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

/**
 * GUI to display FunListFW.
 * I use this to explain:
 * 1. rudiments of AWT using the layout manager as a "strategy" for layout GUI components
 * 2. rudiments of event handlers also as strategy for listening and responding to events.
 * 3. the Model-View-Controller (MVC) paradigm.
 * Copyright 1999, Dung X. Nguyen - All rights reserved.
 *
 * @version 1.01   Sept. 30, 1999
 * @author Dung X. Nguyen
 */
public class FunFWGUI
{
  /*************************************************************
  *  (private) Attributes of the GUI: what the GUI has.
  *  They consist of two groups: one is for the GUI, and  the other
  *  is for the FunListFW itself.
  */
  private Frame     _frame;   // The frame for the GUI.
  private TextField _txtIn;   // Input text for list methods list visitors' methods.
  private TextField _txtOut;  // Output text.
  private TextArea _taListView;   // a TextArea view of the list model
  private TextField _txtListView; // a TextField view of the list model
  /**
	 * The list model.
	 * @SBGen Variable (,model,controller-view,64)
	 */
	private FunListFW _list;
  
  /**************************************************************
  *  Initializes the GUI to a well-defined state.
  *  Need to carry out the following tasks:
  *  1. initialize the internal state of the soda machine,
  *  2. add the desired GUI components, and
  *  3. register events fired by the active components with appropriate event listeners.
  */
  public FunFWGUI()
  {
    Panel pnlView      = makeViewPanel ();
    Panel pnlUserInput = makeUserInputPanel ();
    _frame             = new Frame("FunList Framework GUI");
    ((BorderLayout)(_frame.getLayout ())).setHgap (10);
    ((BorderLayout)(_frame.getLayout ())).setVgap (10);
    _frame.add (pnlView, BorderLayout.CENTER);
    _frame.add (pnlUserInput, "West");
    _frame.addWindowListener (new CloseWindowListener());
    _frame.setSize (240, 300);
    _frame.setVisible (true);
    _txtIn.selectAll ();
    _txtIn.requestFocus ();
  }

  private Panel makeViewPanel ()
  {
    _list = EmptyFW.Singleton ();

    _taListView = new TextArea ();
    _taListView.setEditable (false);
    _txtListView = new TextField (_list.toString ());
    _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;
  }

  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:
    _txtIn = new TextField("0", 4);
    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:
    _txtOut = new TextField("0", 4);
    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;
  }

  private Panel makeButtonPanel ()
  {
    Button btnEmpty = new Button ("Empty");
    btnEmpty.addActionListener (new EmptyListener ());
    Button btnCons = new Button ("Cons");
    btnCons.addActionListener (new ConsListener ());
    Button btnSum = new Button ("Sum");
    btnSum.addActionListener (new SumListener ());
    Button btnGetNth = new Button ("GetNth");
    btnGetNth.addActionListener (new GetNthListener ());
    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;
  }

  /*************************************************************
  * Clears the text area and sets the list model to Empty.
  */
  class EmptyListener implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      _list = EmptyFW.Singleton ();
      _taListView.setText ("");
      _txtListView.setText (_list.toString ());
    }
  }

  /*************************************************************
  * Inserts to the front of the list model and displays it in the text area.
  */
  class ConsListener implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      try
      {
// For debugging and illustration purpose:
System.out.println ("ConsListener.actionPerformed: input = " + _txtIn.getText ());
        int i = Integer.parseInt(_txtIn.getText ());
        _list = new ConsFW (new Integer (i), _list);
        _taListView.setText ("");
        _list.execute (TextAreaPrint.Singleton (), _taListView);
        _txtListView.setText (_list.toString ());
      }
      catch (NumberFormatException x)
      {
// For debugging and illustration purpose:
System.out.println ("ConsListener.actionPerformed: input " + _txtIn.getText () + " is not a number!");
      }
      _txtIn.selectAll ();
      _txtIn.requestFocus ();
    }
  }

  /*************************************************************
  * Sums the integer elements in the list model and displays result in output text field.
  */
  class SumListener implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      Integer sumInt = (Integer)_list.execute (SumAlgo.Singleton (), null);
      _txtOut.setText (sumInt.toString ());
    }
  }

  /*************************************************************
  *
  */
  class GetNthListener implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      int n = Integer.parseInt(_txtIn.getText ());
      Integer nthInt = (Integer)_list.execute (GetNth.Singleton (), new Integer (n));
      _txtOut.setText (nthInt.toString ());
    }
  }

  /*************************************************************
  *  Standard way to free system's resources for Window class when closing.
  */
  class CloseWindowListener extends WindowAdapter
  {
    public void windowClosing(WindowEvent e)
    {
        _frame.dispose (); //frees system's resources.
        System.exit(0);
    }
  }

  /**************************************************************
   * Entry point into the program
   * @param args The parameters for the entry.  They are not used here.
   */
  public static void main(String[] args)
  {
    new FunFWGUI();
  }
}