function setBad(box)
{
	box.style.color = "red"
	box.title = "Chybný, alebo žiadny údaj.";
}

function setOK(box)
{
	box.style.color = "black"
	box.title = "";
}

function checkName(nameBox)
{
	var value = nameBox.value;
	
	if ( value == "" || value.length < 5)
		setBad(nameBox);
	else 
		setOK(nameBox);

	handleSubmitButton();
}

function checkEmail(emailBox)
{
	var email = emailBox.value;
	var emailFilter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;

	if ( email == "" || !emailFilter.test(email) )
		setBad(emailBox);
	else 
		setOK(emailBox);

	handleSubmitButton();
}

function checkText(textBox)
{
	var value = textBox.value;
	
	if ( value == "" || value.length < 5)
		setBad(textBox);
	else 
		setOK(textBox);
	
	handleSubmitButton();
}

function handleSubmitButton()
{
	var bad = false;

	for (i=0; i<document.forms[0].elements.length; i++)
	{
		if ( document.forms[0].elements[i].style.color == 'red' )
			bad = true;
	}
	
	document.forms[0].sendButton.disabled = bad;
}