/**
    * 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 com.vaadin.shared.data.sort.SortDirection.ASCENDING;
  import static info.magnolia.ui.contentapp.JcrDataProviderUtils.*;
  
  import info.magnolia.context.Context;
  import info.magnolia.ui.contentapp.observation.JcrDataSourceObservation;
  import info.magnolia.ui.datasource.jcr.JcrDatasourceDefinition;
  import info.magnolia.ui.framework.ioc.Destructible;
  
  import java.util.Optional;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  import javax.inject.Provider;
  import javax.jcr.Node;
  import javax.jcr.NodeIterator;
  import javax.jcr.RepositoryException;
  import javax.jcr.Session;
  
  import org.apache.commons.collections4.CollectionUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.vaadin.data.provider.AbstractBackEndDataProvider;
  import com.vaadin.data.provider.Query;
  import com.vaadin.data.provider.SortOrder;
  
  import lombok.SneakyThrows;
  
  /**
   * JCR data provider.
   */
  public class JcrDataProvider extends AbstractBackEndDataProvider<Node, DataFilter> implements Destructible {
      private static final Logger log = LoggerFactory.getLogger(JcrDataProvider.class);
      private final JcrDatasourceDefinition definition;
      private final Provider<Context> contextProvider;
      private final JcrDataSourceObservation observation;
  
      public JcrDataProvider(JcrDatasourceDefinition definition, JcrDataSourceObservation observation, Provider<Context> contextProvider) {
          this.definition = definition;
          this.contextProvider = contextProvider;
          this.observation = observation;
          observation.register(definition,this);
      }
  
      @Override
      public void destroy() {
          observation.destroy();
      }
  
      @Override
      public boolean isInMemory() {
          return false;
      }
  
      @Override
      @SneakyThrows
      public Stream<Node> fetchFromBackEnd(Query<Node, DataFilter> query) {
          javax.jcr.query.Query q = createJcrQuery(query);
          q.setLimit(query.getLimit());
          q.setOffset(query.getOffset());
  
          final NodeIterator result = q.execute().getNodes();
          //noinspection unchecked
          return streamQueryResults(query, result);
     }
 
     @Override
     @SneakyThrows
     public int sizeInBackEnd(Query<Node, DataFilter> query) {
         return (int)createJcrQuery(query).execute().getNodes().getSize();
     }
 
     @Override
     @SneakyThrows
     public Object getId(Node item) {
         return item.getIdentifier();
     }
 
     private Session getSession() throws RepositoryException {
         return contextProvider.get().getJCRSession(definition.getWorkspace());
     }
 
     @SneakyThrows
     private javax.jcr.query.Query createJcrQuery(Query<Node, DataFilter> query) {
         final StringBuilder statement = new StringBuilder("select * from [nt:base] as t ");
 
         createWhereClause().ifPresent(clause -> statement.append(clause));
         createOrderByClause(query).ifPresent(clause -> statement.append(clause));
 
         log.debug("JCR query statement is {}", statement);
 
         return getSession()
                         .getWorkspace()
                         .getQueryManager()
                         .createQuery(statement.toString(), javax.jcr.query.Query.JCR_SQL2);
     }
 
     private Stream<Node> streamQueryResults(Query<Node, DataFilter> query, NodeIterator nodes) {
         //noinspection unchecked
         return streamJcrItems(nodes)
                 .map(node -> wrap((Node) node))
                 .filter(node ->
                         query.getFilter()
                                 .map(DataFilter::getPathFilter)
                                 .map(path -> isItemPathMatching((Node) node, path))
                                 .orElse(true));
     }
 
     private Optional<String> createWhereClause() {
         if (CollectionUtils.isEmpty(definition.getAllowedNodeTypes())) {
             return Optional.empty();
         }
         // Using filterByNodeType predicate when calling Stream.count() at size() method
         // will cause a sort of infinite loop where size() seems to be called forever.
         final String types = definition.getAllowedNodeTypes()
                 .stream()
                 .map(type -> String.format("t.[jcr:primaryType] = '%s'", type))
                 .collect(Collectors.joining(" or "));
         return Optional.of(String.format(" where (%s)", types));
     }
 
     private Optional<String> createOrderByClause(Query<Node, DataFilter> query) {
         if (!definition.isSortable()) {
             return Optional.empty();
         }
         StringBuilder sortOrder = new StringBuilder();
 
         // first build the default sort options
         if (CollectionUtils.isNotEmpty(definition.getSortByProperties())) {
             sortOrder.append(definition.getSortByProperties()
                     .stream()
                     .map(o -> String.format("t.[%s] asc", o))
                     .collect(Collectors.joining(",")));
         }
         // build other sort orders possibly set by wrappers, components, etc.
         sortOrder.append(query.getSortOrders()
                 .stream()
                 .map(so -> resolveProperty(so))
                 .collect(Collectors.joining(",")));
 
         return sortOrder.length() == 0 ? Optional.empty() : Optional.of(String.format(" order by %s", sortOrder.toString()));
     }
 
     private String resolveProperty(SortOrder so) {
        return String.format("%s %s", "jcrName".equals(so.getSorted()) ? "lower(name(t))" :
                String.format("t.[%s]", so.getSorted()), so.getDirection() == ASCENDING? "asc" : "desc");
     }
 }