fridge.js

/*!
 * Fridge - A fridge magnet experiment using nodejs & nowjs.
 * Copyright(c) 2010 Marc Dassonneville <marc.dassonneville@gmail.com>
 * MIT Licensed
 */

var express = require('express')
	, nowjs = require('now')
	, server = express.createServer()

// initialising express
server.get('*', function(req, res) { res.render('door.ejs', {layout:false}) })
// initialising nowjs
var everyone = nowjs.initialize(server)

// helper
Number.between = function (min, max) { return Math.floor(Math.random() * (max - min + 1)) + min }

// 
var boardWidth = 1024, boardHeight = 800, boardMargin = 30
var rgb = [ Number.between(80, 130)
			, Number.between(80, 130)
			, Number.between(80, 130)]

// new color, not far from previous one.
rgb.refresh = function () {
	this.forEach(function (v, i) {
		var k = Number.between(-5, 10)
		rgb[i] = (v + k <= 255 && v + k >= 0) ? v + k : v
	})
	return this.concat() // cloning the array.
}

// generating magnets based on alphabet.
var magnetsById = {}, magnets =
"AAAABBCCDDEEEEFFGGHHIIIJJKKLLMMNNOOOPPQQRRSSTTUUUVVWXYZ☺⬅⬆⬇⬈⬉⬊⬋⬌⬍'|-_"
	.split('')
	.map(function (magnet, i) {
		return { 'id' : 'm'+i
			, 'data' : magnet
			, 'angle' : Number.between(-10, 10)
			, 'top' : Number.between(boardMargin, boardHeight-boardMargin)
			, 'left' : Number.between(boardMargin, boardWidth-boardMargin)
			, 'color' : rgb.refresh()
			, 'owner' : null // clientId, used for semaphore
		}
	})
magnets.forEach(function (m) { magnetsById[m.id] = m })

// browser is requesting magnets
everyone.now.requestMagnets = function () {
	console.log(new Date()+'client '+this.user.clientId+' (IP-unknown) requestMagnets()')
	// sending magnets descriptor to the browser
	this.now.updateMagnets(magnets.map(function (o) {
		// minify
		return { 'i' : o.id
			, 'd' : o.data
			, 'a' : o.angle
			, 't' : o.top
			, 'l' : o.left
			, 'c' : o.color
		}
	})) // to a single user.
}

// browser is moving a magnet
everyone.now.moveMagnet = function (magnetId, top, left) {
	console.log(new Date()+'<= client '+this.user.clientId+' moveMagnet('+magnetId+', '+top+', '+left+')')
	magnetsById[magnetId].top = top
	magnetsById[magnetId].left = left 
	everyone.exclude([this.user.clientId]).now.updateMagnet(magnetId, top, left)
}

// semaphore: acquireMagnet/releaseMagnet prevent several users 
//  from moving the same magnet at a time
everyone.now.acquireMagnet = function (magnetId) {
	console.log(new Date()+'<= client '+this.user.clientId+' acquireMagnet('+magnetId+')')
	// a client can only acquire 1 magnet at time.
	var userNow = this.now
	var clientId = this.user.clientId
	
	magnets.filter(function (m) { return m.owner == clientId })
			 .forEach(function (m) {
					// reseting owner
					m.owner = null
					// sending order to disable drag&drop on magnet
					console.log(new Date()+'=> client '+clientId+' magnetLost('+m.id+')')
					userNow.magnetLost(m.id)
				})
	// acquiring magnet
	if (magnetsById[magnetId].owner == null)
	{
		// sending order to enable drag&drop on magnet
		magnetsById[magnetId].owner = clientId
		console.log(new Date()+'=> client '+clientId+' magnetAcquired('+magnetId+')')
		userNow.magnetAcquired(magnetId)
	}
}

everyone.now.releaseMagnet = function (magnetId) {
	console.log(new Date()+'<= client '+this.user.clientId+' releaseMagnet('+magnetId+')')
	if (magnetsById[magnetId].owner = this.user.clientId)
		magnetsById[magnetId].owner = null
}

// when a user disconnect, release all his magnets
nowjs.on('disconnect', function () {
	var clientId = this.user.clientId
	magnets.filter(function (m) { return m.owner == clientId })
			 .forEach(function (m) { m.owner = null })
})

server.listen(80)