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

/**
 * A virtual arrow pad that responds to wasd key presses.
 *
 * @author  Prof. David Bernstein, James Madison University
 * @version 1.0
 */
public class ArrowPad extends JPanel
{
    JButton      down, left, right, up;
    
    /**
     * Default Constructor.
     */
    public ArrowPad()
    {
        super();
        ArrowAction action;        

        down  = new JButton("\u2193");
        left  = new JButton("\u2190");
        right = new JButton("\u2192");
        up    = new JButton("\u2191");

        down.setActionCommand("DOWN");        
        left.setActionCommand("LEFT");        
        right.setActionCommand("RIGHT");        
        up.setActionCommand("UP");        

        // The same Action is used here for all of the JButton
        // objects. One could, instead, have a different Action for
        // each.
        action = new ArrowAction();
        down.addActionListener(action);
        left.addActionListener(action);
        right.addActionListener(action);
        up.addActionListener(action);

        setupKeyBindings();
        performLayout();
    }


    /**
     * Perform the necessary steps to layout this ArrowPad.
     */
    private void performLayout()
    {
        Box         bottom, main, top;

        setLayout(new FlowLayout(FlowLayout.CENTER));

        main   = Box.createVerticalBox();
        bottom = Box.createHorizontalBox();
        top    = Box.createHorizontalBox();
        
        top.add(up);

        bottom.add(left);
        bottom.add(down);
        bottom.add(right);

        main.add(top);
        main.add(bottom);
        
        add(main);
    }


    /**
     * Setup the key bindings to use.
     *
     * In this implementation, the wasd keys correspond to the virtual
     * up, left, down, and right buttons. One could, alternatively or
     * additionally, use the arrow keys and/or the arrow keys on the
     * numeric keypad.
     */
    private void setupKeyBindings()
    {
        ActionMap actionMap;        
        InputMap  inputMap;

        actionMap = this.getActionMap();
        inputMap  = this.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
        
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0), "w");
        actionMap.put("w", new ClickAction(up));

        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0), "a");
        actionMap.put("a", new ClickAction(left));

        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0), "s");
        actionMap.put("s", new ClickAction(down));

        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0), "d");
        actionMap.put("d", new ClickAction(right));
    }
}