package org.csstudio.ui.util.composites;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;

import org.eclipse.swt.widgets.Composite;

/**
 * Implements the bean bound property notification scheme on top of a composite.
 * Subclasses should specify in the documentation which properties are bound.
 * 
 * @author Gabriele Carcassi
 */
public abstract class BeanComposite extends Composite {

	protected final PropertyChangeSupport changeSupport = new PropertyChangeSupport(
			this);

	/**
	 * Pass through constructor to Composite.
	 * 
	 * @param parent
	 *            composite parent
	 * @param style
	 *            SWT style
	 */
	public BeanComposite(Composite parent, int style) {
		super(parent, style);
	}

	/**
	 * Adds a new listener.
	 * 
	 * @param listener
	 *            a new listener
	 */
	public void addPropertyChangeListener(PropertyChangeListener listener) {
		changeSupport.addPropertyChangeListener(listener);
	}

	/**
	 * Removes the given listener.
	 * 
	 * @param listener
	 *            a listener
	 */
	public void removePropertyChangeListener(PropertyChangeListener listener) {
		changeSupport.removePropertyChangeListener(listener);
	}

	/**
	 * Forwards events from the child widget as if events coming from this
	 * widget.
	 * <p>
	 * This method is useful when this composite will be constructed with other
	 * composites and will need to expose parts of them as its own.
	 * 
	 * @param widgetProperty
	 *            a property name of the widget inside the composite
	 * @param panelProperty
	 *            a property name of this widget
	 * @return a new listener
	 */
	protected void forwardPropertyChange(final BeanComposite childWidget,
			final String childProperty, final String property) {
		childWidget.addPropertyChangeListener(new PropertyChangeListener() {

			@Override
			public void propertyChange(PropertyChangeEvent evt) {
				if (childProperty.equals(evt.getPropertyName())) {
					changeSupport.firePropertyChange(property,
							evt.getOldValue(), evt.getNewValue());
				}
			}
		});
	}

}