/*

  * Copyright 2004-2008 the Seasar Foundation and the Others.

  *

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, 

  * either express or implied. See the License for the specific language

  * governing permissions and limitations under the License.

  */

 package org.seasar.uruma.binding.enables.impl;

 import org.eclipse.jface.viewers.ISelectionChangedListener;

 import org.eclipse.jface.viewers.SelectionChangedEvent;

 import org.eclipse.jface.viewers.StructuredSelection;

 import org.eclipse.jface.viewers.StructuredViewer;

 import org.eclipse.jface.viewers.Viewer;

 import org.eclipse.swt.widgets.Widget;

 import org.seasar.uruma.binding.enables.EnablesDependingListener;

 import org.seasar.uruma.binding.enables.EnablesForType;

 import org.seasar.uruma.context.WidgetHandle;

 import org.seasar.uruma.exception.EnablesDependingException;

 import org.seasar.uruma.exception.UnsupportedClassException;

 /**

  * {@link Viewer} に対する {@link EnablesDependingListener} です。<br />

  * 

  * @author y-komori

  */

 public class ViewerEnablesDependingListener extends EnablesDependingListener {

     protected StructuredViewer viewer;

     /**

      * {@link ViewerEnablesDependingListener} を構築します。<br />

      * 

      * @param target

      *            ターゲットの {@link WidgetHandle}

      * @param enabled

      *            イネーブル状態を変更するウィジットの {@link WidgetHandle}

      * @param type

      *            選択条件を表す {@link EnablesForType}

      */

     public ViewerEnablesDependingListener(final WidgetHandle target,

             final WidgetHandle enabled, final EnablesForType type) {

         super(target, enabled, type);

         if (target.getWidget() instanceof Viewer) {

             this.viewer = target.<StructuredViewer> getCastWidget();

         } else {

             throw new UnsupportedClassException(target.getWidgetClass(),

                     StructuredViewer.class);

         }

     }

     /*

      * @see org.seasar.uruma.binding.enables.EnablesDependingListener#setupListener()

      */

     @Override

     protected void setupListener() {

         ISelectionChangedListener listener = new ISelectionChangedListener() {

             public void selectionChanged(SelectionChangedEvent event) {

                 updateEnableState();

             }

         };

         viewer.addSelectionChangedListener(listener);

     }

     /*

      * @see org.seasar.uruma.binding.enables.EnablesDependingListener#updateEnableState()

      */

     @Override

     protected void updateEnableState() {

         if (!viewer.getControl().isDisposed()) {

             Object enabledWidget = enabled.getWidget();

             if (enabledWidget instanceof Widget

                     && ((Widget) enabledWidget).isDisposed()) {

                 return;

             }

             boolean enableState = resolveEnabledState();

             enabledProperty.setValue(enabledWidget, Boolean

                     .valueOf(enableState));

         }

     }

     protected boolean resolveEnabledState() {

         boolean result = false;

         int selectionCount = ((StructuredSelection) viewer.getSelection())

                 .size();

         if (type == EnablesForType.SELECTION) {

             result = (selectionCount > 0);

         } else if (type == EnablesForType.SINGLE) {

             result = (selectionCount == 1);

         } else if (type == EnablesForType.PAIR) {

             result = (selectionCount == 2);

         } else if (type == EnablesForType.NONE) {

             result = (selectionCount == 0);

         } else if (type == EnablesForType.MULTI) {

             result = (selectionCount >= 2);

         } else {

             throw new EnablesDependingException(viewer.getClass(), type);

         }

         return result;

     }

 }