Add language routing

server/middlewares/add-lang.js

@@ -0,0 +1,66 @@
+import supportedLanguages from '../../common/utils/supported-languages';
+import passthroughs from '../utils/lang-passthrough-urls';
+import debug from 'debug';
+
+const log = debug('fcc:middlewares:lang');
+const langTagRegex = /^[a-z]{2}(?:-[a-zA-Z]{2,3})?$/;
+const toLowerCase = String.prototype.toLowerCase;
+
+// redirect(statusOrUrl: String|Number, url?: String) => Void
+function langRedirect(...args) {
+  const url = args.length === 2 ? args[1] : args[0];
+  const { lang } = this.req;
+  const maybeLang = toLowerCase.call(url.split('/')[1]);
+
+  if (
+    passthroughs[maybeLang] ||
+    supportedLanguages[maybeLang]
+  ) {
+    return this._oldRedirect(...arguments);
+  }
+
+  // if language present add to url
+  if (lang) {
+    return this._oldRedirect(`/${lang}${url}`);
+  }
+
+  // default to english
+  return this._oldRedirect(`/en${url}`);
+}
+
+// prefer url lang over user lang
+// if url lang is not supported move to user lang
+// if user lang is not supported default to english
+export default function addLang() {
+  return function(req, res, next) {
+    const { url, user = {} } = req;
+    const maybeLang = url.split('/')[1];
+    const restUrl = url.split('/').slice(2).join('/');
+    const userLang = user.languageTag;
+    let finalLang;
+    if (supportedLanguages[maybeLang]) {
+      finalLang = maybeLang;
+    } else if (supportedLanguages[userLang]) {
+      finalLang = userLang;
+    } else {
+      finalLang = 'en';
+    }
+    // found url lang tag that is not yet supported
+    // redirect to fix url with supported lang tag
+    if (langTagRegex.test(maybeLang) && !supportedLanguages[maybeLang]) {
+      log(`unsupported lang tag ${maybeLang}`);
+      return res.redirect(`/${finalLang}/${restUrl}`);
+    }
+    res.locals.supportedLanguages = supportedLanguages;
+
+    if (supportedLanguages[finalLang]) {
+      req.lang = finalLang;
+      res.locals.lang = finalLang;
+    }
+
+    res._oldRedirect = res.redirect;
+    res.redirect = langRedirect;
+
+    return next();
+  };
+}