Haptic Glove Server.js

/* global require, __dirname */
var socketio = require( "socket.io" ),
    http = require( "http" ),
    mime = require( "mime" ),
    path = require( "path" ),
    fs = require( "fs" ),
    format = require( "util" ).format,
    serialPort = require( "serialport" ),
    os = require( "os" ),
    spawn = require( "child_process" ).spawn,
    startProc = {
      linux: "xdg-open",
      win32: "explorer",
      darwin: "open"
    }[os.platform()],
    webServer = http.createServer( requestHandler ),
    listener = socketio.listen( webServer ),
    baudRate = 9600,
    manufacturer = "Arduino LLC (www.arduino.cc)",
    webServerPort = 9080,
    startPage = "index.html",
    glovePort = null;

function starter () {
  var startUrl = "http://localhost";
  if ( webServerPort !== 80 ) {
    startUrl += ":" + webServerPort;
  }
  spawn( startProc, [ startUrl + "/" + startPage ] );
}

function listenForPort () {
  console.log( "querying for ports" );
  serialPort.list( function ( err, ports ) {
    if ( err ) {
      console.error( err );
    }
    else {
      console.log( "Ports found:" );
      ports.forEach( function ( p ) {
        console.log( format( "\t%s: [%s] %s", p.comName, p.pnpId,
            p.manufacturer ) );
      } );
      var arduinos = ports.filter( function ( p ) {
        return p.manufacturer === manufacturer;
      } );
      if ( arduinos.length === 0 ) {
        console.log( "No Arduinos found" );
        setTimeout( listenForPort, 1000 );
      }
      else {
        var port = arduinos[0];
        connectToPort( port.comName );
      }
    }
  } );
}

function connectToPort ( portName ) {
  console.log( format( "Connecting to port: %s", portName ) );
  glovePort = new serialPort.SerialPort( portName, {
    baudrate: baudRate
  }, false );
  glovePort.open( function ( err ) {
    console.log( "Port open" );
    if ( err ) {
      console.error( err );
    }
    else {
      webServer.listen( webServerPort );
      listener.sockets.on( "connection", acceptConnection );
      starter();
    }
  } );
}

listenForPort();

function requestHandler ( req, res ) {
  var fileName = path.join( __dirname, req.url );
  if ( fileName[fileName.length - 1] === path.sep )
    fileName += "index.html";
  fs.readFile( fileName, function ( err, data ) {
    if ( err )
      send( res, 404, "text/plain", "File not found. Path: ("
          + req.url
          + ") reason: "
          + JSON.stringify( err ) );
    else
      send( res, 200, mime.lookup( fileName ), data );
  } );
}

function send ( res, code, type, data ) {
  res.writeHead( code, { "Content-Type": type } );
  res.end( data );
}

function acceptConnection ( socket ) {
  console.log( "Socket connection made!" );
  var onData = function ( data ) {
    console.log( "from web: " + typeof data + ": " + data );
    if ( typeof data === "number" && 0 <= data && data < 0x20 ) {
      glovePort.write( [ data ] );
    }
    else {
      glovePort.write( data );
    }
  };
  socket.on( "data", onData );
  socket.on( "disconnect", function () {
    socket.removeListener( "data", onData );
    glovePort.write( [ 0 ] );
    console.log( "Socket connection disconnected!" );
  } );
  glovePort.on( "data", function ( data ) {
    console.log( "from glove: " + typeof data + ": " + data );
  } );
}