function newImage(src)
{
	if (document.images)
	{
		var tmp = new Image();
		tmp.src = src;
		return tmp;
	}
	return null;
}

function changeImages()
{
	if (document.images && (preloadFlag == true))
		for (var i=0; i<changeImages.arguments.length; i+=2)
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
}

var preloadFlag = false;
function preloadImages()
{
	if (document.images)
	{
		home_over = newImage("images/menu_01-.jpg");
		sites_over = newImage("images/menu_03-.jpg");
		programs_over = newImage("images/menu_04-.jpg");
		tools_over = newImage("images/menu_05-.jpg");
		contacts = newImage("images/menu_06-.jpg");
		preloadFlag = true;
	}
}


function allValidChars(email)
{
	var parsed = true;
	var validchars = "abcdefghijklmnopqrstuvwxyz0123456789@.-_";
	for (var i=0; i < email.length; i++)
	{
		var letter = email.charAt(i).toLowerCase();
		if (validchars.indexOf(letter) != -1)
			continue;
		parsed = false;
		break;
	}
	return parsed;
}
function isEmail(str)
{
    if (!allValidChars(str))
    	return false;
    if (str.indexOf("@") < 1)
    	return false;
    else if (str.lastIndexOf(".") <= str.indexOf("@"))
    	return false;
    else if (str.indexOf("@") == str.length)
    	return false;
	else if (str.indexOf("..") >=0)
		return false;
	else if (str.indexOf(".") == str.length)
		return false;
	return true;
}

function normalize(elmId)
{
	errorize(elmId, '');
}
function errorize(elmId, errorDesc)
{
	if (errorDesc != '')
		errors = true;
	var elm = document.getElementById(elmId);
	if (!elm) return;
	if (elm.lastChild)
		elm.lastChild.innerHTML = errorDesc;
}

function validateForm(frm)
{
	errors = false;
	normalize('email');
	normalize('subject');
	normalize('question');
	with(frm)
	{
		if (email.value != '' && !isEmail(email.value))
			errorize('email', 'Not valid email address')
		if (email == null || email.value == '')
			errorize('email', 'Email is required');
		if (subject == null || subject.value == '')
			errorize('subject', 'Subject is required');
		if (question == null || question.value == '')
			errorize('question', 'Question is required');
	}
	return !errors;
}