//////////////////////////////////////////////////////////////
// Date Functions
// v1.00 (Budd Wright)
//
// Description:
//////////////////////////////////////////////////////////////
// Contains date validation functions
//////////////////////////////////////////////////////////////
//
// Usage:
//////////////////////////////////////////////////////////////
// <script language="javascript" src="js/date.js"></script>
//////////////////////////////////////////////////////////////
//
// v1.00 Notes
// -----------
//
//
//
// Known Issues
// ------------
// 
//
//////////////////////////////////////////////////////////////



/* CheckDate() Function */
// Date validation
function CheckDate(object_value)
{
	if (object_value.length == 0)	return true;

	// Returns true if value is a date in the mm/dd/yyyy format
	isplit = object_value.indexOf('/');

	if (isplit == -1 || isplit == object_value.length)	return false;

	sMonth = object_value.substring(0, isplit);
	isplit = object_value.indexOf('/', isplit + 1);

	if (isplit == -1 || (isplit + 1 ) == object_value.length)	return false;

	sDay = object_value.substring((sMonth.length + 1), isplit);
	sYear = object_value.substring(isplit + 1);

	// Assume any two-digit year is for this century
	if(sYear < 100)
		sYear = "20" + sYear;

	if (!_CF_checkinteger(sMonth)) //check month
		return false;
	else
		if (!_CF_checkrange(sMonth, 1, 12)) //check month
			return false;
		else
			if (!_CF_checkinteger(sYear)) //check year
				return false;
			else
				if (!_CF_checkrange(sYear, 1890, 9999)) //check year
					return false;
				else
					if (!_CF_checkinteger(sDay)) //check day
						return false;
					else
						if (!_CF_checkday(sYear, sMonth, sDay)) // check day
							return false;
						else
							return true;
}


function _CF_checkday(checkYear, checkMonth, checkDay)
{

maxDay = 31;

if (checkMonth == 4 || checkMonth == 6 ||
checkMonth == 9 || checkMonth == 11)
maxDay = 30;
else
if (checkMonth == 2)
{
if (checkYear % 4 > 0)
maxDay =28;
else
if (checkYear % 100 == 0 && checkYear % 400 > 0)
maxDay = 28;
else
maxDay = 29;
}

return _CF_checkrange(checkDay, 1, maxDay); //check day
}



function _CF_checkinteger(object_value)
{
//Returns true if value is a number or is NULL
//otherwise returns false	

if (object_value.length == 0)
return true;

//Returns true if value is an integer defined as
//   having an optional leading + or -.
//   otherwise containing only the characters 0-9.
var decimal_format = ".";
var check_char;

//The first character can be + -  blank or a digit.
check_char = object_value.indexOf(decimal_format)
//Was it a decimal?
if (check_char < 1)
return _CF_checknumber(object_value);
else
return false;
}



function _CF_numberrange(object_value, min_value, max_value)
{
// check minimum
if (min_value != null)
{
if (object_value < min_value)
return false;
}

// check maximum
if (max_value != null)
{
if (object_value > max_value)
return false;
}

//All tests passed, so...
return true;
}



function _CF_checknumber(object_value)
{
//Returns true if value is a number or is NULL
//otherwise returns false	

if (object_value.length == 0)
return true;

//Returns true if value is a number defined as
//   having an optional leading + or -.
//   having at most 1 decimal point.
//   otherwise containing only the characters 0-9.
var start_format = " .+-0123456789";
var number_format = " .0123456789";
var check_char;
var decimal = false;
var trailing_blank = false;
var digits = false;

//The first character can be + - .  blank or a digit.
check_char = start_format.indexOf(object_value.charAt(0))
//Was it a decimal?
if (check_char == 1)
decimal = true;
else if (check_char < 1)
return false;

//Remaining characters can be only . or a digit, but only one decimal.
for (var i = 1; i < object_value.length; i++)
{
check_char = number_format.indexOf(object_value.charAt(i))
if (check_char < 0)
return false;
else if (check_char == 1)
{
if (decimal)		// Second decimal.
return false;
else
decimal = true;
}
else if (check_char == 0)
{
if (decimal || digits)	
trailing_blank = true;
// ignore leading blanks

}
else if (trailing_blank)
return false;
else
digits = true;
}	
//All tests passed, so...
return true
}



function _CF_checkrange(object_value, min_value, max_value)
{
//if value is in range then return true else return false

if (object_value.length == 0)
return true;


if (!_CF_checknumber(object_value))
{
return false;
}
else
{
return (_CF_numberrange((eval(object_value)), min_value, max_value));
}

//All tests passed, so...
return true;
}