catcher.js

// Run this catcher in a following way:
// 1. Make sure to install tmux, nodejs, and `ws` node package
//		apt-get install tmux npm
//		npm install -g ws
// 2. Start tmux. This is needed to let the program run after logout.
//    When you log in again, `tmux attach` attaches an old session.
// 3. Run catcher in an infinite loop:
//		while true; do node catcher.js YOUR_API_KEY ; sleep 1; done

const Websocket = require('ws');  // npm install -g ws
const token = process.argv[2];    // API token
const https = require('https');
let devices = {};  // device ID -> device mapping
let pubkeys = {};  // pubkey -> customer mapping

if (!token) {
  console.error(`Usage: ${process.argv[1]} API_KEY`);
  process.exit();
}

const fetch = uri => new Promise((resolve, reject) => {
  const cb = resp => {
    let data = '';
    resp.on('data', chunk => data += chunk);
    resp.on('end', ev => resolve(JSON.parse(data)));
  };
  var req = https.get(`https://mdash.net${uri}?access_token=${token}`, cb);
  req.on('error', err => reject(err.message));
});

const mkpubkeys = data => {
  data.forEach(c => {
    for (var id in c.pubkeys) pubkeys[id] = c;
  });
};

const mkdevices = data => {
  data.forEach(d => devices[d.id] = d);
};

fetch('/api/v2/devices').then(data => mkdevices(data));    // Get devices
fetch('/api/v2/customers').then(data => mkpubkeys(data));  // Get customers

// Start catching notifications
const addr = `wss://mdash.net/api/v2/notify?access_token=${token}`;
const ws = new Websocket(addr, { origin: addr });
ws.on('open', () => console.log(`Connected, catching notifications...`));
ws.on('close', () => console.log(`Disconnected.`));
ws.on('message', msg => {
  let notification = JSON.parse(msg.toString());
  let device = devices[notification.id] || {};
  let customer = pubkeys[device.acl.public_key] || {};
  console.log(
      'Got message:', JSON.stringify(notification),
      'customer:', customer.email);
  if (notification.name == 'offline' && customer.email) {
    // Do something
  }
});