GUAC-1053: Pull language from preferences when configuring the translate service. Fallback to US English if there is no such translation file.

guacamole/src/main/webapp/app/locale/services/translationLoader.js

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+/*
+ * Copyright (C) 2015 Glyptodon LLC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/**
+ * Service for loading translation definition files, conforming to the
+ * angular-translate documentation for custom translation loaders:
+ * 
+ * https://github.com/angular-translate/angular-translate/wiki/Asynchronous-loading#using-custom-loader-service
+ */
+angular.module('locale').factory('translationLoader', ['$injector', function translationLoader($injector) {
+
+    // Required services
+    var $http        = $injector.get('$http');
+    var $q           = $injector.get('$q');
+    var cacheService = $injector.get('cacheService');
+
+    /**
+     * Satisfies a translation request for the given key by searching for the
+     * translation files for each key in the given array, in order. The request
+     * fails only if none of the files can be found.
+     *
+     * @param {Deferred} deferred
+     *     The Deferred object to resolve or reject depending on whether at
+     *     least one translation file can be successfully loaded.
+     *
+     * @param {String} requestedKey
+     *     The originally-requested language key.
+     *
+     * @param {String[]} remainingKeys
+     *     The keys of the languages to attempt to load, in order, where the
+     *     first key in this array is the language to try within this function
+     *     call. The first key in the array is not necessarily the originally-
+     *     requested language key.
+     */
+    var satisfyTranslation = function satisfyTranslation(deferred, requestedKey, remainingKeys) {
+
+        // Get current language key
+        var currentKey = remainingKeys.shift();
+
+        // If no languages to try, just fail
+        if (!currentKey) {
+            deferred.reject(requestedKey);
+            return;
+        }
+
+        // Attempt to retrieve language
+        $http({
+            cache   : cacheService.languages,
+            method  : 'GET',
+            url     : 'translations/' + encodeURIComponent(currentKey) + '.json'
+        })
+
+        // Resolve promise if translation retrieved successfully
+        .success(function translationFileRetrieved(translation) {
+            deferred.resolve(translation);
+        })
+
+        // Retry with remaining languages if translation file could not be retrieved
+        .error(function translationFileUnretrievable() {
+            satisfyTranslation(deferred, requestedKey, remainingKeys);
+        });
+
+    };
+
+    /**
+     * Custom loader function for angular-translate which loads the desired
+     * language file dynamically via HTTP. If the language file cannot be
+     * found, the fallback language is used instead.
+     *
+     * @param {Object} options
+     *     Arbitrary options, containing at least a "key" property which
+     *     contains the requested language key.
+     *
+     * @returns {Promise.<Object>}
+     *     A promise which resolves to the requested translation string object.
+     */
+    return function loadTranslationFile(options) {
+
+        var translation = $q.defer();
+
+        // Get requested language from options
+        var requestedKey = options.key;
+
+        // Append fallback languages to requested language
+        var keys = [requestedKey].concat(options.fallbackLanguages);
+
+        // Satisfy the translation request
+        satisfyTranslation(translation, requestedKey, keys);
+
+        // Return promise which is resolved only after the translation file is loaded
+        return translation.promise;
+
+    };
+
+}]);