function checkUsername() {
	var username = document.getElementById('username_reg').value;
							
	xmlHttp = GetXmlHttpObject();
	
	if(xmlHttp == null) {
		alert("Browser does not support HTTP Request");
		return false;
	}	 
	 
	else {
		var url= "../checkusername.ajax.php?username=" + username;
	
		xmlHttp.onreadystatechange = usernameChecked;
		xmlHttp.open("GET", url, true);
		xmlHttp.send(null);
	}
}		

function usernameChecked() { 
	if(xmlHttp.readyState == 4 || xmlHttp.readyState == "complete") { 
		document.getElementById("error_reg").value = xmlHttp.responseText;
					
		checkForm();
	}
}

function checkForm() {
	var email = document.getElementById('email').value;
	var error = document.getElementById("error_reg").value;
	var firstname = document.getElementById('fname').value;
	var lastname = document.getElementById('lname').value;
	var password = document.getElementById('password_reg').value;
	var username = document.getElementById('username_reg').value;
	
	var error_flag = 0;
	var message = "The following errors occured:\n\n";
		
	if(firstname == ""){
		error_flag = 1;
		message += "\t- Please enter your firstname.\n";		
	}
	
	if(lastname == ""){
		error_flag = 1;
		message += "\t- Please enter your lastname.\n";		
	}
	
	if(username == "") {
		error_flag = 1;
		message += "\t- Please enter your username.\n";		
	}
	
	else {
		if(!username.match("^[a-zA-Z0-9]+$")) {
			error_flag = 1;
			message += "\t- The username must consist of the following characters: a-z, A-Z, 0-9.\n";						
		}
	
		else {
			if(error == 1) {
				error_flag = 1;
				message += "\t- The username '" + username + "' has already been registered.\n";				
			}
		}
	}
	
	if(password == ""){
		error_flag = 1;
		message += "\t- Please enter your password.\n";		
	}
	
	if(email != "") {
		if(!email.match("[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?")) {
			error_flag = 1;
			message += "\t- Please enter a correct e-mail address.\n";
		}	
	}
	
	else {
		error_flag = 1;
		message += "\t- Please enter your emailaddress.\n";			
	}
	
	message += "\nPlease correct them in order to continue.";
	
	if(error_flag == 0) {
		var params = 'lname=' + lastname + '&fname=' + firstname + '&username=' + username + '&pass=' + password + '&email=' + email + '&phone_home=' + document.getElementById('phone_home').value + '&phone_work=' + document.getElementById('phone_work').value + '&nickname=' + document.getElementById('nickname').value + '&street=' + document.getElementById('street').value + '&city=' + document.getElementById('city').value + '&province=' + document.getElementById('province').value + '&country=' + document.getElementById('country').value + '&sex=' + document.getElementById('radio').value + '&pcode=' + document.getElementById('pcode').value + '&mobile=' + document.getElementById('mobile').value;
		
		xmlHttp = GetXmlHttpObject();
	
		if(xmlHttp == null) {
			alert("Browser does not support HTTP Request");
		
			return;
		} 
	
		var url= "../register.script.php?" + params;
	
		xmlHttp.onreadystatechange = Reg; 
		xmlHttp.open("GET", url, true);
		xmlHttp.send(null);
	}
	
	else {
		alert(message);	
	}
}

function Reg() { 
	if(xmlHttp.readyState == 4 || xmlHttp.readyState == "complete") { 
		window.location = 'http://www.artapa.com/regok.php';
	}
}