var digits = "0123456789";
var lowercaseLetters = "abcdefghijklmnopqrstuvwxyz"
var uppercaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

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

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

// CONSTANT STRING DECLARATIONS
// m is an abbreviation for "missing"

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

// i is an abbreviation for "invalid"
var iEmail = "This field must be a valid email address (like myname@somewhere.com). Please reenter it now.";

// p is an abbreviation for "prompt"
var pEntryPrompt = "Please enter a ";
var pEmail = "valid email address (like myname@mydomain.com).";

var defaultEmptyOK = false;

// Check whether string s is empty.

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

// 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;
}

// 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;
}

// Removes all characters which do NOT appear in string bag 
// from string s.

function stripCharsNotInBag (s, bag)

{   var i;
    var returnString = "";

    // Search through string's characters one by one.
    // If character is 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;
}

// Removes all whitespace characters from s.
// Global variable whitespace (see above)
// defines which characters are considered whitespace.

function stripWhitespace (s){
  return stripCharsInBag (s, whitespace)
}

// WORKAROUND FUNCTION FOR NAVIGATOR 2.0.2 COMPATIBILITY.
//
// The below function *should* be unnecessary.  In general,
// avoid using it.  Use the standard method indexOf instead.
//
// However, because of an apparent bug in indexOf on 
// Navigator 2.0.2, the below loop does not work as the
// body of stripInitialWhitespace:
//
// while ((i < s.length) && (whitespace.indexOf(s.charAt(i)) != -1))
//   i++;
//
// ... so we provide this workaround function charInString
// instead.
//
// charInString (CHARACTER c, STRING s)
//
// Returns true if single character c (actually a string)
// is contained within string s.

function charInString (c, s)
{   for (i = 0; i < s.length; i++)
    {   if (s.charAt(i) == c) return true;
    }
    return false
}

// Removes initial (leading) whitespace characters from s.
// Global variable whitespace (see above)
// defines which characters are considered whitespace.

function stripInitialWhitespace (s){
   var i = 0;

   while ((i < s.length) && charInString (s.charAt(i), whitespace))
       i++;
    
   return s.substring (i, s.length);
}

// Returns true if character c is an English letter 
// (A .. Z, a..z).
//
// NOTE: Need i18n version to support European characters.
// This could be tricky due to different character
// sets and orderings for various languages and platforms.

function isLetter (c)
{   return ( ((c >= "a") && (c <= "z")) || ((c >= "A") && (c <= "Z")) )
}

// Returns true if character c is a digit 
// (0 .. 9).

function isDigit (c)
{   return ((c >= "0") && (c <= "9"))
}

// Returns true if character c is a letter or digit.

function isLetterOrDigit (c)
{   return (isLetter(c) || isDigit(c))
}

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;
}

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))
    }
}

function isPositiveInteger (s)
{   var secondArg = defaultEmptyOK;

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

    // 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) ) );
}


// isNegativeInteger (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 isNegativeInteger (s)
{   var secondArg = defaultEmptyOK;

    if (isNegativeInteger.arguments.length > 1)
        secondArg = isNegativeInteger.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 negative, not positive, number

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


// isAlphabetic (STRING s [, BOOLEAN emptyOK])
// 
// Returns true if string s is English letters 
// (A .. Z, a..z) only.

function isAlphabetic (s){
  var i;

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

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

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

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

  // All characters are letters.
  return true;
}

// isAlphanumeric (STRING s [, BOOLEAN emptyOK])
// 
// Returns true if string s is English letters 
// (A .. Z, a..z) and numbers only.
//

function isAlphanumeric (s){
  var i;

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

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

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

  // All characters are numbers or letters.
  return true;
}


// isEmail (STRING s [, BOOLEAN emptyOK])
// 
// Email address must be of form a@b.c -- in other words:
// * there must be at least one character before the @
// * there must be at least one character before and after the .
// * the characters @ and . are both required

function isEmail (s){
  if (isEmpty(s)) 
    if (isEmail.arguments.length == 1) 
	  return defaultEmptyOK;
    else 
	  return (isEmail.arguments[1] == true);
   
    // is s whitespace?
  if (isWhitespace(s)) return false;
    
  // there must be >= 1 character before @, so we
  // start looking at character position 1 
  // (i.e. second character)
  var i = 1;
  var sLength = s.length;

  // look for @
  while ((i < sLength) && (s.charAt(i) != "@")){
    i++
  }

  if ((i >= sLength) || (s.charAt(i) != "@")) 
    return false;
  else 
    i += 2;

  // look for .
  while ((i < sLength) && (s.charAt(i) != ".")){
    i++
  }

  // there must be at least one character after the .
  if ((i >= sLength - 1) || (s.charAt(i) != ".")) 
	  return false;
  else return true;
}

/* FUNCTIONS TO NOTIFY USER OF INPUT REQUIREMENTS OR MISTAKES. */

// Display prompt string s in status bar.

function prompt (s)
{   window.status = s
}

// Display data entry prompt string s in status bar.

function promptEntry (s)
{   window.status = pEntryPrompt + s
}

function checkString (theField, s, emptyOK){
  if (checkString.arguments.length == 2) 
    emptyOK = defaultEmptyOK;
  if ((emptyOK == true) && (isEmpty(theField.value)))
    return true;
  if (isWhitespace(theField.value)){
    alert(mPrefix + s + mSuffix);
    theField.focus();
    theField.select();
    return false;
  }
  else return true;
}

function checkEmail (theField, emptyOK){
  if (checkEmail.arguments.length == 1)
    emptyOK = defaultEmptyOK;
  if ((emptyOK == true) && (isEmpty(theField.value))) 
    return true;
  else {
    if (!isEmail(theField.value, false)){
      alert(iEmail);
      theField.focus();
      theField.select();
      return false;
    }
    else return true;
  }
}

function checkAlpha(theField){
  if (!isAlphabetic(theField.value)) {
    alert("This field can only contain alphabetic characters. Please try again.");
    theField.focus();
    theField.select();
    return false;
  }
  else
	return true;
}

// Get checked value from radio button.

function getRadioButtonValue (radio){
   for (var i = 0; i < radio.length; i++){
     if (radio[i].checked)
       break 
   }
   return radio[i].value
}

// Is at least one checkbox checked?

function getCheckBoxChecked(theForm) {
  var oneChecked = false;
  for (i=0; i<theForm.elements.length; i++){
    with (theForm.elements[i])
      if (type == "checkbox"){
        if (checked) oneChecked = true;
        else value=0;
      }
  }
  return oneChecked;
}

function SetFocusCheckBox(theForm) {
  for (i=0; i<theForm.elements.length; i++)
    with (theForm.elements[i])
      if (type == "checkbox"){
        focus();
        break;
      }
  return true;
}