// Email-Validierung
// Code: Sandeep V. Tamhankar (stamhankar@hotmail.com)
function emailCheck (emailStr, lang) {

// KB zugefuegt: Sprache festlegen, damit individuellere Fehlermeldungen ausgegeben werden koennen
var language = lang;
	
// 1 = checks that address ends in a 2-letter country plus other often used TLD	
var checkTLD=1;  

/* list of known TLDs that an e-mail address must end with. */
var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;

/* pattern 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 +")*$");

// START CHECKING....

/* 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. */
	if ("en" == language)
	{
		alert("Email address seems incorrect (check @ and .'s)");
	} 
	else
	{
		alert("Die Email-Adresse scheint nicht korrekt zu sein (bitte überprüfen Sie die @ und .'s)");	
	}
	return false;
}

var user=matchArray[1];
var domain=matchArray[2];

// Start by checking that only basic ASCII characters are in the strings (0-127).
for (i=0; i<user.length; i++) 
{
	if (user.charCodeAt(i)>127) 
	{
		if ("en" == language)
		{
			alert("The username contains invalid characters.");
		}
		else
		{
			alert("Der Anwendername besitzt ungültige Zeichen!");
		}
		return false;
   	}
}
for (i=0; i<domain.length; i++) 
{
	if (domain.charCodeAt(i)>127) 
	{
		if ("en" == language)
		{
			alert("The domain name contains invalid characters.");
		}
		else
		{
			alert("Die Dom&auml;ne (nach @) besitzt ungültige Zeichen!");
		}
		return false;
   	}
}

// See if "user" is valid 
if (user.match(userPat)==null) 
{
	// user is not valid
	if ("en" == language)
	{
		alert("The username doesn't seem to be valid.");
	}
	else
	{
		alert("Der Benutzername scheint nicht gültig zu sein.");	
	}
	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) 
		{
			if ("en" == language)
			{
				alert("Destination IP address is invalid!");
			}
			else
			{
				alert("Die angegebene IP Adresse ist ungültig!");
			}
			return false;
   		}
	}
	return true;
}

// Domain is symbolic name.  Check if it's valid.
var atomPat=new RegExp("^" + atom + "$");
var domArr=domain.split(".");
var len=domArr.length;
for (i=0;i<len;i++) 
{
	if (domArr[i].search(atomPat)==-1) 
	{
		if ("en" == language)
		{
			alert("The domain name does not seem to be valid.");
		}
		else
		{
			alert("Der Domänenname scheint ungültig zu sein.");
		}
		return false;
   	}
}

/* domain name seems valid, but now make sure that it ends in a known top-level domain (like com, edu, gov) or a two-letter word,
   representing country (uk, nl), and that there's a hostname preceding the domain or country. */
if (checkTLD && domArr[domArr.length-1].length!=2 && domArr[domArr.length-1].search(knownDomsPat)==-1) 
{
	if ("en" == language)
	{
		alert("The address must end in a well-known domain or two letter ");
	}
	else
	{
		alert("Die Adresse muss mit einem bekannten Suffix enden ");	
	}
	return false;
}

// Make sure there's a host name preceding the domain.
if (len<2)  
{
	if ("en" == language)
	{
		alert("This address is missing a hostname!");
	}
	else
	{
		alert("Der Adresse fehlt der Hostname!");		
	}
	return false;
}

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