// simpele browser check
var BROWSER_IE = false;
if (navigator.userAgent.toLowerCase().indexOf('msie')+1) BROWSER_IE = true;

var currentHelpId = 'none';
function showHelp(helpid){
  if (currentHelpId != 'none' && currentHelpId != helpid){ // hide help
    document.getElementById('help'+currentHelpId).style.display='none';
  }
  currentHelpId = helpid;
  current = document.getElementById('help'+helpid).style.display;
  newstatus = (current=='block'?'none':'block');
  document.getElementById('help'+helpid).style.display=newstatus;
}

function toggleDisplay(target_id){
  document.getElementById(target_id).style.display=(document.getElementById(target_id).style.display=='none')?'inline':'none';
}

function chkField(field,message){
  f = document.getElementById(field);
  if (f.value=="") {
    alert(message);
    return false;
  }
  return true;
}

function checkPostScreen(is_newtopic){
  if (is_newtopic && document.getElementById('subject').value=="") {
    alert('U bent vergeten een onderwerp in te vullen.');
    return false;
  }
  if (document.getElementById('msg').value==""){
    alert('Het is niet mogelijk om een leeg bericht te plaatsen.');
    return false;
  }
  
  return true;
}

function checkEmail(adres){
	var result = true;
	
	if (!adres){
		alert("U bent vergeten om uw e-mail adres in te vullen.");
		result = false;
	}
	if (result && !adres.match(/^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/)){
		alert("Het door u opgegeven e-mail adres ("+adres+") is ongeldig.");
		result = false;
	}
	
	return result;
}

function copyAddress(source, destination, fields, checkField)
{
	if (typeof(checkField)!="undefined"){
		var checkFieldElem = document.getElementById(checkField);
		var result = checkFieldElem && checkFieldElem.checked;
		for(var i in fields){
			var destinationField = document.getElementById(destination+"_"+fields[i]);
			if (destinationField) destinationField.disabled = result;
		}
		if (!result)
			return;
	}

	for(var i in fields){
		var sourceField = document.getElementById(source+"_"+fields[i]);
		var destinationField = document.getElementById(destination+"_"+fields[i]);

		if (sourceField && destinationField){
			destinationField.value = sourceField.value;
		}
	}
}