MortgageCalculator = function()
{
	this.dom = new newsi.HTML.DOM();
	//this.pv = new ProcessValue();
	this._execComputeMortgage();	
}

//MortgageCalculator.prototype = new ProcessValue();

	MortgageCalculator.prototype._execComputeMortgage = function()
	{
		this["calculate"] = new newsi.Event();
		this["calculate"].addListener("onclick","calculateMortgage",this,"checkMortgageBounds","false");
	}
	
	MortgageCalculator.prototype.checkMortgageBounds = function()
	{
		
		this.checkForEmptyFields();
		//this.computeMortgage();
		if ( !mc.checkNumber( document.form1.amount , 1 , 9999999 , "Mortgage required" ) ||
			!mc.checkNumber( document.form1.rate , .001 , 1000 , "Interest rate" ) ||
			!mc.checkNumber( document.form1.period , 3 , 40 , "Repayment period" ) ) 
		{
		
		}
	}
	
	MortgageCalculator.prototype.checkNumber = function( input , min , max , msg ) 
	{
		msg = msg + " has invalid data: " + input.value;
		var str = input.value;
		for ( var i = 0 ; i < str.length ; i++ ) 
		{
			var ch = str.substring( i , i + 1 )
			if ( ( ch < "0" || "9" < ch ) && ch != '.' ) 
			{
				alert(msg);
				return false;
			}
		}
		var number = 0 + str
		if ( number < min || max < number ) {
			alert( msg + " Enter a value in range: " + min + " - " + max );
			return false;
		}
		input.value = str;
		return true;
	}	
	
	MortgageCalculator.prototype.extractMortgageValues = function()
	{
		var mv, 
		mv = document.form1.amount.value;
		mv = mv.split(",");
		mv = mv.join("");
		this.A = parseFloat(mv);
		this.T = document.form1.period.value;
		this.R = document.form1.rate.value;
		document.form1.amount.value = mc.poundsPence( this.A );
	}
	
	MortgageCalculator.prototype.checkForEmptyFields = function()
	{
		this.extractMortgageValues();
		if( this.A == null || this.A.length == 0 || isNaN( this.A ))
		{
		document.form1.amount.value = "";
		document.form1.amount.focus();
		}
		else if( this.T == null || this.T.length == 0 ) 
		{
			document.form1.period.focus();
		}
		else if( this.R == null || this.R.length == 0 )
		{
			document.form1.rate.focus();
		}
		else{
		this.repaymentsCalculations();
		}
	}
	
	MortgageCalculator.prototype.repaymentsCalculations = function()
	{
		R = this.R / 100;
		var P = (((  this.A * R ) / 12 ) * ( 1 / ( 1 - ( Math.pow( 1 / ( 1+R ) , this.T ))))).toFixed(0);
		document.form1.mp.value = mc.poundsPence( P );
		P = (( this.A * R )/ 12 ).toFixed(0)
		document.form1.ei.value = mc.poundsPence( P );
	}

	MortgageCalculator.prototype.poundsPence = function( N ) 
	{
		S = new String( N );
		var i = S.indexOf( '.' );
		if ( i != -1 ) {
			S = S.substr( 0, i+3 );
			if ( S.length-i < 3 )
				S = S + '0';
		}
		return S;
	}