function Messaging() {
	var ws = new WebSocket('ws://' + window.location.hostname + '/play/');
	var keepAlivePeriod = 20000;
	var receiveHook;
	var queue = []
	ws.addEventListener('message', messageListener);

	return {
		receive: receive,
		send: send
	}

	function messageListener(event) {
		var o = JSON.parse(event.data);
		if(o.tag == "Error") {
			console.log(o.error);
		} else {
			if(receiveHook != undefined) {
				receiveHook(o);
			} else {
				queue.push(o);
			}
		}
	};

	function receive(predicate) {
		predicate = predicate || function() {return true;};
		return function(f) {
			for(var i = 0; i < queue.length; i++) {
				if(predicate(queue[i])) {
					return f(queue.splice(i, 1)[0]);
				}
			}
			receiveHook = function(message) {
				if(predicate(message)) {
					receiveHook = null;
					f(message);
				} else {
					queue.push(o);
				}
			}
		};
	}

	function send(o) {
		ws.send(JSON.stringify(o));
	}

	function ping() {
		setTimeout(function() {send({tag: "Ping"});}, keepAlivePeriod);
	}
}