package edu.princeton.swing;

import java.beans.*;
import java.util.Vector;

import javax.swing.*;

/**
 * PDefaultListSelectionModel extends to add DefaultListSelectionModel support.
 */
public class PDefaultListSelectionModel extends DefaultListSelectionModel
                                        implements PListSelectionModel
{
    private Vector propertyChangeListeners;

    /**
     * Creates a new PDefaultListSelectionModel.
     */
    public PDefaultListSelectionModel()
    {
        super();

        propertyChangeListeners = new Vector();
    }

    /**
     * Adds a PropertyChangeListener to the model to listen for changes in "selectionMode".
     *
     * @param listener The new PropertyChangeListener to add.
     */
    public void addPropertyChangeListener(PropertyChangeListener listener)
    {
        if (listener == null)
            throw new NullPointerException();

        propertyChangeListeners.add(listener);
    }

    /**
     * Removes a PropertyChangeListener from the model.
     *
     * @param listener The old PropertyChangeListener to add.
     */
    public void removePropertyChangeListener(PropertyChangeListener listener)
    {
        if (listener == null)
            throw new NullPointerException();

        propertyChangeListeners.remove(listener);
    }

    /**
     * Intercept setSelectionMode calls to fire ProprtyChangeEvents when necessary.
     */
    public void setSelectionMode(int selectionMode)
    {
        int oldValue = getSelectionMode();

        super.setSelectionMode(selectionMode);

        int newValue = getSelectionMode();

        if (newValue != oldValue && !propertyChangeListeners.isEmpty())
        {
            PropertyChangeEvent e = new PropertyChangeEvent(
                this,
                "selectionMode",
                new Integer(oldValue),
                new Integer(newValue)
                );
            
            Object array[] = propertyChangeListeners.toArray();

            for (int ctr = 0; ctr < array.length; ctr++)
                ((PropertyChangeListener)array[ctr]).propertyChange(e);
        }
    }
}