var startingTime;
var totalTimeout; //In milliseconds.
var timeoutElem;

function startTimer(objId, timeout){
	obj = document.getElementById(objId);
	if(obj != null){
		totalTimeout = timeout / 1000;
		timeoutElem = obj;
		startingTime = new Date();
		refreshTimeout();
	}
}

function refreshTimeout(){
	if(timeoutElem){
		timeoutAux = totalTimeout - parseInt((new Date() - startingTime) / 1000);

		if(timeoutAux <= 0){
			timeoutElem.innerHTML = '<span style="color: #ff0000; font-weight: bold;">00:00</span>';
		} else {
			var minutes = parseInt((timeoutAux - timeoutAux % 60) / 60);

			if(minutes < 10)
				minutes = "0" + minutes;

			var seconds = parseInt(timeoutAux % 60);
			if(seconds < 10)
				seconds = "0" + seconds;

			var time = minutes + ":" + seconds;

			if (minutes < 5)
				timeoutElem.innerHTML = '<span style="color: #ff0000; font-weight: bold;">' + time + "</span>";
			else
				timeoutElem.innerHTML = time;
		}

		//Even if it has finished, we call it again, in case the session is renewed.
		setTimeout("refreshTimeout();", 1000);
	}
}