/*

Name: jsDate
Desc: VBScript native Date functions emulated for Javascript
Author: Rob Eberhardt, Slingshot Solutions - http://slingfive.com/
History:
	2005-08-04	v0.94		scrapped new dateDiff approach to better match VBScript's simplistic Y/M/Q
	2005-08-03	v0.93		fixed dateDiff/leapyear bug with yyyy/m/q intervals
	2004-11-26	v0.91		fixed datePart/ww bug, added weekdayName() & monthName()
	2004-08-30	v0.9		brand new
	
*/

/* used by dateAdd, dateDiff, datePart, weekdayName, and monthName*/
/* note: less strict than VBScript's isDate, since JS allows invalid dates to overflow (e.g. Jan 32 transparently becomes Feb 1)*/
function isDate(p_Expression){
	return !isNaN(new Date(p_Expression));		/* <<--- this needs checking*/
}


/* REQUIRES: isDate()*/
function dateAdd(p_Interval, p_Number, p_Date){
	if(!isDate(p_Date)){return "invalid date: '" + p_Date + "'";}
	if(isNaN(p_Number)){return "invalid number: '" + p_Number + "'";}	

	p_Number = new Number(p_Number);
	var dt = new Date(p_Date);
	switch(p_Interval.toLowerCase()){
		case "yyyy": {/* year */
			dt.setFullYear(dt.getFullYear() + p_Number);
			break;
		}
		case "q": {		/* quarter*/
			dt.setMonth(dt.getMonth() + (p_Number*3));
			break;
		}
		case "m": {		/* month*/
			dt.setMonth(dt.getMonth() + p_Number);
			break;
		}
		case "y":		/* day of year*/
		case "d":		/* day*/
		case "w": {		/* weekday*/
			dt.setDate(dt.getDate() + p_Number);
			break;
		}
		case "ww": {	/* week of year*/
			dt.setDate(dt.getDate() + (p_Number*7));
			break;
		}
		case "h": {		/* hour*/
			dt.setHours(dt.getHours() + p_Number);
			break;
		}
		case "n": {		/* minute*/
			dt.setMinutes(dt.getMinutes() + p_Number);
			break;
		}
		case "s": {		/* second*/
			dt.setSeconds(dt.getSeconds() + p_Number);
			break;
		}
		case "ms": {		/* second*/
			dt.setMilliseconds(dt.getMilliseconds() + p_Number);
			break;
		}
		default: {
			return "invalid interval: '" + p_Interval + "'";
		}
	}
	return dt;
}



/* REQUIRES: isDate()*/
/* NOT SUPPORTED: firstdayofweek and firstweekofyear (defaults for both)*/
function dateDiff(p_Interval, p_Date1, p_Date2, p_firstdayofweek, p_firstweekofyear){
	if(!isDate(p_Date1)){return "invalid date: '" + p_Date1 + "'";}
	if(!isDate(p_Date2)){return "invalid date: '" + p_Date2 + "'";}
	var dt1 = new Date(p_Date1);
	var dt2 = new Date(p_Date2);

	/* get ms between dates (UTC) and make into "difference" date*/
	var iDiffMS = dt2.valueOf() - dt1.valueOf();
	var dtDiff = new Date(iDiffMS);

	/* calc various diffs*/
	var nYears  = dt2.getUTCFullYear() - dt1.getUTCFullYear();
	var nMonths = dt2.getUTCMonth() - dt1.getUTCMonth() + (nYears!=0 ? nYears*12 : 0);
	var nQuarters = parseInt(nMonths/3);	/*<<-- different than VBScript, which watches rollover not completion*/
	
	var nMilliseconds = iDiffMS;
	var nSeconds = parseInt(iDiffMS/1000);
	var nMinutes = parseInt(nSeconds/60);
	var nHours = parseInt(nMinutes/60);
	var nDays  = parseInt(nHours/24);
	var nWeeks = parseInt(nDays/7);


	/* return requested difference*/
	var iDiff = 0;		
	switch(p_Interval.toLowerCase()){
		case "yyyy": return nYears;
		case "q": return nQuarters;
		case "m": return nMonths;
		case "y": 		/* day of year*/
		case "d": return nDays;
		case "w": return nDays;
		case "ww":return nWeeks;		/* week of year	// <-- inaccurate, WW should count calendar weeks (# of sundays) between*/
		case "h": return nHours;
		case "n": return nMinutes;
		case "s": return nSeconds;
		case "ms":return nMilliseconds;	/* millisecond	// <-- extension for JS, NOT available in VBScript*/
		default: return "invalid interval: '" + p_Interval + "'";
	}
}



/* REQUIRES: isDate(), dateDiff()*/
/* NOT SUPPORTED: firstdayofweek and firstweekofyear (does system default for both)*/
function datePart(p_Interval, p_Date, p_firstdayofweek, p_firstweekofyear){
	if(!isDate(p_Date)){return "invalid date: '" + p_Date + "'";}

	var dtPart = new Date(p_Date);
	switch(p_Interval.toLowerCase()){
		case "yyyy": return dtPart.getFullYear();
		case "q": return parseInt(dtPart.getMonth()/3)+1;
		case "m": return dtPart.getMonth()+1;
		case "y": return dateDiff("y", "1/1/" + dtPart.getFullYear(), dtPart);			/* day of year*/
		case "d": return dtPart.getDate();
		case "w": return dtPart.getDay();	/* weekday*/
		case "ww":return dateDiff("ww", "1/1/" + dtPart.getFullYear(), dtPart);		/* week of year*/
		case "h": return dtPart.getHours();
		case "n": return dtPart.getMinutes();
		case "s": return dtPart.getSeconds();
		case "ms":return dtPart.getMilliseconds();	/* millisecond	// <-- extension for JS, NOT available in VBScript*/
		default: return "invalid interval: '" + p_Interval + "'";
	}
}


/* REQUIRES: isDate()*/
/* NOT SUPPORTED: firstdayofweek (does system default)*/
function weekdayName(p_Date, p_abbreviate){
	if(!isDate(p_Date)){return "invalid date: '" + p_Date + "'";}
	var dt = new Date(p_Date);
	var retVal = dt.toString().split(' ')[0];
	var retVal = Array('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday')[dt.getDay()];
	if(p_abbreviate==true){retVal = retVal.substring(0, 3)}	/* abbr to 1st 3 chars*/
	return retVal;
}
/* REQUIRES: isDate()*/
function monthName(p_Date, p_abbreviate){
	if(!isDate(p_Date)){return "invalid date: '" + p_Date + "'";}
	var dt = new Date(p_Date);	
	var retVal = Array('January','February','March','April','May','June','July','August','September','October','November','December')[dt.getMonth()];
	if(p_abbreviate==true){retVal = retVal.substring(0, 3)}	/* abbr to 1st 3 chars*/
	return retVal;
}

 function addZero(vNumber){ 
    return ((vNumber < 10) ? "0" : "") + vNumber 
  } 
        
  function formatDate(vDate, vFormat){ 
    var vDay                      = addZero(vDate.getDate()); 
    var vMonth            = addZero(vDate.getMonth()+1); 
    var vYearLong         = addZero(vDate.getFullYear()); 
    var vYearShort        = addZero(vDate.getFullYear().toString().substring(3,4)); 
    var vYear             = (vFormat.indexOf("yyyy")>-1?vYearLong:vYearShort) 
    var vHour             = addZero(vDate.getHours()); 
    var vMinute           = addZero(vDate.getMinutes()); 
    var vSecond           = addZero(vDate.getSeconds()); 
    var vDateString       = vFormat.replace(/dd/g, vDay).replace(/MM/g, vMonth).replace(/y{1,4}/g, vYear) 
    vDateString           = vDateString.replace(/hh/g, vHour).replace(/mm/g, vMinute).replace(/ss/g, vSecond) 
    return vDateString 
  } 







/* ====================================*/

/* bootstrap different capitalizations*/
function IsDate(p_Expression){
	return isDate(p_Expression);
}
function DateAdd(p_Interval, p_Number, p_Date){
	return dateAdd(p_Interval, p_Number, p_Date);
}
function DateDiff(p_interval, p_date1, p_date2, p_firstdayofweek, p_firstweekofyear){
	return dateDiff(p_interval, p_date1, p_date2, p_firstdayofweek, p_firstweekofyear);
}
function DatePart(p_Interval, p_Date, p_firstdayofweek, p_firstweekofyear){
	return datePart(p_Interval, p_Date, p_firstdayofweek, p_firstweekofyear);
}
function WeekdayName(p_Date){
	return weekdayName(p_Date);
}
function MonthName(p_Date){
	return monthName(p_Date);
}