1 files changed, 70 insertions, 0 deletions
diff --git a/toolkit/jetpack/sdk/l10n/loader.js b/toolkit/jetpack/sdk/l10n/loader.js
new file mode 100644
index 000000000..60e219e44
--- /dev/null
+++ b/toolkit/jetpack/sdk/l10n/loader.js
@@ -0,0 +1,70 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+module.metadata = {
+  "stability": "unstable"
+};
+
+const { Cc, Ci } = require("chrome");
+const { getPreferedLocales, findClosestLocale } = require("./locale");
+const { readURI } = require("../net/url");
+const { resolve } = require("../core/promise");
+
+function parseJsonURI(uri) {
+  return readURI(uri).
+    then(JSON.parse).
+    then(null, function (error) {
+      throw Error("Failed to parse locale file:\n" + uri + "\n" + error);
+    });
+}
+
+// Returns the array stored in `locales.json` manifest that list available
+// locales files
+function getAvailableLocales(rootURI) {
+  let uri = rootURI + "locales.json";
+  return parseJsonURI(uri).then(function (manifest) {
+    return "locales" in manifest &&
+           Array.isArray(manifest.locales) ?
+           manifest.locales : [];
+  });
+}
+
+// Returns URI of the best locales file to use from the XPI
+function getBestLocale(rootURI) {
+  // Read localization manifest file that contains list of available languages
+  return getAvailableLocales(rootURI).then(function (availableLocales) {
+    // Retrieve list of prefered locales to use
+    let preferedLocales = getPreferedLocales();
+
+    // Compute the most preferable locale to use by using these two lists
+    return findClosestLocale(availableLocales, preferedLocales);
+  });
+}
+
+/**
+ * Read localization files and returns a promise of data to put in `@l10n/data`
+ * pseudo module, in order to allow l10n/json/core to fetch it.
+ */
+exports.load = function load(rootURI) {
+  // First, search for a locale file:
+  return getBestLocale(rootURI).then(function (bestMatchingLocale) {
+    // It may be null if the addon doesn't have any locale file
+    if (!bestMatchingLocale)
+      return resolve(null);
+
+    let localeURI = rootURI + "locale/" + bestMatchingLocale + ".json";
+
+    // Locale files only contains one big JSON object that is used as
+    // an hashtable of: "key to translate" => "translated key"
+    // TODO: We are likely to change this in order to be able to overload
+    //       a specific key translation. For a specific package, module or line?
+    return parseJsonURI(localeURI).then(function (json) {
+      return {
+        hash: json,
+        bestMatchingLocale: bestMatchingLocale
+      };
+    });
+  });
+}