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

/**
 * Another version of the MVC pattern to display FunList.
 * In this version, all the controllers for the view of the list model are
 * created in a separate class called FLControl.  The view, FLGUI, has hook
 * methods to install the necessary controllers.
 * 
 * Copyright 1999, Dung X. Nguyen - All rights reserved.
 * @version 1.1   Oct. 08, 1999
 * @author Dung X. Nguyen
 * @author Robert S. Cartwright
 * @dependency java.awt.event.ActionListener uses
 */
public class FLGUI {
  // Initialize all components:
  private TextField txtIn = new TextField("0", 4);  // Input text for list and visitors' methods.
  private TextField txtOut = new TextField("0", 4); // Output text.
  private TextArea  taListView = new TextArea ();   // a TextArea view of the list model
  private TextField txtListView = new TextField (); // a TextField view of the list model
  // Buttons to manipulate the list model:
  private Button  btnEmpty = new Button("Empty");
  private Button  btnCons = new Button("Cons");
  private Button  btnSum = new Button("Sum");
  private Button  btnGetNth = new Button("GetNth");

  /**
  * Lays out GUI components, registers a listener for WindowClosing, and
    initializes the GUI to a well-defined state.
  */
  public FLGUI() {
    // Set up a frame for the GUI components to be displayed.
    final Frame frame // MUST be final to be accessible by inner classes.
    = new Frame("FunList Framework GUI Application");
    ((BorderLayout)(frame.getLayout ())).setHgap (10);
    ((BorderLayout)(frame.getLayout ())).setVgap (10);
    frame.add(makeViewPanel(), BorderLayout.CENTER);
    frame.add(makeUserInputPanel(), "West");

    // Standard use of anonymous WindowAdapter class to free system's resources when closing.
    // This is a view property.
    frame.addWindowListener (
      new WindowAdapter() {
        public void windowClosing(WindowEvent e) {
          frame.dispose(); // In order for this inner class to access frame, frame MUST be final.
          System.exit(0);
        }
      }
    );
    frame.setSize(300, 300);
    frame.setVisible(true);
    txtIn.selectAll();
    txtIn.requestFocus();
  }

  private Panel makeViewPanel() {
    taListView.setEditable(false);
    txtListView.setEditable(false);
    Panel pnl = new Panel();
    pnl.setLayout(new BorderLayout(10, 10));
    pnl.add(new Label ("List Display"), "North");
    pnl.add(taListView, BorderLayout.CENTER);
    pnl.add(txtListView, "South");
    return pnl;
  }

  public void updateView(FunList fl) {
    // Update the TextArea View:
    taListView.setText ("");
    fl.execute(new TextAreaPrint(taListView));

    // Update the TextField view:
    txtListView.setText(fl.toString());
  }

  private Panel makeUserInputPanel () {
    Panel pnlInOut  = makeInOutPanel();
    Panel pnlButtons = makeButtonPanel();
    Panel pnlInput  = new Panel();
    pnlInput.setLayout(new BorderLayout (10, 10));
    pnlInput.add(pnlInOut, "North");
    pnlInput.add(pnlButtons, "South");
    return pnlInput;
  }

  private Panel makeInOutPanel () {
    // Make a panel for input text:
    Panel pnlIn = new Panel();
    pnlIn.setLayout (new BorderLayout());
    pnlIn.add (new Label("Input Integer:"), "North");
    pnlIn.add (txtIn, "South");

    // Make a panel for output text:
    Panel pnlOut = new Panel();
    pnlOut.setLayout(new BorderLayout ());
    pnlOut.add(new Label ("Output:"), "North");
    pnlOut.add(txtOut, "South");

    // Make a panel for both input and output texts and return this panel:
    Panel pnlInOut = new Panel ();
    pnlInOut.setLayout(new BorderLayout ());
    pnlInOut.add(pnlIn, "North");
    pnlInOut.add(pnlOut, "South");
    return pnlInOut;
  }

   public String getInput() {
    txtIn.selectAll();
    txtIn.requestFocus();
    return txtIn.getText();
  }

  public void setOutput(String s) {
    txtOut.setText(s);
  }

  private Panel makeButtonPanel() {
    Panel pnlButtons = new Panel();
    pnlButtons.setLayout(new GridLayout (4, 1, 10, 10));
    pnlButtons.add(btnEmpty);
    pnlButtons.add(btnCons);
    pnlButtons.add(btnSum);
    pnlButtons.add(btnGetNth);
    return pnlButtons;
  }

  /**
  * Registers an ActionListener for the Empty button.
  */
  public void addEmptyListener(ActionListener al) {
    btnEmpty.addActionListener(al);
  }

  /**
  * Registers an ActionListener for the Cons button.
  */
  public void addConsListener(ActionListener al) {
    btnCons.addActionListener(al);
  }

  /**
  * Registers an ActionListener for the Sum button.
  */
  public void addSumListener(ActionListener al) {
    btnSum.addActionListener(al);
  }

  /**
  * Registers an ActionListener for the GetNth button.
  */
  public void addGetNthListener(ActionListener al) {
    btnGetNth.addActionListener(al);
  }
}