// validation constants
var TEXT = 1;
var CHECKBOX = 2;
var RADIO = 3;

// validation for required fields
function validateForm(params,formname) {
	// true if no items passed
	if (params == null || params.length == 0) return true;
	if (formname == null) formname = "form";
	var form = eval("document."+formname);
	// doesn't validate if it can't find the form
	if (!form) return true;
	var invalidFields = "";
	for (var i = 0; i < params.length; i++) {
		var param = params[i];
		var p_name = param[0];
		var p_type = param[1];
		var p_req = param[2];
		
		// validate fields by field type
		if (p_type == TEXT && p_req) invalidFields += checkText(p_name);
		else if (p_type == CHECKBOX && p_req) invalidFields += checkCheckbox(p_name);
		else if (p_type == RADIO && p_req) invalidFields += checkRadio(p_name);
	}
	
	// return error message
	if (invalidFields.length > 0) {
		alert("The following fields are required:\n"+invalidFields);
		return false;
	} else return true;
	
	// text field validation
	function checkText(n) {
		var field = form[n];
		if (!field) return "";	// valid if field doesn't exist
		if (field.disabled) return "";	// valid if disabled
		if (field.value.length == 0) return "\n - "+field.title;
		return "";
	}
	// checkbox validation
	function checkCheckbox(n) {
		var check = form[n];
		if (!check || !check[0]) return "";		// valid if check doesn't exist
		var hasCheck = false;
		var isDisabled = true;
		for (var j = 0; j < check.length; j++) {
			var chk = check[j];
			if (!chk.disabled) isDisabled = false;
			if (chk.checked) {
				hasCheck = true;
				break;
			}
		}
		if (!isDisabled && !hasCheck) return "\n - "+check[0].title;
		return "";
	}
	// radio button validation
	function checkRadio(n) {
		var radio = form[n];
		if (!radio || !radio[0]) return "";		// valid if radio doesn't exist
		var hasCheck = false;
		var isDisabled = true;
		for (var j = 0; j < radio.length; j++) {
			var rdo = radio[j];
			if (!rdo.disabled) isDisabled = false;
			if (rdo.checked) {
				hasCheck = true;
				break;
			}
		}
		if (!isDisabled && !hasCheck) return "\n - "+radio[0].title;
		return "";
	}
}