/*******************************************************************************
 * Copyright (c) 2000, 2006 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.ui.IActionDelegate;
import org.eclipse.ui.IEditorActionDelegate;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.WorkbenchException;

/**
 * Extends PartPluginAction for usage in editor parts. Objects
 * of this class are created by reading the registry (extension point "editorActions").
 */
public final class EditorPluginAction extends PartPluginAction {
    private IEditorPart currentEditor;

    /**
     * This class adds the requirement that action delegates
     * loaded on demand implement IViewActionDelegate
     */
    public EditorPluginAction(IConfigurationElement actionElement,
            IEditorPart part, String id, int style) {
        super(actionElement, id, style);
        if (part != null) {
			editorChanged(part);
		}
    }

    /* (non-Javadoc)
     * Method declared on PluginAction.
     */
    protected IActionDelegate validateDelegate(Object obj)
            throws WorkbenchException {
        if (obj instanceof IEditorActionDelegate) {
			return (IEditorActionDelegate) obj;
		} else {
			throw new WorkbenchException(
                    "Action must implement IEditorActionDelegate"); //$NON-NLS-1$
		}
    }

    /* (non-Javadoc)
     * Method declared on PluginAction.
     */
    protected void initDelegate() {
        super.initDelegate();
        ((IEditorActionDelegate) getDelegate()).setActiveEditor(this,
                currentEditor);
    }

    /**
     * Handles editor change by re-registering for selection
     * changes and updating IEditorActionDelegate.
     */
    public void editorChanged(IEditorPart part) {
        if (currentEditor != null) {
			unregisterSelectionListener(currentEditor);
		}

        currentEditor = part;

        if (getDelegate() == null && isOkToCreateDelegate()) {
			createDelegate();
		}
        if (getDelegate() != null) {
			((IEditorActionDelegate) getDelegate()).setActiveEditor(this, part);
		}

        if (part != null) {
			registerSelectionListener(part);
		}
    }
	
	/* (non-Javadoc)
	 * @see org.eclipse.ui.internal.PluginAction#dispose()
	 */
	public void dispose() {
        if (currentEditor != null) {
            unregisterSelectionListener(currentEditor);
			currentEditor = null;
        }
		super.dispose();
	}
}