server.js

const express = require("express");
const bodyParser = require("body-parser");
const einsteinAuth = require("./libs/einstein_auth.js");
const chat = require("./libs/hangout-chat.js");

var app = express();

var port = process.env.PORT || 5001;
var https_port = process.env.HTTPS_PORT || parseInt(port) + 1;

var jsonParser = bodyParser.json();

app.get("/", function(req, res) {
  res.send("Nothing to see here");
});

// Change the URL to an individual AND hard to guess URL
// https://developers.google.com/hangouts/chat/how-tos/bots-develop#registering_the_bot
app.post("/ThisIsMyHardToGuessUrl", jsonParser, function(req, res) {
  if (chat.securityCheck(req, res)) {
    chat.processChat(req.body, res);
  }
});

app.listen(port, function() {
  console.log("Example bot listening on " + port);
});

einsteinAuth.getAccessToken();