taverna-workbench-edits-impl/src/main/java/net/sf/taverna/t2/workbench/edits/impl/menu/AbstractUndoAction.java

/*******************************************************************************
 * Copyright (C) 2012 The University of Manchester
 *
 *  Modifications to the initial code base are copyright of their
 *  respective authors, or their employers as appropriate.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2.1 of
 *  the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 ******************************************************************************/
package net.sf.taverna.t2.workbench.edits.impl.menu;

import static java.awt.Toolkit.getDefaultToolkit;
import static java.awt.event.KeyEvent.VK_Y;
import static java.awt.event.KeyEvent.VK_Z;
import static javax.swing.KeyStroke.getKeyStroke;
import static net.sf.taverna.t2.workbench.icons.WorkbenchIcons.redoIcon;
import static net.sf.taverna.t2.workbench.icons.WorkbenchIcons.undoIcon;

import java.awt.event.ActionEvent;

import javax.swing.AbstractAction;

import net.sf.taverna.t2.lang.observer.Observable;
import net.sf.taverna.t2.lang.observer.Observer;
import net.sf.taverna.t2.lang.observer.SwingAwareObserver;
import net.sf.taverna.t2.workbench.edits.EditManager;
import net.sf.taverna.t2.workbench.edits.EditManager.AbstractDataflowEditEvent;
import net.sf.taverna.t2.workbench.edits.EditManager.EditManagerEvent;
import net.sf.taverna.t2.workbench.selection.SelectionManager;
import net.sf.taverna.t2.workbench.selection.events.PerspectiveSelectionEvent;
import net.sf.taverna.t2.workbench.selection.events.SelectionManagerEvent;
import net.sf.taverna.t2.workbench.selection.events.WorkflowBundleSelectionEvent;
import uk.org.taverna.scufl2.api.container.WorkflowBundle;

/**
 * @author David Withers
 */
@SuppressWarnings("serial")
public abstract class AbstractUndoAction extends AbstractAction {
	protected EditManager editManager;
	private SelectionManager selectionManager;

	public AbstractUndoAction(String label, EditManager editManager) {
		super(label);
		this.editManager = editManager;
		if (label.equals("Undo")) {
			this.putValue(SMALL_ICON, undoIcon);
			this.putValue(SHORT_DESCRIPTION, "Undo an action");
			putValue(
					ACCELERATOR_KEY,
					getKeyStroke(VK_Z, getDefaultToolkit()
							.getMenuShortcutKeyMask()));
		} else if (label.equals("Redo")) {
			this.putValue(SMALL_ICON, redoIcon);
			this.putValue(SHORT_DESCRIPTION, "Redo an action");
			putValue(
					ACCELERATOR_KEY,
					getKeyStroke(VK_Y, getDefaultToolkit()
							.getMenuShortcutKeyMask()));
		}
		editManager.addObserver(new EditManagerObserver());
		updateStatus();
	}

	@Override
	public void actionPerformed(ActionEvent e) {
		WorkflowBundle workflowBundle = getCurrentDataflow();
		if (workflowBundle != null)
			performUndoOrRedo(workflowBundle);
	}

	/**
	 * Check if action should be enabled or disabled and update its status.
	 */
	public void updateStatus() {
		WorkflowBundle workflowBundle = getCurrentDataflow();
		if (workflowBundle == null)
			setEnabled(false);
		setEnabled(isActive(workflowBundle));
	}

	/**
	 * Retrieve the current dataflow from the {@link ModelMap}, or
	 * <code>null</code> if no workflow is active.
	 * 
	 * @return The current {@link Dataflow}
	 */
	protected WorkflowBundle getCurrentDataflow() {
		if (selectionManager == null)
			return null;
		return selectionManager.getSelectedWorkflowBundle();
	}

	/**
	 * Return <code>true</code> if the action should be enabled when the given
	 * {@link Dataflow} is the current, ie. if it's undoable or redoable.
	 * 
	 * @param dataflow
	 *            Current {@link Dataflow}
	 * @return <code>true</code> if the action should be enabled.
	 */
	protected abstract boolean isActive(WorkflowBundle workflowBundle);

	/**
	 * Called by {@link #actionPerformed(ActionEvent)} when the current dataflow
	 * is not <code>null</code>.
	 * 
	 * @param dataflow
	 *            {@link Dataflow} on which to undo or redo
	 */
	protected abstract void performUndoOrRedo(WorkflowBundle workflowBundle);

	public void setSelectionManager(SelectionManager selectionManager) {
		this.selectionManager = selectionManager;
		if (selectionManager != null)
			selectionManager.addObserver(new SelectionManagerObserver());
	}

	/**
	 * Update the status if there's been an edit done on the current workflow.
	 * 
	 */
	protected class EditManagerObserver implements Observer<EditManagerEvent> {
		@Override
		public void notify(Observable<EditManagerEvent> sender,
				EditManagerEvent message) throws Exception {
			if (!(message instanceof AbstractDataflowEditEvent))
				return;
			AbstractDataflowEditEvent dataflowEdit = (AbstractDataflowEditEvent) message;
			if (dataflowEdit.getDataFlow().equals(dataflowEdit.getDataFlow()))
				// It's an edit that could effect our undoability
				updateStatus();
		}
	}

	private final class SelectionManagerObserver extends
			SwingAwareObserver<SelectionManagerEvent> {
		private static final String DESIGN_PERSPECTIVE_ID = "net.sf.taverna.t2.ui.perspectives.design.DesignPerspective";

		@Override
		public void notifySwing(Observable<SelectionManagerEvent> sender,
				SelectionManagerEvent message) {
			if (message instanceof WorkflowBundleSelectionEvent)
				updateStatus();
			else if (message instanceof PerspectiveSelectionEvent) {
				PerspectiveSelectionEvent perspectiveSelectionEvent = (PerspectiveSelectionEvent) message;
				if (DESIGN_PERSPECTIVE_ID.equals(perspectiveSelectionEvent
						.getSelectedPerspective().getID()))
					updateStatus();
				else
					setEnabled(false);
			}
		}
	}
}