// Check if a string has at least one non-null space.
function isWhitespace(s) {   
	var whitespace = " \t\r\n";
	var i;

	if (s != null) {
		// return false if it contains any non-white space
		for (i = 0; i < s.length; i++) {   
			if (whitespace.indexOf(s.charAt(i)) == -1)
				return false;
		}
	}
	return true;
}

// validate email address
function emailCheck(emailStr) {
	var emailPat=/^(.+)@(.+)$/
	var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]"
	var validChars="\[^\\s" + specialChars + "\]"
	var quotedUser="(\"[^\"]*\")"
	var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/
	var atom=validChars + '+'
	var word="(" + atom + "|" + quotedUser + ")"
	var userPat=new RegExp("^" + word + "(\\." + word + ")*$")
	var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$")

	var matchArray=emailStr.match(emailPat)
	if (matchArray==null) { // The address does not match <user>@<domain>
		//alert("Email address seems incorrect (check @ and .'s)")
		return false
	}
	var user=matchArray[1]
	var domain=matchArray[2]

	// See if "user" is valid 
	if (user.match(userPat)==null) { // check if user is not valid
    //alert("The username doesn't seem to be valid.")
    return false
	}

	// validate when domain name is ip
	var IPArray=domain.match(ipDomainPat)
	if (IPArray!=null) {  // this is an IP address
		for (var i=1;i<=4;i++) {
			if (IPArray[i]>255) {
				//alert("Destination IP address is invalid!")
				return false
			}
		}
		return true
	}

	// Validate domain if it is a symbolic name
	var domainArray=domain.match(domainPat)
	if (domainArray==null) {
		//alert("The domain name doesn't seem to be valid.")
    return false
	}

	// break up the domain name to validate
	var atomPat=new RegExp(atom,"g")
	var domArr=domain.match(atomPat)
	var len=domArr.length
	if (len<2) { // Make sure there's a host name preceding the domain.
 	  //alert("This address is missing a hostname!");
 	  return false
	}
	// domain name now can have 2,3,4 charactes, such as .us, .com or .info
	if (domArr[domArr.length-1].length<2 || 
 	   domArr[domArr.length-1].length>4) {
 	  //alert("The address must end in a three-letter domain, or two letter country.")
 	  return false
	}
	return true;
}

function verify_contact_form(form_name) {
	srcform = document.forms[form_name];
	if (isWhitespace(srcform.name.value)) {
		alert("Please enter your name.");
		srcform.name.focus();
		return false;
	}
	if (isWhitespace(srcform.email_address.value)) {
		alert("Please enter your email address.");
		srcform.email_address.focus();
		return false;
	}
	if (! emailCheck(srcform.email_address.value)) {
		alert("'" + srcform.email_address.value + "' is not a valid email address");
		//"Please enter a valid email address.");
		srcform.email_address.focus();
		return false;
	}
	if (isWhitespace(srcform.comments.value)) {
		alert("Please enter your questions or comments.");
		srcform.comments.focus();
		return false;
	}
	return true;
}