function openPreview(mod) {
	var url = document.form_preview_form.preview_url.value;
	var email = document.form_preview_form.preview_email.value;

	if (!validateUrl(url)) {
		alert("Bitte gültige URL angeben.");
		document.form_preview_form.preview_url.focus();
		return false;
	}

	if (!validateEmail(email)) {
		alert("Bitte gültige Email-Adresse angeben.");
		document.form_preview_form.preview_email.focus();
		return false;
	}
	
	window.open('preview.php?url=' + url + '&mod=' + mod, 'WebactorPreview',
			'width=950,height=710,location=0,resizable=1,dependent=1');

	return true;
}

function validateUrl(url) {
	if (url.length == 0) {
		return false;
	}
	var urlTest = "http://www." + url;
	var RegExp = /(ftp|http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?/;

    if(RegExp.test(urlTest)){
    	return true;
    }
    else {
    	return false;
	}
}

function validateEmail(str) {
	var at = "@";
	var dot = ".";
	var lat = str.indexOf(at);
	var lstr = str.length;
	var ldot = str.indexOf(dot);
	if (str.indexOf(at) == -1) {
		return false;
	}

	if (str.indexOf(at) == -1 || str.indexOf(at) == 0 || str.indexOf(at) == lstr) {
		return false;
	}

	if (str.indexOf(dot) == -1 || str.indexOf(dot) == 0 || str.indexOf(dot) == lstr) {
		return false;
	}

	if (str.indexOf(at, (lat + 1)) != -1) {
		return false;
	}

	if (str.substring(lat - 1, lat) == dot
			|| str.substring(lat + 1, lat + 2) == dot) {
		return false;
	}

	if (str.indexOf(dot, (lat + 2)) == -1) {
		return false;
	}

	if (str.indexOf(" ") != -1) {
		return false;
	}

	return true;
}