a few changes to make A/B testing easier

common/locales.js

@@ -0,0 +1,51 @@
+const gen = require('../build/generate_l10n_map');
+
+const isServer = typeof gen === 'function';
+const prefix = isServer ? '/' : '';
+let manifest = {};
+try {
+  //eslint-disable-next-line node/no-missing-require
+  manifest = require('../dist/manifest.json');
+} catch (e) {
+  // use middleware
+}
+
+const locales = isServer ? manifest : gen;
+
+function getLocale(name) {
+  return prefix + locales[`public/locales/${name}/send.ftl`];
+}
+
+function serverTranslator(name) {
+  return require(`../dist/${locales[`public/locales/${name}/send.ftl`]}`);
+}
+
+function browserTranslator() {
+  return locales.translate;
+}
+
+const translator = isServer ? serverTranslator : browserTranslator;
+
+const instance = {
+  get: getLocale,
+  getTranslator: translator,
+  setMiddleware: function(middleware) {
+    if (middleware) {
+      const _eval = require('require-from-string');
+      instance.get = function getLocaleWithMiddleware(name) {
+        const f = middleware.fileSystem.readFileSync(
+          middleware.getFilenameFromUrl('/manifest.json')
+        );
+        return prefix + JSON.parse(f)[`public/locales/${name}/send.ftl`];
+      };
+      instance.getTranslator = function(name) {
+        const f = middleware.fileSystem.readFileSync(
+          middleware.getFilenameFromUrl(instance.get(name))
+        );
+        return _eval(f.toString());
+      };
+    }
+  }
+};
+
+module.exports = instance;