// Copyright 2008 Christian Davén

function clearMessages()
{
	document.getElementById("resultsp").style.display = "none";
	
	document.getElementById("msg_payments").firstChild.nodeValue = "";
	document.getElementById("msg_rent").firstChild.nodeValue = "";
	document.getElementById("msg_years").firstChild.nodeValue = "";
	document.getElementById("msg_interest").firstChild.nodeValue = "";
}

function calculate()
{
	var ok = 1;

	clearMessages();

	var payments = getAndParseString("payments", true);
	if(interest == -999) ok = 0;
	var rent = getAndParseString("rent", true);
	if(rent == -999) ok = 0;
	var years = getAndParseString("years", true);
	if(years == -999) ok = 0;
	var interest = getAndParseString("interest", true);
	if(interest == -999) ok = 0;

	if(!ok) return;

	interest = 1 + interest / (1200.0);
	var months = years * 12.0;
	payments -= rent;
	
	var maxLoan = payments * (Math.pow(interest, months) - 1) / (Math.pow(interest, months) * (interest - 1));

	if(maxLoan == Infinity || maxLoan > 999999999999999999999)
		showResults("Beloppet blir för stort");
	else if(isNaN(maxLoan))
		showResults("Kunde inte räkna ut resultatet");
	else if(maxLoan <= 0)
		showResults("Du har inte råd att låna något alls");
	else
		showResults("Du har råd att låna " + FormatNumberBy3(maxLoan.toFixed(0), ".", " ") + " kr");
}