// Form Field Validation Functions:
//
// isValidExpDate(formField,fieldLabel,required)
//   -- checks for date in the format MM/YY or MM/YYYY against the current date
// isValidCreditCardNumber(formField,ccType,fieldLabel,required)
//   -- checks for valid credit card format using the Luhn check and known digits about various cards
//

function validRequired(formField,fieldLabel)
{
	var result = true;
	
	if (formField.value == "")
	{
		alert('Please enter a value for the "' + fieldLabel +'" field.');
		formField.focus();
		result = false;
	}
	
	return result;
}


function allDigits(str)
{
	return inValidCharSet(str,"0123456789");
}

function inValidCharSet(str,charset)
{
	var result = true;
	
	for (var i=0;i<str.length;i++)
		if (charset.indexOf(str.substr(i,1))<0)
		{
			result = false;
			break;
		}
	
	return result;
}

function isValidExpDate(formField,fieldLabel,required)
{
	var result = true;
	var formValue = formField;

	//if (required && !validRequired(formField,fieldLabel))
	//	result = false;
  
 	if (result && (formField.length>0))
 	{
		var elems = formValue.split("/");
 		
 		result = (elems.length == 2); // should be two components
 		var expired = false;
 		
 		if (result)
 		{
			var month = parseInt(elems[0],10);
 			var year = parseInt(elems[1],10);
 			
 			//if (elems[1].length == 2)
 			//	year += 2000;
 			
 			var now = new Date();
 			
 			var nowMonth = now.getMonth() + 1;
 			var nowYear = now.getFullYear();
			
 			 if((nowYear >year) || ((nowYear == year ) && (nowMonth>month)))
			 {
			 	expired =true;
			}
			else
			{
				 expired = false; 
			}
 			
			if(allDigits(elems[0]) && (month > 0) && (month < 13) &&
					 allDigits(elems[1]) && ((elems[1].length == 2) || (elems[1].length == 4)))
			{
					 result = true; 
			}
			else
			{
				 result = false; 
			}
 		}
 		
  		if (!result)
 		{
 			alert('Please enter a date in the format MM/YY for the "' + fieldLabel +'" field.');
			//formField.focus();
		}
		else if (expired)
		{
 			result = false;
 			alert('The date for "' + fieldLabel +'" has expired.');
			///formField.focus();
		}
	} 
	
	return result;
}

function isValidCreditCardNumber(formField,ccType,fieldLabel,required)
{
	var result = true;
 	var ccNum = formField.value;

	if (required && !validRequired(formField,fieldLabel))
		result = false;
 
  	if (result && (formField.value.length>0))
 	{ 
 		if (!allDigits(ccNum))
 		{
 			alert('Please enter only numbers (no dashes or spaces) for the "' + fieldLabel +'" field.');
			formField.focus();
			result = false;
		}	

		if (result)
 		{ 
 			var type = ccType.options[ccType.selectedIndex].value;
	
 			if(type=="0" || type.length==0)
			{
				alert("Select a credit card type");
				return false;
			}
 			if (!LuhnCheck(ccNum) || !validateCCNum(type,ccNum))
 			{
 				alert('Please enter a valid card number for the "' + fieldLabel +'" field.');
				formField.focus();
				result = false;
			}	
		} 

	} 
	
	return result;
}

function LuhnCheck(str) 
{
  var result = true;

  var sum = 0; 
  var mul = 1; 
  var strLen = str.length;
  
  for (i = 0; i < strLen; i++) 
  {
    var digit = str.substring(strLen-i-1,strLen-i);
    var tproduct = parseInt(digit ,10)*mul;
    if (tproduct >= 10)
      sum += (tproduct % 10) + 1;
    else
      sum += tproduct;
    if (mul == 1)
      mul++;
    else
      mul--;
  }
  if ((sum % 10) != 0)
    result = false;
    
  return result;
}



function GetRadioValue(rArray)
{
	for (var i=0;i<rArray.length;i++)
	{
		if (rArray[i].checked)
			return rArray[i].value;
	}
	
	return null;
}


function validateCCNum(cardType,cardNum)
{
	var result = false;
	
	var cardLen = cardNum.length;
	var firstdig = cardNum.substring(0,1);
	var seconddig = cardNum.substring(1,2);
	var first4digs = cardNum.substring(0,4);
	/*
	46 2	CREDIT CARD TYPE	VC	Visa Card	
	47 3	CREDIT CARD TYPE	AE	American Express
	48 1 CREDIT CARD TYPE	MC	Master Card
	49 5 CREDIT CARD TYPE	DC	DinersClub
	50 4	CREDIT CARD TYPE	DV	Discover
	*/
	switch (cardType)
	{
		case "1":
			var validNums = "12345";
			result = (cardLen == 16) && (firstdig == "5") && (validNums.indexOf(seconddig)>=0);
			break;
			
		case "2":
			result = ((cardLen == 16) || (cardLen == 13)) && (firstdig == "4");
			break;
		case "3":
			var validNums = "47";
			result = (cardLen == 15) && (firstdig == "3") && (validNums.indexOf(seconddig)>=0);
			break;
	
		case "4":
			result = (cardLen == 16) && (first4digs == "6011");
			break;
		case "5":
			var validNums = "068";
			result = (cardLen == 14) && (firstdig == "3") && (validNums.indexOf(seconddig)>=0);
			break;
	}
	return result;
}

function validCCForm(ccTypeField,ccNumField,ccExpMonth,ccExpYear)
{
	var ExpDate=ccExpMonth.value+"/"+ccExpYear.value;
	var result = isValidCreditCardNumber(ccNumField,ccTypeField,"Credit Card Number",true) &&
		isValidExpDate(ExpDate,"Expiration Date",true);
	return result;
}


function valCard(strCCType,strCCNum,intExpMonth,intExpYear)
{   
	return validCCForm(strCCType,strCCNum,intExpMonth,intExpYear); 
	//document.getElementByName("ddl_crtype"),document.getElementByName("txt_crno"),document.getElementByName(""),document.getElementByName("txt_cryear"));
	//return validCCForm(ddl_crtype,txt_crno,txt_crmonth,txt_cryear); document.myform.ddl_crtype.value,document.myform.txt_crno.value,document.myform.txt_crmonth.value,document.myform.txt_cryear.value

}