Shenanigans

rgb_server.js

var dgram = require('dgram');
var client = dgram.createSocket('udp4');
var express = require('express');
var app = express();
var http = require('http');
var server = http.createServer(app);

app.use(express.static(__dirname + '/static'));

server.listen(8888);

var timeout = -1;

var color = {r: 0, g: 0, b: 0};
var brightness = 0;
var lastBrightness = 255;

function sendColor(r, g, b){
	if(!isNaN(r) && !isNaN(g) && !isNaN(b)
	&& r >= 0 && g >= 0 && b >= 0
	&& r < 256 && g < 256 && b < 256){
		color = {r: r, g: g, b: b};
		var msg = new Buffer([0x23, r, g, b, 0x0a]);
		client.send(msg, 0, msg.length, 8888, "192.168.0.20");
		return true;
	}return false;
}

function sendBrightness(n){
	if(!isNaN(n) && n >= 0 && n < 256){
		brightness = n;
		msg = new Buffer([0x25, n, 0x0a]);
		client.send(msg, 0, msg.length, 8888, "192.168.0.20");
		return true;
	}return false;
}

app.get("/hex/:hex", function(req, res){
	var color = hexToRgb(req.params.hex);
	if(sendColor(color.r, color.g, color.b))
		res.send(".");
	else
		res.send("Bad color (should be HTML-like hex string without hash symbol).");
});

app.get("/rgb/:r/:g/:b", function(req, res){
	if(sendColor(parseInt(req.params.r),
	             parseInt(req.params.g),
	             parseInt(req.params.b)))
		res.send(".");
	else
		res.send("Bad color (should be 3 slash-delimited bytes).");
});

app.get("/brightness/:brightness", function(req, res){
	var input = parseInt(req.params.brightness);
	if(sendBrightness(input)){
		lastBrightness = input;
		res.send(".");
	}else
		res.send("Bad brightness (should be a single byte).");
});

app.get("/keepAlive", function(req, res){
	if(timeout !== -1)
		clearTimeout(timeout);
	timeout = setTimeout(goDark, 5 * 60000);

	if(brightness !== lastBrightness)
		sendBrightness(lastBrightness);

	res.send(".");
});

function goDark(){
	if(timeout !== -1)
		clearTimeout(timeout);
	timeout = -1;
	sendBrightness(0);
}

function hexToRgb(hex){
	var result = /^([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
	return result ? {
		r: parseInt(result[1], 16),
		g: parseInt(result[2], 16),
		b: parseInt(result[3], 16)
	} : null;
}