From b9ee89fc466f09288be365af9be6ccc4ec12c880 Mon Sep 17 00:00:00 2001
From: Robert Sese <robert.sese@gmail.com>
Date: Thu, 5 Aug 2021 16:46:57 -0500
Subject: [PATCH] Add redirects for language-less homepage requests (#20494)

* Redirect homepage to user's language

* Redirect URLs with no language code

* Add leading forward slash

* Revert "Redirect URLs with no language code"

This reverts commit f817ac1136ea0c7e11c4d61327a4445b56a2f5d6.

* Simplify per @zeke

* Add homepage language redirect tests

* Update middleware/redirects/handle-redirects.js

Co-authored-by: Kevin Heis <heiskr@users.noreply.github.com>

* braces are good

Co-authored-by: Kevin Heis <heiskr@users.noreply.github.com>
---
 middleware/redirects/handle-redirects.js | 16 ++++++++++++++--
 tests/routing/redirects.js               | 14 ++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/middleware/redirects/handle-redirects.js b/middleware/redirects/handle-redirects.js
index 503aab1bdd..94e1996c7f 100644
--- a/middleware/redirects/handle-redirects.js
+++ b/middleware/redirects/handle-redirects.js
@@ -1,13 +1,25 @@
 import patterns from '../../lib/patterns.js'
 import { URL } from 'url'
+import languages from '../../lib/languages.js'
 
 export default function handleRedirects(req, res, next) {
   // never redirect assets
   if (patterns.assetPaths.test(req.path)) return next()
 
-  // blanket redirects for languageless homepage to English homepage
+  // blanket redirects for languageless homepage
   if (req.path === '/') {
-    return res.redirect(301, '/en')
+    let language = 'en'
+
+    // if set, redirect to user's preferred language translation or else English
+    if (
+      req.context.userLanguage &&
+      languages[req.context.userLanguage] &&
+      !languages[req.context.userLanguage].wip
+    ) {
+      language = req.context.userLanguage
+    }
+
+    return res.redirect(301, `/${language}`)
   }
 
   // begin redirect handling
diff --git a/tests/routing/redirects.js b/tests/routing/redirects.js
index 5d8b7efa85..3acdd51304 100644
--- a/tests/routing/redirects.js
+++ b/tests/routing/redirects.js
@@ -119,6 +119,20 @@ describe('redirects', () => {
     })
   })
 
+  describe('home page redirects', () => {
+    test('homepage redirects to english by default', async () => {
+      const res = await get('/')
+      expect(res.statusCode).toBe(301)
+      expect(res.headers.location).toBe('/en')
+    })
+
+    test('homepage redirects to preferred language', async () => {
+      const res = await get('/', { headers: { 'Accept-Language': 'ja' } })
+      expect(res.statusCode).toBe(301)
+      expect(res.headers.location).toBe('/ja')
+    })
+  })
+
   describe('external redirects', () => {
     test('work for top-level request paths', async () => {
       const res = await get('/git-ready')