/*
   Script:                 dateValidate.js

   Source:                 http://www.shastrynetcom/

   Author:                 Subramanya Shastry Y V H
						   shastry@email.com

   Description:            Generic Date validation routine.

   Usage:                  Include this file with script tag and pass the date value to be
                           validated to the function 'isProperDate()'

						   This file can be included with the script tag
						   <script src="dateValidate.js"></script>

						   It is my advice that you include this file directly from my
						   site, so that you get to use the script which is up-to-date.
						   You can do so with the script tag
						   <script src="http://www.shastrynet.com/javascript/dateValidate.js"></script>

   Copyright:              This script can be freely used with or without modifications.
  
                           The author cannot be held responsible for any possible mistakes
                           in the coding. It is the responsibility of the user to make
                           sure that the code is working fine and is bug-less.
  
                           This Script cannot be distributed without prior permission from
                           the author.
*/

//------------------------------------------------------------------------------------
// function: isProperDate
//           Function to tell whether the given date is valid or not
//           This function expects date in the format of mm/dd/yyyy or mm/dd/yy
//           or mm-dd-yyyy or mm-dd-yy
//------------------------------------------------------------------------------------
function isProperDate(argDate) {
	var tmpDay = getDay(argDate)
	var tmpMon = getMonth(argDate)
	var tmpYear = getYear(argDate)

	return isProperDay(tmpDay, tmpMon, tmpYear) && isProperMonth(tmpMon) && isProperYear(tmpYear)
}

//------------------------------------------------------------------------------------
// function: isWhiteSpace
//           Function to check whether the given argument consists of charactes other
//           than a space and \t
//------------------------------------------------------------------------------------
function isWhiteSpace(argWhiteSpace) {
	argWs = argWhiteSpace.toString()
	
	for (var intI=0; intI < argWs.length; intI++)
		if (argWs.charAt(intI) != ' ' && argWs.charAt(intI) != '\t')
			return false
	
	return true
}

//------------------------------------------------------------------------------------
// function: isLeapYear
//           Function to tell, whether the given year is leap year or not
//------------------------------------------------------------------------------------
function isLeapYear(argYear) {
	return ((argYear % 4 == 0) && (argYear % 100 != 0)) || (argYear % 400 == 0) 
}

//------------------------------------------------------------------------------------
// function: daysInMonth
//           Function to return the maximum number of days in a given month of a
//           given year
//------------------------------------------------------------------------------------
function daysInMonth(argMonth, argYear) {
	switch (Number(argMonth)) {
		case 1:		// Jan
		case 3:		// Mar
		case 5:		// May
		case 7:		// Jul
		case 8:		// Aug
		case 10:		// Oct
		case 12:		// Dec
			return 31;
			break;
		
		case 4:		// Apr
		case 6:		// Jun
		case 9:		// Sep
		case 11:		// Nov
			return 30;
			break;
		
		case 2:		// Feb
			if (isLeapYear(argYear))
				return 29
			else
				return 28
			break;
		
		default:
			return 0;
	}
}

//------------------------------------------------------------------------------------
// function: getDateSeparator
//           Function to return the date separator
//           This function expects date in the format of mm/dd/yyyy or mm/dd/yy
//           or mm-dd-yyyy or mm-dd-yy
//------------------------------------------------------------------------------------
function getDateSeparator(argDate) {
	// Are there invalid separators?
	if ((argDate.indexOf('-') > 0) && (argDate.indexOf('/') > 0))
		return ' '

	if (argDate.indexOf('-') > 0)
		return '-'
	else
		if (argDate.indexOf('/') > 0)
			return '/'
		else
			return ' '
}

//------------------------------------------------------------------------------------
// function: getYear
//           Function to return the year part of the given date.
//           This function expects date in the format of mm/dd/yyyy or mm/dd/yy
//           or mm-dd-yyyy or mm-dd-yy
//------------------------------------------------------------------------------------
function getYear(argDate) {
	var dateSep = getDateSeparator(argDate)
	
	if (dateSep == ' ')
		return 0

	if(argDate.split(dateSep).length == 3)
		return argDate.split(dateSep)[2]
	else
		return 0
}

//------------------------------------------------------------------------------------
// function: getMonth
//           Function to return the month part of the given date.
//           This function expects date in the format of mm/dd/yyyy or mm/dd/yy
//           or mm-dd-yyyy or mm-dd-yy
//------------------------------------------------------------------------------------
function getMonth(argDate) {
	var dateSep = getDateSeparator(argDate)
	
	if (dateSep == ' ')
		return 0

	if(argDate.split(dateSep).length == 3)
		return argDate.split(dateSep)[0]
	else
		return 0
}

//------------------------------------------------------------------------------------
// function: getDay
//           Function to return the day part of the given date.
//           This function expects date in the format of mm/dd/yyyy or mm/dd/yy
//           or mm-dd-yyyy or mm-dd-yy
//------------------------------------------------------------------------------------
function getDay(argDate) {
	var dateSep = getDateSeparator(argDate)
	
	if (dateSep == ' ')
		return 0

	if(argDate.split(dateSep).length == 3)
		return argDate.split(dateSep)[1]
	else
		return 0
}

//------------------------------------------------------------------------------------
// function: isProperDay
//           Function to tell whether the given day of the given month is valid
//------------------------------------------------------------------------------------
function isProperDay(argDay, argMonth, argYear) {
	if ((isWhiteSpace(argDay)) || (argDay == 0))
		return false

	if ((argDay > 0) && (argDay < daysInMonth(argMonth, argYear) + 1))
		return true
	else 
		return false
}

//------------------------------------------------------------------------------------
// function: isProperMonth
//           Function to tell whether the given month is a valid one
//------------------------------------------------------------------------------------
function isProperMonth(argMonth) {
	if ((isWhiteSpace(argMonth)) || (argMonth == 0))
		return false
	
	if ((argMonth > 0) && (argMonth < 13))
		return true
	else
		return false
}

//------------------------------------------------------------------------------------
// function: isProperYear
//           Function to tell whether the given Year is a valid one
//------------------------------------------------------------------------------------
function isProperYear(argYear) {
	if ((isWhiteSpace(argYear)) || (argYear.toString().length > 4) || (argYear.toString().length == 3))
		return false
	
	switch (argYear.toString().length) {
		case 1:
			if (argYear >=0 && argYear < 10)
				return true
			else
				return false
			
		case 2:
			if (argYear >=0 && argYear < 100)
				return true
			else
				return false
			
		case 4:
			if (((argYear >=1900) || (argYear >=2000)) && ((argYear < 3000) || (argYear < 2000)))
				return true
			else
				return false
		
		default:
			return false
	}
}