org.eclipse.osbp.runtime.web.vaadin.databinding/src/org/eclipse/osbp/runtime/web/vaadin/databinding/model/internal/MultiSelectionListChangeListener.java

/**
 * Copyright (c) 2011, 2015 - Lunifera GmbH (Gross Enzersdorf, Austria), Loetz GmbH&Co.KG (69115 Heidelberg, Germany)
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *         Florian Pirchner - Initial implementation
 */
package org.eclipse.osbp.runtime.web.vaadin.databinding.model.internal;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import org.eclipse.core.databinding.observable.Diffs;
import org.eclipse.core.databinding.observable.list.ListDiff;
import org.eclipse.core.databinding.property.IProperty;
import org.eclipse.core.databinding.property.ISimplePropertyListener;
import org.eclipse.core.databinding.property.NativePropertyListener;

import com.vaadin.data.Container;
import com.vaadin.data.Container.Viewer;
import com.vaadin.data.Property;
import com.vaadin.data.Property.ValueChangeEvent;
import com.vaadin.data.Property.ValueChangeNotifier;
import com.vaadin.ui.AbstractSelect;

/**
 */
@SuppressWarnings("serial")
public class MultiSelectionListChangeListener extends NativePropertyListener
		implements Property.ValueChangeListener {

	private ArrayList<Object> oldItems;
	private Object source;

	public MultiSelectionListChangeListener(IProperty property,
			ISimplePropertyListener listener) {
		super(property, listener);
	}

	protected void doAddTo(Object source) {
		this.source = source;
		getNotifier(source).addValueChangeListener(this);

		cacheOldValues(source);
	}

	protected void cacheOldValues(Object source) {
		Collection<?> oldValues = (Collection<?>) getWidget(source).getValue();
		oldItems = new ArrayList<Object>(oldValues);
	}

	protected Property.ValueChangeNotifier getNotifier(Object source) {
		return (ValueChangeNotifier) source;
	}

	protected AbstractSelect getWidget(Object source) {
		return (AbstractSelect) source;
	}

	protected Container getContainer(Object source) {
		Container.Viewer viewer = (Viewer) source;
		Container ds = viewer.getContainerDataSource();
		return ds;
	}

	protected void doRemoveFrom(Object source) {
		getNotifier(source).removeValueChangeListener(this);
	}

	@Override
	public void valueChange(ValueChangeEvent event) {
		List<Object> oldValues = oldItems;
		ListDiff diffs = Diffs.computeListDiff(oldValues,
				convertToList((Collection<?>) event.getProperty().getValue()));
		cacheOldValues(source);

		fireChange(source, diffs);
	}

	@SuppressWarnings("unchecked")
	private List<Object> convertToList(Collection<?> itemIds) {
		return (List<Object>) ((itemIds instanceof List) ? itemIds
				: new ArrayList<Object>(itemIds));
	}
}