server.js

const http2 = require("http2")
const express = require('express')
const { parse } = require('url')
const next = require('next')
const fs = require('fs');
const readline = require('readline');
const {google} = require('googleapis');

const dev = process.env.NODE_ENV === 'development'
const app = next({ dev })
const handle = app.getRequestHandler()
let queue = { devices : {
    A: {
        values: []
    },
    B: {
        values: []
    },
    C: {
        values: []
    }
}
}

calendar = [];

app.prepare().then(() => {
    const server = express()

  
    server.get('/status', (req, res) => {
      res.send("Health: ok")
    })

    server.get('/queue', (req, res) => {
        res.send(queue);
    })

    server.get('/calendar', (req, res) => {
        getCalendar();
        res.send(calendar)
    })
  
    server.get('*', (req, res) => {
      return handle(req, res)
    })
  
    server.listen("3001", err => {
      if (err) throw err
      console.log(`> Dashboard ready on http://localhost:3001`)
    })
  })

const HTTP2Server = http2.createServer();
HTTP2Server.on("stream", (stream, requestHeaders) => {
  console.log(requestHeaders);
  let deviceID = requestHeaders[":path"];
  deviceID = deviceID.substr(1);
  if (deviceID === "A" || deviceID === "B" || deviceID === "C") {
    queue.devices[deviceID].values.push(JSON.parse(requestHeaders.payload));
  }
  stream.respond({
    ":status": 200,
    "content-type": "text/html",
  });
  stream.end("Entry saved in queue");
});
HTTP2Server.listen("999");


// If modifying these scopes, delete token.json.
const SCOPES = ['https://www.googleapis.com/auth/calendar.readonly'];
// The file token.json stores the user's access and refresh tokens, and is
// created automatically when the authorization flow completes for the first
// time.
const TOKEN_PATH = 'token.json';

function getCalendar() {
    // Load client secrets from a local file.
    fs.readFile('credentials.json', (err, content) => {
        if (err) return console.log('Error loading client secret file:', err);
        // Authorize a client with credentials, then call the Google Calendar API.
        authorize(JSON.parse(content), listEvents);
    });
}

/**
 * Create an OAuth2 client with the given credentials, and then execute the
 * given callback function.
 * @param {Object} credentials The authorization client credentials.
 * @param {function} callback The callback to call with the authorized client.
 */
function authorize(credentials, callback) {
  const {client_secret, client_id, redirect_uris} = credentials.installed;
  const oAuth2Client = new google.auth.OAuth2(
      client_id, client_secret, redirect_uris[0]);

  // Check if we have previously stored a token.
  fs.readFile(TOKEN_PATH, (err, token) => {
    if (err) return getAccessToken(oAuth2Client, callback);
    oAuth2Client.setCredentials(JSON.parse(token));
    callback(oAuth2Client);
  });
}

/**
 * Get and store new token after prompting for user authorization, and then
 * execute the given callback with the authorized OAuth2 client.
 * @param {google.auth.OAuth2} oAuth2Client The OAuth2 client to get token for.
 * @param {getEventsCallback} callback The callback for the authorized client.
 */
function getAccessToken(oAuth2Client, callback) {
  const authUrl = oAuth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES,
  });
  console.log('Authorize this app by visiting this url:', authUrl);
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });
  rl.question('Enter the code from that page here: ', (code) => {
    rl.close();
    oAuth2Client.getToken(code, (err, token) => {
      if (err) return console.error('Error retrieving access token', err);
      oAuth2Client.setCredentials(token);
      // Store the token to disk for later program executions
      fs.writeFile(TOKEN_PATH, JSON.stringify(token), (err) => {
        if (err) console.error(err);
        console.log('Token stored to', TOKEN_PATH);
      });
      callback(oAuth2Client);
    });
  });
}

/**
 * Lists the next 10 events on the user's primary calendar.
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
function listEvents(auth) {
  const calendar = google.calendar({version: 'v3', auth});
  calendar.events.list({
    calendarId: 'primary',
    timeMin: (new Date()).toISOString(),
    maxResults: 3,
    singleEvents: true,
    orderBy: 'startTime',
  }, (err, res) => {
    if (err) return console.log('The API returned an error: ' + err);
    const events = res.data.items;
    if (events.length) {
      events.map((event, i) => {
        const start = event.start.dateTime || event.start.date;
        this.calendar[i] = `${start} - ${event.summary}`;
      });
    } else {
      console.log('No upcoming events found.');
    }
  });
}