function check_form() {
	valid = true;
	if (document.signupform.firstname.value == "" && document.signupform.surname.value == "")
    {
        alert ("Please fill in your name.");
        valid = false;
    }
	else if (document.signupform.email.value == "")
    {
        alert ("Please fill in your email address.");
        valid = false;
    } else if (!check_email(document.signupform.email)) {
		alert ("Please enter a valid email address.");
		valid = false;
	}
    return valid;
}

function check_email(email) {
	var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (!filter.test(email.value)) return false;
	return true;	
}

function open_window(url) {
	window.open(url,"Diffused Music Player","width=378,height=208");	
}

function resetTabs() {
	document.getElementById("homenav").className="home";
	document.getElementById("artistsnav").className="artists";
	document.getElementById("releasesnav").className="releases";
	document.getElementById("livenav").className="live";
	document.getElementById("linksnav").className="links";
	document.getElementById("contactsnav").className="contacts";
}

function resizeIframe(iframe) {
	iframe.height = 0;
    iframe.height = iframe.contentWindow.document.body.scrollHeight;
	var location = iframe.contentWindow.location.toString();
	var locarray = location.split("/");
	var len = locarray.length;
	var page = locarray[len-1];
	resetTabs();
	if (page.indexOf('home_content.php')!=-1) {
		document.getElementById("homenav").className="homecurrent";
	}
	if (page.indexOf('artists_content.php')!=-1) {
		document.getElementById("artistsnav").className="artistscurrent";
	}
	if (page.indexOf('gallery.php')!=-1) {
		document.getElementById("artistsnav").className="artistscurrent";
	}
	if (page.indexOf('artistlinks.php')!=-1) {
		document.getElementById("artistsnav").className="artistscurrent";
	}
	if (page.indexOf('releases_content.php')!=-1) {
		document.getElementById("releasesnav").className="releasescurrent";
	}
	if (page.indexOf('live_content.php')!=-1) {
		document.getElementById("livenav").className="livecurrent";
	}
	if (page.indexOf('links_content.php')!=-1) {
		document.getElementById("linksnav").className="linkscurrent";
	}
	if (page.indexOf('contacts_content.php')!=-1) {
		document.getElementById("contactsnav").className="contactscurrent";
	}
}