var element_username = $('username').next();

var url = '/wOnline/register/check.php';

element_username.observe('blur', checkUsername);
element_username.observe('keyup', checkUsernameChars);
element_username.observe('keydown', checkUsernameChars);
element_username.observe('focus', checkUsername);
/*element_username.observe('focus', function() {$('username_message').innerHTML = ' ';$('username_message').style.background = ''});*/

function checkUsername() {
	if(element_username.value.length > 0) {
		new Ajax.Request(url, {
		  method: 'get',
		  parameters: 'user='+element_username.value, 
		  onSuccess: function(transport) {
		    var notice = $('notice');
		    if (transport.responseText.length < 1) {
		      $('username_message').innerHTML = 'Der gewünschte Benutzername ist frei.';
			  $('username_message').style.background = 'url(/wOnline/wGlobal/layout/images/icons/success.png) no-repeat left';
			  $('username_message').style.paddingLeft = '20px';
			  $('username_message').style.display = 'block';
			  $('username_message').style.color = '#33CC00';
		    } else {
		      $('username_message').innerHTML = 'Der gewünschte Benutzername ist leider besetzt. Sie können die Alternative "'+transport.responseText+'" verwenden oder einen anderen Benutzernamen eingeben.';
			  $('username_message').style.color = '#AF4F4A';
			  $('username_message').style.background = 'url(/wOnline/wGlobal/layout/images/icons/error.png) no-repeat left';
			  $('username_message').style.paddingLeft = '20px';
			  $('username_message').style.display = 'block';
			  element_username.value = transport.responseText;
			}
		  }
		});
	}
}

function checkUsernameChars() {
	element_username.value = element_username.value.replace(' ', '_');
	element_username.value = element_username.value.replace(/[^\w\._]/, '');
}