// 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 = "()- ";

// begin function list

// remove leading spaces
function lTrim(s)
{
	for (var i=0; i<s.length; i++)	{
		if (s.charAt(i) != " ") {break;}
	}
	return s.substring(i, s.length);
}

// remove trailing spaces
function rTrim(s)
{
	for (var i=s.length-1; i>=0; i--)	{
		if (s.charAt(i) != " ") {break;}
	}
	return s.substring(0, i+1);
}

// remove leading and trailing spaces
function trim(s)
{
	return lTrim(rTrim(s));
}

// function mid(STRING s , INTEGER start [, INTEGER len])
// returns a VB style MID function
function mid(s,start)
{
var len;
var newString = "";

	// see if length argument provided
	if (mid.arguments.length == 3) 
		len = mid.arguments[2];
	else
		len = s.length;

	for (i = start; i < s.length; i++)
	{
		ch = s.charAt(i);
		if (i < start + len)
			newString += ch;	
		else
			break;
	}
	return newString;
}

// Repeats a character expression a specified number of times.
// if count <= 0 function returns an empty string
function replicate(ch,count)
{
	var i;
	var expr="";
	
	if (count <= 0) return "";

	for (i=0; i < count; i++)
		expr += ch;

	return expr;			
}

// 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)
}


// reformat (TARGETSTRING, STRING, INTEGER, STRING, INTEGER ... )       
//
// Handy function for arbitrarily inserting formatting characters
// or delimiters of various kinds within TARGETSTRING.
//
// reformat takes one named argument, a string s, and any number
// of other arguments.  The other arguments must be integers or
// strings.  These other arguments specify how string s is to be
// reformatted and how and where other strings are to be inserted
// into it.
//
// reformat processes the other arguments in order one by one.
// * If the argument is an integer, reformat appends that number 
//   of sequential characters from s to the resultString.
// * If the argument is a string, reformat appends the string
//   to the resultString.
//
// NOTE: The first argument after TARGETSTRING must be a string.
// (It can be empty.)  The second argument must be an integer.
// Thereafter, integers and strings must alternate.  This is to
// provide backward compatibility to Navigator 2.0.2 JavaScript
// by avoiding use of the typeof operator.
//
// It is the caller's responsibility to make sure that we do not
// try to copy more characters from s than s.length.
//
// EXAMPLES:
//
// * To reformat a 10-digit U.S. phone number from "1234567890"
//   to "(123) 456-7890" make this function call:
//   reformat("1234567890", "(", 3, ") ", 3, "-", 4)
//
// * To reformat a 9-digit U.S. Social Security number from
//   "123456789" to "123-45-6789" make this function call:
//   reformat("123456789", "", 3, "-", 2, "-", 4)
//
// HINT:
//
// If you have a string which is already delimited in one way
// (example: a phone number delimited with spaces as "123 456 7890")
// and you want to delimit it in another way using function reformat,
// call function stripCharsNotInBag to remove the unwanted 
// characters, THEN call function reformat to delimit as desired.
//
// EXAMPLE:
//
// reformat (stripCharsNotInBag ("123 456 7890", digits), "(", 3, ") ", 3, "-", 4)

function reformat (s)

{   var arg;
    var sPos = 0;
    var resultString = "";

    for (var i = 1; i < reformat.arguments.length; i++) {
       arg = reformat.arguments[i];
       if (i % 2 == 1) resultString += arg;
       else {
           resultString += s.substring(sPos, sPos + arg);
           sPos += arg;
       }
    }
    return resultString;
}

function emailCheck (emailStr) {
/* The following pattern is used to check if the entered e-mail address
   fits the user@domain format.  It also is used to separate the username
   from the domain. */
var emailPat=/^(.+)@(.+)$/
/* The following string represents the pattern for matching all special
   characters.  We don't want to allow special characters in the address. 
   These characters include ( ) < > @ , ; : \ " . [ ]    */
var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]"
/* The following string represents the range of characters allowed in a 
   username or domainname.  It really states which chars aren't allowed. */
var validChars="\[^\\s" + specialChars + "\]"
/* The following pattern applies if the "user" is a quoted string (in
   which case, there are no rules about which characters are allowed
   and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com
   is a legal e-mail address. */
var quotedUser="(\"[^\"]*\")"
/* The following pattern applies for domains that are IP addresses,
   rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal
   e-mail address. NOTE: The square brackets are required. */
var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/
/* The following string represents an atom (basically a series of
   non-special characters.) */
var atom=validChars + '+'
/* The following string represents one word in the typical username.
   For example, in john.doe@somewhere.com, john and doe are words.
   Basically, a word is either an atom or quoted string. */
var word="(" + atom + "|" + quotedUser + ")"
// The following pattern describes the structure of the user
var userPat=new RegExp("^" + word + "(\\." + word + ")*$")
/* The following pattern describes the structure of a normal symbolic
   domain, as opposed to ipDomainPat, shown above. */
var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$")


/* Finally, let's start trying to figure out if the supplied address is
   valid. */

/* Begin with the coarse pattern to simply break up user@domain into
   different pieces that are easy to analyze. */
var matchArray=emailStr.match(emailPat)
if (matchArray==null) {
  /* Too many/few @'s or something; basically, this address doesn't
     even fit the general mould of a valid e-mail address. */
	alert("Email address seems incorrect (check @ and .'s)")
	return false
}
var user=matchArray[1]
var domain=matchArray[2]

// See if "user" is valid 
if (user.match(userPat)==null) {
    // user is not valid
    alert("The username doesn't seem to be valid.")
    return false
}

/* if the e-mail address is at an IP address (as opposed to a symbolic
   host name) make sure the IP address is valid. */
var IPArray=domain.match(ipDomainPat)
if (IPArray!=null) {
    // this is an IP address
	  for (var i=1;i<=4;i++) {
	    if (IPArray[i]>255) {
	        alert("Destination IP address is invalid!")
		return false
	    }
    }
    return true
}

// Domain is symbolic name
var domainArray=domain.match(domainPat)
if (domainArray==null) {
	alert("The domain name doesn't seem to be valid.")
    return false
}

/* domain name seems valid, but now make sure that it ends in a
   three-letter word (like com, edu, gov) or a two-letter word,
   representing country (uk, nl), and that there's a hostname preceding 
   the domain or country. */

/* Now we need to break up the domain to get a count of how many atoms
   it consists of. */
var atomPat=new RegExp(atom,"g")
var domArr=domain.match(atomPat)
var len=domArr.length
if (domArr[domArr.length-1].length<2 || 
    domArr[domArr.length-1].length>3) {
   // the address must end in a two letter or three letter word.
   alert("The address must end in a three-letter domain, or two letter country.")
   return false
}

// Make sure there's a host name preceding the domain.
if (len<2) {
   var errStr="This address is missing a hostname!"
   alert(errStr)
   return false
}

// If we've gotten this far, everything's valid!
return true;
}