//*******************************************
//DO NOT REMOVE THIS COPYWRITE INFO!
//Mortgage Balance Calculator
//2008 Daniel C. Peterson ALL RIGHTS RESERVED
//Created: 02/08/2008
//Last Modified: 02/08/2008
//This script may not be copied, edited, distributed or reproduced
//without express written permission from
//Daniel C. Peterson of Web Winder Website Services
//For commercial use rates, contact:
//Dan Peterson:
//Web Winder Website Services
//P.O. Box 11
//Bemidji, MN  56619
//dan@webwinder.com
//http://www.webwinder.com
//Commercial User Licence #:5782-1237-155-1198
//Commercial Licence Date:2008-09-11
//*******************************************



function stripNum(num) {

   num=num.toString();


   var len = num.length;
   var rnum = "";
   var test = "";
   var j = 0;

   var b = num.substring(0,1);
   if(b == "-") {
      rnum = "-";
   }

   for(i = 0; i <= len; i++) {

      b = num.substring(i,i+1);

      if(b == "0" || b == "1" || b == "2" || b == "3" || b == "4" || b == "5" || b == "6" || b == "7" || b == "8" || b == "9" || b == ".") {
         rnum = rnum + "" + b;

      }

   }

   if(rnum == "" || rnum == "-") {
      rnum = 0;
   }

   rnum = Number(rnum);

   return rnum;

}



function formatNumberDec(num, places, comma) {

var isNeg=0;

    if(num < 0) {
       num=num*-1;
       isNeg=1;
    }

    var myDecFact = 1;
    var myPlaces = 0;
    var myZeros = "";
    while(myPlaces < places) {
       myDecFact = myDecFact * 10;
       myPlaces = eval(myPlaces) + eval(1);
       myZeros = myZeros + "0";
    }
    
	onum=Math.round(num*myDecFact)/myDecFact;
		
	integer=Math.floor(onum);

	if (Math.ceil(onum) == integer) {
		decimal=myZeros;
	} else{
		decimal=Math.round((onum-integer)* myDecFact)
	}
	decimal=decimal.toString();
	if (decimal.length<places) {
        fillZeroes = places - decimal.length;
	   for (z=0;z<fillZeroes;z++) {
        decimal="0"+decimal;
        }
     }

   if(places > 0) {
      decimal = "." + decimal;
   }

   if(comma == 1) {
	integer=integer.toString();
	var tmpnum="";
	var tmpinteger="";
	var y=0;

	for (x=integer.length;x>0;x--) {
		tmpnum=tmpnum+integer.charAt(x-1);
		y=y+1;
		if (y==3 & x>1) {
			tmpnum=tmpnum+",";
			y=0;
		}
	}

	for (x=tmpnum.length;x>0;x--) {
		tmpinteger=tmpinteger+tmpnum.charAt(x-1);
	}


	finNum=tmpinteger+""+decimal;
   } else {
      finNum=integer+""+decimal;
   }

    if(isNeg == 1) {
       finNum = "-" + finNum;
    }

	return finNum;
}



function calc_balance(form) {

      if(form.principal.value == 0 || form.principal.value == "") {
         alert("Please enter the original mortgage amount.");
         form.principal.focus();
      } else
      if(form.interest.value == 0 || form.interest.value == "") {
         alert("Please enter the mortgage's annual interest rate.");
         form.interest.focus();
      } else
      if(form.years.value == 0 || form.years.value == "") {
         alert("Please enter the mortgage's repayment term in number of years.");
         form.years.focus();
      } else
      if(form.payment.value == 0 || form.payment.value == "") {
         alert("Please enter the mortgage's monthly payment amount.");
         form.payment.focus();
      } else
      if(form.monthStart.selectedIndex == 0 && form.pmtsMade.value == "" && form.pmtsLeft.value == "") {
         alert("Please either choose a first payment month and enter a year, or enter the number of payments made, or enter the number of payments remaining.");
         form.monthStart.focus();
      } else
      if(form.monthStart.selectedIndex > 0 && (form.yearStart.value == "" || form.yearStart.value.length < 4)) {
         alert("Please enter the 4-digit year the mortgage was originated.");
         form.yearStart.focus();
      } else {

         var v_principal = stripNum(form.principal.value);
         var v_interest = stripNum(form.interest.value);
         var v_payment = stripNum(form.payment.value);
         var v_years = stripNum(form.years.value);
         var v_npr = v_years * 12;
         var v_pmts_made_in = stripNum(form.pmtsMade.value);
         var v_pmts_left = stripNum(form.pmtsLeft.value);
         var v_start_month = form.monthStart.selectedIndex;
         var v_start_year = stripNum(form.yearStart.value);

         var apr = v_interest;
         if(apr >= 1) {
            apr /= 100;
         }
         apr /= 12;

         var chk_pmt_int = v_principal * apr;


         if(chk_pmt_int > v_payment) {
            alert("The mortgage terms you entered are not valid. Please either lower the principal, lower the interest rate, or increase the payment amount, or a combination of all three.");
            form.principal.focus();
         } else {

            var v_pmts_made = 0;

            if(form.monthStart.selectedIndex > 0) {
               var now = new Date();
               var now_month = eval(now.getMonth()) + eval(1);
               var now_year = now.getFullYear();

               var tot_now_months = eval(now_year * 12) + eval(now_month);
               var tot_start_months = eval(v_start_year * 12) + eval(v_start_month);
               var v_pmts_made = eval(tot_now_months) - eval(tot_start_months);
            } else
            if(v_pmts_made_in > 0) {
               v_pmts_made = v_pmts_made_in;
            } else {
               v_pmts_made = eval(v_npr) - eval(v_pmts_left);
            }


            var prin = v_principal;
            var int_port = 0;
            var prin_port = 0;
            
            for(var i=0; i<v_pmts_made; i++) {
               int_port = Math.round(prin * apr * 100) / 100;
               prin_port = eval(v_payment) - eval(int_port);
               prin = eval(prin) - eval(prin_port);
            }

            form.num_pmts_made.value = v_pmts_made;
            form.balance.value = "$" + formatNumberDec(prin,2,1);

      }



   }
}


function clear_results(form) {

   form.num_pmts_made.value = "";
   form.balance.value = "";

}