import java.util.*;
import java.text.*;

/** Print a month page.
 * Only works for the Western calendar. 
 * @author	Ian F. Darwin, http://www.darwinsys.com/
 * @version $Id: CalendarPage.java,v 1.7 2004/03/07 03:19:41 ian Exp $
 */
public class CalendarPage {

	/** The names of the months */
	String[] months = {
		"January", "February", "March", "April",
		"May", "June", "July", "August",
		"September", "October", "November", "December"
	};

	/** The days in each month. */
	public final static int[] dom = {
			31, 28, 31, 30,	/* jan feb mar apr */
			31, 30, 31, 31, /* may jun jul aug */
			30, 31, 30, 31	/* sep oct nov dec */
	};

	/** Compute which days to put where, in the Cal panel */
	public void print(int mm, int yy) {
		/** The number of days to leave blank at the start of this month */
		int leadGap = 0;

		System.out.print(months[mm]);		// print month and year
		System.out.print(" ");
		System.out.print(yy);
		System.out.println();

		if (mm < 0 || mm > 11)
			throw new IllegalArgumentException("Month " + mm + " bad, must be 0-11");
		GregorianCalendar calendar = new GregorianCalendar(yy, mm, 1);

		System.out.println("Su Mo Tu We Th Fr Sa");

		// Compute how much to leave before the first.
		// get(DAY_OF_WEEK) returns 0 for Sunday, which is just right.
		leadGap = calendar.get(Calendar.DAY_OF_WEEK)-1;

		int daysInMonth = dom[mm];
		if (calendar.isLeapYear(calendar.get(Calendar.YEAR)) && mm == 1)
			++daysInMonth;

		// Blank out the labels before 1st day of month
		for (int i = 0; i < leadGap; i++) {
			System.out.print("   ");
		}

		// Fill in numbers for the day of month.
		for (int i = 1; i <= daysInMonth; i++) {

			// This "if" statement is simpler than fiddling with NumberFormat
			if (i<=9)
				System.out.print(' ');
			System.out.print(i);

			if ((leadGap + i) % 7 == 0)		// wrap if end of line.
				System.out.println();
			else
				System.out.print(' ');
		}
		System.out.println();
	}

	/** For testing, a main program */
	public static void main(String[] av) {
		int month, year;

		CalendarPage cp = new CalendarPage();

		// print the current month.
		if (av.length == 2) {
			cp.print(Integer.parseInt(av[0])-1, Integer.parseInt(av[1]));
		} else {
			Calendar c = Calendar.getInstance();
			cp.print(c.get(Calendar.MONTH), c.get(Calendar.YEAR));
		}
	}
}