//Validates an Email Address
function emailCheck (emailStr) {
	var checkTLD=1;
	var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;
	var emailPat=/^(.+)@(.+)$/;
	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 +")*$");
	var matchArray=emailStr.match(emailPat);
	if (matchArray==null) {
		return false;
	}
	var user=matchArray[1];
	var domain=matchArray[2];
	for (i=0; i<user.length; i++) {
		if (user.charCodeAt(i)>127) {
			return false;
		}
	}
	for (i=0; i<domain.length; i++) {
		if (domain.charCodeAt(i)>127) {
			return false;
		 }
	}
	if (user.match(userPat)==null) {	
		return false;
	}
	var IPArray=domain.match(ipDomainPat);
	if (IPArray!=null) {
		for (var i=1;i<=4;i++) {
			if (IPArray[i]>255) {
				return false;
			}
		}
		return true;
	}
	var atomPat=new RegExp("^" + atom + "$");
	var domArr=domain.split(".");
	var len=domArr.length;
	for (i=0;i<len;i++) {
		if (domArr[i].search(atomPat)==-1) {
			return false;
		}
	}
	if (checkTLD && domArr[domArr.length-1].length!=2 && domArr[domArr.length-1].search(knownDomsPat)==-1) {
		return false;
	}
	if (len<2) {
		return false;
	}
	return true;
}

//Validates ZIP Codes
function validateZIP(field) {
	var valid = "0123456789-";
	var hyphencount = 0;

	if (field.length!=5 && field.length!=10) {
		return false;
	}
	for (var i=0; i < field.length; i++) {
		temp = "" + field.substring(i, i+1);
		if (temp == "-") hyphencount++;
		if (valid.indexOf(temp) == "-1") {
			return false;
		}
		if ((hyphencount > 1) || ((field.length==10) && ""+field.charAt(5)!="-")) {
			return false;
	   }
	}
	return true;
}

//Validates a Number (Birth Year)
function validateNumber(field) {
	var valid = "0123456789";
	if (field.length!=4) {
		return false;
	}
	for (var i=0; i < field.length; i++) {
		temp = "" + field.substring(i, i+1);
		if (valid.indexOf(temp) == "-1") {
			return false;
		}
	}
	return true;
}

function checkSignUpForm(form){
	var errors = '';
	if (form.first.value==''){
		errors += 'First Name\n';
	}
	if (form.last.value==''){
		errors += 'Last Name\n';
	}
	if (form.email.value==''){
		errors += 'E-Mail Address\n';
	}
	else if (emailCheck(form.email.value) != true){
		errors += 'E-Mail Address is invalid.\n';
	}
	if (form.verify_email.value==''){
		errors += 'Verify E-Mail Address\n';
	}
	else if (form.verify_email.value!=form.email.value){
		errors += 'E-Mail Addresses do not match.\n';
	}
	if (form.custom_birth_year[form.custom_birth_year.selectedIndex].value==''){
		errors += 'Birth Year \n';
	}
	if (form.zip.value==''){
		errors += 'Zip Code\n';
	}
	else {
		if (!validateZIP(form.zip.value)){
			errors += 'Zip Code is invalid.\n';
		}
	}
	if (form.slid_1.checked != true && form.slid_2.checked != true && form.slid_3.checked != true){
		errors += 'You must sign up for at least ONE list!.\n';
	}
	if (form.agreement.checked==false){
		errors += 'Terms of agreement \n';
	}	
	if (errors == ''){
		return true;
	}
	else {
		var alert_msg = 'The following required information is missing or invalid:\n';
		alert_msg += '---------------------------------------\n';
		alert_msg += errors;
		alert_msg += '---------------------------------------\n';
		window.alert(alert_msg);
		return false;
	}			
}