function isBlank(s)
{
  // Returns true if string contains only whitespace
  var i;
  var c;

  for (i = 0; i < s.length; i++) {
    c = s.charAt(i);
    if (c != ' ' && c != '\n' && c != '\t')
      return false;
  }
  return true;
}

function checkForm(form)
{
    var emptyFields = "";
    var errors      = "";
    var elem;
    for (var i = 0; i < form.length; i++) {
        elem = form.elements[i];
        if (elem.date != null) {
              if (elem.value > elem.date.value) {
                  errors += "- " + elem.text1 + " date must be greater than " + elem.text2 + " date\n";
              }
              continue;
        }
        if ((elem.type == "password" || elem.type == "text" || elem.type == "textarea" || elem.type == "file") && elem.required){
            if (elem.value == null || elem.value == "" || isBlank(elem.value)) {
                emptyFields += "          " + elem.text + "\n";
                continue;
            }
        }
        if (elem.required || (!elem.required && elem.value != "")) {
            if (elem.numeric || elem.min != null || elem.max != null) {
                n = parseFloat(elem.value);
                if  (isNaN(n)
                     || (elem.min != null && (n < elem.min))
                     || (elem.max != null && (n > elem.max))) {
                    errors += "- The field '" + elem.text + "' must be a number";
                    if ((elem.min != null) && (n < elem.min)) {
                        errors += " that is greater than " + (elem.min - 1);
                    } else if ((elem.max != null) && (n > elem.max)) {
                        errors += " that is less than " + (elem.max + 1);
                    }
                    errors += "\n";
                } else {
                    elem.value = n;
                }
            }
        }
    }
    if (emptyFields == "" && errors == "") {
        return true;
    } else {
        msg = "The form was not submited due to the following error(s)\n";
        if (emptyFields != "") {
            msg += "\n- The followind fields must be entered:\n" + emptyFields;
        }
        if (errors != "") {
            msg += "\n" + errors;
        }
        alert(msg);
        return false;
    }
}

function emailCheck (emailStr)
{
    var emailPat=/^(.+)@(.+)$/;
    var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]";
    var validChars="\[^\\s" + specialChars + "\]";
    var quotedUser="(\"[^\"]*\")";
    var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
    var atom=validChars + '+';
    var word="(" + atom + "|" + quotedUser + ")";
    // The following pattern describes the structure of the user
    var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
    var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");
    var matchArray=emailStr.match(emailPat);
    if (matchArray == null)
    {
        alert("Email address seems incorrect (check @ and .'s)");
        return false;
    }
    var user=matchArray[1];
    var domain=matchArray[2];
    if (user.match(userPat)==null)
    {
    // user is not valid
        alert("The username doesn't seem to be valid.");
        return false;
    }
    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;
    }
    var domainArray=domain.match(domainPat);
    if (domainArray==null)
    {
        alert("The domain name doesn't seem to be valid.");
        return false;
    }
    var atomPat=new RegExp(atom,"g");
    var domArr=domain.match(atomPat);
    var len=domArr.length;
    if (domArr[domArr.length-1].length<2 || domArr[domArr.length-1].length>3)
    {
        alert("The address must end in a three-letter domain, or two letter country.");
        return false;
    }
    if (len<2)
    {
        var errStr="This address is missing a hostname!";
        alert(errStr);
        return false;
    }
    return true;
}

function checkFormPwdFields()
{
	var form = document.reg_frm;

	if (form.usr_pwd.value.length > 0 || form.usr_conf_pwd.value.length > 0)
    {
		if (!checkPasswords(form.usr_pwd, form.usr_conf_pwd))
        return false;
	}

	return true;
}

function checkPasswords(password, confirm_password)
{
    var errors = "";
    if (password.value != confirm_password.value)
	{
        errors += "- The 2 password fields do not match\n";
    }
    if (password.value.length < 6) 
	{
        errors += "- Password must be at least 6 characters long\n";
    }
    if (errors != "") 
	{
        var msg = "The form was not submited due to the following error(s)\n" + errors;
        alert(msg);
        return false;
    }
    return true;

}

function chkRegisterFields()
{
/*------------------------------------------------
	Check is empty all fields on registration form.
-------------------------------------------------*/

    var form = document.reg_frm;

    form.usr_name.required         = true; 
    form.usr_name.text             = "First Name";  
    form.usr_last_name.required    = true; 
    form.usr_last_name.text        = "Last Name"; 
    form.usr_email.required        = true; 
    form.usr_email.text            = "E-mail";
    form.usr_login.required        = true; 
    form.usr_login.text            = "Login";  
    form.usr_pwd.required          = true; 
    form.usr_pwd.text              = "Password";  
    form.usr_conf_pwd.required     = true; 
    form.usr_conf_pwd.text         = "Confirm password";

	var usr_email = form.usr_email.value;

	if ( checkForm(form) == true)
	{
		if (emailCheck(usr_email) == true)
		{
			if (checkFormPwdFields() == true)
			{
				form.submit();
				return true;
			}
			else
			{
				form.usr_pwd.value = '';
				form.usr_conf_pwd.value = '';
				form.usr_pwd.focus();
			}
		}
		else
		{
			form.usr_email.focus();
		}
	}

	return false;
}