index.js

const express = require("express");
var mqtt = require("mqtt");
var hexToBinary = require("hex-to-binary");
var atob = require("atob");
const cors = require("cors");
var axios = require("axios");
const bodyParser = require("body-parser");
const wakeUpDyno = require("./wokeDyno");

const app = express();
app.use(cors());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

const API_URL = "https://iot-smart-meter.herokuapp.com/new_recording";
const API_MQTT_URL = "https://iot-smart-meter-mqtt.herokuapp.com/";

const corsWhitelist = [
  "http://localhost:8070/",
  "http://localhost:8100/",
  "http://localhost:3000/",
  "http://localhost:8080/",
];

const port = process.env.PORT || 8071;

app.use((req, res, next) => {
  res.header("Access-Control-Allow-Origin", "*");
  if (corsWhitelist.indexOf(req.headers.origin) !== -1) {
    res.header("Access-Control-Allow-Origin", req.headers.origin);
    res.header(
      "Access-Control-Allow-Headers",
      "Origin, Content-Type, X-Requested-With, Accept, Authorization"
    );
  }
  if (req.method === "OPTIONS") {
    res.header("Access-Control-Allow-Methods", "GET, PUT, POST, PATCH, DELETE");
    res.status(200).json({});
  }
  next();
});

var client = mqtt.connect("mqtts://influx.itu.dk", {
  username: "smartreader",
  password: "4mp3r3h0ur",
  port: 8883,
  rejectUnauthorized: false,
});

client.on("connect", function () {
  console.log("CONNECTED");
  client.subscribe("IoT2020sec/meters", function (err) {
    console.log("SUBSCRIBED");
  });
});

client.on("message", function (topic, message) {
  const base64Message = message.toString();
  const bin = atob(base64Message);

  let hexString = "";
  for (let i = 0; i < bin.length; i++) {
    const hex = bin.charCodeAt(i).toString(16);
    hexString += hex.length === 2 ? hex : "0" + hex;
  }
  console.log("hexString: " + hexString);
  const binaryMessage = hexToBinary(hexString);
  console.log("binary: " + binaryMessage);

  const measurementType = binaryMessage.slice(0, 1);
  const meterId = binaryMessage.slice(1, 8);
  const timestamp_binary = binaryMessage.slice(8, 40);
  const reading = binaryMessage.slice(40, 56);

  const timestamp = new Date(parseInt(timestamp_binary, 2) * 1000);

  const req = {
    meter_id: parseInt(meterId, 2),
    reading: parseInt(reading, 2),
    timestamp: timestamp,
    type: measurementType,
  };

  axios.post(API_URL, req, { headers: { mqtt_key: "G3.j*8d*~oT8x!w" } }).then(
    (response) =>
      console.log("Successfully sent data to DB for meter id:" + req.meter_id),
    (err) => console.log(err)
  );
});

client.on("error", function (error) {
  console.log("Can't connect" + error);
});

app.listen(port, () => {
  console.log("Listening to 8070...");
  wakeUpDyno(API_MQTT_URL);
});