document.observe('dom:loaded', function(){
		$$('.cart input.quantity').each( function(inputEl){
				inputEl.observe('keyup', editQuantity);
			});
	});

function editQuantity(){
	var id = getProductId(this);
	new Ajax.Request('/kosik/pridat/'+id+'/'+this.value, {
		method: 'get',
		onSuccess: function(response){
				var quantity = response.responseText;
				// $('quantity_'+id).value = quantity;
				$('total_price_'+id).update(quantity * $('price_'+id).innerHTML);
				updateTotalCartPrice();
			},
		onFailure: err
	});

}

function updateTotalCartPrice(){
	var totalCartPrice = 0;
	$$('.cart input.quantity').each( function(inputEl){
			totalCartPrice += parseInt(
				$('total_price_'+getProductId(inputEl)).innerHTML );
		});
	$('total_cart_price').update(totalCartPrice);
}

function err(t) {
	alert('Error ' + t.status + ' -- ' + t.statusText);
}

function getProductId(inputEl){
	return inputEl.id.substr(inputEl.id.lastIndexOf('_') + 1);
}