function setCat(cat){
	var add = "";
	var input = $("categories").value;
	var re = new RegExp("(^|,) *"+cat+" *(,|$)");
	if (!input.match(re)){
		if (input!=""){
			var add = " , ";
		} 
		document.getElementById("categories").value = input + add + cat;
	}
	else {alert (cat+ " already exist");}
}
function clearCat(){
		document.getElementById("categories").value = "";
}
function hide_by_id(id){
		$(id).style.display = "none";
}
function show_by_id(id){
		$(id).style.display = "";
		$(id).style.visibility = "";
}
function show_hide_by_id(id){
	if($(id).style.display == ""){
		hide_by_id(id);
	}else{
		show_by_id(id);
	}
}
/**
 * @author aneverovsky 
 * only for comentform.tpl
 * @param {int} tab
 */
function set_tab(tab) {
	 
	$("tab_now").value = tab;
	
	var tab1 = document.getElementById('com_form_tab1');
	var tab2 = document.getElementById('com_form_tab2');
	var tab3 = document.getElementById('com_form_tab3');
	var body1 = document.getElementById('tab_login');
	var body2 = document.getElementById('tab_guest');
	var body3 = document.getElementById('tab_new_user');
	
	switch (tab) {
		case '1':
			tab2.className = '';
			tab3.className = '';
			tab1.className = 'active';
			body2.style.display = 'none';
			body3.style.display = 'none';
			body1.style.display = 'block';
			break;
		case '2':
			tab1.className = '';
			tab3.className = '';
			tab2.className = 'active';
			body1.style.display = 'none';
			body3.style.display = 'none';
			body2.style.display = 'block';
			break;
		case '3':
			tab1.className = '';
			tab2.className = '';
			tab3.className = 'active';
			body1.style.display = 'none';
			body2.style.display = 'none';
			body3.style.display = 'block';
			break;
	}
}


function validate_guest_form()
{
	var tab_now = $("tab_now").value;
	var error_msg = "";
	
	var validate = new Validator();
	switch (tab_now) {
		case '1':
			break;
		case '2':
			if (validate.isEmpty($('serendipity_commentform_name').value))
				error_msg += "Invalid value for 'Name' field.\n";
			if (!validate.isEmail($('serendipity_commentform_email').value))
				error_msg += "Invalid value for 'Email' field.\n";	
			break;
		case '3':
			if (validate.isEmpty($('serendipity_commentform_name_newuser').value))
				error_msg += "Invalid value for 'Name' field.\n";
			if (!validate.isEmail($('serendipity_commentform_email_newuser').value))
				error_msg += "Invalid value for 'Email' field.\n";	
			break;
	}
	
	if (error_msg == "") return true;

	alert(error_msg);
	return false;	
}