function validate(){
	msg = 'Please complete all fields\n\n';
	
	if(document.signup_form.email.value == ''){
		msg += 'E-Mail\n';
	} else {
		if(!checkEmail(document.signup_form.email.value)){
			msg += 'Non valid E-Mail address\n';
		}
	}
	
	if(msg == 'Please complete all fields\n\n'){
		document.signup_form.submit();
	} else {
		alert(msg);
	}
}

function validate_share(){
	var msg = '';
	
	if(document.share_form.friend_1.value == '' && document.share_form.friend_2.value == '' && document.share_form.friend_3.value == '' && document.share_form.friend_4.value == '' && document.share_form.friend_5.value == ''){
		msg = 'Please complete at least one e-mail address\n\n';	
	} else {
		if(document.share_form.friend_1.value != ''){
			if(!checkEmail(document.share_form.friend_1.value)){
				msg += 'Friend 1: non valid E-Mail address\n';
			}	
		}
		
		if(document.share_form.friend_2.value != ''){
			if(!checkEmail(document.share_form.friend_1.value)){
				msg += 'Friend 2: non valid E-Mail address\n';
			}	
		}
		
		if(document.share_form.friend_3.value != ''){
			if(!checkEmail(document.share_form.friend_1.value)){
				msg += 'Friend 3: non valid E-Mail address\n';
			}	
		}
		
		if(document.share_form.friend_4.value != ''){
			if(!checkEmail(document.share_form.friend_1.value)){
				msg += 'Friend 4: non valid E-Mail address\n';
			}	
		}
		
		if(document.share_form.friend_5.value != ''){
			if(!checkEmail(document.share_form.friend_1.value)){
				msg += 'Friend 5: non valid E-Mail address\n';
			}	
		}
	}
	
	if(msg == ''){
		document.share_form.submit();
	} else {
		alert(msg);	
	}
}

function checkEmail(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;				
}