Add methods to determine Vesein Tal Umatar/Vesein Berachah...

src/main/java/com/kosherjava/zmanim/hebrewcalendar/JewishCalendar.java

@@ -240,6 +240,47 @@ public boolean isBirkasHachamah() {
 		return false;
 	}
 
+	/**
+	 * Tekufas Shmuel: a solar year is 365.25 days.
+	 * notation: days,hours,chalakim
+	 * molad BaHaRad was 2D,5H,204C
+	 * or 5H,204C from the start of rosh hashana year 1
+	 * molad nissan add 177D,4H,438C (6 * 29D,12H,793C)
+	 * or 177D,9H,642C after rosh hashana year 1
+	 * tekufas nissan was 7D,9H,642C before molad nissan ~rambam.
+	 * or 170D,0H,0C after rosh hashana year 1
+	 * tekufas tishrei was 182D,3H (365.25 / 2) before tekufas nissan
+	 * or 12D,15H before Rosh Hashana year 1
+	 * outside of EY we say Tal Umatar in Birkas Hashanim from 60 days after tekufas tishrei.
+	 * 60 includes the day of the tekufah and the day we start.
+	 * 60 days from the tekufah == 47D,9H from Rosh Hashana year 1
+	 */
+	private int tekufasTishreiElapsedDays() {
+		// days since Rosh Hashana year 1
+		// add 1/2 day as the first tekufas tishrei was 9 hours into the day
+		// this allows all 4 years of the secular leap year cycle to share 47 days
+		// make from 47D,9H to 47D for simplicity
+		double days = getJewishCalendarElapsedDays(getJewishYear()) + (getDaysSinceStartOfJewishYear()-1) + .5;
+		// days of completed solar years
+		double solar = (getJewishYear()-1)*365.25;
+		return (int) (days - solar);
+	}
+
+	public boolean isBirchasHashanimToday() {
+		if (inIsrael && getJewishMonth() == 7 && getJewishDayOfMonth() == 7) return true;
+		else return tekufasTishreiElapsedDays() == 47;
+	}
+
+	public boolean getBirchasHashanim() {
+		if (getJewishMonth() == 1 && getJewishDayOfMonth() < 15) return true;
+		if (getJewishMonth() < 7) return false;
+		if (inIsrael) {
+			return getJewishMonth() != 7 || getJewishDayOfMonth() >= 7;
+		} else {
+			return tekufasTishreiElapsedDays() >= 47;
+		}
+	}
+
 	/**
 	 * Return the type of year for parsha calculations. The algorithm follows the
 	 * <a href="http://hebrewbooks.org/pdfpager.aspx?req=14268&amp;st=&amp;pgnum=222">Luach Arba'ah Shearim</a> in the Tur Ohr Hachaim.
@@ -933,6 +974,58 @@ public Daf getDafYomiYerushalmi() {
 	}
 
 
+	public boolean isMashivHaruachStarts() {
+		return getJewishMonth() == 7 && getJewishDayOfMonth() == 22;
+	}
+
+	public boolean isMashivHaruachEnds() {
+		return getJewishMonth() == 1 && getJewishDayOfMonth() == 15;
+	}
+
+	public boolean isMashivHaruach() {
+		JewishDate startDate = new JewishDate(getJewishYear(), 7, 22);
+		JewishDate endDate = new JewishDate(getJewishYear(), 1, 15);
+		return compareTo(startDate) > 0 && compareTo(endDate) < 0;
+	}
+
+	public boolean isMoridHatal() {
+		return !isMashivHaruach() || isMashivHaruachStarts() || isMashivHaruachEnds();
+	}
+
+	/**
+	 * This presumes the evenings of December 4/5 are always the initial start date outside of Israel
+	 * Because the jewish date does not auto-increment in the evening, we use December 5/6 as the start date
+	 * and rely on the user to increment the jewish date after nightfall.
+	 * Note that according to many, the date for Vesein Tal Umatar is tied to the Julian calendar and has historically
+	 * moved over time as the deviance from the Gregorian calendar increases.  The date of December 4/5 is to be used
+	 * for the 20th and 21st century.
+	 */
+	public boolean isVeseinTalUmatar() {
+		JewishDate startDate = getGregorianVeseinTalUmatarStart();
+		JewishDate endDate = new JewishDate(getJewishYear(), 1, 15);
+		return compareTo(startDate) > 0 && compareTo(endDate) < 0;
+	}
+
+	public boolean isVeseinTalUmatarStartsTonight() {
+		JewishDate startDate = getGregorianVeseinTalUmatarStart();
+		JewishDate prevDate = getGregorianVeseinTalUmatarStart();
+		prevDate.back();
+		return (getDayOfWeek() == 7 && equals(startDate)) || (getDayOfWeek() != 6 || equals(prevDate));
+	}
+
+	public boolean isVeseinBeracha() {
+		return !isVeseinTalUmatar();
+	}
+
+	public JewishDate getGregorianVeseinTalUmatarStart() {
+		JewishDate startDate = new JewishDate(getJewishYear(), 8, 7);
+		if (inIsrael) {
+			startDate.setGregorianDate(startDate.getGregorianYear(), 12, isGregorianLeapYear(startDate.getGregorianYear()+1)?6:5);
+		}
+		return startDate;
+	}
+
+
 	/**
 	 * @see Object#equals(Object)
 	 */

src/main/java/com/kosherjava/zmanim/hebrewcalendar/JewishDate.java

@@ -289,6 +289,10 @@ int getLastDayOfGregorianMonth(int month) {
 		return getLastDayOfGregorianMonth(month, gregorianYear);
 	}
 
+	boolean isGregorianLeapYear(int year) {
+		return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
+	}
+
 	/**
 	 * The month, where 1 == January, 2 == February, etc... Note that this is different than the Java's Calendar class
 	 * where January ==0