// FormChek.js
//
// SUMMARY
//
// This is a set of JavaScript functions for validating input on 
// an HTML form.  Functions are provided to validate:
//
//      - U.S. and international phone/fax numbers
//      - U.S. ZIP codes (5 or 9 digit postal codes)
//      - U.S. Postal Codes (2 letter abbreviations for names of states)
//      - U.S. Social Security Numbers (abbreviated as SSNs)
//      - email addresses
//	- dates (entry of year, month, and day and validity of combined date)
//	- credit card numbers
//
// Supporting utility functions validate that:
//
//      - characters are Letter, Digit, or LetterOrDigit
//      - strings are a Signed, Positive, Negative, Nonpositive, or
//        Nonnegative integer
//      - strings are a Float or a SignedFloat
//      - strings are Alphabetic, Alphanumeric, or Whitespace
//      - strings contain an integer within a specified range
//
// 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:
//
// isWhitespace (s)                    Check whether string s is empty or whitespace.
// isLetter (c)                        Check whether character c is an English letter 
// isDigit (c)                         Check whether character c is a digit 
// isLetterOrDigit (c)                 Check whether character c is a letter or digit.
// isInteger (s [,eok])                True if all characters in string s are numbers.
// 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.
// isNonnegativeInteger (s [,eok])     True if string s is an integer >= 0.
// isNegativeInteger (s [,eok])        True if s is an integer < 0.
// isNonpositiveInteger (s [,eok])     True if s is an integer <= 0.
// 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.)
// isAlphabetic (s [,eok])             True if string s is English letters 
// isAlphanumeric (s [,eok])           True if string s is English letters and numbers only.
// 
// isSSN (s [,eok])                    True if string s is a valid U.S. Social Security Number.
// isUSPhoneNumber (s [,eok])          True if string s is a valid U.S. Phone Number. 
// isInternationalPhoneNumber (s [,eok]) True if string s is a valid international phone number.
// 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
// isEmail (s [,eok])                  True if string s is a valid email address.
// isYear (s [,eok])                   True if string s is a valid Year number.
// isIntegerInRange (s, a, b [,eok])   True if string s is an integer between a and b, inclusive.
// 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.
// daysInFebruary (year)               Returns number of days in February of that year.
// isDate (year, month, day)           True if string arguments form a valid date.


// 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.
// stripWhitespace (s)                 Removes all whitespace characters from s.
// stripInitialWhitespace (s)          Removes initial (leading) whitespace characters from s.
// reformat (TARGETSTRING, STRING,     Function for inserting formatting characters or
//   INTEGER, STRING, INTEGER ... )       delimiters into TARGETSTRING.                                       
// reformatZIPCode (ZIPString)         If 9 digits, inserts separator hyphen.
// reformatSSN (SSN)                   Reformats as 123-45-6789.
// reformatUSPhone (USPhone)           Reformats as (123) 456-789.


// 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.
// 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.
// checkUSPhone (theField [,eok])      Check that theField.value is a valid US Phone.
// checkInternationalPhone (theField [,eok])  Check that theField.value is a valid International Phone.
// checkEmail (theField [,eok])        Check that theField.value is a valid Email.
// checkSSN (theField [,eok])          Check that theField.value is a valid SSN.
// checkYear (theField [,eok])         Check that theField.value is a valid Year.
// checkMonth (theField [,eok])        Check that theField.value is a valid Month.
// checkDay (theField [,eok])          Check that theField.value is a valid Day.
// checkDate (yearField, monthField, dayField, labelString, OKtoOmitDay)
//                                     Check that field values form a valid date.
// getRadioButtonValue (radio)         Get checked value from radio button.
// checkCreditCard (radio, theField)   Validate credit card info.


// CREDIT CARD DATA VALIDATION FUNCTIONS
// 
// isCreditCard (st)              True if credit card number passes the Luhn Mod-10 test.
// isVisa (cc)                    True if string cc is a valid VISA number.
// isMasterCard (cc)              True if string cc is a valid MasterCard number.
// isAmericanExpress (cc)         True if string cc is a valid American Express number.
// isDinersClub (cc)              True if string cc is a valid Diner's Club number.
// isCarteBlanche (cc)            True if string cc is a valid Carte Blanche number.
// isDiscover (cc)                True if string cc is a valid Discover card number.
// isEnRoute (cc)                 True if string cc is a valid enRoute card number.
// isJCB (cc)                     True if string cc is a valid JCB card number.
// isAnyCard (cc)                 True if string cc is a valid card number for any of the accepted types.
// isCardMatch (Type, Number)     True if Number is valid for credic card of type Type.
//
// Other stub functions are retained for backward compatibility with LivePayment code.
// See comments below for details.
//
// Performance hint: when you deploy this file on your website, strip out the
// comment lines from the source code as well as any of the functions which
// you don't need.  This will give you a smaller .js file and achieve faster
// downloads.
//
// 18 Feb 97 created Eric Krock
//
// (c) 1997 Netscape Communications Corporation



// VARIABLE DECLARATIONS

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 = "."


// non-digit characters which are allowed in phone numbers
var phoneNumberDelimiters = "()- ";


// characters which are allowed in US phone numbers
var validUSPhoneChars = digits + phoneNumberDelimiters;


// characters which are allowed in international phone numbers
// (a leading + is OK)
var validWorldPhoneChars = digits + phoneNumberDelimiters + "+";


// non-digit characters which are allowed in 
// Social Security Numbers
var SSNDelimiters = "- ";



// characters which are allowed in Social Security Numbers
var validSSNChars = digits + SSNDelimiters;



// U.S. Social Security Numbers have 9 digits.
// They are formatted as 123-45-6789.
var digitsInSocialSecurityNumber = 9;



// U.S. phone numbers have 10 digits.
// They are formatted as 123 456 7890 or (123) 456-7890.
var digitsInUSPhoneNumber = 10;



// 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


// non-digit characters which are allowed in credit card numbers
var creditCardDelimiters = " "


// CONSTANT STRING DECLARATIONS
// (grouped for ease of translation and localization)

// 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."

// s is an abbreviation for "string"

var sUSLastName = "Last Name"
var sUSFirstName = "First Name"
var sWorldLastName = "Family Name"
var sWorldFirstName = "Given Name"
var sTitle = "Title"
var sCompanyName = "Company Name"
var sUSAddress = "Street Address"
var sWorldAddress = "Address"
var sCity = "City"
var sStateCode = "State Code"
var sWorldState = "State, Province, or Prefecture"
var sCountry = "Country"
var sZIPCode = "ZIP Code"
var sWorldPostalCode = "Postal Code"
var sPhone = "Phone Number"
var sFax = "Fax Number"
var sDateOfBirth = "Date of Birth"
var sExpirationDate = "Expiration Date"
var sEmail = "Email"
var sSSN = "Social Security Number"
var sCreditCardNumber = "Credit Card Number"
var sOtherInfo = "Other Information"




// i is an abbreviation for "invalid"

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 iUSPhone = "This field must be a 10 digit U.S. phone number (like 415 555 1212). Please reenter it now."
var iWorldPhone = "This field must be a valid international phone number. Please reenter it now."
var iSSN = "This field must be a 9 digit U.S. social security number (like 123 45 6789). Please reenter it now."
var iEmail = "This field must be a valid email address (like foo@bar.com). Please reenter it now."
var iCreditCardPrefix = "This is not a valid "
var iCreditCardSuffix = " credit card number. (Click the link on this form to see a list of sample numbers.) Please reenter it now."
var iDay = "This field must be a day number between 1 and 31.  Please reenter it now."
var iMonth = "This field must be a month number between 1 and 12.  Please reenter it now."
var iYear = "This field must be a 2 or 4 digit year number.  Please reenter it now."
var iDatePrefix = "The Day, Month, and Year for "
var iDateSuffix = " do not form a valid date.  Please reenter them now."



// p is an abbreviation for "prompt"

var pEntryPrompt = "Please enter a "
var pStateCode = "2 character code (like CA)."
var pZIPCode = "5 or 9 digit U.S. ZIP Code (like 94043)."
var pUSPhone = "10 digit U.S. phone number (like 415 555 1212)."
var pWorldPhone = "international phone number."
var pSSN = "9 digit U.S. social security number (like 123 45 6789)."
var pEmail = "valid email address (like foo@bar.com)."
var pCreditCard = "valid credit card number."
var pDay = "day number between 1 and 31."
var pMonth = "month number between 1 and 12."
var pYear = "2 or 4 digit year number."


// 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.
//
// You can change this default behavior globally (for all 
// functions which use defaultEmptyOK) by changing the value
// of defaultEmptyOK.
//
// 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.

var defaultEmptyOK = false




// Attempting to make this library run on Navigator 2.0,
// so I'm supplying this array creation