// FormChek.js
//
// SUMMARY
//
// This is a set of JavaScript functions for validating input on 
// an HTML form.  Functions are provided to validate:
//
//      - U.S. phone/fax numbers
//      - U.S. ZIP codes (5 or 9 digit postal codes)
//      - email addresses
//
// Supporting utility functions validate that:
//
//      - characters are Letter, Digit, or LetterOrDigit
//      - strings are Alphanumeric
//
// Functions are also provided to interactively check the
// above kinds of data and prompt the user if they have
// been entered incorrectly.
//
// Other utility functions are provided to:
//
// 	- remove from a string characters which are/are not 
//	  in a "bag" of selected characters	
// 	- reformat a string, adding delimiter characters
//	- strip whitespace/leading whitespace from a string
//      - reformat U.S. phone numbers, ZIP codes, and Social
//        Security numbers
//
//
// Many of the below functions take an optional parameter eok (for "emptyOK")
// which determines whether the empty string will return true or false.
// Default behavior is controlled by global variable defaultEmptyOK.
//
// BASIC DATA VALIDATION FUNCTIONS:
//
// isInteger (s [,eok])                True if all characters in string s are numbers.
// isAlphanumeric (s [,eok])           True if string s is English letters and numbers only.
// 
// isUSPhoneNumber (s [,eok])          True if string s is a valid U.S. Phone Number. 
// isZIPCode (s [,eok])                True if string s is a valid U.S. ZIP code.
// isEmail (s [,eok])                  True if string s is a valid email address.

// FUNCTIONS TO REFORMAT DATA:
//
// stripCharsInBag (s, bag)            Removes all characters in string bag from string s.
// stripCharsNotInBag (s, bag)         Removes all characters NOT in string bag from string s.


// FUNCTIONS TO PROMPT USER:
//
// prompt (s)                          Display prompt string s in status bar.
// promptEntry (s)                     Display data entry prompt string s in status bar.
// warnEmpty (theField, s)             Notify user that required field theField is empty.
// warnInvalid (theField, s)           Notify user that contents of field theField are invalid.


// FUNCTIONS TO INTERACTIVELY CHECK FIELD CONTENTS:
//
// checkString (theField, s [,eok])    Check that theField.value is not empty or all whitespace.
// checkZIPCode (theField [,eok])      Check that theField.value is a valid ZIP code.
// checkUSPhone (theField [,eok])      Check that theField.value is a valid US Phone.
// checkEmail (theField [,eok])        Check that theField.value is a valid Email.
//
// REGULAR EXPRESSION DECLARATIONS
// Notes which apply to all the regexps below:
// (1) We want to only match strings exactly. In other words,
//     we only want to return true if the string being tested
//     matches the regular expression with no leading or trailing
//     unmatched characters. So, we begin each regexp with
//     the special character ^ (which matches beginning of input)
//     and end each regexp with the special character $ (which
//     matches end of input).
// (2) For explanations of the regexp special characters such as
//     ^ $ \s + [] \d * ! ? \ .
//     see http://developer.netscape.com/library/documentation/communicator/jsguide/regexp.htm


// VARIABLE DECLARATIONS
var phoneNumberDelimiters = "()- ";
var defaultEmptyOK = false;
var digitsInUSPhoneNumber = 10;
var digitsInZIPCode1 = 5
var digitsInZIPCode2 = 9

var reInteger = /^\d+$/
var reAlphanumeric = /^[a-zA-Z0-9\s]+$/
var reEmail = /^[\w\.-]+@[\w\.-]+\.[a-zA-Z]+$/

//var reEmail = /^.+\@.+\..+$/

// Global variable defaultEmptyOK defines default return value 
// for many functions when they are passed the empty string. 
// By default, they will return defaultEmptyOK.
//
// defaultEmptyOK is false, which means that by default, 
// these functions will do "strict" validation.  Function
// isInteger, for example, will only return true if it is
// passed a string containing an integer; if it is passed
// the empty string, it will return false.
//
// Most of these functions have an optional argument emptyOK
// which allows you to override the default behavior for 
// the duration of a function call.
//
// This functionality is useful because it is possible to
// say "if the user puts anything in this field, it must
// be an integer (or a phone number, or a string, etc.), 
// but it's OK to leave the field empty too."
// This is the case for fields which are optional but which
// must have a certain kind of content if filled in.

// VALIDATION FUNCTIONS

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

function checkUSPhone (theField, emptyOK)
{   if (checkUSPhone.arguments.length == 1) emptyOK = defaultEmptyOK;
	if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    {  var normalizedPhone = stripCharsInBag(theField.value, phoneNumberDelimiters)
       if (!isUSPhoneNumber(normalizedPhone, false)) 
          return false//warnInvalid (theField, "Phone Number is not in correct format");
       else 
       {  // if you don't want to reformat as (123) 456-789, comment next line out
          theField.value = normalizedPhone//reformatUSPhone(normalizedPhone)
          return true;
       }
    }
}
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, phoneNumberDelimiters)
      if (!isZIPCode(normalizedZIP, false)) 
         return false//warnInvalid (theField, "Zip Code is not correct format.");
      else 
      {  // if you don't want to insert a hyphen, comment next line out
         theField.value = normalizedZIP//reformatZIPCode(normalizedZIP)
         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)) 
       return false//warnInvalid (theField, iEmail);
    else return true;
}

function isAlphanumeric (s)

{   var i;

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

    else {
       return reAlphanumeric.test(s)
    }
}

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

function isEmail (s)

{   if (isEmpty(s)) 
       if (isEmail.arguments.length == 1) return defaultEmptyOK;
       else return (isEmail.arguments[1] == true);
    
    else {
       return reEmail.test(s)
    }
}

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

function isInteger (s)

{   var i;

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

    return reInteger.test(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;
}

function isUSPhoneNumber (s)
{	if (isEmpty(s)) 
       if (isUSPhoneNumber.arguments.length == 1) return defaultEmptyOK;
       else return (isUSPhoneNumber.arguments[1] == true);
    return (isInteger(s) && s.length == digitsInUSPhoneNumber)
}

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