/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.uitools.app.swing;

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

import javax.swing.ComboBoxModel;

import org.eclipse.persistence.tools.workbench.uitools.app.CollectionValueModel;
import org.eclipse.persistence.tools.workbench.uitools.app.ListValueModel;
import org.eclipse.persistence.tools.workbench.uitools.app.PropertyValueModel;
import org.eclipse.persistence.tools.workbench.uitools.app.ValueModel;
import org.eclipse.persistence.tools.workbench.utility.string.StringTools;


/**
 * This javax.swing.ComboBoxModel can be used to keep a ListDataListener
 * (e.g. a JComboBox) in synch with a ListValueModel (or a CollectionValueModel).
 * For combo boxes, the model object that holds the current selection is
 * typically a different model object than the one that holds the collection
 * of choices.
 *
 * For example, a MWReference (the selectionOwner) has an attribute
 * "sourceTable" (the collectionOwner)
 * which holds on to a collection of MWDatabaseFields. When the selection
 * is changed this model will keep the listeners aware of the changes.
 * The inherited list model will keep its listeners aware of changes to the
 * collection model
 *
 * In addition to the collection holder required by the superclass,
 * an instance of this ComboBoxModel must be supplied with a
 * selection holder, which is a PropertyValueModel that provides access
 * to the selection (typically a PropertyAspectAdapter).
 */
public class ComboBoxModelAdapter extends ListModelAdapter implements ComboBoxModel {

    protected PropertyValueModel selectionHolder;
    protected PropertyChangeListener selectionListener;


    // ********** constructors **********

    /**
     * Constructor - the list holder and selection holder are required;
     */
    public ComboBoxModelAdapter(ListValueModel listHolder, PropertyValueModel selectionHolder) {
        super(listHolder);
        if (selectionHolder == null) {
            throw new NullPointerException();
        }
        this.selectionHolder = selectionHolder;
    }

    /**
     * Constructor - the collection holder and selection holder are required;
     */
    public ComboBoxModelAdapter(CollectionValueModel collectionHolder, PropertyValueModel selectionHolder) {
        super(collectionHolder);
        if (selectionHolder == null) {
            throw new NullPointerException();
        }
        this.selectionHolder = selectionHolder;
    }


    // ********** initialization **********

    /**
     * Extend to build the selection listener.
     */
    protected void initialize() {
        super.initialize();
        this.selectionListener = this.buildSelectionListener();
    }

    protected PropertyChangeListener buildSelectionListener() {
        return new PropertyChangeListener() {
            public void propertyChange(PropertyChangeEvent e) {
                // notify listeners that the selection has changed
                ComboBoxModelAdapter.this.fireSelectionChanged();
            }
            public String toString() {
                return "selection listener";
            }
        };
    }


    // ********** ComboBoxModel implementation **********

    /**
     * @see javax.swing.ComboBoxModel#getSelectedItem()
     */
    public Object getSelectedItem() {
        return this.selectionHolder.getValue();
    }

    /**
     * @see javax.swing.ComboBoxModel#setSelectedItem(Object)
     */
    public void setSelectedItem(Object selectedItem) {
        this.selectionHolder.setValue(selectedItem);
    }


    // ********** behavior **********

    /**
     * Extend to engage the selection holder.
     */
    protected void engageModel() {
        super.engageModel();
        this.selectionHolder.addPropertyChangeListener(ValueModel.VALUE, this.selectionListener);
    }

    /**
     * Extend to disengage the selection holder.
     */
    protected void disengageModel() {
        this.selectionHolder.removePropertyChangeListener(ValueModel.VALUE, this.selectionListener);
        super.disengageModel();
    }

    /**
     * Notify the listeners that the selection has changed.
     */
    protected void fireSelectionChanged() {
        // I guess this will work...
        this.fireContentsChanged(this, -1, -1);
    }

    public String toString() {
        return StringTools.buildToStringFor(this, this.selectionHolder + ":" + this.listHolder);
    }

}