$(function() {
	var first_run = true;
	
	$(".no_js").addClass("hidden");			// Hide the "you need JavaScript" paragraph
	$("#mortgage_calculator").addClass("enabled");				// Display the mortgage assessor div
	
	// Set the submit handler
	$("#mortgage_calculator > form").submit(function(evt) {
		var mortgage, duration, rate, pattern;
		var mortgage_repayment, mortgage_interest, eight_repayment, eight_interest;
		
		mortgage = $("#mortgage")[0].value;
		duration = $("#duration")[0].value;
		rate = $("#rate")[0].value;
		pattern = /^\d*\.{0,1}\d+$/;
		
		if ((!pattern.test(mortgage)) || (!pattern.test(duration)) || (!pattern.test(rate))) {
			alert("Please enter valid amounts.");
		} else {
			rate /= 100;	
			monthly_repayment = ((mortgage * rate) / 12) * (1 / (1 - (Math.pow(1 / (1 + rate), duration))));
			monthly_interest = (mortgage * rate) / 12;
			
			// Repayment at 8%
			eight_repayment = ((mortgage * 0.08) / 12) * (1 / (1 - (Math.pow((1 / 1.08), duration))));
			eight_interest = (mortgage * 0.08) / 12;
			
			// Need to create the elements
			if (first_run) {
				$("#mortgage_calculator").append(document.createElement("dl"));
				$("#mortgage_calculator dl").append($(document.createElement("dt")).append("Monthly capital repayment")).append(document.createElement("dd"));
				$("#mortgage_calculator dl").append($(document.createElement("dt")).append("Monthly interest repayment")).append(document.createElement("dd"));
				$("#mortgage_calculator dl").append($(document.createElement("dt")).append("Monthly capital repayment at 8%")).append(document.createElement("dd"));
				$("#mortgage_calculator dl").append($(document.createElement("dt")).append("Monthly interest repayment at 8%")).append(document.createElement("dd"));
			} // if
			
			// Display the results
			$("#mortgage_calculator dl dd:nth-child(2)").empty().append(formatAsCurrency(monthly_repayment));
			$("#mortgage_calculator dl dd:nth-child(4)").empty().append(formatAsCurrency(monthly_interest));
			$("#mortgage_calculator dl dd:nth-child(6)").empty().append(formatAsCurrency(eight_repayment));
			$("#mortgage_calculator dl dd:nth-child(8)").empty().append(formatAsCurrency(eight_interest));
			
			if (first_run) {first_run = false; $("#mortgage_calculator dl").slideDown("medium");}
		} // if - else
		
		evt.preventDefault();
	}); // submit handler	
});