Move cache to separate file

cache.js

@@ -0,0 +1,29 @@
+// we get the old files from the deployment
+const needle = require('needle')
+const config = require('./config.json')
+
+const getCached = () => {
+  return new Promise((resolve, reject) => {
+    const cached = { catalog: [] }
+    needle.get(`https://${config['netlify-domain']}/lastUpdate.json`, config.needle, (err, resp, body) => {
+    // if an update was done less than 12h ago, then prefer updating from cache
+    if ((body || {}).time) {
+      cached.time = body.time
+      console.log('got last known website update time')
+    } else {
+      console.log('warning: could not get last update time')
+    }
+
+    needle.get(`https://${config['netlify-domain']}/catalog.json`, config.needle, (err, resp, body) => {
+      if ((body || [])[0].transportUrl && body[0].transportName && body[0].manifest) {
+        console.log('loaded old addon catalog')
+        cached.catalog = body
+      } else {
+        console.log('warning: could not load old addon catalog')
+      }
+      resolve(cached)
+    })
+  })
+}
+
+module.exports = getCached