//
// ************************************************
//
//      Philip J. Porvaznik
//
//      Java programming I
//
//      Finds date for Easter for 1982 to 2048
//
//      problem #3 page 287
//
// ************************************************
//

import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class Easter extends Frame
{

   private static Frame outputDisplay;
   private static TextField tYear;
   private static Label outputLabel;

   ///////////////////////////////////////////////////////////
   //
   // Add Action Handler and Listener
   //
   ///////////////////////////////////////////////////////////

   private static class ActionHandler implements ActionListener

   {

      public void actionPerformed (ActionEvent event)
      {


	     // get the command button id (Exit or Compute)

	     String id = event.getActionCommand ();

	     if (id == "Exit")
		 {
		    outputDisplay.dispose();
            System.exit(0);
		 }

	     // not Exit so must be Compute

	     int a, b, c, d, e;
	     int day, year;

         String month;

         // get the year from the text box tYear

         year = Integer.valueOf (tYear.getText()).intValue();

         // perform calculations

         a = year % 19;
         b = year % 4;
         c = year % 7;
         d = (19 * a + 24) % 30;
         e = (2 * b + 4 * c + 6 * d + 5) % 7;

         // get the final calculation for day

         day = 22 + d + e;

         month = "March";

         // set to March, if greater than 31 we have April

         if (day > 31)

         { month = "April"; day = day - 31; }

         // output the computed date

         outputLabel.setText("The date is " + month + " " + day);

      }

   }

   /////////////////////////////////////////////////////////////
   //
   // MAIN HERE
   //
   ////////////////////////////////////////////////////////////

   public static void main(String args[])

   {

      String month = "";
      int day = 0;
      ActionHandler action;

      // Create a Frame and display it on the screen

      outputDisplay = new Frame ();
      outputDisplay.setLayout (new GridLayout (3,3) );

      // Add intro message

      outputDisplay.add (new Label("Finds date for Easter Sunday 1982 to 2048"));

      // Add a text field for input

      outputDisplay.add (new Label("Enter the year: "));

      tYear = new TextField ("", 4);

      outputDisplay.add (tYear);

      // Add two buttons for compute and exit

      Button bExit = new Button ("Exit");
      bExit.setActionCommand ("Exit");

      action = new ActionHandler();
      bExit.addActionListener(action);

      outputDisplay.add (bExit);

      Button bCompute = new Button ("Compute Date");
      bCompute.setActionCommand ("Compute");

      action = new ActionHandler();
      bCompute.addActionListener(action);

      outputDisplay.add (bCompute);

      // Add computed result and text

      outputLabel = new Label("The computed date shows here");
      outputDisplay.add (outputLabel);

      outputDisplay.add (new Label("To quit close window or click exit"));

      // Show the frame we created

      outputDisplay.pack ();
      outputDisplay.show ();

      // Event handler for window closing

      outputDisplay.addWindowListener(new WindowAdapter()

      // Create a WindowAdapter

      {
         public void windowClosing(WindowEvent event)
         {
            outputDisplay.dispose();
            System.exit(0);
         }
      });

   }


}