/*
    * The baseCode project
    * 
    * Copyright (c) 2013 University of British Columbia
    * 
    * Licensed 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 ubic.basecode.ontology.search;
  
  import java.io.IOException;
  import java.util.Arrays;
  import java.util.Iterator;
  
  import org.apache.jena.larq.ARQLuceneException;
  import org.apache.jena.larq.HitLARQ;
  import org.apache.jena.larq.IndexLARQ;
  import org.apache.jena.larq.LARQ;
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.index.MultiReader;
  import org.apache.lucene.search.Filter;
  import org.apache.lucene.search.IndexSearcher;
  import org.apache.lucene.search.Query;
  import org.apache.lucene.search.ScoreDoc;
  import org.apache.lucene.search.TopDocs;
  
  import com.hp.hpl.jena.util.iterator.Map1;
  import com.hp.hpl.jena.util.iterator.Map1Iterator;
  
  /**
   * Customization to deal with MultiReader and 'open' while indexing is going on ...? Might not be needed.
   * 
   * @author  Paul
   * 
   */
  public class SearchIndex extends IndexLARQ {
  
      public SearchIndex( IndexReader r ) {
          super( r );
      }
  
      public SearchIndex( MultiReader r, Analyzer a ) {
          super( r, a );
      }
  
      @SuppressWarnings("resource")
      @Override
      public Iterator<HitLARQ> search( String queryString ) {
          try {
              final IndexSearcher s = getIndexSearcher();
              Query query = getLuceneQueryParser().parse( queryString );
  
              TopDocs topDocs = s.search( query, ( Filter ) null, LARQ.NUM_RESULTS );
  
              Map1<ScoreDoc, HitLARQ> converter = new Map1<ScoreDoc, HitLARQ>() {
                  @Override
                  public HitLARQ map1( ScoreDoc object ) {
                      return new HitLARQ( s, object );
                  }
              };
              Iterator<ScoreDoc> iterScoreDoc = Arrays.asList( topDocs.scoreDocs ).iterator();
              Iterator<HitLARQ> iter = new Map1Iterator<>( converter, iterScoreDoc );
  
              return iter;
          } catch ( Exception e ) {
              throw new ARQLuceneException( "Error during search for '" + queryString + ";", e );
          }
      }
  
      private synchronized IndexSearcher getIndexSearcher() throws IOException {
          if ( !reader.isCurrent() ) {
              // this is the problematic line ... multireader cannot be reopened; was IndexReader newReader =
              // IndexReader.openIfChanged(reader, true) ;
  
              IndexReader newReader = IndexReader.openIfChanged( reader );
              if ( newReader != null ) {
                  reader.close();
                  reader = newReader;
                  searcher = new IndexSearcher( reader );
              }
          }
  
          return searcher;
      }
  
  }