/**
    * 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;
  
  import static info.magnolia.ui.contentapp.JcrDataProviderUtils.*;
  
  import info.magnolia.jcr.RuntimeRepositoryException;
  import info.magnolia.jcr.iterator.FilteringPropertyIterator;
  import info.magnolia.jcr.predicate.AbstractPredicate;
  import info.magnolia.jcr.predicate.JCRMgnlPropertyHidingPredicate;
  import info.magnolia.jcr.util.NodeUtil;
  import info.magnolia.ui.datasource.jcr.JcrDatasource;
  import info.magnolia.ui.datasource.jcr.JcrDatasourceDefinition;
  import info.magnolia.ui.filter.DataFilter;
  
  import java.util.Collection;
  import java.util.Comparator;
  import java.util.stream.Stream;
  
  import javax.jcr.Item;
  import javax.jcr.Node;
  import javax.jcr.Property;
  import javax.jcr.RepositoryException;
  
  import com.google.common.collect.Lists;
  import com.machinezoo.noexception.Exceptions;
  import com.vaadin.data.provider.AbstractBackEndHierarchicalDataProvider;
  import com.vaadin.data.provider.HierarchicalQuery;
  import com.vaadin.data.provider.Query;
  
  /**
   * Hierarchical JCR data provider.
   */
  public class HierarchicalJcrDataProvider extends AbstractBackEndHierarchicalDataProvider<Item, DataFilter> {
  
      private final JcrDatasource datasource;
      private final JcrDatasourceDefinition datasourceDefinition;
  
      public HierarchicalJcrDataProvider(JcrDatasourceDefinition definition, JcrDatasource datasource) {
          this.datasource = datasource;
          this.datasourceDefinition = definition;
      }
  
      @Override
      public int getChildCount(HierarchicalQuery<Item, DataFilter> query) {
          Item parent = query.getParent() == null ? getRootNode() : query.getParent();
          return (int) getChildren(parent, datasourceDefinition.isIncludeProperties(), query).count();
      }
  
      @Override
      public boolean hasChildren(Item item) {
          return getChildren(item, datasourceDefinition.isIncludeProperties(), new Query<>()).count() > 0;
      }
  
      @Override
      protected Stream<Item> fetchChildrenFromBackEnd(HierarchicalQuery<Item, DataFilter> query) {
          final Item parent = query.getParent() == null ? getRootNode() : query.getParent();
          return getChildren(parent, datasourceDefinition.isIncludeProperties(), query)
                  .skip(query.getOffset())
                  .limit(query.getLimit());
      }
  
      private Item getRootNode() {
          try {
              return datasource.getJCRSession().getNode(datasourceDefinition.getRootPath());
          } catch (RepositoryException e) {
              throw new RuntimeRepositoryException(e);
          }
     }
 
     private Stream<Item> getChildren(Item item, boolean includeProperties, Query<Item, DataFilter> query) {
         Stream<? extends Item> stream = Stream.empty();
         if (item.isNode()) {
             Node node = (Node) item;
             Collection<AbstractPredicate<Node>> predicates = query.getFilter()
                     .map(dataFilter -> Lists.newArrayList(new NodeTypeFilteringPredicate(datasourceDefinition), new PropertyFilteringPredicate(query), new ActivationStatusFilteringPredicate(query)))
                     .orElse(Lists.newArrayList(new NodeTypeFilteringPredicate(datasourceDefinition)));
 
             stream = streamJcrItems((Exceptions.wrap().get(() -> NodeUtil.getNodes(node, new ChainedPredicate(predicates)).iterator())));
             if (includeProperties) {
                 Stream<Property> properties = streamJcrItems(Exceptions.wrap().get(() -> new FilteringPropertyIterator(node.getProperties(), shouldIncludeSystemProperties(query) ? new AlwaysTruePredicate() : new JCRMgnlPropertyHidingPredicate())));
                 stream = Stream.concat(stream, properties.sorted(Comparator.comparing(Exceptions.wrap().function(Item::getName))));
             }
         }
         return (Stream<Item>) stream;
     }
 
     private boolean shouldIncludeSystemProperties(Query<Item, DataFilter> query) {
         return query.getFilter()
                 .map(dataFilter -> dataFilter.<Boolean>getProperty("includeSystemProperties"))
                 .orElse(false);
     }
 }