automatic token refresh, initial stage

backend/helpers/token.js

@@ -0,0 +1,19 @@
+const config = require('../config');
+var ObjectID = require ('mongodb').ObjectID;
+
+module.exports = {
+    updateTokens : function (refresh_token, access_token, expires_in, db){
+        let newTokenDocument = {
+            id:1,
+            refresh_token:refresh_token,
+            access_token: access_token,
+            expires_in: (new Date() / 1000) + expires_in
+        }
+        let result = db.collection('token_list').update({id:1}, newTokenDocument,{upsert:true}, (err, result)=>{
+            if (err) throw new Error(err);
+            config.REFRESH_TOKEN = refresh_token;
+            config.TOKEN = access_token;
+            config.TOKEN_EXPIRES_IN = newTokenDocument.expires_in;
+        });
+    }
+};