window.onload = initForms;

function resetLabels() {
	var allLabels = document.getElementsByTagName("label");
	for (var i=0; i<allLabels.length; i++) {
		allLabels[i].className = "";
	}
}


function initForms() {
	
	for (var i=0; i< document.forms.length; i++) {
		document.forms[i].onsubmit = function() {resetLabels(); return validForm(); }
	}
}


function validForm() {
	var allGood = true;
	var allTags = document.getElementsByTagName("input");

	for (var i=0; i<allTags.length; i++) {
		if (!validTag(allTags[i])) {
			allGood = false;
		}
	}
	return allGood;

	function validTag(thisTag) {

		var outClass = "";
		var allClasses = thisTag.className.split(" ");
	
		for (var j=0; j<allClasses.length; j++) {
			outClass += validBasedOnClass(allClasses[j]) + " ";
		}
	
		thisTag.className = outClass;
	
		if (outClass.indexOf("invalid") > -1) {
			invalidLabel(thisTag.parentNode);
			thisTag.focus();
			if (thisTag.nodeName == "INPUT") {
				thisTag.select();
			}
			return false;
		}
		return true;
		
		function validBasedOnClass(thisClass) {
			var classBack = "";
		
			switch(thisClass) {
				case "":
				case "invalid":
					break;
				case "reqd":
					if (allGood && thisTag.value == "") {classBack = "invalid ";
					alert('Please fill in all required fields.');}
					classBack += thisClass;
					break;
				case "radio":
					if (allGood && !radioPicked(thisTag.name)) { classBack = "invalid ";
					alert('Please confirm your ability to perform all essential functions.');}
					classBack += thisClass;
					break;
				case "is3Num":
					if (allGood && !valid3Num(thisTag.value)) {classBack = "invalid ";
					alert('This is not a valid value for this field.');}
					classBack += thisClass;
					break;
				case "is2Num":
					if (allGood && !valid2Num(thisTag.value)) {classBack = "invalid ";
					alert('This is not a valid value for this field.');}
					classBack += thisClass;
					break;
				case "is4Num":
					if (allGood && !valid4Num(thisTag.value)) {classBack = "invalid ";
					alert('This is not a valid value for this field.');}
					classBack += thisClass;
					break;
				case "isZip":
					if (allGood && !validZip(thisTag.value)) {classBack = "invalid ";
					alert('This is not a valid zip code.');}
					classBack += thisClass;
					break;
				case "email":
					if (allGood && !validEmail(thisTag.value)) { classBack = "invalid ";
					alert('This is not a valid email address.');}
					classBack += thisClass;
					break;
				default:
					if (allGood && !crossCheck(thisTag,thisClass)) classBack = "invalid ";
					classBack += thisClass;
			}
			return classBack;
		}
				
		function crossCheck(inTag,otherFieldID) {
			if (!document.getElementById(otherFieldID)) return false;
			return (inTag.value != "" || document.getElementById(otherFieldID).value != "");
		}
		
		function validEmail(email) {
				 var re = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;
				 return re.test(email);
				}
		function validZip(zip) {
				 var re = /[0-9][0-9][0-9][0-9][0-9]/;
				 return re.test(zip);
				}
		function valid2Num(num) {
				 var re = /[0-9][0-9]/;
				 return re.test(num)
				}
		function valid3Num(num) {
				 var re = /[0-9][0-9][0-9]/;
				 return re.test(num)
				}
		function valid4Num(num) {
				 var re = /[0-9][0-9][0-9][0-9]/;
				 return re.test(num);
				}
		
		function radioPicked(radioName) {
			var radioSet = "";

			for (var k=0; k<document.forms.length; k++) {
				if (!radioSet) {
					radioSet = document.forms[k][radioName];
				}
			}
			if (!radioSet) return false;
			for (k=0; k<radioSet.length; k++) {
				if (radioSet[k].checked) {
					return true;
				}
			}
			return false;
		}
		
		function invalidLabel(parentTag) {
			if (parentTag.nodeName == "LABEL") {
				parentTag.className += " invalid";
			}
		}
	}
}