Feat: refactor routes.js express entrypoint config

Feat: express config script refactor

Feat: add state and settingsCache files

lib/middlewares/populateSettings.js

@@ -0,0 +1,42 @@
+const state = require('./state')
+const settingsCache = require('./settingsCache')
+const newSettingsLoader = require('../new-settings-loader')
+const helpers = require('../route-helpers')
+
+const SETTINGS_CACHE_REFRESH = 60 * 60 * 1000
+
+const populateSettings = function (req, res, next) {
+  const versionId = req.headers['config-version']
+  if (versionId !== state.oldVersionId) {
+    state.oldVersionId = versionId
+  }
+
+  // Clear cache every hour
+  if (Date.now() - settingsCache.getTimestamp() > SETTINGS_CACHE_REFRESH) {
+    settingsCache.clearCache()
+  }
+
+  if (!versionId && settingsCache.getCache()) {
+    req.settings = settingsCache.getCache()
+    return next()
+  }
+
+  if (!versionId && !settingsCache.getCache()) {
+    return newSettingsLoader.loadLatest()
+      .then(settings => {
+        settingsCache.setCache(settings)
+        settingsCache.setTimestamp(Date.now())
+        req.settings = settings
+      })
+      .then(() => next())
+      .catch(next)
+  }
+
+  newSettingsLoader.load(versionId)
+    .then(settings => { req.settings = settings })
+    .then(() => helpers.updateDeviceConfigVersion(versionId))
+    .then(() => next())
+    .catch(next)
+}
+
+module.exports = populateSettings