//---------------------------------------------------------------------
//Name : isEmpty()
//
//Data IN 
//	String
//
//Data OUT
//	true or false (boolean)
//
//Supporting functions :
//
//Comments :
// Returns true if string passed in is empty, false if it is not 
//
//Example :
//---------------------------------------------------------------------
function isEmpty(theString)
{
	theString = String(theString).toUpperCase();
	if (theString == "" || theString == "NULL" || theString == "UNDEFINED")
		return true;
	return false;
}
//---------------------------------------------------------------------
//Name : stripBlanks()
//
//Data IN 
//	String
//
//Data OUT
//	Stripped string
//
//Supporting functions :
//
//Comments :
// Strips blank spaces either side of the string passed in
//
//Example :
//---------------------------------------------------------------------
function stripBlanks(theString)
{
	var newString = "";
	for (i=0; i < theString.length; i++)
	{
		if (theString.substring(i,i+1) != " ")
		{
			newString = theString.substring(i,theString.length);
			break;
		}
	}
	for (j=newString.length; j > 0; j--)
	{
		if (newString.substring(j-1,j) != " ")
		{
			newString = newString.substring(0,j);
			break;
		}
	}
	return newString;
}
//---------------------------------------------------------------------
//Name : checkEmail()
//
//Data IN 
//	emailAddress String
//
//Data OUT
//	true or false (boolean)
//
//Supporting functions :
//
//Comments :
// Checks that email address is formatted correctly
//
//Example :
//---------------------------------------------------------------------
function checkEmail(emailAddr)
{
	<!-- Begin
	var emailStr = emailAddr;
	/* 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. */
		return false
	}
	var user=matchArray[1]
	var domain=matchArray[2]
	
	// See if "user" is valid 
	if (user.match(userPat)==null) {
		// user is not 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) {
			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;
	//  End -->	
}
//---------------------------------------------------------------------
//Name : checkEntry()
//
//Data IN 
//	formName String
//
//Data OUT
//	
//
//Supporting functions :
//
//Comments :
// Redirects to correct validation routine
//
//Example :
//---------------------------------------------------------------------
function checkEntry()
{
	if (isEmpty(stripBlanks(document.regform.emailAddress.value)))
	{
		alert("Please enter your e-mail address before continuing");
		document.regform.emailAddress.select();
		return false;
	}
	else
	{
		var validEmail = checkEmail(document.regform.emailAddress.value);
		if (!validEmail)
		{
			alert("Invalid e-mail address entered")
			return false
		}
	}
	return true;
}
function checkEmailFriendEntry()
{
	if (isEmpty(stripBlanks(document.emailform.yourName.value)))
	{
		alert("Please enter your name before continuing");
		document.emailform.yourName.focus();
		document.emailform.yourName.select();
		return false;
	}
	if (isEmpty(stripBlanks(document.emailform.emailAddress.value)))
	{
		alert("Please enter your e-mail address before continuing");
		document.emailform.emailAddress.select();
		return false;
	}
	else
	{
		var validEmail = checkEmail(document.emailform.emailAddress.value);
		if (!validEmail)
		{
			alert("Invalid e-mail address entered")
			document.emailform.emailAddress.select();
			return false
		}
	}
	if (isEmpty(stripBlanks(document.emailform.friendEmailAddress.value)))
	{
		alert("Please enter your friend's e-mail address before continuing");
		document.emailform.friendEmailAddress.select();
		return false;
	}
	else
	{
		var validEmail = checkEmail(document.emailform.friendEmailAddress.value);
		if (!validEmail)
		{
			alert("Invalid e-mail address entered for your friend")
			document.emailform.friendEmailAddress.select();
			return false
		}
	}
}