internet_checker/check_internet_script.js

Check internet connection and emmit sound when there's no internet. This is very useful when your connection is not stable and you don't want to waste time checking often if your internet connection is really down.

/*jshint esversion: 6 */

const ping = require('ping');
const spawn = require('child_process').spawn;
let Observable = require('rxjs').Observable;

/**
 * Frequency to check internet connectecion in miliseconds
 * @type {Number}
 */
const frequency = 10000; //10 seconds

/**
 * A flag to know if the internet ok notification was made
 */
let notifyInternetOk = false;

let notificationsCount = 0;

/**
 * How many times we notify when the internet is ok
 */
const NotificationsInternetOkQuantity = 3;

// Subscribe to listen the ping responses
Observable.interval(frequency)
  // Every 10 seconds (for ex) we will make a ping to google
  .flatMap( () => Observable.fromPromise(ping.promise.probe('8.8.8.8')) )
  .subscribe( res => {

    // There is internet
    if (res.alive === true)
      thereIsInternet(res.time);
    // No internet
    else
      thereIsNOInternet();
});

/**
 * Execute this function when we have internet
 *
 * @param time the time of the package took to arrive
 */
function thereIsInternet(time) {

  // Emit a sound "internet OK" only 3 times, once spoken, just print
  if (!notifyInternetOk){

    spawn('espeak',['Internet OK']);
    notificationsCount++;

    if (notificationsCount >= NotificationsInternetOkQuantity) {
      notifyInternetOk = true;
      notificationsCount = 0;
    }
  }

  console.log(`Intenet connection OK! Response time=${time}ms`);
}

/**
 * Execute this function when we have NOT internet
 *
 * Here we send 10 ping packages very fast and if that package
 */
function thereIsNOInternet() {

  // Take only 10 ping responses
  let takeOnly = 10;

  // Expresed on percentage, the rate of package lost to consider than there is no internet
  let noInternetRate = 60;

  notifyInternetOk = false;

  // That +3 is to get sure that all this packages are sent before the next internet checker interval is made
  Observable.interval(frequency/(takeOnly+3) )
    // make ping
    .flatMap( () => Observable.fromPromise(ping.promise.probe('8.8.8.8')) )
    // take only 10
    .take( takeOnly )
    // Just count how many times the ping could not complete the journey
    .reduce( (lostPackages, res) => {
      // Count one if the response is false
      if(res.alive === false)
        return ++lostPackages;
    }, 0 )
    // Filter only when the lost packages are greater than the noInternetRate
    .filter( lostPackages => (lostPackages*100/takeOnly) >= noInternetRate )
    .subscribe( () => {
      console.log('NO INTERNET!');
      spawn('espeak',['fucking maduro'])
    });
}