/* This file contains common javascript functions to validate various form fields. */

/*****************************************************
PROGRAMMER: Ashish Dutt Sharma, B.Tech. (Hons.)
	    Computer Science and Engineering
*****************************************************/
		
// ------------------ Function to check whether a field is empty --------------------

function emptyCheck(thefield, thename)
{
	if(thefield.value == "")
	{
		alert("You must enter '" +thename+ "' to continue !!");
		thefield.focus();
		return false;
	}
	else
	{ 	
		return true;
	}
}


// -------- Function to check if the field length is within specified range ---------

function lengthCheck(thefield, thename, min, max)
{
	var theinput  = thefield.value;
	var thelength = theinput.length;
		
	if(thelength < min || thelength > max)
	{
		alert("You must enter '" +thename+ "' having atleast " +min+ " and atmost " +max+ " characters !!");
		thefield.focus();
		return false;
	}
	else
	{ 	
		return true;
	}
}

// ------------- Function to check whether the field value is numeric ---------------
 
function numberCheck(thefield, thename)
{
	var theinput  = thefield.value;
	var thelength = theinput.length;
	var goodvalue = true;
	
	for(var i=0; i<thelength; i++)
	{
		var thechar = theinput.substring(i, i+1);

		if(thechar<"0" || thechar>"9")
		{
			goodvalue=false;
		}
	}
	
	if(!goodvalue)
	{
		alert("You must write only digits in '" +thename+ "' !!");
		thefield.focus();
		return false;
	}
	else
	{ 	
		return true;
	}
}

// -------------- Function to check equality of two string arguments ----------------

function stringCheck(str1, str2)
{
	var equal;

	equal = true;

	if(str1.length == str2.length)
	{
		for(var i=0; i<str1.length; i++)
		{
			if(str1.charAt(i) != str2.charAt(i))
			{
				equal = false;
				break;	
			}
		}
	}
	else
		equal = false;

	return equal;
}

// -------- Function to check if the field allows only letters and digits -----------

function alphaCheck(thefield, thename)
{
	var checkpassOK = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  	var checkpassStr = thefield.value;
  	var allValidpass = true;
  
	for (i = 0;  i < checkpassStr.length;  i++)
  	{
	    ch = checkpassStr.charAt(i);

	    for (j = 0;  j < checkpassOK.length;  j++)	

      		if (ch == checkpassOK.charAt(j))
		        break;

		if (j == checkpassOK.length)
    	{
      		allValidpass = false;
      		break;
    	}
	}
	    
	if(!allValidpass)
	{
		alert("You must not include spaces or special characters in the  '" +thename+ "' !!");
		thefield.focus();
		return false;
	}
	else
	{ 	
		return true;
	}
}


// ------------ Function to validate the format of e-mail address field -------------


function emailCheck (emailStr) 
{

/* The following variable tells the rest of the function whether or not
to verify that the address ends in a two-letter country or well-known
TLD.  1 means check it, 0 means don't. */

var checkTLD=1;

/* The following is the 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)$/;

/* 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];

// 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) {
alert("Ths username contains invalid characters.");
return false;
   }
}
for (i=0; i<domain.length; i++) {
if (domain.charCodeAt(i)>127) {
alert("Ths domain name contains invalid characters.");
return false;
   }
}

// 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.  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) {
alert("The domain name does not seem to be valid.");
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) {
alert("The address must end in a well-known domain or two letter " + "country.");
return false;
}

// Make sure there's a host name preceding the domain.

if (len<2) {
alert("This address is missing a hostname!");
return false;
}

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

// ------------- Function to check whether the date entered is valid ---------------

function dateCheck(dd, mm, yyyy)
{
	var day 	= parseInt(dd);
	var month	= parseInt(mm);
	var year	= parseInt(yyyy);

	if ((month == 4 || month == 6 || month == 9 || month == 11) && day > 30)
	{
		alert("Date entered is Invalid !!");
		return false;
	}
	else if((month == 2) && day > 29)
	{
		alert("Date entered is Invalid !!");
		return false;
	}
	else if((month == 2) && day == 29)
	{
		if((yyyy % 4) == 0 || (yyyy % 100) == 0 || (yyyy % 400) == 0)
		{
			return true;
		}
		else
		{
			alert("Date entered is Invalid !!");
			return false;
		}
	}
}

/* End of 'Validations.js' File */