/* Copyright Grovelawn 2005-2010 */
var mcalc={};
var Calculators=function( frm )
{
	/* Defaults */
	var	stamp_duty_normal		= [ 125000, 0.01, 250000, 0.03, 500000, 0.04 ],
		stamp_duty_disadvantaged	= [ 150000, 0.01, 250000, 0.03, 500000, 0.04 ],
		borrow_single_min = 350,	borrow_joint_min = 275,		borrow_ltv = 90,
		borrow_single_max = 500,	borrow_joint_max = 450,		borrow_bonus_ratio = 100,
		buy_to_let_pay_rate_pc = 125,	buy_to_let_interest_rate_pc = 5.35,
		buy_to_let_maximum_ltv = 75,
		early_repayment_charge = 1750;

	/* Helpers */
	function getInt(n)	{ var x = frm[n].value; return Math.round( x.replace( /[^0-9.]/g, '' )-0 ); }
	function getNum(n)	{ var x = frm[n].value; return x.replace( /[^0-9.]/g, '' )-0.0; }
	function getTxt(n)	{ return ( frm[n].selectedIndex ? frm[n].options[ frm[n].selectedIndex ].value : frm[n].value ); }
	function setInt(n,i)	{ if( frm && frm[n] ) { frm[n].value = Math.round(i-0); } }
	function setMny(n,i)	{ if( frm && frm[n] ) { frm[n].value = Math.round((i-0)*100)/100; } }
	function setNum(n,i)	{ if( frm && frm[n] ) { frm[n].value = i-0.0; } }
	function setTxt(n,t)	{ if( frm && frm[n] ) { frm[n].value = t; } }
	function getChk(n)	{ if( frm && frm[n] ) { return frm[n].checked ? true : false; } return false; }
	function getRepay( price, rate, term )
	{
		var n, r=rate/12.0, t=term*12, tp=1;
		for( n=0; n<t; ++n ) tp *= ( 1+(r/100) );
		return ( price*r/100 ) / ( 1-(1/tp) );
	}
	function getInterest( price, rate, term )
	{
		var r=rate/12.0, t=term*12;
		return ( price*r/100 );
	}

	/* Calculators */
	this.stampDuty = function ()
	{
		var n, r=0.0, v=getInt( 'price' ), a=( frm.disadv[0].checked ? stamp_duty_disadvantaged : stamp_duty_normal );
		for( n=0; n<a.length; n+=2 ) if( a[n]<v ) r=a[n+1]; else break;
		setInt( 'total', v*r );
		setTxt( 'tell', 'Stamp Duty on a £' + v + ' property would be approx £' + Math.round(v*r) );
	};
	this.mortgageRepayment = function ()
	{
		var n, p=getInt( 'price' ), r=getNum( 'rate' ), t=getInt( 'term' );
		var p1=getRepay( p,r,t ), i1=getInterest( p,r,t ), p2=getRepay( p,r+1,t ), i2=getInterest( p,r+1,t );
		setMny( 'month', p1 );		setMny( 'monthp1', p2 );
		setMny( 'intrs', i1 );		setMny( 'intrsp1', i2 );
		setMny( 'total', t*p1*12 );	setMny( 'totalp1', t*p2*12 );
		setTxt( 'tell', 'Mortgage repayment on a £' + p + ' loan over ' + t + ' years at ' + r + '% would be £' + p1 + ' pcm (£' + t*p1*12 + ' total) or £' + i1 + ' pcm (£' + t*i1*12 + ' total)' );
	};
	this.remortgageRepayment = function ()
	{
		var n, p=getInt( 'price' ), r=getNum( 'rate' ), t=getInt( 'term' )*12;
		var np=getNum( 'nprice' ), nr=getNum( 'nrate' ), nt=getInt( 'nterm' )*12;
		var p1=getRepay( p,r,t/12 ), p2=getRepay( p,r+1,t/12 ), p1n=getRepay( np,nr,nt/12 ), p2n=getRepay( np,nr+1,nt/12 );
		var s1=t*p1-nt*p1n, s2=t*p2-nt*p2n, s1y=(t<24?t:24)*p1-(nt<24?nt:24)*p1n, s2y=(t<24?t:24)*p2-(nt<24?nt:24)*p2n;
		setMny( 'month', p1 );		setMny( 'monthp1', p2 );
		setMny( 'nmonth', p1n );		setMny( 'nmonthp1', p2n );
		setTxt( 'saves', ( 0<=s1 ? Math.round(s1) + ' saving' : (0-Math.round(s1)) + ' more' ) );
		setTxt( 'save2', ( 0<=s1y ? Math.round(s1y) + ' saving' : (0-Math.round(s1y)) + ' more' ) );
		setTxt( 'savesp1', ( 0<=s2 ? Math.round(s1) + ' saving' : (0-Math.round(s2)) + ' more' ) );
		setTxt( 'save2p1', ( 0<=s2y ? Math.round(s1y) + ' saving' : (0-Math.round(s2y)) + ' more' ) );
		setTxt( 'tell', 'By remortgaging there would be ' + ( 0<=s1 ? ' a £' + Math.round(s1) + ' saving' : ' £' + (0-Math.round(s1)) + ' more' ) + ' when changing the term to ' + t + ' years at ' + r + '%' );
	};
	this.howMuchBorrow = function ()
	{
		var m=getInt( 'maxltv' ), p=getInt( 'property' );
		var i1=getInt( 'incomem' ), i2=getInt( 'incomep' ), b1=getInt( 'bonusm' ), b2=getInt( 'bonusp' );
		var xx=getNum( 'mulbonus' ), xj=getNum( 'muljoint' ), xb=getNum( 'mulbest' );
		var d, a=xj*( i1+i2+xx*(b1+b2) ), am=xb*( i1+xx*b1 ), ap=xb*( i2+xx*b2 );
		d = ( ( p-( a = Math.max( a, Math.max( am, ap ) ) ) )/100 + 1 ) * 100;
		setInt( 'deposit', d>0 ? d:'none (' + d + ')' );
		setInt( 'borrow', Math.min( a, p ) );
		setTxt( 'tell', 'A mortgage of upto £' + Math.min( a, p ) + ' with a typical deposit of around £' +
			(d>0?d:0) + ' should be availiable for your wages (subject to terms and conditions)' );
	};
	this.howMuchBorrow2 = function ()
	{
		var i1=getInt('income1')+getInt('bonus1')*borrow_bonus_ratio/100, i2=getInt('income2')+getInt('bonus2')*borrow_bonus_ratio/100;
		setInt( 'borrow', Math.floor( ( frm.joint.checked ? (i1+i2)*borrow_joint_min : i1*borrow_single_min )*borrow_ltv/10000 ) );
		setInt( 'borrowmax', Math.floor( ( frm.joint.checked ? (i1+i2)*borrow_joint_max : i1*borrow_single_max )*borrow_ltv/10000 ) );
	};
	this.howMuchBorrowBTL = function ()
	{
		var p=getInt( 'property' ), r=getNum( 'rent' );
		var ml=p*buy_to_let_maximum_ltv/100, mx=(r*12/(buy_to_let_pay_rate_pc/100.0))/(buy_to_let_interest_rate_pc/100.0);
		setInt( 'maxloan', Math.floor( mx<ml?mx:ml ) );
	};
	this.requiredRentalBTL = function ()
	{
		var b=getInt( 'property' )-getInt( 'deposit' );
		setInt( 'rent', Math.ceil( ((b*(buy_to_let_interest_rate_pc/100.0))/12.0) * (buy_to_let_pay_rate_pc/100.0) ) );
	};
	this.requiredRate = function ()
	{
		var l=getInt( 'loan' ), r=getNum( 'rate' ), t=getInt( 'term' ), p=getNum( 'penalty' );
		if( 'p'==getTxt( 'type' ) ) { p=l*(p/100); }
		setNum( 'nofee', getChk( 'addv' ) ? ((l*r/100*(t/12))-p) / (((t/12)/100)*(l+p)) : r-((p/l)*1200)/t );
		setNum( 'payfee', getChk( 'addv' ) ? ((l*r/100*(t/12))-p-early_repayment_charge) / (((t/12)/100)*(l+p)) : r-((((early_repayment_charge*100)/l)+(p/l)*100)*12)/t );
	};
};
function checkNumber(num) { var n = num.value.replace( /[, ]/g, '' ); if( isNaN( n - 0 ) ) { num.value = num.value.replace( /[^0-9]/g, '' ); } }
window.onload = function() { var n, x; for( n=0; n<document.forms.length; ++n ) if( document.forms[n].className = 'calculator' ) mcalc = new Calculators( document.forms[n] ); if( !!( x = document.getElementById('apr') ) ) x.innerHTML = '4.50%'; return true; };