// ===================================================================
// Author: Matt Kruse <matt@mattkruse.com>
// WWW: http://www.mattkruse.com/
//
// NOTICE: You may use this code for any purpose, commercial or
// private, without any further permission from the author. You may
// remove this notice from your final code if you wish, however it is
// appreciated by the author if at least my web site address is kept.
//
// You may *NOT* re-distribute this code in any way except through its
// use. That means, you can include it in your product, or your web
// site, or any other form where the code is actually being used. You
// may not put the plain javascript up on your site for download or
// include it in your javascript libraries for download. 
// If you wish to share this code with others, please just point them
// to the URL instead.
// Please DO NOT link directly to my .js files from your site. Copy
// the files to your server and use them there. Thank you.
// ===================================================================


// ------------------------------------------------------------------
// These functions use the same 'format' strings as the 
// java.text.SimpleDateFormat class, with minor exceptions.
// The format string consists of the following abbreviations:
// 
// Field        | Full Form          | Short Form
// -------------+--------------------+-----------------------
// Year         | yyyy (4 digits)    | yy (2 digits), y (2 or 4 digits)
// Month        | MMM (name or abbr.)| MM (2 digits), M (1 or 2 digits)
// Day of Month | dd (2 digits)      | d (1 or 2 digits)
// Hour (1-12)  | hh (2 digits)      | h (1 or 2 digits)
// Hour (0-23)  | HH (2 digits)      | H (1 or 2 digits)
// Hour (0-11)  | KK (2 digits)      | K (1 or 2 digits)
// Hour (1-24)  | kk (2 digits)      | k (1 or 2 digits)
// Minute       | mm (2 digits)      | m (1 or 2 digits)
// Second       | ss (2 digits)      | s (1 or 2 digits)
// AM/PM        | a                  |
//
// NOTE THE DIFFERENCE BETWEEN MM and mm! Month=MM, not mm!
// Examples:
//  "MMM d, y" matches: January 01, 2000
//                      Dec 1, 1900
//                      Nov 20, 00
//  "M/d/yy"   matches: 01/20/00
//                      9/2/00
//  "MMM dd, yyyy hh:mm:ssa" matches: "January 01, 2000 12:30:45AM"
// ------------------------------------------------------------------

var MONTH_NAMES=new Array('January', 'February', 'March', 'April', 'May', 'June', 'July', 
													'August', 'September', 'October', 'November', 'December', 'Jan',
													'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec');
function LZ(x) {
	return(x < 0 || x > 9?"":"0") + x
}

// ------------------------------------------------------------------
// isDate ( date_string, format_string )
// Returns true if date string matches format of format string and
// is a valid date. Else returns false.
// It is recommended that you trim whitespace around the value before
// passing it to this function, as whitespace is NOT ignored!
// ------------------------------------------------------------------
function isValidDate(val, format) {
	var date = getDateFromFormat(val, format);
	if (date == 0) { 
		return false; 
	}
	return true;
}

// -------------------------------------------------------------------
// compareDates(date1,date1format,date2,date2format)
//   Compare two date strings to see which is greater.
//   Returns:
//   1 if date1 is greater than date2
//   0 if date2 is greater than date1 of if they are the same
//  -1 if either of the dates is in an invalid format
// -------------------------------------------------------------------
function compareDates(date1, dateformat1, date2, dateformat2) {
	var d1 = getDateFromFormat(date1, dateformat1);
	var d2 = getDateFromFormat(date2, dateformat2);
	if (d1 == 0 || d2 == 0) {
		return -1;
	} else if (d1 > d2) {
		return 1;
	}
	return 0;
}

// ------------------------------------------------------------------
// formatDate (date_object, format)
// Returns a date in the output format specified.
// The format string uses the same abbreviations as in getDateFromFormat()
// ------------------------------------------------------------------
function formatDate(date, format) {

	format = format + "";
	var result = "";
	var i_format = 0;
	var c = "";
	var token = "";	
	var y = date.getYear() + "";
	var M = date.getMonth() + 1;
	var d = date.getDate();
	var H = date.getHours();
	var m = date.getMinutes();
	var s = date.getSeconds();
	var yyyy, yy, MMM, MM, dd, hh, h, mm, ss, ampm, HH, H, KK, K, kk, k;
	// Convert real date parts into formatted versions
	var value = new Object();
	if (y.length < 4) {
		y = "" + (y - 0 + 1900);
	}
	value["y"] = "" + y;
	value["yyyy"] = y;
	value["yy"] = y.substring(2, 4);
	value["M"] = M;
	value["MM"] = LZ(M);
	value["MMM"] = MONTH_NAMES[M - 1];
	value["d"] = d;
	value["dd"] = LZ(d);
	value["H"] = H;
	value["HH"] = LZ(H);
	if (H == 0){
		value["h"]=12;
	} else if (H > 12){
		value["h"] = H - 12;
	} else {
		value["h"] = H;
	}
	value["hh"] = LZ(value["h"]);
	if (H > 11){
		value["K"] = H - 12;
	} else {
		value["K"]=H;
	}
	value["k"] = H + 1;
	value["KK"] = LZ(value["K"]);
	value["kk"] = LZ(value["k"]);
	if (H > 11) { 
		value["a"] = "PM"; 
	} else { 
		value["a"] = "AM"; 
	}
	value["m"] = m;
	value["mm"] = LZ(m);
	value["s"] = s;
	value["ss"] = LZ(s);
	while (i_format < format.length) {
		c = format.charAt(i_format);
		token = "";
		while ((format.charAt(i_format) == c) && (i_format < format.length)) {
			token += format.charAt(i_format++);
		}
		if (value[token] != null) { 
			result=result + value[token]; 
		} else { 
			result=result + token; 
		}
	}
	return result;
}
	
// ------------------------------------------------------------------
// Utility functions for parsing in getDateFromFormat()
// ------------------------------------------------------------------
function _isInteger(val) {
	var digits="1234567890";
	for (var i = 0; i < val.length; i++) {
		if (digits.indexOf(val.charAt(i)) == -1) { 
			return false; 
		}
	}
	return true;
}

function _getInt(str,i,minlength,maxlength) {
	for (var x = maxlength; x >= minlength; x--) {
		var token = str.substring(i, i + x);
		if (token.length < minlength) { 
			return null; 
		}
		if (_isInteger(token)) { 
			return token; 
		}
	}
	return null;
}
	
// ------------------------------------------------------------------
// getDateFromFormat( date_string , format_string )
//
// This function takes a date string and a format string. It matches
// If the date string matches the format string, it returns the 
// getTime() of the date. If it does not match, it returns 0.
// ------------------------------------------------------------------
function getDateFromFormat(val, format) {
	val = val + "";
	format = format + "";
	var i_val = 0;
	var i_format = 0;
	var c = "";
	var token = "";
	var token2 = "";
	var x, y;
	var now = new Date();
	var year = now.getYear();
	var month = now.getMonth() + 1;
	var date = now.getDate();
	var hh = now.getHours();
	var mm = now.getMinutes();
	var ss = now.getSeconds();
	var ampm = "";
	
	while (i_format < format.length) {
		// Get next token from format string
		c = format.charAt(i_format);
		token = "";
		while ((format.charAt(i_format) == c) && (i_format < format.length)) {
			token += format.charAt(i_format++);
		}
		// Extract contents of value based on format token
		if (token == "yyyy" || token == "yy" || token == "y") {
			if (token == "yyyy") { 
				x = 4;
				y = 4; 
			}
			if (token == "yy")   { 
				x = 2;
				y = 2; 
			}
			if (token == "y")    { 
				x=2;
				y=4; 
			}
			year = _getInt(val, i_val, x, y);
			if (year == null) { 
				return 0; 
			}
			i_val += year.length;
			if (year.length == 2) {
				if (year > 70) { 
					year = 1900 + (year - 0); 
				} else { 
					year = 2000 + (year - 0); 
				}
			}
		} else if (token == "MMM"){
			month = 0;
			for (var i = 0; i < MONTH_NAMES.length; i++) {
				var month_name = MONTH_NAMES[i];
				if (val.substring(i_val, i_val + month_name.length).toLowerCase() == month_name.toLowerCase()) {
					month = i + 1;
					if (month > 12) { 
						month -= 12; 
					}
					i_val += month_name.length;
					break;
				}
			}
			if ((month < 1) || (month > 12)){
				return 0;
			}
		} else if (token == "MM" || token == "M") {
			month = _getInt(val, i_val, token.length, 2);
			if (month == null || (month < 1) || (month > 12)){
				return 0;
			}
			i_val += month.length;
		} else if (token == "dd" || token == "d") {
			date =_getInt(val, i_val, token.length, 2);
			if (date == null || (date < 1) || (date > 31)){
				return 0;
			}
			i_val += date.length;
		} else if (token == "hh" || token == "h") {
			hh=_getInt(val, i_val, token.length, 2);
			if (hh == null || (hh < 1) || (hh > 12)){
				return 0;
			}
			i_val += hh.length;
		} else if (token == "HH" || token == "H") {
			hh = _getInt(val, i_val, token.length, 2);
			if (hh == null || (hh < 0) || (hh > 23)){
				return 0;
			}
			i_val += hh.length;
		} else if (token == "KK" || token == "K") {
			hh = _getInt(val, i_val, token.length, 2);
			if (hh == null || (hh < 0) || (hh > 11)){
				return 0;
			}
			i_val += hh.length;
		} else if (token == "kk" || token == "k") {
			hh = _getInt(val, i_val, token.length, 2);
			if (hh == null || (hh < 1) || (hh > 24)){
				return 0;
			}
			i_val += hh.length;
			hh--;
		} else if (token == "mm" || token == "m") {
			mm = _getInt(val, i_val, token.length, 2);
			if (mm == null || (mm < 0) || (mm > 59)){
				return 0;
			}
			i_val += mm.length;
		} else if (token == "ss" || token == "s") {
			ss = _getInt(val, i_val, token.length, 2);
			if (ss == null || (ss < 0) || (ss > 59)){
				return 0;
			}
			i_val += ss.length;
		} else if (token == "a") {
			if (val.substring(i_val, i_val + 2).toLowerCase() == "am") {
				ampm = "AM";
			} else if (val.substring(i_val, i_val + 2).toLowerCase() == "pm") {
				ampm = "PM";
			} else {
				return 0;
			}
			i_val += 2;
		} else {
			if (val.substring(i_val, i_val + token.length) != token) {
				return 0;
			} else {
				i_val += token.length;
			}
		}
	}
	// If there are any trailing characters left in the value, it doesn't match
	if (i_val != val.length) { 
		return 0; 
	}
	// Is date valid for month?
	if (month == 2) {
		// Check for leap year
		if ( ( (year%4 == 0) && (year%100 != 0) ) || (year%400 == 0) ) { // leap year
			if (date > 29){ 
				return false; 
			}
		} else { 
			if (date > 28) { 
				return false; 
			} 
		}
	}
	if ((month == 4) || (month == 6) || (month == 9) || (month == 11)) {
		if (date > 30) { 
			return false; 
		}
	}
	// Correct hours value
	if (hh < 12 && ampm == "PM") { 
		hh = hh - 0 + 12; 
	} else if (hh > 11 && ampm == "AM") { 
		hh -= 12; 
	}
	var newdate = new Date(year, month - 1, date, hh, mm, ss);
	return newdate.getTime();
}