Add middleware for redirects

gatsby-config.js

@@ -6,6 +6,7 @@ require('./config/prismjs/dvc')
 require('./config/prismjs/usage')
 
 const apiMiddleware = require('./middlewares/api')
+const redirectsMiddleware = require('./middlewares/redirects')
 
 const title = 'Data Version Control · DVC'
 const description =
@@ -93,6 +94,7 @@ module.exports = {
     title
   },
   developMiddleware: app => {
-    app.use('/api', apiMiddleware)
+    app.use(redirectsMiddleware)
+    app.get('/api', apiMiddleware)
   }
 }

middlewares/redirects/index.js

@@ -0,0 +1,32 @@
+/* eslint-env node */
+
+const { getRedirect } = require('../../src/utils/redirects')
+const { parse } = require('url')
+const { stringify } = require('querystring')
+
+const dev = process.env.NODE_ENV !== 'production'
+
+module.exports = (req, res, next) => {
+  const parsedUrl = parse(req.url, true)
+  const { pathname, query } = parsedUrl
+  const host = req.headers.host
+
+  let [redirectCode, redirectLocation] = getRedirect(host, pathname, {
+    req,
+    dev
+  })
+
+  if (redirectLocation) {
+    // HTTP redirects
+
+    const queryStr = stringify(query)
+    if (queryStr) {
+      redirectLocation += '?' + queryStr
+    }
+    res.writeHead(redirectCode, {
+      Location: redirectLocation
+    })
+  }
+
+  next()
+}