// ===================================================================
// 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
// ------------------------------------------------------------------
// May 17, 2003: Fixed bug in parseDate() for dates <1970
// 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"
// ------------------------------------------------------------------

function DateUtils ()
{

   this.MONTH_NAMES = new Array('January','February','March','April','May','June','July','August','September','October','November','December');
   this.MONTH_NAMES_SH = new Array('Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec');
   this.DAY_NAMES = new Array('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday');
   this.DAY_NAMES_SH = new Array('Sun','Mon','Tue','Wed','Thu','Fri','Sat');
   
   this.LZ = function (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!
   // ------------------------------------------------------------------
   this.isDate = function(val,format) {
   	var date = this.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
   // -------------------------------------------------------------------
   this.compareDates = function(date1,dateformat1,date2,dateformat2) {
   	var d1 = this.getDateFromFormat(date1,dateformat1);
   	var d2 = this.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()
   // ------------------------------------------------------------------
   this.formatDate = function(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"]=this.MONTH_NAMES[M-1];
   	value["NNN"]=this.MONTH_NAMES_SH[M];
   	value["d"]=d;
   	value["dd"]=LZ(d);
   	value["E"]=this.DAY_NAMES_SH[E];
   	value["EE"]=this.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()
   // ------------------------------------------------------------------
   this._isInteger = function(val) {
   	var digits="1234567890";
   	for (var i=0; i < val.length; i++) {
   		if (digits.indexOf(val.charAt(i))==-1) { return false; }
   		}
   	return true;
   }
   
   this._getInt = function(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 (this._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.
   // ------------------------------------------------------------------
   this.getDateFromFormat = function(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=this._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<this.MONTH_NAMES.length; i++) {
   				var month_name=this.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<this.DAY_NAMES.length; i++) {
   				var day_name=this.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=this._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=this._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=this._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=this._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=this._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=this._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=this._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=this._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.
   // ------------------------------------------------------------------
   this.parseDate = function(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=this.getDateFromFormat(val,l[j]);
   			if (d!=0) { return new Date(d); }
   			}
   		}
   	return null;
   	}

}