function onRadioButtonClick(button_id)
{
	var medium_id = button_id.substring(6);
	var amplifier_id_input = $('#amplifier_id_' + medium_id);
	var amplifier_id = amplifier_id_input.attr('value');
	
	$('#amplifier_id').attr('value', amplifier_id);
	$('#medium_id').attr('value', medium_id);
	
	updateQuantity();
	updateTotalPrice();
}

function updateQuantity()
{
	var medium_id = $('#medium_id').attr('value');
	var quantity = parseInt($('#quantity_' + medium_id).attr('value'));
	if (isNaN(quantity))
	{
		$('#quantity_' + medium_id).attr('value', '1');
		quantity = 1;
	}
	$('#quantity').attr('value', quantity);
	
	updateTotalPrice();
}

function updateTotalPrice()
{
	var medium_id = $('#medium_id').attr('value');
	var quantity = parseInt($('#quantity').attr('value'));
	var price = parseFloat($('#price_' + medium_id).attr('value'));
	var total_price = (quantity * price).toString();
	var decimal_place_index = total_price.indexOf('.');
	if (decimal_place_index == -1)
		total_price += '.00';
	else if (decimal_place_index == total_price.length - 2)
		total_price += '0';
	$('#price').html('$' + total_price);
	
	var hide_postage = parseInt($('#postage_' + medium_id).attr('value'));
	if (hide_postage)
		$('#postage').addClass('hidden');
	else
		$('#postage').removeClass('hidden');
}

function addToCart()
{
	var amplifier_id = $('#amplifier_id').attr('value');
	var quantity = $('#quantity').attr('value');
	
	var url = 'http://ffd.amplifier.co.nz/addtobasket.do?id=' + amplifier_id + '&quantity=' + quantity;
	var width = 480;
 	var height = 780;

	var features = 'scrollbars = yes,resizable = yes,status = no,location = no,toolbar = no,';
	features = features + 'width = '+ width +',height = ' + height;
	window.open(url, 'purchase', features);
}