//kas 10/09/03 from http://developer.netscape.com/docs/examples/javascript/formval/overview.html

// isWhitespace (s)                    Check whether string s is empty or whitespace.
// isYear (s [,eok])                   True if string s is a valid Year number.
// isMonth (s [,eok])                  True if string s is a valid month between 1 and 12.
// isDay (s [,eok])                    True if string s is a valid day between 1 and 31.
// isDate (year, month, day)           True if string arguments form a valid date.
// daysInFebruary (year)               Returns number of days in February of that year.
// isNonnegativeInteger (s [,eok])     True if string s is an integer >= 0.
// isIntegerInRange (s, a, b [,eok])   True if string s is an integer between a and b, inclusive.
// isSignedInteger (s [,eok])          True if all characters in string s are numbers; leading + or - allowed.
// isPositiveInteger (s [,eok])        True if string s is an integer > 0.
// isInteger (s [,eok])                True if all characters in string s are numbers.
// isDigit (c)                         Check whether character c is a digit 
// isFloat (s [,eok])                  True if string s is an unsigned floating point (real) number. (Integers also OK.)
// isSignedFloat (s [,eok])            True if string s is a floating point number; leading + or - allowed. (Integers also OK.)
// stripCharsInBag (s, bag)            Removes all characters in string bag from string s.

// isZIPCode (s [,eok])                True if string s is a valid U.S. ZIP code.
// isStateCode (s [,eok])              True if string s is a valid U.S. Postal Code

// warnEmpty (theField, s)             Notify user that required field theField is empty.
// warnInvalid (theField, s)           Notify user that contents of field theField are invalid.

// checkString (theField, s [,eok])    Check that theField.value is not empty or all whitespace.
// checkStateCode (theField)           Check that theField.value is a valid U.S. state code.
// checkZIPCode (theField [,eok])      Check that theField.value is a valid ZIP code.


var daysInMonth = Array(12);
daysInMonth[1] = 31;
daysInMonth[2] = 29;   // must programmatically check this
daysInMonth[3] = 31;
daysInMonth[4] = 30;
daysInMonth[5] = 31;
daysInMonth[6] = 30;
daysInMonth[7] = 31;
daysInMonth[8] = 31;
daysInMonth[9] = 30;
daysInMonth[10] = 31;
daysInMonth[11] = 30;
daysInMonth[12] = 31;


var digits = "0123456789";

// whitespace characters
var whitespace = " \t\n\r";

// Valid U.S. Postal Codes for states, territories, armed forces, etc.
// See http://www.usps.gov/ncsc/lookups/abbr_state.txt.
var USStateCodeDelimiter = "|";
var USStateCodes = "AL|AK|AS|AZ|AR|CA|CO|CT|DE|DC|FM|FL|GA|GU|HI|ID|IL|IN|IA|KS|KY|LA|ME|MH|MD|MA|MI|MN|MS|MO|MT|NE|NV|NH|NJ|NM|NY|NC|ND|MP|OH|OK|OR|PW|PA|PR|RI|SC|SD|TN|TX|UT|VT|VI|VA|WA|WV|WI|WY|AE|AA|AE|AE|AP"

// Global variable defaultEmptyOK defines default return value 
// for many functions when they are passed the empty string. 
// By default, they will return defaultEmptyOK.
var defaultEmptyOK = false;

// decimal point character differs by language and culture
var decimalPointDelimiter = "."

// non-digit characters which are allowed in ZIP Codes
var ZIPCodeDelimiters = "-";
// our preferred delimiter for reformatting ZIP Codes
var ZIPCodeDelimeter = "-"
// characters which are allowed in Social Security Numbers
var validZIPCodeChars = digits + ZIPCodeDelimiters
// U.S. ZIP codes have 5 or 9 digits.
// They are formatted as 12345 or 12345-6789.
var digitsInZIPCode1 = 5
var digitsInZIPCode2 = 9

var mPrefix = "You did not enter a value into the "
var mSuffix = " field. This is a required field. Please enter it now."

var iStateCode = "This field must be a valid two character U.S. state abbreviation (like CA for California). Please reenter it now."
var iZIPCode = "This field must be a 5 or 9 digit U.S. ZIP Code (like 94043). Please reenter it now."
var iEmail = "This field must be a valid email address (like foo@bar.com). Please reenter it now."


// isYear (STRING s [, BOOLEAN emptyOK])
// 
// isYear returns true if string s is a valid 
// Year number.  Must be 2 or 4 digits only.
// 
// For Year 2000 compliance, you are advised
// to use 4-digit year numbers everywhere.
//
// And yes, this function is not Year 10000 compliant, but 
// because I am giving you 8003 years of advance notice,
// I don't feel very guilty about this ...
//
// For B.C. compliance, write your own function. ;->
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.
function isYear (s)
{   if (isEmpty(s)) 
       if (isYear.arguments.length == 1) return defaultEmptyOK;
       else return (isYear.arguments[1] == true);
    if (!isNonnegativeInteger(s)) return false;
    return ((s.length == 2) || (s.length == 4));
}


// isMonth (STRING s [, BOOLEAN emptyOK])
// 
// isMonth returns true if string s is a valid 
// month number between 1 and 12.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.
function isMonth (s)
{   if (isEmpty(s)) 
       if (isMonth.arguments.length == 1) return defaultEmptyOK;
       else return (isMonth.arguments[1] == true);
    return isIntegerInRange (s, 1, 12);
}


// isDay (STRING s [, BOOLEAN emptyOK])
// 
// isDay returns true if string s is a valid 
// day number between 1 and 31.
// 
// For explanation of optional argument emptyOK,
// see comments of function isInteger.
function isDay (s)
{   if (isEmpty(s)) 
       if (isDay.arguments.length == 1) return defaultEmptyOK;
       else return (isDay.arguments[1] == true);   
    return isIntegerInRange (s, 1, 31);
}


// isDate (STRING year, STRING month, STRING day)
//
// isDate returns true if string arguments year, month, and day 
// form a valid date.
// 
function isDate (year, month, day)
{   // catch invalid years (not 2- or 4-digit) and invalid months and days.
    if (! (isYear(year, false) && isMonth(month, false) && isDay(day, false))) return false;

    // Explicitly change type to integer to make code work in both
    // JavaScript 1.1 and JavaScript 1.2.
    var intYear = parseInt(year);
    var intMonth = parseInt(month);
    var intDay = parseInt(day);

    // catch invalid days, except for February
    if (intDay > daysInMonth[intMonth]) return false; 

    if ((intMonth == 2) && (intDay > daysInFebruary(intYear))) return false;

    return true;
}

// isIntegerInRange (STRING s, INTEGER a, INTEGER b [, BOOLEAN emptyOK])
// 
// isIntegerInRange returns true if string s is an integer 
// within the range of integer arguments a and b, inclusive.
// 
// For explanation of optional argument emptyOK,
// see comments of function isInteger.
function isIntegerInRange (s, a, b)
{   if (isEmpty(s)) 
       if (isIntegerInRange.arguments.length == 1) return defaultEmptyOK;
       else return (isIntegerInRange.arguments[1] == true);

    // Catch non-integer strings to avoid creating a NaN below,
    // which isn't available on JavaScript 1.0 for Windows.
    if (!isInteger(s, false)) return false;

    // Now, explicitly change the type to integer via parseInt
    // so that the comparison code below will work both on 
    // JavaScript 1.2 (which typechecks in equality comparisons)
    // and JavaScript 1.1 and before (which doesn't).
    var num = parseInt (s);
    return ((num >= a) && (num <= b));
}
// daysInFebruary (INTEGER year)
// 
// Given integer argument year,
// returns number of days in February of that year.


function daysInFebruary (year)
{   // February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (  ((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0) ) ) ? 29 : 28 );
}


// isSignedInteger (STRING s [, BOOLEAN emptyOK])
// 
// Returns true if all characters are numbers; 
// first character is allowed to be + or - as well.
//
// Does not accept floating point, exponential notation, etc.
//
// We don't use parseInt because that would accept a string
// with trailing non-numeric characters.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.
//
// EXAMPLE FUNCTION CALL:          RESULT:
// isSignedInteger ("5")           true 
// isSignedInteger ("")            defaultEmptyOK
// isSignedInteger ("-5")          true
// isSignedInteger ("+5")          true
// isSignedInteger ("", false)     false
// isSignedInteger ("", true)      true
function isSignedInteger (s)

{   if (isEmpty(s)) 
       if (isSignedInteger.arguments.length == 1) return defaultEmptyOK;
       else return (isSignedInteger.arguments[1] == true);

    else {
        var startPos = 0;
        var secondArg = defaultEmptyOK;

        if (isSignedInteger.arguments.length > 1)
            secondArg = isSignedInteger.arguments[1];

        // skip leading + or -
        if ( (s.charAt(0) == "-") || (s.charAt(0) == "+") )
           startPos = 1;    
        return (isInteger(s.substring(startPos, s.length), secondArg))
    }
}


// isPositiveInteger (STRING s [, BOOLEAN emptyOK])
// 
// Returns true if string s is an integer > 0.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isPositiveInteger (s)
{   var secondArg = defaultEmptyOK;

    if (isPositiveInteger.arguments.length > 1)
        secondArg = isPositiveInteger.arguments[1];

    // The next line is a bit byzantine.  What it means is:
    // a) s must be a signed integer, AND
    // b) one of the following must be true:
    //    i)  s is empty and we are supposed to return true for
    //        empty strings
    //    ii) this is a positive, not negative, number

    return (isSignedInteger(s, secondArg)
         && ( (isEmpty(s) && secondArg)  || (parseInt (s) > 0) ) );
}


// isNonnegativeInteger (STRING s [, BOOLEAN emptyOK])
// 
// Returns true if string s is an integer >= 0.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isNonnegativeInteger (s)
{   var secondArg = defaultEmptyOK;

    if (isNonnegativeInteger.arguments.length > 1)
        secondArg = isNonnegativeInteger.arguments[1];

    // The next line is a bit byzantine.  What it means is:
    // a) s must be a signed integer, AND
    // b) one of the following must be true:
    //    i)  s is empty and we are supposed to return true for
    //        empty strings
    //    ii) this is a number >= 0

    return (isSignedInteger(s, secondArg)
         && ( (isEmpty(s) && secondArg)  || (parseInt (s) >= 0) ) );
}



// isInteger (STRING s [, BOOLEAN emptyOK])
// 
// Returns true if all characters in string s are numbers.
//
// Accepts non-signed integers only. Does not accept floating 
// point, exponential notation, etc.
//
// We don't use parseInt because that would accept a string
// with trailing non-numeric characters.
//
// By default, returns defaultEmptyOK if s is empty.
// There is an optional second argument called emptyOK.
// emptyOK is used to override for a single function call
//      the default behavior which is specified globally by
//      defaultEmptyOK.
// If emptyOK is false (or any value other than true), 
//      the function will return false if s is empty.
// If emptyOK is true, the function will return true if s is empty.
//
// EXAMPLE FUNCTION CALL:     RESULT:
// isInteger ("5")            true 
// isInteger ("")             defaultEmptyOK
// isInteger ("-5")           false
// isInteger ("", true)       true
// isInteger ("", false)      false
// isInteger ("5", false)     true

function isInteger (s)

{   var i;

    if (isEmpty(s)) 
       if (isInteger.arguments.length == 1) return defaultEmptyOK;
       else return (isInteger.arguments[1] == true);

    // Search through string's characters one by one
    // until we find a non-numeric character.
    // When we do, return false; if we don't, return true.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character is number.
        var c = s.charAt(i);

        if (!isDigit(c)) return false;
    }

    // All characters are numbers.
    return true;
}

// Returns true if character c is a digit 
// (0 .. 9).
function isDigit (c)
{   return ((c >= "0") && (c <= "9"))
}

// Check whether string s is empty.

function isEmpty(s)
{   return ((s == null) || (s.length == 0))
}


// isFloat (STRING s [, BOOLEAN emptyOK])
// 
// True if string s is an unsigned floating point (real) number. 
//
// Also returns true for unsigned integers. If you wish
// to distinguish between integers and floating point numbers,
// first call isInteger, then call isFloat.
//
// Does not accept exponential notation.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isFloat (s)

{   var i;
    var seenDecimalPoint = false;

    if (isEmpty(s)) 
       if (isFloat.arguments.length == 1) return defaultEmptyOK;
       else return (isFloat.arguments[1] == true);

    if (s == decimalPointDelimiter) return false;

    // Search through string's characters one by one
    // until we find a non-numeric character.
    // When we do, return false; if we don't, return true.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character is number.
        var c = s.charAt(i);

        if ((c == decimalPointDelimiter) && !seenDecimalPoint) seenDecimalPoint = true;
        else if (!isDigit(c)) return false;
    }

    // All characters are numbers.
    return true;
}





// isSignedFloat (STRING s [, BOOLEAN emptyOK])
// 
// True if string s is a signed or unsigned floating point 
// (real) number. First character is allowed to be + or -.
//
// Also returns true for unsigned integers. If you wish
// to distinguish between integers and floating point numbers,
// first call isSignedInteger, then call isSignedFloat.
//
// Does not accept exponential notation.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isSignedFloat (s)

{   if (isEmpty(s)) 
       if (isSignedFloat.arguments.length == 1) return defaultEmptyOK;
       else return (isSignedFloat.arguments[1] == true);

    else {
        var startPos = 0;
        var secondArg = defaultEmptyOK;

        if (isSignedFloat.arguments.length > 1)
            secondArg = isSignedFloat.arguments[1];

        // skip leading + or -
        if ( (s.charAt(0) == "-") || (s.charAt(0) == "+") )
           startPos = 1;    
        return (isFloat(s.substring(startPos, s.length), secondArg))
    }
}





// isPercent (STRING s [, BOOLEAN emptyOK])
// 
// True if string s is an unsigned floating point 
// (real) number from 0 to 100.
//
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isPercent (s)

{   if (isEmpty(s)) 
       if (isPercent.arguments.length == 1) return defaultEmptyOK;
       else return (isPercent.arguments[1] == true);

    else {
        var secondArg = defaultEmptyOK;

        if (isPercent.arguments.length > 1)
            secondArg = isPercent.arguments[1];

        return (
                isFloat(s, secondArg) &&
                (Number(s) >= 0) &&
                (Number(s) <= 100)
               );
    }
}

// Returns true if string s is empty or 
// whitespace characters only.

function isWhitespace (s)

{   var i;

    // Is s empty?
    if (isEmpty(s)) return true;

    // Search through string's characters one by one
    // until we find a non-whitespace character.
    // When we do, return false; if we don't, return true.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);

        if (whitespace.indexOf(c) == -1) return false;
    }

    // All characters are whitespace.
    return true;
}

// isZIPCode (STRING s [, BOOLEAN emptyOK])
// 
// isZIPCode returns true if string s is a valid 
// U.S. ZIP code.  Must be 5 or 9 digits only.
//
// NOTE: Strip out any delimiters (spaces, hyphens, etc.)
// from string s before calling this function.  
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isZIPCode (s)
{  if (isEmpty(s)) 
       if (isZIPCode.arguments.length == 1) return defaultEmptyOK;
       else return (isZIPCode.arguments[1] == true);
   return (isInteger(s) && 
            ((s.length == digitsInZIPCode1) ||
             (s.length == digitsInZIPCode2)))
}





// isStateCode (STRING s [, BOOLEAN emptyOK])
// 
// Return true if s is a valid U.S. Postal Code 
// (abbreviation for state).
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isStateCode(s)
{   if (isEmpty(s)) 
       if (isStateCode.arguments.length == 1) return defaultEmptyOK;
       else return (isStateCode.arguments[1] == true);
    return ( (USStateCodes.indexOf(s) != -1) &&
             (s.indexOf(USStateCodeDelimiter) == -1) )
}


// checkStateCode (TEXTFIELD theField [, BOOLEAN emptyOK==false])
//
// Check that string theField.value is a valid U.S. state code.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function checkStateCode (theField, emptyOK)
{   if (checkStateCode.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    {  theField.value = theField.value.toUpperCase();
       if (!isStateCode(theField.value, false)) 
          return warnInvalid (theField, iStateCode);
       else return true;
    }
}

// checkZIPCode (TEXTFIELD theField [, BOOLEAN emptyOK==false])
//
// Check that string theField.value is a valid ZIP code.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function checkZIPCode (theField, emptyOK)
{   if (checkZIPCode.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    { var normalizedZIP = stripCharsInBag(theField.value, ZIPCodeDelimiters)
      if (!isZIPCode(normalizedZIP, false)) 
         return warnInvalid (theField, iZIPCode);
      else 
      {  // if you don't want to insert a hyphen, comment next line out
         //theField.value = reformatZIPCode(normalizedZIP)
         return true;
      }
    }
}



// Notify user that required field theField is empty.
// String s describes expected contents of theField.value.
// Put focus in theField and return false.

function warnEmpty (theField, s)
{   theField.focus()
    alert(mPrefix + s + mSuffix)
    return false
}



// Notify user that contents of field theField are invalid.
// String s describes expected contents of theField.value.
// Put select theField, pu focus in it, and return false.

function warnInvalid (theField, s)
{   theField.focus()
    theField.select()
    alert(s)
    return false
}

// Removes all characters which appear in string bag from string s.

function stripCharsInBag (s, bag)

{   var i;
    var returnString = "";

    // Search through string's characters one by one.
    // If character is not in bag, append to returnString.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }

    return returnString;
}

// checkString (TEXTFIELD theField, STRING s, [, BOOLEAN emptyOK==false])
//
// Check that string theField.value is not all whitespace.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function checkString (theField, s, emptyOK)
{   // Next line is needed on NN3 to avoid "undefined is not a number" error
    // in equality comparison below.
    if (checkString.arguments.length == 2) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    if (isWhitespace(theField.value)) 
       return warnEmpty (theField, s);
    else return true;
}