/*******************************************************************************
 * 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;

import java.util.Iterator;

import org.eclipse.persistence.tools.workbench.utility.Model;
import org.eclipse.persistence.tools.workbench.utility.events.TreeChangeEvent;
import org.eclipse.persistence.tools.workbench.utility.events.TreeChangeListener;
import org.eclipse.persistence.tools.workbench.utility.iterators.NullIterator;


/**
 * This extension of PropertyAdapter provides TreeChange support.
 *
 * The typical subclass will override the following methods:
 * #getValueFromSubject()
 *     at the very minimum, override this method to return an iterator
 *     on the subject's tree aspect; it does not need to be overridden if
 *     #getValue() is overridden and its behavior changed
 * #addNode(Object[], Object) and #removeNode(Object[])
 *     override these methods if the client code needs to *change* the contents of
 *     the subject's tree aspect; oftentimes, though, the client code
 *     (e.g. UI) will need only to *get* the value
 * #getValue()
 *     override this method only if returning an empty iterator when the
 *     subject is null is unacceptable
 */
public abstract class TreeAspectAdapter
    extends AspectAdapter
    implements TreeValueModel
{
    /**
     * The name of the subject's tree that we use for the value.
     */
    protected String treeName;

    /** A listener that listens to the subject's tree aspect. */
    protected TreeChangeListener treeChangeListener;


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

    /**
     * Construct a TreeAspectAdapter for the specified subject
     * and tree.
     */
    protected TreeAspectAdapter(String treeName, Model subject) {
        super(subject);
        this.treeName = treeName;
    }

    /**
     * Construct a TreeAspectAdapter for the specified subject holder
     * and tree.
     */
    protected TreeAspectAdapter(ValueModel subjectHolder, String treeName) {
        super(subjectHolder);
        this.treeName = treeName;
    }


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

    protected void initialize() {
        super.initialize();
        this.treeChangeListener = this.buildTreeChangeListener();
    }

    /**
     * The subject's tree aspect has changed, notify the listeners.
     */
    protected TreeChangeListener buildTreeChangeListener() {
        // transform the subject's tree change events into VALUE tree change events
        return new TreeChangeListener() {
            public void nodeAdded(TreeChangeEvent e) {
                TreeAspectAdapter.this.nodeAdded(e);
            }
            public void nodeRemoved(TreeChangeEvent e) {
                TreeAspectAdapter.this.nodeRemoved(e);
            }
            public void treeChanged(TreeChangeEvent e) {
                TreeAspectAdapter.this.treeChanged(e);
            }
            public String toString() {
                return "tree change listener: " + TreeAspectAdapter.this.treeName;
            }
        };
    }


    // ********** ValueModel implementation **********

    /**
     * Return the value of the subject's tree aspect.
     * This should be an *iterator* on the tree.
     * @see ValueModel#getValue()
     */
    public Object getValue() {
        if (this.subject == null) {
            return NullIterator.instance();
        }
        return this.getValueFromSubject();
    }

    /**
     * Return the value of the subject's tree aspect.
     * This should be an *iterator* on the tree.
     * At this point we can be sure that the subject is not null.
     * @see ValueModel#getValue()
     */
    protected Iterator getValueFromSubject() {    // private-protected
        throw new UnsupportedOperationException();
    }


    // ********** TreeValueModel implementation **********

    /**
     * Insert the specified node in the subject's tree aspect.
     * @see TreeValueModel#addNode(Object[])
     */
    public void addNode(Object[] parentPath, Object node) {
        throw new UnsupportedOperationException();
    }

    /**
     * Remove the specified node from the subject's tree aspect.
     * @see TreeValueModel#removeNode(Object[])
     */
    public void removeNode(Object[] path) {
        throw new UnsupportedOperationException();
    }


    // ********** AspectAdapter implementation **********

    /**
     * @see AspectAdapter#hasListeners()
     */
    protected boolean hasListeners() {
        return this.hasAnyTreeChangeListeners(VALUE);
    }

    /**
     * @see AspectAdapter#fireAspectChange(Object, Object)
     */
    protected void fireAspectChange(Object oldValue, Object newValue) {
        this.fireTreeStructureChanged(VALUE);
    }

    /**
     * @see AspectAdapter#engageNonNullSubject()
     */
    protected void engageNonNullSubject() {
        ((Model) this.subject).addTreeChangeListener(this.treeName, this.treeChangeListener);
    }

    /**
     * @see AspectAdapter#disengageNonNullSubject()
     */
    protected void disengageNonNullSubject() {
        ((Model) this.subject).removeTreeChangeListener(this.treeName, this.treeChangeListener);
    }

    /**
     * @see org.eclipse.persistence.tools.workbench.utility.AbstractModel#toString(StringBuffer)
     */
    public void toString(StringBuffer sb) {
        sb.append(this.treeName);
    }


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

    protected void nodeAdded(TreeChangeEvent e) {
        this.fireNodeAdded(VALUE, e.getPath());
    }

    protected void nodeRemoved(TreeChangeEvent e) {
        this.fireNodeRemoved(VALUE, e.getPath());
    }

    protected void treeChanged(TreeChangeEvent e) {
        this.fireTreeStructureChanged(VALUE, e.getPath());
    }

}