function replace(paramList, param){

	var strList = paramList.substr(paramList.indexOf("LANG"));
	var items = strList.split("&");
	var item = items[0];
	
	return paramList.replace(item, "LANG=" + param); 

}

function buildParamList(param){
	var strHref = window.location.href;
  	var paramList = ""; 
  	if ( strHref.indexOf("?") > -1 ){
    	paramList = strHref.substr(strHref.indexOf("?"));
    	if ( strHref.indexOf("LANG") > -1 ){
    		paramList = replace(paramList, param);
    	}
    	else
    		paramList = paramList + "&LANG=" + param;
    }
    else
    	paramList = "?LANG=" + param;
	
	return paramList;
}


function refresh(param)
{
    var sURL = window.location.pathname;
    
    window.location.href = sURL + buildParamList(param);
    
}


function luhn_check(cardNumber)
{	
    var cardNumbersOnly = cardNumber.replace(/ /g,"");
    var cardNumberLength = cardNumbersOnly.length;
	
    var numberProduct;
    var numberProductDigitIndex;
    var checkSumTotal = 0;

    for (digitCounter = cardNumberLength - 1; 
      digitCounter >= 0; 
      digitCounter--)
    {
      checkSumTotal += parseInt (cardNumbersOnly.charAt(digitCounter));
      digitCounter--;
      numberProduct = String((cardNumbersOnly.charAt(digitCounter) * 2));
      for (var productDigitCounter = 0;
        productDigitCounter < numberProduct.length; 
        productDigitCounter++)
      {
        checkSumTotal += 
          parseInt(numberProduct.charAt(productDigitCounter));
      }
    }
    return (checkSumTotal % 10 == 0);
}

function checkMod10(card_number, labelId) {
	if(luhn_check(card_number))
		document.getElementById(labelId).style.color='black';
	else
		document.getElementById(labelId).style.color='red';
}