app.js

const express = require('express')
const pubsub = require('pubsub-js');
const global = require('./constants');
const phidget = require('./phidgetServer');
const math = require('mathjs'); // for accurate math

const app = express()
var debug = require('debug')('stalker:server');
const url = require('url');


const fs = require('fs');
const path = require('path');
const port = 3000

app.use(express.static(__dirname + '/www'));
var http = require('http');



app.set('port', port);

/**
 * Create HTTP server.
 */

var server = http.createServer(app);

/**
 * Listen on provided port, on all network interfaces.
 */

server.listen(port);
server.on('error', onError);
server.on('listening', function () {
  console.log('Listening to ', port);
});

const socketServer = function () {

  io.on('connection', function (socket) {
    console.log('user connected');
    socket.on('connectStalker', function (data) {
      if (data == 'true') {
        console.log("connection request received");
        pubsub.publish(global.roverconnection_command, "connect");


      }
      else {
        console.log("disconnect request received");
        pubsub.publish(global.rovervelocity_command, "0");
        pubsub.publish(global.roverconnection_command, "disconnect");

      }
    });
    socket.on('velocity', function (data) {
      console.log('velocity change received');
      var v = math.round(data, 2);
      pubsub.publish(global.rovervelocity_command, v);
    });
    socket.on('steering', function (data) {
      console.log('steering change received');
      var v = math.round(data, 2);
      pubsub.publish(global.roversteering_command, v);
    });
    socket.on('motorstatus', function (data) {
      console.log('motorstatus request received');
      pubsub.publish(global.rovervelocity_statusrequest, 'data');
    });
    socket.on('GamePad', function (data) {
      // Parse the transport object and push the right pubsub
      console.log("Got a GampePad socket request");
      var gpTransport = JSON.parse(data);
      if (gpTransport.RightY == 0) {
        console.log('publishing gamePad velocity command of 0');
        pubsub.publish(global.rovervelocity_command, 0);
        return;
      }
      var velocity = math.round(math.number(- gpTransport.RightY) * 100, 2);//multiple incoming velocity by 100 to match values from the slider
      console.log("Publishing GampePad Velocity: " + gpTransport.RightY)
      pubsub.publish(global.rovervelocity_command, velocity);
      if (math.number(gpTransport.LeftY) == 0) {
        //console.log("Publishing GampePad Steering: 0")
       // pubsub.publish(global.roversteering_command, 0);
      }
      else {
        var leftx = math.number(gpTransport.LeftX) * 50; // because the phidgetServer steering routine divides by 50
        var lefty = math.number(gpTransport.LeftY) * 50;
        var steeringVectorLength = Math.sqrt(Math.pow(LeftX, 2) + Math.pow(LeftY, 2));
        steeringVectorLength = math.round(steeringVectorLength, 2);
        if (!isNaN(steeringVectorLength) && (math.number(gpTransport.RightY) > 0.10 || math.number(gpTransport.RightY) < 0.10)) {
         // console.log("Publishing GamePadsteering vector: " + steeringVectorLength)
        //  pubsub.publish(global.roversteering_command, steeringVectorLength);
        }
      }

    });
    pubsub.subscribe(global.roverconnection_status, function (msg, data) {
      if (data == "connected") {
        socket.emit('connectionStatus', 'Stalker is connected');
      }
      else if (data == "disconnected") {
        socket.emit('connectionStatus', 'Stalker is not connected');
      }
    });
    pubsub.subscribe(global.rovervelocity_statusreport, function (msg, data) {
      var responseArray = data;
      var jsonResponse = JSON.stringify(responseArray);
      socket.emit('velocityReport', jsonResponse);
    });
    pubsub.subscribe(global.errorreport, function (msg, data) {
      var responseArray = data;
      var jsonResponse = JSON.stringify(responseArray);
      socket.emit('errorReport', jsonResponse);
    });
  });

}
const setConnectionStatus = function (status) {
  if (status == "on") {
    io.on('connection', function (socket) {
      {
        socket.emit('connectionStatus', 'Stalker is connected');
      }
    });
  }
}



//
// start up socket server for communication with web page
//
var io = require('socket.io').listen(server);
socketServer();
// for test:
//setConnectionStatus("on");
//
// startup phidget interface for communication with rover
//
phidget.phidgetServer();
/**
 * Normalize a port into a number, string, or false.
 */

function normalizePort(val) {
  var port = parseInt(val, 10);

  if (isNaN(port)) {
    // named pipe
    return val;
  }

  if (port >= 0) {
    // port number
    return port;
  }

  return false;
}

/**
 * Event listener for HTTP server "error" event.
 */

function onError(error) {
  if (error.syscall !== 'listen') {
    throw error;
  }

  var bind = typeof port === 'string'
    ? 'Pipe ' + port
    : 'Port ' + port;

  // handle specific listen errors with friendly messages
  switch (error.code) {
    case 'EACCES':
      console.error(bind + ' requires elevated privileges');
      process.exit(1);
      break;
    case 'EADDRINUSE':
      console.error(bind + ' is already in use');
      process.exit(1);
      break;
    default:
      throw error;
  }
}