/* kdate.js - Kaluach Javascript Hebrew date routines
 *   Version 1.00
 * Copyright (C) 5760,5761 (2000 CE), by Abu Mami and Yisrael Hersch.
 *   All Rights Reserved.
 *   All copyright notices in this script must be left intact.
 * Based on the formula by Gauss
 * Terms of use:
 *   - Permission will be granted to use this script on personal
 *     web pages. All that's required is that you please ask.
 *     (Of course if you want to send a few dollars, that's OK too :-)
 *   - Use on commercial web sites requires a $50 payment.
 * website: http://www.kaluach.net
 * email: abumami@kaluach.net
 */

function Gauss(year) {
	var a,b,c;
	var m;
	var	Mar;	// "day in March" on which Passover falls (return value)

	a = Math.floor((12 * year + 17) % 19);
	b = Math.floor(year % 4);
	m = 32.044093161144 + 1.5542417966212 * a +  b / 4.0 - 0.0031777940220923 * year;
	if (m < 0)
		m -= 1;
	Mar = Math.floor(m);
	if (m < 0)
		m++;
	m -= Mar;

	c = Math.floor((Mar + 3 * year + 5 * b + 5) % 7);
	if(c == 0 && a > 11 && m >= 0.89772376543210 )
		Mar++;
	else if(c == 1 && a > 6 && m >= 0.63287037037037)
		Mar += 2;
	else if(c == 2 || c == 4 || c == 6)
		Mar++;

	Mar += Math.floor((year - 3760) / 100) - Math.floor((year - 3760) / 400) - 2;
	return Mar;
}

function leap(y) {
	return ((y % 400 == 0) || (y % 100 != 0 && y % 4 == 0));
}

function civMonthLength(month, year) {
	if(month == 2)
		return 28 + leap(year);
	else if(month == 4 || month == 6 || month == 9 || month == 11)
	   return 30;
	else
		return 31;
}

function civ2heb(day, month, year) {
//alert("civ2heb reports " + day + " " + month + " " + year);
	var d = day;
	var	m = month;
	var y = year;
	var hy;
	var Passover;
	var anchor;
	var adarType;
	m -= 2;
	if (m <= 0) { // Jan or Feb
		m += 12;
		y -= 1;
	}

	d += Math.floor(7 * m / 12 + 30 * (m - 1)); // day in March
	hy = y + 3760;	// get Hebrew year
	Passover = Gauss(hy);
	if (d <= Passover - 15) { // before 1 Nisan
		anchor = Passover;
		d += 365;
		if(leap(y))
			d++;
		y -= 1;
		hy -= 1;
		Passover = Gauss(hy);
	}
	else
		anchor = Gauss(hy + 1);

	d -= Passover - 15;
	anchor -= Passover - 12;
	y++;
	if(leap(y))
		anchor++;

	for(m = 0; m < 11; m++) {
		var days;
		if(m == 7 && anchor % 30 == 2)
			days = 30; // Cheshvan
		else if(m == 8 && anchor % 30 == 0)
			days = 29; // Kislev
		else
			days = 30 - m % 2;
		if(d <= days)
			break;
		d -= days;
	}

	adarType = 0;			// plain old Adar
	if (m == 11 && anchor >= 30) {
		if (d > 30) {
			adarType = 2;	// Adar 2
			d -= 30;
		}
		else
			adarType = 1;	// Adar 1
	}

	if(m >= 6)		// Tishrei or after?
		hy++;		// then bump up year

	if(m == 11)			// Adar?
		m += adarType;	// adjust for Adars
//alert("civ2heb reports " + d + ' ' + m + ' ' + hy);
	return (d + ' ' + m + ' ' + hy);
}


function DOW(day,month,year) {
	var a = Math.floor((14 - month)/12);
	var y = year - a;
	var m = month + 12*a - 2;
	var d = (day + y + Math.floor(y/4) - Math.floor(y/100) +
			Math.floor(y/400) + Math.floor((31*m)/12)) % 7;
	return d + 1;
}

function NthDOW(nth,weekday,month,year) {
	if (nth > 0)
		return (nth - 1) * 7 + 1 + (7 + weekday - DOW((nth - 1) * 7 + 1, month, year)) % 7;
	var days = civMonthLength(month, year);
	return days - (DOW(days, month, year) - weekday + 7) % 7;
}


function moadim(cday, cmonth, cyear, hday, hmonth, dow) {
	if(hmonth == 6) {
		if(hday == 1 || hday == 2)
			return "Rosh Hashana"
		else if(hday == 10)
			return "Yom Kippur"
	}
	else if(hmonth == 8) {
		if(hday >= 25)
			return "Chanukkah"
	}
	else if(hmonth == 9) {
		if(hday <= 2) {
			return "Chanukkah"
		}
		else if(hday == 3) {
			// Kislev can be malei or chaser
			if(cday == 1) {
				cday = 29;
				cmonth = 11;
			}
			else if(cday == 2) {
				cday = 30;
				cmonth = 11;
			}
			else
				cday -= 3;
			var hdate = civ2heb(cday, cmonth, cyear);
			hd = eval(hdate.substring(0, hdate.indexOf(' ')));
			if(hd == 29)
				return "Chanukkah"
		}
	}
	else if(hmonth == 0) {
		if(hday >= 15 && hday <= 21)
			return "Passover"
		else if(hday == 22)
			return "Passover (d)"
	}

	return "";
}