// ----------------------------------------------------------------------
// Javascript form validation routines.
// Author: Stephen Poley
//
// Simple routines to quickly pick up obvious typos.
// All validation routines return true if executed by an older browser:
// in this case validation must be left to the server.
//
// Update Jun 2005: discovered that reason IE wasn't setting focus was
// due to an IE timing bug. Added 0.1 sec delay to fix.
//
// Update Oct 2005: minor tidy-up: unused parameter removed
//
// Update Jun 2006: minor improvements to variable names and layout
// ----------------------------------------------------------------------

var nbsp = 160; 	// non-breaking space char
var node_text = 3; // DOM text node-type
var emptyString = /^\s*$/;
var global_valfield; // retain valfield for timer thread

// --------------------------------------------
//                  trim
// Trim leading/trailing whitespace off string
// --------------------------------------------

function trim(str) {
    return str.replace(/^\s+|\s+$/g, '');
}


// --------------------------------------------
//                  setfocus
// Delayed focus setting to get around IE bug
// --------------------------------------------

function setFocusDelayed() {
    global_valfield.focus();
}

function setfocus(valfield) {
    // save valfield in global variable so value retained when routine exits
    global_valfield = valfield;
    setTimeout('setFocusDelayed()', 100);
}


// --------------------------------------------
//                  msg
// Display warn/error message in HTML element.
// commonCheck routine must have previously been called
// --------------------------------------------

function msg(fld,     // id of element to display message in
             msgtype, // class to give element ("warn" or "error")
             message) // string to display
{
    // setting an empty string can give problems if later set to a 
    // non-empty string, so ensure a space present. (For Mozilla and Opera one could 
    // simply use a space, but IE demands something more, like a non-breaking space.)
    var dispmessage;
    if (emptyString.test(message))
        dispmessage = String.fromCharCode(nbsp);
    else
        dispmessage = message;

    var elem = document.getElementById(fld);
    elem.firstChild.nodeValue = dispmessage;

    elem.className = msgtype;   // set the CSS class to adjust appearance of message
}

// --------------------------------------------
//            commonCheck
// Common code for all validation routines to:
// (a) check for older / less-equipped browsers
// (b) check if empty fields are required
// Returns true (validation passed), 
//         false (validation failed) or 
//         proceed (don't know yet)
// --------------------------------------------

var proceed = 2;

function commonCheck(valfield,   // element to be validated
                         infofield,  // id of element to receive info/error msg
                         required)   // true if required
{
    if (!document.getElementById)
        return true;  // not available on this browser - leave validation to the server
    var elem = document.getElementById(infofield);
    if (!elem.firstChild) return true;  // not available on this browser 
    if (elem.firstChild.nodeType != node_text) return true;  // infofield is wrong type of node  

    if (emptyString.test(valfield.value)) {
        if (required) {
            msg(infofield, "error", "ERROR: required");
            setfocus(valfield);
            return false;
        }
        else {
            msg(infofield, "warn", "");   // OK
            return true;
        }
    }
    return proceed;
}

// --------------------------------------------
//            validatePresent
// Validate if something has been entered
// Returns true if so 
// --------------------------------------------

function validatePresent(valfield,   // element to be validated
                         infofield) // id of element to receive info/error msg
{
    var stat = commonCheck(valfield, infofield, true);
    if (stat != proceed) return stat;

    msg(infofield, "warn", "");
    return true;
}

// --------------------------------------------
//               validateEmail
// Validate if e-mail address
// Returns true if so (and also if could not be executed because of old browser)
// --------------------------------------------

function validateEmail(valfield,   // element to be validated
                         infofield,  // id of element to receive info/error msg
                         required)   // true if required
{
    var stat = commonCheck(valfield, infofield, required);
    if (stat != proceed) return stat;

    var tfld = trim(valfield.value);  // value of field with whitespace trimmed off
    var email = /^[^@]+@[^@.]+\.[^@]*\w\w$/;
    if (!email.test(tfld)) {
        msg(infofield, "error", "ERROR: not a valid e-mail address");
        setfocus(valfield);
        return false;
    }

    var email2 = /^[A-Za-z][\w.-]+@\w[\w.-]+\.[\w.-]*[A-Za-z][A-Za-z]$/;
    if (!email2.test(tfld))
        msg(infofield, "warn", "Unusual e-mail address - check if correct");
    else
        msg(infofield, "warn", "");
    return true;
}


// --------------------------------------------
//            validateTelnr
// Validate telephone number
// Returns true if so (and also if could not be executed because of old browser)
// Permits spaces, hyphens, brackets and leading +
// --------------------------------------------

function validateTelnr(valfield,   // element to be validated
                         infofield,  // id of element to receive info/error msg
                         required)   // true if required
{
    var stat = commonCheck(valfield, infofield, required);
    if (stat != proceed) return stat;

    var tfld = trim(valfield.value);  // value of field with whitespace trimmed off
    var telnr = /^\+?[0-9 ()-]+[0-9]$/;
    if (!telnr.test(tfld)) {
        msg(infofield, "error", "ERROR: not a valid telephone number. Characters permitted are digits, space ()- and leading +");
        setfocus(valfield);
        return false;
    }

    var numdigits = 0;
    for (var j = 0; j < tfld.length; j++)
        if (tfld.charAt(j) >= '0' && tfld.charAt(j) <= '9') numdigits++;

    if (numdigits < 6) {
        msg(infofield, "error", "ERROR: " + numdigits + " digits - too short");
        setfocus(valfield);
        return false;
    }

    if (numdigits > 14)
        msg(infofield, "warn", numdigits + " digits - check if correct");
    else {
        if (numdigits < 10)
            msg(infofield, "warn", "Only " + numdigits + " digits - check if correct");
        else
            msg(infofield, "warn", "");
    }
    return true;
}

// --------------------------------------------
//             validateAge
// Validate person's age
// Returns true if OK 
// --------------------------------------------

function validateAge(valfield,   // element to be validated
                         infofield,  // id of element to receive info/error msg
                         required)   // true if required
{
    var stat = commonCheck(valfield, infofield, required);
    if (stat != proceed) return stat;

    var tfld = trim(valfield.value);
    var ageRE = /^[0-9]{1,3}$/
    if (!ageRE.test(tfld)) {
        msg(infofield, "error", "ERROR: not a valid age");
        setfocus(valfield);
        return false;
    }

    if (tfld >= 200) {
        msg(infofield, "error", "ERROR: not a valid age");
        setfocus(valfield);
        return false;
    }

    if (tfld > 110) msg(infofield, "warn", "Older than 110: check correct");
    else {
        if (tfld < 7) msg(infofield, "warn", "Bit young for this, aren't you?");
        else msg(infofield, "warn", "");
    }
    return true;
}