/* $Id: ActionAddExtensionPoint.java 18709 2010-08-30 22:38:37Z bobtarling $

  *****************************************************************************

  * Copyright (c) 2009-2010 Contributors - see below

  * 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:

  *    Bob Tarling

  *    Laurent Braud

  *****************************************************************************

  *

  * Some portions of this file was previously release using the BSD License:

  */

 // Copyright (c) 1996-2006 The Regents of the University of California. All

 // Rights Reserved. Permission to use, copy, modify, and distribute this

 // software and its documentation without fee, and without a written

 // agreement is hereby granted, provided that the above copyright notice

 // and this paragraph appear in all copies.  This software program and

 // documentation are copyrighted by The Regents of the University of

 // California. The software program and documentation are supplied "AS

 // IS", without any accompanying services from The Regents. The Regents

 // does not warrant that the operation of the program will be

 // uninterrupted or error-free. The end-user understands that the program

 // was developed for research purposes and is advised not to rely

 // exclusively on the program for any reason.  IN NO EVENT SHALL THE

 // UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,

 // SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS,

 // ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF

 // THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF

 // SUCH DAMAGE. THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY

 // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE

 // PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF

 // CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT,

 // UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 package org.argouml.uml.diagram.ui;

 import java.awt.event.ActionEvent;

 import javax.swing.Action;

 import org.argouml.application.helpers.ResourceLoaderWrapper;

 import org.argouml.i18n.Translator;

 import org.argouml.model.Model;

 import org.argouml.ui.targetmanager.TargetEvent;

 import org.argouml.ui.targetmanager.TargetListener;

 import org.argouml.ui.targetmanager.TargetManager;

 import org.argouml.ui.UndoableAction;

 /**

  * A class to implement the addition of extension points to use cases.<p>

  *

  * This is a singleton. Implemented with a private constructor and a static

  * access method. Marked as final, since it can't sensibly be subclassed (the

  * access method wouldn't work properly).<p>

  *

  * @author  Jeremy Bennett (mail@jeremybennett.com).

  * @stereotype singleton

  */

 public final class ActionAddExtensionPoint extends UndoableAction {

     /**

      * Our private copy of the instance. Only accessible through the proper

      * access method.

      */

     private static ActionAddExtensionPoint singleton;

     ///////////////////////////////////////////////////////////////////////////

     //

     // Constructors

     //

     ///////////////////////////////////////////////////////////////////////////

     /**

      * Constructor is private, since it cannot be called directly for a

      * singleton. Make use of the access funtion.<p>

      */

     public ActionAddExtensionPoint() {

         super(Translator.localize("button.new-extension-point"),

                 ResourceLoaderWrapper.lookupIcon("button.new-extension-point"));

         // Set the tooltip string:

         putValue(Action.SHORT_DESCRIPTION, 

                 Translator.localize("button.new-extension-point"));

     }

     ///////////////////////////////////////////////////////////////////////////

     //

     // Main methods

     //

     ///////////////////////////////////////////////////////////////////////////

     /**

      * Get the single instance of the action.<p>

      *

      * Since we are a singleton, this is the only way of accessing the

      * instance, which is created if it does not exist.<p>

      *

      * @return The singleton instance.

      */

     public static ActionAddExtensionPoint singleton() {

         // Create the singleton if it does not exist, and then return it

         if (singleton == null) {

             singleton = new ActionAddExtensionPoint();

             // When a new target is selected, we have to check if it 's a use case.

             //Then, the icone "add extension point" have to become enabled.

             TargetManager.getInstance().addTargetListener(new TargetListener() {

                 public void targetAdded(TargetEvent e) {

                     setTarget();

                 }

                 public void targetRemoved(TargetEvent e) {

                     setTarget();

                 }

                 public void targetSet(TargetEvent e) {

                     setTarget();

                 }

                 private void setTarget() {

                     singleton.setEnabled(singleton.shouldBeEnabled());

                 }

             });

             singleton.setEnabled(singleton.shouldBeEnabled());

         }

         return singleton;

     }

     /**

      * Called if this action is invoked.<p>

      *

      * @see java.awt.event.ActionListener#actionPerformed(java.awt.event.ActionEvent)

      * @param ae  The action that caused us to be invoked.

      */

     public void actionPerformed(ActionEvent ae) {

         super.actionPerformed(ae);

         // Find the target in the project browser. We can only do anything if

         // its a use case.

         Object target = TargetManager.getInstance().getModelTarget();

         if (!(Model.getFacade().isAUseCase(target))) {

             return;

         }

         // Create a new extension point and make it the browser target. Then

         // invoke the superclass action method.

         Object ep =

             Model.getUseCasesFactory()

                 .buildExtensionPoint(target);

         TargetManager.getInstance().setTarget(ep);

     }

     /**

      * A predicate to determine if this action is enabled.<p>

      *

      * @see org.tigris.gef.undo.UndoableAction#isEnabled()

      * @return  <code>true</code> if the superclass affirms this action is

      *          enabled and the target is a use case. <code>false</code>

      *          otherwise.

      */

     public boolean isEnabled() {

         Object target = TargetManager.getInstance().getModelTarget();

         return super.isEnabled()

                 && (Model.getFacade().isAUseCase(target));

     }

     /**

      * Called when a new target is selected, in order to display Action

      * @return true if the target is a use case, otherwise false

      * 

      * @since 2010-08-30

      */

     public boolean shouldBeEnabled() {

         Object target = TargetManager.getInstance().getSingleModelTarget();

         if (target == null) {

             return false;

         }

         return Model.getFacade().isAUseCase(target);

     }

 } /* end class ActionAddExtensionPoint */