/*  THE FOLLOWING TWO FUNCTIONS CHECK THAT ALL NUMERIC VALUES ARE REAL NUMBER AND REMOVE DOUBLE DECIMALS */
function doSum(a){ 
   a.value = check(a.value);
}
function check(a) 
{
   var pest = 0;
   var b = "";
   for(i=0;i<=a.length;i++)
   {
   var u = a.charAt(i);
      if((u>="0"&&u<="9")||u==".")
      {
      	if(u=="."){
      	var pest = pest+1
      	if(pest==2){break;}}
var b = b + u;    	}}
return b;
}

/* FUNCTION CONFIRMS THAT THE VALUE ENTERED INTO A FIELD FALLS WITHIN THE PRE-DETERMINED MINIMUM AND MAXIMUM VALUES */
function checkNumber(quest,input, min, max, msg)
{

    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;
        }
    }
    if(input.value!="")
    {
    var num = 0 + str
    if (num < min || max < num) {
 var sendn = "Question " + quest + ": ("+ msg + ")";
    var sendq = "You have entered " + input.value + ". Please enter a number between " + min + " and " + max + ".";
  fixpro(sendn,sendq);

        return false;
    }
    input.value = str;
    return true;
	}
	

}


/* CALLS UPON THE FUNCTIONS TO DETERMINE IF THE NUMBERS ENTERED ARE VALID AND TO CALCULATE THE RESULTS OF THE ENTERED DATA */
function computeField(quest,input,min,max,msage)
{
doSum(input); 
checkNumber(quest,input,min,max,msage);     
}        

/* ROUNDS OFF MONETARY NUMBERS TO TWO DECIMALS (PENNIES) */
function roundPen(n)
{
if(n > 0){
pennies = n*100;
pennies = Math.round(pennies);
strPennies = "" + pennies;
len = strPennies.length;

return strPennies.substring(0, len - 2) + "." + strPennies.substring(len -2, len);
}
else return 0;
}

/* CALCULATES VALUES DISPLAYED WHEN COMPUTE IS CLICKED. FIRST CHECKS THAT THERE ARE VALUES IN ALL OF THE FIELDS. THE RESULTS ARE SENT TO THE TEXT BOXES - MAXIMUM MORTGAGE AND MONTHLY PAYMENT */

function getMaxPayment(){

if((document.calculator.totinc.value == null || document.calculator.totinc.value.length == 0)|| (document.calculator.totinc.value < 10000 || document.calculator.totinc.value > 1000000)){
fixpro('Question 1: (Annual Family Income)','Please enter a number between 10000 and 1000000.');return;}


if((document.calculator.protax.value == null || document.calculator.protax.value.length == 0)|| (document.calculator.protax.value < 100 || document.calculator.protax.value > 50000)){
fixpro('Question 2: (Annual Property Taxes)','Please enter a number between 100 and 50000.');return;}

if((document.calculator.proheat.value == null || document.calculator.proheat.value.length == 0)|| (document.calculator.proheat.value < 20 || document.calculator.proheat.value > 1500)){
fixpro('Question 3: (Monthly Heating Costs/Condo Fees)','Please enter a number between 20 and 1500.');return;}

if((document.calculator.debt.value == null || document.calculator.debt.value.length == 0)|| (document.calculator.debt.value < 0 || document.calculator.debt.value > 5000)){
fixpro('Question 4: (Monthly Debt Payments)','Please enter a number between 0 and 5000.');return;}

if((document.calculator.second.value == null || document.calculator.second.value.length == 0)|| (document.calculator.second.value < 0 || document.calculator.second.value > 5000)){
fixpro('Question 5: (Secondary Financing Payment)','Please enter a number between 0 and 5000.');return;}

if((document.calculator.rate.value == null || document.calculator.rate.value.length == 0)|| (document.calculator.rate.value < 2 || document.calculator.rate.value > 25)){
fixpro('Question 6: (Interest Rate)','Please enter a number between 2.0 and 25.0.');return;}


var RATE = document.calculator.rate.value/100;
var income = document.calculator.totinc.value;
var tax = document.calculator.protax.value;
var heat = document.calculator.proheat.value*12;
var debt = document.calculator.debt.value*12;
var second = document.calculator.second.value*12;
var compound = 2/12;
var monTime = 25 * 12;
var yrRate = RATE/2;
var rdefine    = Math.pow((1.0 + yrRate),compound)-1.0;
var purchcompound = Math.pow((1.0 + rdefine),monTime);


var maxgdsr =.32;
var maxtdsr =.42;


var GDSPAY = (maxgdsr*income) - tax - heat - second;
var TDSPAY = (maxtdsr*income) - tax - heat - second - debt;

var PAYMENT = (GDSPAY<TDSPAY) ? GDSPAY/12 : TDSPAY/12;
var MORTGAGE = (0 +((PAYMENT*(purchcompound-1.0))/rdefine))/purchcompound;


document.calculator.amt.value = '$'+roundPen(MORTGAGE);
document.calculator.pay.value = '$'+roundPen(PAYMENT);
return;
}

/* TESTS VERSIONS FOR WHICH WILL SUPPORT POP UP WINDOWS */
function versTest()
{
var one = '';
var two = '';

if (
(navigator.appName.substring(0,8)=="Netscape" && (navigator.appVersion.substring(0,3) == "3.0" ||  navigator.appVersion.substring(0,3) =="4.0")))
{var one='true';}
if(
 (navigator.appName.substring(0,9) == "Microsoft" && navigator.appVersion.substring(0,3) == "3.0" && navigator.appVersion.indexOf("Macintosh")>=0))
{var two='true';}

if(one=='true' || two=='true' ||
(navigator.appName.substring(0,9) == "Microsoft" && navigator.appVersion.indexOf("MSIE 3.0")>=0 && 
navigator.appVersion.indexOf("Windows 3.1")>=0)
)
{return true;}
else
{return false;}


}

/* TESTS IF VERSION IS MSIE 3.0 FOR MAC */
function msTest()
{
if(navigator.appName.substring(0,9) == "Microsoft" && 		(navigator.appVersion.substring(0,3) == "3.0" && navigator.appVersion.indexOf("Macintosh")>=0))
{return true;}
else
{return false;}

}


function nineTest()
{
if(navigator.appName.substring(0,9) == "Microsoft" && (navigator.appVersion.substring(0,3)=="3.0" || navigator.appVersion.indexOf("MSIE 3.0")>=0) && (navigator.appVersion.indexOf("Macintosh")==-1 || navigator.appVersion.indexOf("Windows 3.1")== -1)
)
{return true;}
else
{return false;}
}


/* OPENS WINDOW FOR PRESENCE & DATA VALIDATION */
 function fixpro(n,q)
{
	if(versTest() == true){
		if(msTest()==true){
			var winNam='';
		}
		else{
			var slash = location.href.lastIndexOf("/")+1;
			var filNam = location.href.substring(0,slash);
			var winNam = filNam+'maxem.html';
		}
fix = window.open(winNam,'FIX','toolbar=no,location=no,directories=no,status=no,scrollbars=yes,resizable=no,copyhistory=no,width=300,height=100,outerWidth=350,outerHeight=150');
		if(navigator.appName.substring(0,8) == "Netscape"){
			fix.focus();
		}
fix.document.write('<html><head><title>OME</title>');
fix.document.write('</head><body bgcolor=ffffff><form name=fixer>');
fix.document.write('<font size=2 face="Arial, Helvetica" color=306798>'+n+'</font><p><font size=2 face="Arial, Helvetica">'+q+'<p>');
fix.document.write('<center><input type=button value=OK onClick=self.close()>');
fix.document.write('</center></form></body></html>');
fix.document.close();

	}
	else{
		alert(n+'\n'+q);
	}
}

/* OPENS POP UP WINDOW TO DISPLAY HELP MESSAGES IN NETSCAPE 3.0 AND 4.0 */
function winopen(name)
{
var linkit = "help/"+name;
if(versTest() == true || nineTest()==true){	
maxMo=window.open(linkit,'helpscreen','toolbar=no,location=no,directories=no,status=no,scrollbars=yes,resizable=no,copyhistory=no,width=250,height=180,outerWidth=300,outerHeight=230');
if(navigator.appName.substring(0,8) == "Netscape")
{maxMo.focus();}
}

else{location.href=linkit;}

}


function StringArray(n)
{
this.length = n;
for (var i = 1; i <= n; i++)
this[i] = '' 
return this
}


maxtitle = new StringArray(9);
maxtitle['A'] = 'Total Annual Income';
maxtitle['B'] = 'Annual Property Taxes';
maxtitle['C'] = 'Monthly Heating Costs';
maxtitle['D'] = 'Other Monthly Debt Payments';
maxtitle['E'] = 'Mortgage Term';
maxtitle['F'] = 'Interest Rate';
maxtitle['G'] = 'Special Circumstances';
maxtitle['H'] = 'Second Mortgage Payments';
maxtitle['I'] = 'Maintenance Fees';



function browTest()
{
if((navigator.appVersion.substring(0,3) == 3.0 || navigator.appVersion.substring(0,3) == 4.0)&& navigator.appName.substring(0,8)=="Netscape"){
	return true;
}
else{
	return false;
}
}

function makeImg()
{
if(browTest()==true){
Img = new Image();
Img.src = "graphics/back_on.gif"; 
document.images.Back_button.src=Img.src;
}
else{}
} 

function clearImg()
{
if(browTest()==true){
OrImg= new Image();
OrImg.src="graphics/back_off.gif";
document.images.Back_button.src=OrImg.src;
}
else{}
}

function loadImg()
{
if(browTest()==true){
Img = new Image();
Img.src = "graphics/back_on.gif"
}
else{}
}