// (c) 2006 conscious.co.uk

function calcmillionaire() {
// Calculates how long it will take to become a millionaire on current salary

   var formnames = new Array("startingbalance", "monthlydeposit", "avginterestrate", "avginflationrate", "amountdesired");
   var formdisplayednames = new Array("Starting Balance", "Monthly Deposit", "Average Annual Interest Rate", "Average Annual Inflation Rate", "Final Amount Desired");
   var formvals = new Array();
   var outnames = new Array("goalreachedin", "amounttodaysmoney");
   var outvals = new Array();


   // get form values      
   for (i=0; i<formnames.length; i++)
      for (j=0,m=document.millionaireform.elements.length;j<m;j++)
         if (document.millionaireform.elements[j].name == formnames[i])
            formvals[formnames[i]] = document.millionaireform.elements[j].value;

   // Error checking
   var isvalidnum = true;
   for (j=0; j<formnames.length; j++) {
      formvals[formnames[j]] = formvals[formnames[j]].replace("£", "");
      for (i=0; i<formvals[formnames[j]].length; i++) {
         if ((formvals[formnames[j]].charAt(i) != "0")
         && (formvals[formnames[j]].charAt(i) != ".")
         && (!parseFloat(formvals[formnames[j]].charAt(i)))) {
            isvalidnum = false;
            alert("Please enter a valid number in the "+formdisplayednames[j]+" field");
            break;

      }
   }
   }
   
   if (isvalidnum) {
      
      for (i=0; i<formnames.length; i++) {
         
         if ((i== 1) || (i == 2)) formvals[formnames[i]] = parseFloat(formvals[formnames[i]]);
         else formvals[formnames[i]] = parseInt(formvals[formnames[i]]);
         
      }
      
      
      formvals['avginterestrate'] = (formvals['avginterestrate'] / 100);  // for rounding purposes
      formvals['avginflationrate'] = (formvals['avginflationrate'] / 100); // for rounding purposes
      var tempvalA = (formvals['avginterestrate'] / 12); // interest rate per month
      var tempvalB = (formvals['monthlydeposit'] / tempvalA); // monthly interest rate on deposits
      var tempvalC = (formvals['amountdesired'] + tempvalB) / (formvals['startingbalance'] + tempvalB);  // not on one line due to JavaScript and rounding
      var tempvalD = ((Math.log(tempvalC)) / (Math.log(1+tempvalA)));  // number of months to achieve the goal
      outvals['goalreachedin'] = (tempvalD/12);  // converts from months to years
      outvals['amounttodaysmoney'] = (formvals['amountdesired'] / ( Math.pow((1+formvals['avginflationrate']),outvals['goalreachedin'])));  // converts to todays value given approximate inflation over the period
      outvals['goalreachedin'] = (Math.round(outvals['goalreachedin']*10)/10);  // rounded to one decimal place.
        for (i=0; i<outnames.length; i++) if (!parseFloat(outvals[outnames[i]])) outvals[outnames[i]] = 0;

      outvals[outnames[1]] = poundsandpence(outvals[outnames[1]], false, true);	
	
   // output values
   for (i=0; i<outnames.length; i++)
      for (j=0,m=document.millionaireform.elements.length;j<m;j++)
         if (document.millionaireform.elements[j].name == outnames[i])
            document.millionaireform.elements[j].value = outvals[outnames[i]];	
   }
}



function poundsandpence(numnotrounded, returnasfloat, isthousands) {
// makes number conform to pounds and 2 decimal (pence) digits, with options of commas denoting thousands
var decbit = (numnotrounded.toString()).split(".");

if (!decbit[1]) var decpart = "00";
else if ((decbit[1].length) == 1) var decpart = decbit[1]+"0";
else if ((decbit[1].length) == 2) var decpart = decbit[1];
else {
// Varies to get right result - check
   var tempbit = (Math.round((decbit[0]+decbit[1].substring(0,2))+"."+(decbit[1].substring(2)))).toString();
   var decpart = tempbit.substring((tempbit.length-2));
   decbit[0] = tempbit.substring(0, (tempbit.length-2));
//   var decpart = (decbit[1].substring(0, 2));

}

if ((!returnasfloat) && (isthousands) && (decbit[0].length > 3)) {  // add commas for thousands if appropriate
   var afterthousands = "";
   for (tocommas = 0; tocommas < (decbit[0].length / 3); tocommas++) afterthousands = ","+decbit[0].substring((decbit[0].length-((tocommas+1)*3)), (decbit[0].length-(tocommas*3)))+afterthousands;
   afterthousands = afterthousands.substring(1);

}
else afterthousands = decbit[0];

var wholebit = afterthousands+"."+decpart;

if (!returnasfloat) return wholebit;
else return parseFloat(wholebit);
}