app.js

// module dependencies
var express = require('express')
    , http = require('http')
//, routes = require('./routes')
    , path = require('path')
    , uuid = require('node-uuid')
    , _ = require('lodash');

var app = express();

// configuration
app.set('port', process.env.PORT || 3000);
app.set('views', __dirname + '/views');
app.set('view engine', 'jade');
app.use(express.favicon());
app.use(express.logger('dev'));
app.use(express.json());
app.use(express.urlencoded());
app.use(express.methodOverride());
app.use(express.cookieParser('your secret here'));
app.use(express.session());
app.use(app.router);
app.use(require('less-middleware')({ src: __dirname + '/public' }));
app.use(express.static(path.join(__dirname, 'public')));

app.configure('development', function () {
  app.use(express.errorHandler());
});

// start the server
var server = http.createServer(app).listen(app.get('port'), function () {
  console.log('Express server listening on port ' + app.get('port'));
});
//attach socket.io
var io = require('socket.io', { serveClient: false, path: 'sockets/gummiwars'}).listen(server);

// ----- routes -----

// root route: returns game page
app.get('/', function (req, res) {
  res.render('index', { title: 'GummiWars' });
});
//app.get('/', routes.index);


var rooms = [];
var Room = function () {
  this.id = uuid.v4();
  this.playerIds = [];
};

// packs the room list and statistics onto the data message
function addRoomsToData(data) {
  // filter down to only rooms that can accept a new player
  var availableRooms = _.filter(rooms, function (room) {
    return room.playerIds.length < 4;
  });

  // if no rooms are available, create a new room
  if (availableRooms.length == 0) {
    var newRoom = new Room();
    rooms.push(newRoom);
    availableRooms.push(newRoom);
  }

  // convert available rooms to just room id and player count
  // and attach to data message
  data.rooms = _.map(availableRooms, function (room) {
    return {
      roomId: room.id,
      playerCount: room.playerIds.length
    };
  });

  // attach total number of rooms to data message
  data.totalRooms = rooms.length;

  // map-reduce to get total number of players in game
  // and attach to message
  var roomCounts = _.map(rooms, function (room) {
    return room.playerIds.length;
  });
  data.playersInRooms = _.reduce(roomCounts, function (sum, count) {
    return sum + count;
  });
}

// does the heavy lifting for leaving a room
function leaveRoom(roomToLeave, socket) {
  // check for null/undefined
  if (roomToLeave) {

    // remove the player from the room data
    roomToLeave.playerIds = _.filter(roomToLeave.playerIds, function (id) {
      return id != socket.id;
    });

    // if the room is now empty, remove it from the room list
    if (roomToLeave.playerIds.length == 0) {
      rooms = _.filter(rooms, function (room) {
        return room.id != roomToLeave.id;
      });
    }
    // otherwise, notify other players in the room of the disconnection
    else {
      var data = {};
      data.playerId = socket.id;
      socket.broadcast.to(roomToLeave.id).emit('playerDisconnected', data);
    }

    // remove the player from the socket.io room
    socket.leave(roomToLeave.id);
  }
}

// ----- socket.io -----
io.sockets.on('connection', function (socket) {
// sends player their id and a list of rooms
  socket.on('playerConnect', function () {
    var data = {};
    data.playerId = socket.id;

    // add room info to message
    addRoomsToData(data);

    // send message to user
    socket.emit('connectionReply', data);
  });

// sends player an update room list
  socket.on('getRooms', function () {
    var data = {};

    // add room info to message
    addRoomsToData(data);

    // send message to user
    socket.emit('updatedRoomList', data);
  });

  // handle player disconnection:
  socket.on('disconnect', function () {
    // find the room being left
    var roomToLeave = _.find(rooms, function (room) {
      return _.any(room.playerIds, function (id) {
        // capture socket id in closure scope
        return id == socket.id;
      });
    });
    // handle the rest of the disconnection
    leaveRoom(roomToLeave, socket);
  });

// attempts to allow a player to join a game:
// if successful, the player id is added to the room and notified;
// if failed, the player is sent a refusal;
  socket.on('joinRoom', function (data) {
    // find the room being requested
    var room = _.find(rooms, {id: data.roomId});

    // verify that player can join room:
    // room must exist and have less than 4 players
    if (!room || room.playerIds.length >= 4) {
      // send refusal
      socket.emit('connectionRefused');
      return;
    }

    // register player with room
    room.playerIds.push(socket.id);
    socket.join(room.id);

    // send verification that room was joined to the player with room id
    socket.emit('roomJoined', {roomId: room.id});
  });

// handle a user leaving a room not by disconnection
  socket.on('leaveRoom', function (data) {
    // find the room being left
    var roomToLeave = _.find(rooms, {id: data.roomId});

    // handle the rest of the disconnection
    leaveRoom(roomToLeave, data);
  });

// handles rebroadcast of gameplay messages to other players in the room
  socket.on('clientSend', function (data) {
    socket.broadcast.to(data.roomId).emit('clientReceive', data);
  });

// handles rebroadcast of gameplay messages to other players in the room
  socket.on('localPlayerDied', function (data) {
    socket.broadcast.to(data.roomId).emit('remotePlayerDied', data);
  });
});