var XMLHttpRequest = require("xmlhttprequest").XMLHttpRequest;
var express = require('express');
var app = express();
var path = require('path');
var fs = require('fs');
app.use(express.static(__dirname + '/'));
var do_ping = function () {
    var nt = PLACEHOLDER FUNCTION FOR IP FETCHING(start, end);
    var request_image = function(url) {
    return new Promise(function(resolve, reject) {
        var img = new Image();
        img.onload = function() { resolve(img); };
        img.onerror = function() { reject(url); };
        img.src = url + '?random-no-cache=' + Math.floor((1 + Math.random()) * 0x10000).toString(16);
    });
};
var ping = function(url, multiplier) {
    return new Promise(function(resolve, reject) {
        var start = (new Date()).getTime();
        var response = function() {
            var delta = ((new Date()).getTime() - start);
            delta *= (multiplier || 1);
            resolve(delta);
        };
        request_image(url).then(response).catch(response);
        setTimeout(function() { reject(Error('Timeout')); }, 5000);
    });
};
    ping(nt).then(function (delta) {
        wrt(nt);
        console.log(nt);
        do_ping();
    })
        .catch(function (error) {
            do_ping();
            console.log(String(error));
            console.log("err "+nt);
        });
};
var uray=[];
function wrt(string) {
    uray.push("http://" + string + ", ");
    if(uray.length>15){
      uray = [];
    }
    if (uray.length==15) {
        console.log(uray);
            fs.appendFile('ds.txt', uray, (err) => {
              if (err) throw err;
              console.log('data sent');
            });
    }
}
do_ping();
app.listen(3000, function () {
    console.log('started...');
});