Add fallback system to frontend I18n system

Load the default locale and fall back to it on missing key
and interpolation errors

app/assets/javascripts/helpers/i18n.js

@@ -1,47 +1,70 @@
-/*   Copyright (c) 2010-2011, Diaspora Inc.  This file is
- *   licensed under the Affero General Public License version 3 or later.  See
- *   the COPYRIGHT file.
- */
-
 Diaspora.I18n = {
   language: "en",
-  locale: {},
+  locale: {
+    pluralizationKey: function(n) { return this.fallback.pluralizationKey(n); },
+    data: {},
+    fallback: {
+      pluralizationKey: function(n) { return n == 1 ? "one" : "other"; },
+      data: {}
+    }
+  },
 
-  loadLocale: function(locale, language) {
-    this.locale = $.extend(this.locale, locale);
+  load: function(locale, language, fallbackLocale) {
+    this.updateLocale(this.locale, locale);
+    this.updateLocale(this.locale.fallback, fallbackLocale);
     this.language = language;
-    rule = this.t('pluralization_rule');
-    if (rule === "")
-    rule = 'function (n) { return n == 1 ? "one" : "other" }';
-    eval("this.pluralizationKey = "+rule);
+  },
+
+  updateLocale: function(locale, data) {
+    locale.data = $.extend(locale.data, data);
+
+    rule = this.resolve(locale, ['pluralization_rule']);
+    if (rule !== "") {
+      eval("locale.pluralizationKey = "+rule);
+    }
   },
 
   t: function(item, views) {
-    var items = item.split("."),
-      translatedMessage,
-      nextNamespace;
+    var items = item.split(".");
+    return this.resolve(this.locale, items, views);
+  },
+
+  resolve: function(locale, items, views) {
+      var translatedMessage, nextNamespace, originalItems = items.slice();
 
     if(views && typeof views.count !== "undefined") {
-      items.push(this.pluralizationKey(views.count));
+      items.push(locale.pluralizationKey(views.count));
     }
 
     while(nextNamespace = items.shift()) {
       translatedMessage = (translatedMessage)
         ? translatedMessage[nextNamespace]
-        : this.locale[nextNamespace];
+        : locale.data[nextNamespace];
 
       if(typeof translatedMessage === "undefined") {
+        if (typeof locale.fallback === "undefined") {
           return "";
+        } else {
+          return this.resolve(locale.fallback, originalItems, views);
+        }
       }
     }
 
+    try {
       return _.template(translatedMessage, views || {});
+    } catch (e) {
+      if (typeof locale.fallback === "undefined") {
+        return "";
+      } else {
+        return this.resolve(locale.fallback, originalItems, views);
+      }
+    }
   },
 
   reset: function() {
-    this.locale = {};
+    this.locale.data = {};
 
     if( arguments.length > 0 && !(_.isEmpty(arguments[0])) )
-      this.locale = arguments[0];
+      this.locale.data = arguments[0];
   }
 };

app/helpers/layout_helper.rb

@@ -31,7 +31,9 @@ module LayoutHelper
   def load_javascript_locales(section = 'javascripts')
     content_tag(:script) do
       <<-JS.html_safe
-        Diaspora.I18n.loadLocale(#{get_javascript_strings_for(I18n.locale, section).to_json}, "#{I18n.locale}");
+        Diaspora.I18n.load(#{get_javascript_strings_for(I18n.locale, section).to_json},
+                           "#{I18n.locale}",
+                           #{get_javascript_strings_for(DEFAULT_LANGUAGE, section).to_json});
         Diaspora.Page = "#{params[:controller].camelcase}#{params[:action].camelcase}";
       JS
     end

spec/javascripts/app/collections/aspects_spec.js

@@ -1,6 +1,6 @@
 describe("app.collections.Aspects", function(){
   beforeEach(function(){
-    Diaspora.I18n.loadLocale({
+    Diaspora.I18n.load({
       'and' : "and",
       'comma' : ",",
       'my_aspects' : "My Aspects"

spec/javascripts/app/views/aspects_list_view_spec.js

@@ -1,7 +1,7 @@
 describe("app.views.AspectsList", function(){
   beforeEach(function(){
     setFixtures('<ul id="aspects_list"></ul>');
-    Diaspora.I18n.loadLocale({ aspect_navigation : {
+    Diaspora.I18n.load({ aspect_navigation : {
       'select_all' : 'Select all',
       'deselect_all' : 'Deselect all'
     }});

spec/javascripts/app/views/comment_stream_view_spec.js

@@ -58,7 +58,7 @@ describe("app.views.CommentStream", function(){
       });
 
       it("doesn't add the comment to the view, when the request fails", function(){
-        Diaspora.I18n.loadLocale({failed_to_post_message: "posting failed!"});
+        Diaspora.I18n.load({failed_to_post_message: "posting failed!"});
         this.request.response({status: 500});
 
         expect(this.view.$(".comment-content p").text()).not.toEqual("a new comment");

spec/javascripts/app/views/feedback_view_spec.js

@@ -2,7 +2,7 @@ describe("app.views.Feedback", function(){
   beforeEach(function(){
    loginAs({id : -1, name: "alice", avatar : {small : "http://avatar.com/photo.jpg"}});
 
-    Diaspora.I18n.loadLocale({stream : {
+    Diaspora.I18n.load({stream : {
       'like' : "Like",
       'unlike' : "Unlike",
       'public' : "Public",

spec/javascripts/app/views/likes_info_view_spec.js

@@ -2,7 +2,7 @@ describe("app.views.LikesInfo", function(){
   beforeEach(function(){
     loginAs({id : -1, name: "alice", avatar : {small : "http://avatar.com/photo.jpg"}});
 
-    Diaspora.I18n.loadLocale({stream : {
+    Diaspora.I18n.load({stream : {
       pins : {
         zero : "<%= count %> Pins",
         one : "<%= count %> Pin"}

spec/javascripts/app/views/publisher_view_spec.js

@@ -431,7 +431,7 @@ describe("app.views.Publisher", function() {
 
       context('successful completion', function() {
         beforeEach(function() {
-          Diaspora.I18n.loadLocale({ photo_uploader: { completed: '<%= file %> completed' }});
+          Diaspora.I18n.load({ photo_uploader: { completed: '<%= file %> completed' }});
           $('#photodropzone').html('<li class="publisher_photo loading"><img src="" /></li>');
 
           this.uploader.onComplete(null, 'test.jpg', {
@@ -469,7 +469,7 @@ describe("app.views.Publisher", function() {
 
       context('unsuccessful completion', function() {
         beforeEach(function() {
-          Diaspora.I18n.loadLocale({ photo_uploader: { completed: '<%= file %> completed' }});
+          Diaspora.I18n.load({ photo_uploader: { completed: '<%= file %> completed' }});
           $('#photodropzone').html('<li class="publisher_photo loading"><img src="" /></li>');
 
           this.uploader.onComplete(null, 'test.jpg', {

spec/javascripts/app/views/stream_post_spec.js

@@ -21,7 +21,7 @@ describe("app.views.StreamPost", function(){
     beforeEach(function(){
       loginAs({name: "alice", avatar : {small : "http://avatar.com/photo.jpg"}});
 
-      Diaspora.I18n.loadLocale({stream : {
+      Diaspora.I18n.load({stream : {
         reshares : {
           one : "<%= count %> reshare",
           other : "<%= count %> reshares"

spec/javascripts/helpers/SpecHelper.js

@@ -24,7 +24,7 @@ beforeEach(function() {
   var Page = Diaspora.Pages["TestPage"];
   $.extend(Page.prototype, Diaspora.EventBroker.extend(Diaspora.BaseWidget));
 
-  Diaspora.I18n.loadLocale({}, 'en');
+  Diaspora.I18n.load({}, 'en', {});
 
   Diaspora.page = new Page();
   Diaspora.page.publish("page/ready", [$(document.body)]);

spec/javascripts/widgets/i18n-spec.js

@@ -24,27 +24,28 @@ describe("Diaspora.I18n", function() {
     Diaspora.I18n.reset();   // run tests with clean locale
   });
 
-  describe("::loadLocale", function() {
+  describe("::load", function() {
     it("sets the class's locale variable", function() {
-      Diaspora.I18n.loadLocale(locale);
+      Diaspora.I18n.load(locale, "en", locale);
 
-      expect(Diaspora.I18n.locale).toEqual(locale);
+      expect(Diaspora.I18n.locale.data).toEqual(locale);
+      expect(Diaspora.I18n.locale.fallback.data).toEqual(locale);
     });
 
     it("extends the class's locale variable on multiple calls", function() {
       var data = {another: 'section'},
           extended = $.extend(locale, data);
 
-      Diaspora.I18n.loadLocale(locale);
-      Diaspora.I18n.loadLocale(data);
+      Diaspora.I18n.load(locale, "en", locale);
+      Diaspora.I18n.load(data, "en", data);
 
-      expect(Diaspora.I18n.locale).toEqual(extended);
+      expect(Diaspora.I18n.locale.data).toEqual(extended);
     });
   });
 
   describe("::t", function() {
     var translation;
-    beforeEach(function() { Diaspora.I18n.loadLocale(locale); });
+    beforeEach(function() { Diaspora.I18n.load(locale, "en", {fallback: "fallback", namespace: {template: "no template"}}); });
 
     it("returns the specified translation", function() {
       translation = Diaspora.I18n.t("namespace.message");
@@ -67,20 +68,28 @@ describe("Diaspora.I18n", function() {
     it("returns an empty string if the translation is not found", function() {
       expect(Diaspora.I18n.t("missing.locale")).toEqual("");
     });
+
+    it("falls back on missing key", function() {
+      expect(Diaspora.I18n.t("fallback")).toEqual("fallback");
+    });
+
+    it("falls back on interpolation errors", function() {
+      expect(Diaspora.I18n.t("namespace.template")).toEqual("no template");
+    });
   });
 
   describe("::reset", function(){
     it("clears the current locale", function() {
-      Diaspora.I18n.loadLocale(locale);
+      Diaspora.I18n.load(locale, "en", locale);
       Diaspora.I18n.reset()
-      expect(Diaspora.I18n.locale).toEqual({});
+      expect(Diaspora.I18n.locale.data).toEqual({});
     });
 
     it("sets the locale to only a specific value", function() {
       var data = { some: 'value' };
-      Diaspora.I18n.loadLocale(locale);
+      Diaspora.I18n.load(locale, "en", locale);
       Diaspora.I18n.reset(data);
-      expect(Diaspora.I18n.locale).toEqual(data);
+      expect(Diaspora.I18n.locale.data).toEqual(data);
     });
   });
 });