var zipcodeStart = false;
var zipcodeEnd = false;


	$(document).ready(function(){
		$("#btn-bereken").attr("disabled", "true");
		$("#postcodeStart").keyup(function(){
			if(!validateZipCode($(this).val()))
			{
				zipcodeStart = false;
				$(this).removeClass("correctZipCode");
				$(this).addClass("incorrectZipCode");
				$(this).css({
					'background-color' : 'Red'
				});
			}
			else
			{
				zipcodeStart = true;
				$(this).removeClass("incorrectZipCode");
				$(this).addClass("correctZipCode");
				$(this).css({
					'background-color' : '#fff'
				});
			}
			handleSubmit();
		});
		$("#postcodeEnd").keyup(function(){
			if(!validateZipCode($(this).val()))
			{
				zipcodeEnd = false;
				$(this).removeClass("correctZipCode");
				$(this).addClass("incorrectZipCode");
				$(this).css({
					'background-color' : 'Red'
				});
			}
			else
			{
				zipcodeEnd = true;
				$(this).removeClass("incorrectZipCode");
				$(this).addClass("correctZipCode");
				$(this).css({
					'background-color' : '#fff'
				});
			}
			handleSubmit();
		});
	});
	
	function validateZipCode(val)
	{
		var length = val.length;
		if (length > 6 || length < 6)
		{
			return false;
		}
		
		var cijferString = val.substring(0,4);
		if (!IsNumeric(cijferString)) return false;
		
		var letterString = val.substring(4,6);
		if (!IsText(letterString)) return false;
		
		return true;
	}
	
	function IsNumeric(sText)
	{
	   var ValidChars = "0123456789.";
	   var IsNumber=true;
	   var Char;

	 
	   for (i = 0; i < sText.length && IsNumber == true; i++) 
		  { 
		  Char = sText.charAt(i); 
		  if (ValidChars.indexOf(Char) == -1) 
			 {
			 IsNumber = false;
			 }
		  }
	   return IsNumber;
	   
	}
	
	function IsText(sText)
	{
	   var ValidChars = "abcdefghijklmnopqrstuvwxyz";
	   var IsText=true;
	   var Char;

		sText = sText.toLowerCase();
	 
	   for (i = 0; i < sText.length && IsText == true; i++) 
		  { 
		  Char = sText.charAt(i); 
		  if (ValidChars.indexOf(Char) == -1) 
			 {
			 IsText = false;
			 }
		  }
	   return IsText;
	   
	}

	
	function handleSubmit(){
		if (zipcodeStart && zipcodeEnd)
		{
			$("#btn-bereken").removeAttr('disabled');
		}
		else
			$("#btn-bereken").attr("disabled", "true");
	}