function Email(estring) {

	var email = estring;
	var reg_exp = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$/;
	if (reg_exp.test(email) == false || email.indexOf('@') == -1 || email.indexOf('@') <= 1 || email.substr(email.lastIndexOf('@')+1).length <= 4 || email.indexOf('.') == -1 || email.indexOf('.') == 0 || email.lastIndexOf('.') == email.length-1 || email.substr(email.lastIndexOf('.')+1).length <= 1 || email.indexOf('.@') != -1 || email.indexOf('@.') != -1) { return false; }
}

function CheckField(field) {

	var form = $('mainForm');
	var elm = form[field];
	var elm_value = $(elm).getValue();

	if (elm_value == "" || elm_value.charAt(0) == " ") {
		return false;
	}
}

function CheckForm() {

	if (CheckField('firstname') == false) {
		alert('Imię?');
		$('mainForm').firstname.focus();
	} else if (CheckField('lastname') == false) {
		alert('Nazwisko?');
		$('mainForm').lastname.focus();
	} else if (CheckField('company') == false) {
		alert('Firma?');
		$('mainForm').company.focus();
	} else if (CheckField('address') == false) {
		alert('Adres');
		$('mainForm').address.focus();
	} else if (CheckField('city') == false) {
		alert('Miasto?');
		$('mainForm').city.focus();
	} else if (Email($('mainForm').email.value) == false) {
		alert('Adres e-mail?');
		$('mainForm').email.focus();
	} else if (CheckField('phone') == false) {
		alert('Telefon?');
		$('mainForm').phone.focus();
	} else if (CheckField('partner') == false) {
		alert('Jakie oprogramowanie firmy Autodesk, posiada Państwa firma?');
		$('mainForm').partner.focus();
	} else {
		$('submit_btn').update('');
		$('loader').addClassName('loading');

		Event.observe('mainForm', 'submit', function(event) {
			Event.stop(event);
		});

		$('mainForm').request({
			onComplete: function() {
				$('mainForm').reset();
				$('loader').removeClassName('loading');
				$('mainForm').hide();
				$('welcome_txt').hide();
				$('thanks_txt').appear();
			}
		});
	}

	return false;
}