// get querystring parameter
function GetParam(name) {
    var start = location.search.indexOf("?" + name + "=");
    if (start < 0) start = location.search.indexOf("&" + name + "=");
    if (start < 0) return '';
    start += name.length + 2;
    var end = location.search.indexOf("&", start) - 1;
    if (end < 0) end = location.search.length;
    var result = location.search.substring(start, end);
    var result = '';
    for (var i = start; i <= end; i++) {
        var c = location.search.charAt(i);
        result = result + (c == '+' ? ' ' : c);
    }
    return unescape(result);
}

// get Html Element from DOM
GetElement = function(id) {
    var element;
    if (document.getElementById) {
        element = document.getElementById(id);
    } else {
        element = document.all[id];
    }
    if (element == "undefined" || element == null) {
        alert(id + " could not be found");
        return document.createElement("input");
    }
    return element;
}

// validate registration form
function validateForm() {
    var error = "";
    var br = "\n";
    var tab = "  -";
    var emailExp = new RegExp("^([a-zA-Z0-9_\\-\\.]+)@((\\[[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.)|(([a-zA-Z0-9\\-]+\\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\\]?)$");
    try {
        var cidParam = GetParam("cid");
        if(cidParam != "") GetElement("cid").value = cidParam;
        if (GetElement("fname").value == "") error += tab + "First Name" + br;
        if (GetElement("lname").value == "") error += tab + "Last Name" + br;
        if (GetElement("email").value == "") {
            error += tab + "Email" + br;
        } else if (emailExp.exec(GetElement("email").value) == null) {
            error += tab + "Email" + br;
        }
    }
    catch (Error) {
        alert(Error);
    }
    if (error != "") {
        alert("Please correct the following fields:" + br + error);
        return false;
    }
    return true;
}