// ===================================================================
// 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.
// ===================================================================

// HISTORY

// ------------------------------------------------------------------

// March 11, 2003: Added parseDate() function

// March 11, 2003: Added "NNN" formatting option. Doesn't match up

//                 perfectly with SimpleDateFormat formats, but 

//                 backwards-compatability was required.



// ------------------------------------------------------------------

// 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)

//              | NNN (abbr.)        |

// Day of Month | dd (2 digits)      | d (1 or 2 digits)

// Day of Week  | EE (name)          | E (abbr)

// 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');

var DAY_NAMES=new Array('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sun','Mon','Tue','Wed','Thu','Fri','Sat');

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 isDate(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 E=date.getDay();

	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["NNN"]=MONTH_NAMES[M+11];

	value["d"]=d;

	value["dd"]=LZ(d);

	value["E"]=DAY_NAMES[E+7];

	value["EE"]=DAY_NAMES[E];

	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=1;

	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"||token=="NNN"){

			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()) {

					if (token=="MMM"||(token=="NNN"&&i>11)) {

						month=i+1;

						if (month>12) { month -= 12; }

						i_val += month_name.length;

						break;

						}

					}

				}

			if ((month < 1)||(month>12)){return 0;}

			}

		else if (token=="EE"||token=="E"){

			for (var i=0; i<DAY_NAMES.length; i++) {

				var day_name=DAY_NAMES[i];

				if (val.substring(i_val,i_val+day_name.length).toLowerCase()==day_name.toLowerCase()) {

					i_val += day_name.length;

					break;

					}

				}

			}

		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 0; }

			}

		else { if (date > 28) { return 0; } }

		}

	if ((month==4)||(month==6)||(month==9)||(month==11)) {

		if (date > 30) { return 0; }

		}

	// 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();

	}



// ------------------------------------------------------------------

// parseDate( date_string [, prefer_euro_format] )

//

// This function takes a date string and tries to match it to a

// number of possible date formats to get the value. It will try to

// match against the following international formats, in this order:

// y-M-d   MMM d, y   MMM d,y   y-MMM-d   d-MMM-y  MMM d

// M/d/y   M-d-y      M.d.y     MMM-d     M/d      M-d

// d/M/y   d-M-y      d.M.y     d-MMM     d/M      d-M

// A second argument may be passed to instruct the method to search

// for formats like d/M/y (european format) before M/d/y (American).

// Returns a Date object or null if no patterns match.

// ------------------------------------------------------------------

function parseDate(val) {

	var preferEuro=(arguments.length==2)?arguments[1]:false;

	generalFormats=new Array('y-M-d','MMM d, y','MMM d,y','y-MMM-d','d-MMM-y','MMM d');

	monthFirst=new Array('M/d/y','M-d-y','M.d.y','MMM-d','M/d','M-d');

	dateFirst =new Array('d/M/y','d-M-y','d.M.y','d-MMM','d/M','d-M');

	var checkList=new Array('generalFormats',preferEuro?'dateFirst':'monthFirst',preferEuro?'monthFirst':'dateFirst');

	var d=null;

	for (var i=0; i<checkList.length; i++) {

		var l=window[checkList[i]];

		for (var j=0; j<l.length; j++) {

			d=getDateFromFormat(val,l[j]);

			if (d>0) { return new Date(d); }

			}

		}

	return null;

	}