content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
   *
   * This library 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 library 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.
   *
   * For further information about Alkacon Software, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://www.opencms.org
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.opencms.ui.contextmenu;
  
  import org.opencms.main.CmsLog;
  
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.ServiceLoader;
  
  import org.apache.commons.logging.Log;
  
  import com.google.common.collect.ClassToInstanceMap;
  import com.google.common.collect.Lists;
  import com.google.common.collect.MutableClassToInstanceMap;
  
  /**
   * Class used to manage multiple context menu item providers through a single instance.<p>
   *
   * Also keeps track of available menu entries by their global id.<p>
   */
  public class CmsContextMenuItemProviderGroup implements I_CmsContextMenuItemProvider {
  
      /** Logger instance for this class. */
      private static final Log LOG = CmsLog.getLog(CmsContextMenuItemProviderGroup.class);
  
      /** Map of provider classes. */
      ClassToInstanceMap<I_CmsContextMenuItemProvider> m_providerMap = MutableClassToInstanceMap.create();
  
      /** Item cache. */
      private List<I_CmsContextMenuItem> m_itemCache = Lists.newArrayList();
  
      /**
       * Creates a new instance.<p>
       */
      public CmsContextMenuItemProviderGroup() {
          Iterator<I_CmsContextMenuItemProvider> providersIt = ServiceLoader.load(
              I_CmsContextMenuItemProvider.class).iterator();
          while (providersIt.hasNext()) {
              try {
                  addProvider(providersIt.next());
              } catch (Throwable t) {
                  LOG.error("Error loading context menu provider from classpath.", t);
              }
          }
      }
  
      /**
       * Adds a new provider class.<p>
       *
       * @param providerClass the provider class
       */
      public void addProvider(Class<? extends I_CmsContextMenuItemProvider> providerClass) {
  
          try {
              m_providerMap.put(providerClass, providerClass.newInstance());
          } catch (Exception e) {
              LOG.error(e.getLocalizedMessage(), e);
          }
      }
  
      /**
       * Adds a provider.<p>
       *
       * Note that no two providers of the same exact class may be added.<p>
       *
       * @param instance the provider instance to add
       */
      public void addProvider(I_CmsContextMenuItemProvider instance) {
  
          m_providerMap.put(instance.getClass(), instance);
  
      }
  
      /**
       * @see org.opencms.ui.contextmenu.I_CmsContextMenuItemProvider#getMenuItems()
       */
      public List<I_CmsContextMenuItem> getMenuItems() {
  
          return Collections.unmodifiableList(m_itemCache);
      }
  
      /**
       * Initializes this instance.<p>
       *
       * This must be called after the provider classes have been added.
       */
      public synchronized void initialize() {
  
          List<I_CmsContextMenuItem> result = Lists.newArrayList();
          for (I_CmsContextMenuItemProvider provider : m_providerMap.values()) {
              result.addAll(provider.getMenuItems());
          }
          m_itemCache = result;
      }
  
  }
  