/*
 * CalcGui.java
 *
 * Version:
 *    $Id$
 *
 * Revisions:
 *    $Log$
 */

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

/**
 * A Graphic view for a simple 4 function calculator.
 *
 * @author Paul Tymann
 */

public class CalcGui implements ActionListener {
    // Labels for the buttons

    private static final String labels = "789X456/123-0C=+" ;

    private static final int NUMROWS = 4 ;       // Rows and cols for buttons
    private static final int NUMCOLS = 4 ;

    private Calculator myCalc ;                  // The "model"

    private JLabel display ;                     // The display

    /**
     * Create a new Calculator GUI (view).
     *
     * @param calc the model for this view
     * @param name stirng to appear as the title in the main frame
     */
    
    public CalcGui( Calculator calc, String name ) {
	// Keep a reference to the model

        myCalc = calc ;

	// A Frame for the calculator

	JFrame win = new JFrame( name );

	// Frames do not handle close by default ...

	win.addWindowListener(
	    new WindowAdapter() {
	        public void windowClosing( WindowEvent e ) { 
                    System.exit( 0 ); 
                }
	    }
        );

	// Create the button panel

	JPanel buttons = new JPanel() ;
	buttons.setLayout( new GridLayout( NUMROWS, NUMCOLS ) );

	JButton b ;

	// Create the buttons, place them into the panel, and
	// register this object as the action listener for the
	// buttons

	for ( int i = 0 ; i < labels.length() ; i++ ) {
	    b = new JButton( labels.substring( i, i + 1 ) );
	    b.addActionListener( this );
	    buttons.add( b );
	}

	// Create the display

	display = new JLabel( "0", JLabel.RIGHT );

	// "Assemble" the calculator

	Container content = win.getContentPane();

	content.setLayout( new BorderLayout() );

	content.add( "North", display );
	content.add( "Center", buttons );

	// Display it and let the user run with it :-)

	win.pack();
	win.show();
    }

    /**
      * Return the current value in the display.
      *
      * @return A string representation of the current display.
      */

    public String getDisplay() {
      return new String( display.getText() );
    }

    /**
      * Change the display.
      *
      * @param String New value to be displayed on the calculator
      */

    public void setDisplay( String text ) {
      display.setText( text );
    }

    /**
      * Button event handler.  Calls handleButton() in the model
      * to do the actual processing.
      *
      * @param ActionEvent The button event
      */

    public void actionPerformed( ActionEvent e ) {
	String s = e.getActionCommand();  // Label of button pressed

        myCalc.handleButton( s );
    }

} // CalcGui