).with(:locales, locale: :en).returns(en: 'English')
+      I18n.stubs(:t).with(:custom, locale: :en).returns(nil)
+      I18n.stubs(:t).with(:locales, locale: :ja).returns(ja: 'Japanese')
+      I18n.stubs(:t).with(:custom, locale: :ja).returns(true)
+      expect(ls.available_locales).to eq('en' => 'English')
+
+      PluginSetting.create!(name: 'i18n', settings: { 'ja' => true })
+      expect(ls.available_locales).to eq('en' => 'English', 'ja' => 'Japanese')
+    end
+  end
 end