import javax.swing.*;

public class EasterSundayCalculator{
	
	public EasterSundayCalculator(){
		init();
	}
	
	public static void main(String[] args){
		new EasterSundayCalculator();
	}
	
	public void init(){
		boolean done = false;
		while (!done){
			int year = getYear();
			JOptionPane.showMessageDialog(null,calculateEasterSunday(year));
			done = (JOptionPane.showConfirmDialog(null,"Would you like to calculate another?") != JOptionPane.YES_OPTION);
		}
		System.exit(0);
	}
	
	public int getYear(){
		int year = -1;
		while (year < 0){
			String message = "Enter a 4 digit year between 1982 and 2048";
			String input = JOptionPane.showInputDialog(null,message);
			try{
				year = Integer.parseInt(input);
			}catch(NumberFormatException nfe){
				System.err.println("NumberFormatException: " + nfe.getMessage());
				year = -1;
			}
			System.err.println("year: " + year);
			if ((year < 1982)|| (year > 2048)) {
				year = -1;
				JOptionPane.showMessageDialog(null,"That was not a valid year input. Try again!","Invalid year", JOptionPane.ERROR_MESSAGE);
			}
		}
		return year;		
	}


	/**	a is year %19
	*	b is year % 4
	*	c is year % 7
	*	d is (19 * a + 24) % 30
	*	e is (2 * b + 4 * c + 6 * d + 5) % 7
	*	Easter Sunday is March (22 + d + e)3(cubed)
	*/
	public String calculateEasterSunday(int year){

		int a= year %19;
		int b = year % 4;
		int c = year % 7;
		int d = (19 * a + 24) % 30;
		int e = (2 * b + 4 * c + 6 * d + 5) % 7;
		int result = (22 + d + e) * (int)Math.sqrt(3);
		String month = "March";
		if (result > 31){
			month = "April";
			result = result - 31;
		}
		return "Easter Sunday is " + month + " " 
			+ String.valueOf (result) +  " in the year " 
			+ String.valueOf(year);
	}
	
	
}