/**
    * This file Copyright (c) 2018 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.ui.contentapp.observation;
  
  import info.magnolia.ui.datasource.jcr.JcrDatasourceDefinition;
  import info.magnolia.ui.framework.ioc.Destructible;
  
  import java.util.Collections;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.function.Consumer;
  
  import javax.jcr.RepositoryException;
  import javax.jcr.observation.EventIterator;
  
  import org.apache.commons.lang3.StringUtils;
  
  import com.vaadin.data.provider.DataProvider;
  import com.vaadin.shared.Registration;
  
  import lombok.SneakyThrows;
  
  /**
   * JCR Observation utility wrapper to be used within UI framework.
   */
  public class JcrDataSourceObservation implements Destructible {
  
      private final JcrObservation jcrObservation;
      private final Set<Registration> registrations = Collections.newSetFromMap(new ConcurrentHashMap<>());
  
      public JcrDataSourceObservation(JcrObservation jcrObservation) {
          this.jcrObservation = jcrObservation;
      }
  
      public void register(JcrDatasourceDefinition datasourceDefinition, DataProvider dataProvider) {
          Consumer<EventIterator> consumer = new Consumer<EventIterator>() {
              @SneakyThrows(RepositoryException.class)
              @Override
              public void accept(EventIterator eventIterator) {
                  if (eventIterator.hasNext()) {
                      String path = StringUtils.substringBeforeLast(eventIterator.nextEvent().getPath(), "/");
                      if (StringUtils.startsWith(path, datasourceDefinition.getRootPath())) {
                          dataProvider.refreshAll();
                      }
                  }
              }
          };
          jcrObservation.register(consumer, datasourceDefinition.getWorkspace());
          registrations.add(() -> jcrObservation.unregister(consumer, datasourceDefinition.getWorkspace()));
      }
  
      @Override
      public void destroy() {
          registrations.removeIf(registration -> {
              registration.remove();
              return true;
          });
      }
  }