/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.exoplatform.services.jcr.impl.core.query.lucene;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Sort;
import org.exoplatform.commons.utils.SecurityHelper;
import org.exoplatform.services.jcr.dataflow.ItemDataConsumer;
import org.exoplatform.services.jcr.datamodel.InternalQName;
import org.exoplatform.services.jcr.impl.core.SessionImpl;
import org.exoplatform.services.jcr.impl.core.query.lucene.constraint.EvaluationContext;

import java.io.IOException;
import java.security.PrivilegedExceptionAction;

/**
 * <code>JackrabbitIndexSearcher</code> implements an index searcher with
 * jackrabbit specific optimizations.
 */
public class JcrIndexSearcher extends IndexSearcher implements EvaluationContext
{

   /**
    * The session that executes the query.
    */
   private final SessionImpl session;

   /**
    * The underlying index reader.
    */
   private final IndexReader reader;

   /**
    * The item state manager of the workspace.
    */
   private final ItemDataConsumer ism;

   /**
    * Creates a new jackrabbit index searcher.
    *
    * @param s the session that executes the query.
    * @param r the index reader.
    * @param ism the shared item state manager.
    */
   public JcrIndexSearcher(SessionImpl s, IndexReader r, ItemDataConsumer ism)
   {
      super(r);
      this.session = s;
      this.reader = r;
      this.ism = ism;
   }

   /**
    * Executes the query and returns the hits that match the query.
    *
    * @param query           the query to execute.
    * @param sort            the sort criteria.
    * @param resultFetchHint a hint on how many results should be fetched.
    * @param selectorName    the single selector name for the query hits.
    * @return the query hits.
    * @throws IOException if an error occurs while executing the query.
    */
   public MultiColumnQueryHits execute(Query query, Sort sort, long resultFetchHint, InternalQName selectorName)
      throws IOException
   {
      return new QueryHitsAdapter(evaluate(query, sort, resultFetchHint), selectorName);
   }

   /**
    * Evaluates the query and returns the hits that match the query.
    *
    * @param query           the query to execute.
    * @param sort            the sort criteria.
    * @param resultFetchHint a hint on how many results should be fetched.
    * @return the query hits.
    * @throws IOException if an error occurs while executing the query.
    */
   public QueryHits evaluate(final Query query, final Sort sort, final long resultFetchHint) throws IOException
   {
      return SecurityHelper.doPrivilegedIOExceptionAction(new PrivilegedExceptionAction<QueryHits>()
      {
         public QueryHits run() throws Exception
         {
            Query localQuery = query.rewrite(reader);
            QueryHits hits = null;
            if (localQuery instanceof JcrQuery)
            {
               hits = ((JcrQuery)localQuery).execute(JcrIndexSearcher.this, session, sort);
            }
            if (hits == null)
            {
               if (sort == null || sort.getSort().length == 0)
               {
                  hits = new LuceneQueryHits(reader, JcrIndexSearcher.this, query);
               }
               else
               {
                  hits = new SortedLuceneQueryHits(reader, JcrIndexSearcher.this, localQuery, sort, resultFetchHint);
               }
            }
            return hits;
         }
      });
   }

   //------------------------< EvaluationContext >-----------------------------

   /**
    * Evaluates the query and returns the hits that match the query.
    *
    * @param query           the query to execute.
    * @return the query hits.
    * @throws IOException if an error occurs while executing the query.
    */
   public QueryHits evaluate(Query query) throws IOException
   {
      return evaluate(query, new Sort(), Integer.MAX_VALUE);
   }

   /**
    * @return session that executes the query.
    */
   public SessionImpl getSession()
   {
      return session;
   }

   /**
    * @return the item state manager of the workspace.
    */
   public ItemDataConsumer getItemStateManager()
   {
      return ism;
   }
}