var displayed = false;
var slide;
var objInterval;
var interval = 1000;

/*
 * create slider for drop down, and provide reasonable values
 */
function init() {

	slide = new Fx.Slide('calculator', {duration: 280, fps: 30, transition:Fx.Transitions.Sine.easeOut});
	slide.hide();
	slide.addEvent('onStart', function(){
		if (!displayed) { 
			document.getElementById("seesaving").src = "img/seesaving-down.png";
			displayed = true;
		} else {
			displayed = false;
		}
	});

	slide.addEvent('onComplete', function(){
		if (!displayed)
			document.getElementById("seesaving").src = "img/seesaving.png";
	});

	$('toggle').addEvent('click', function(e){
		e = new Event(e);
		slide.toggle();
		e.stop();
	});

//	calculate_savings();
}

/*
 * apply the formula
 */
function calculate_savings() {

	weekly_gas = document.getElementById("gas").value;
	weekly_non_gas = document.getElementById("non_gas").value;

	
	if (!isNaN(weekly_gas) && !isNaN(weekly_non_gas)) {
	

	
		a = weekly_gas * 52 * 0.04;
		
		if (weekly_non_gas * 52 < 5000) 
		b = weekly_non_gas * 52 * 0.005;
		else b =  ((((weekly_non_gas * 52) - 5000) * 0.01)+25);
		
			//c = (((5000 * 0.005+weekly_non_gas * 52) - 5000) * 0.01);
	
		c = 0;
		_rv = ((a + b  + c) > 0) ? (a + b  + c) : 0;
		
		
		
		if (_rv > 600) _rv = 600		
		replaceText("savings", (_rv).toFixed(2));	
	}
}




/*
 * control the user input
 *
 * disallow 16, 65-90, possible numpads 96-105, 106-[110]-111, 186-189, 191-192, 219-222, and multiple dots
 *
 */

function validate(evt, target) {
	if ((evt = (evt) ? evt : (window.event) ? window.event : "")) {
		key = (evt.which) ? evt.which : evt.keyCode;
		
		if (key ==13)
			calculate_savings();
		else if ((key >= 16 && key <= 18) || (key >= 65 && key <= 90) || 
				(key >= 106 && key <= 109) || (key >= 186 && key <= 189) ||
				key == 191 || key == 192 || (key >= 219 && key <= 222) || (key == 111))
			return false;
		else if (key == 190 && target.value.indexOf(".") != -1)
			return false;
	}
	return true;
}


/*
 * Start/stop polling
 * called from blur/focus events
 */
function stopPolling() {
	if (objInterval)
		clearInterval(objInterval);
}

function startPolling() {
	if (objInterval)
		clearInterval(objInterval);
	objInterval = setInterval(calculate_savings, interval);
}

function replaceText(id, value) {
	if ((field=document.getElementById(id))) {
		while(field.firstChild) field.removeChild(field.firstChild);
		field.appendChild(document.createTextNode(value));
	}
}