var ss = document.createElement("link");
ss.type = "text/css";
ss.rel = "stylesheet";
ss.href = "http://www.usedcarsza.co.za/scripts/clc-calculator.css";
document.getElementsByTagName("head")[0].appendChild(ss);

function clc_getObj(name) {
   if (document.getElementById) {
		 this.obj = document.getElementById(name);
		 this.style = document.getElementById(name).style;
   } else if (document.all) {
		 this.obj = document.all[name];
		 this.style = document.all[name].style;
   } else if (document.layers) {
		 this.obj = document.layers[name];
		 this.style = document.layers[name];
   }
 }

 function clc_numbersonly(e, decimal) {
   var key;
   var keychar;
   
   if (window.event) {
	  key = window.event.keyCode;
   }
   else if (e) {
	  key = e.which;
   }
   else {
	  return true;
   }
   keychar = String.fromCharCode(key);
   
   if ((key==null) || (key==0) || (key==8) ||  (key==9) || (key==13) || (key==27) ) {
	  return true;
   }
   else if ((("0123456789").indexOf(keychar) > -1)) {
	  return true;
   }
   else if (decimal && (keychar == ".")) { 
	 return true;
   }
   else
	  return false;
}

function clc_calculate() {
  var amountError = new clc_getObj('amount-error');
  amountError.obj.innerHTML = '';
  var interestError = new clc_getObj('interest-error');
  interestError.obj.innerHTML = '';
  var termError = new clc_getObj('term-error');
  termError.obj.innerHTML = '';
  
  var result = new clc_getObj('result');
  result.obj.innerHTML = '';
  
  var amountField = new clc_getObj('amount');
  var interestField = new clc_getObj('interest');
  var termField = new clc_getObj('term');
  var error = false;
  
  var principle = amountField.obj.value;
  var interestRate = interestField.obj.value/100;
  var term = termField.obj.value-(termField.obj.value*2);
  
  if(amountField.obj.value == '' || amountField.obj.value == null || amountField.obj.value == 0) {       
	 amountError.obj.innerHTML = '* Please enter a loan amount';
	 error = true;
  }
  
  if(interestField.obj.value == '' || interestField.obj.value == null || interestField.obj.value == 0) {       
	 interestError.obj.innerHTML = '* Please enter the interest rate';
	 error = true;
  }
  
  if(termField.obj.value == '' || termField.obj.value == null || termField.obj.value == 0) {       
	 termError.obj.innerHTML = '* Please enter the loan term';
	 error = true;
  }
  
  if(error) return;

  var monthlyPayment = (principle*(interestRate/12))/(1-Math.pow((1+(interestRate/12)), term));
  var payment = monthlyPayment.toFixed(2);
  
  var calc = document.createElement("div");
  calc.innerHTML = '<div class="clc-result"><div class="clc-sub-label">Loan Amount:</div><div class="clc-sub-label-value">R'+amountField.obj.value+'</div><div class="clc-sub-label">Interest Rate:</div><div class="clc-sub-label-value">'+interestField.obj.value+'%</div><div class="clc-sub-label">Loan Duration:</div><div class="clc-sub-label-value">'+termField.obj.value+' Months</div><div class="clc-sub-label">Monthly Payment:</div><div class="clc-sub-label-value">R'+payment+'</div><div class="clc-divider"></div></div>';
  result.obj.innerHTML = '';
  result.obj.appendChild(calc);
}