port/port.js

Spawn Pd (Pure Data) and communicate through TCP sockets

var net = require('net'),
	spawn = require('child_process').spawn,
	event = require('events').EventEmitter;


function Port(options){
	if (!(this instanceof Port)) return new Port(options);
	this.setOptions(options);
}


Port.prototype = Object.create(event.prototype);


Port.prototype.setOptions = function(options){
	if (!this.options) this.options = {
		host: 'localhost',
		read: null, // [connect <port>( -> [netsend]
		write: null, // [netreceive <port>]
		encoding: null, // 'ascii', 'utf8', 'base64', 'hex'
		max: 1, // max connections
		basepath: '', // prefix -path flags
		pd: (('darwin' == process.platform)
			? '/Applications/Pd-0.45-5-64bit.app/Contents/Resources/bin/pd'
			: 'pd'),
		flags: {} // {'nogui': true, 'stderr': true, 'open': './port.pd'}
	};

	for (var key in options){
		this.options[key] = options[key];
	}

	return this;
};

Port.prototype.parseFlags = function(flags){
	var array = [],
		basepath = (this.options && this.options.basepath) || '';

	if (Array.isArray(flags)) return flags;
	for (var f in flags){
		if (/debug|path|open/.test(f) || !flags[f]) continue;
		array.push(/^-/.test(f) ? f : '-' + f);
		if (typeof flags[f] != 'boolean') array.push(flags[f]);
	}

	var path = flags['-path'] || flags['path'] || '';

	if (!!basepath || !!path){
		if (!!basepath && !(/\/$/.test(basepath))) basepath += '/';
		
		if (!Array.isArray(path)) array.push('-path', basepath + path);
		else for (var i = 0, l = path.length; i < l; ++i){
			array.push('-path', basepath + path[i]);
		}
	}

	array.push('-open', flags['-open'] || flags['open']);
	return array;
};

// start pd process
Port.prototype.spawn = function(){
	if (this.options.debug) console.log(this.options.pd, this.parseFlags(this.options.flags));
	if (!this.options.pd) return this;
	var child = this.child = spawn(this.options.pd, this.parseFlags(this.options.flags));
	if (!!this.options.encoding) child.stderr.setEncoding(this.options.encoding);
	child.on('exit', this.emit.bind(this, 'exit'));
	child.stderr.on('data', this.emit.bind(this, 'stderr'));
	return this;
};

Port.prototype.isRunning = function(){
	return (!!this.child && !this.child.killed && !!this.sender && this.sender.writable) || false;
};

// on [netsend] connection
function connection(socket){
	this.socket = socket;
	if (!!this.options.encoding) socket.setEncoding(this.options.encoding);
	socket.on('data', this.emit.bind(this, 'data'));
	this.emit('connection', socket);
}

// listen for [netsend]
Port.prototype.listen = function(){
	var receiver = this.receiver = net.createServer();
	if (!!this.options.max) receiver.maxConnections = this.options.max;
	receiver.listen(this.options.read, this.options.host);
	receiver.on('listening', this.emit.bind(this, 'listening'));
	receiver.on('connection', connection.bind(this));
	receiver.on('error', this.emit.bind(this, 'error'));
};

// connect to [netreceive]
Port.prototype.connect = function(){
	var sender = this.sender = new net.Socket();
	if (!!this.options.encoding) sender.setEncoding(this.options.encoding);
	sender.on('connect', this.emit.bind(this, 'connect', sender));
	sender.on('error', this.emit.bind(this, 'error'));
	this.sender.connect(this.options.write, this.options.host);
};

// send data to [netreceive]
Port.prototype.write = function(data){
	if (data != null) this.sender.write(data);
	return this;
};

// start Port
Port.prototype.create = function(){
	process.once('exit', this.destroy);
	if (!!this.options.write) this.on('connection', this.connect);
	if (!this.options.read) return this.spawn();
	this.on('listening', this.spawn);
	this.listen();
	return this;
};

// stop Port
Port.prototype.destroy = function(){
	process.removeListener('exit', this.destroy);
	this.removeAllListeners('listening');
	this.removeAllListeners('connection');
	if (!!this.sender){
		this.sender.destroy();
		this.sender.removeAllListeners('connect');
		this.sender.removeAllListeners('error');
		delete this.sender;
	}
	if (!!this.receiver){
		this.receiver.close();
		this.receiver.removeAllListeners('listening');
		this.receiver.removeAllListeners('connection');
		this.receiver.removeAllListeners('error');
		delete this.receiver;
	}
	if (!!this.socket) this.socket.destroy();

	if (!!this.child){
		this.child.stderr.removeAllListeners('data');
		this.child.kill();
	}
	this.emit('destroy');
	return this;
};


module.exports = Port;