package org.apache.lucene.codecs.lucene40;

/*
 * 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.
 */

import java.io.IOException;

import org.apache.lucene.codecs.NormsFormat;
import org.apache.lucene.codecs.PerDocConsumer;
import org.apache.lucene.codecs.PerDocProducer;
import org.apache.lucene.index.DocValues;
import org.apache.lucene.index.DocValues.Type;
import org.apache.lucene.index.FieldInfo;
import org.apache.lucene.index.FieldInfos;
import org.apache.lucene.index.AtomicReader;
import org.apache.lucene.index.PerDocWriteState;
import org.apache.lucene.index.SegmentReadState;
import org.apache.lucene.store.CompoundFileDirectory; // javadocs

/**
 * Lucene 4.0 Norms Format.
 * <p>
 * Files:
 * <ul>
 *   <li><tt>.nrm.cfs</tt>: {@link CompoundFileDirectory compound container}</li>
 *   <li><tt>.nrm.cfe</tt>: {@link CompoundFileDirectory compound entries}</li>
 * </ul>
 * Norms are implemented as DocValues, so other than file extension, norms are 
 * written exactly the same way as {@link Lucene40DocValuesFormat DocValues}.
 * 
 * @see Lucene40DocValuesFormat
 * @lucene.experimental
 */
public class Lucene40NormsFormat extends NormsFormat {
  private final static String NORMS_SEGMENT_SUFFIX = "nrm";

  /** Sole constructor. */
  public Lucene40NormsFormat() {
  }
  
  @Override
  public PerDocConsumer docsConsumer(PerDocWriteState state) throws IOException {
    return new Lucene40NormsDocValuesConsumer(state, NORMS_SEGMENT_SUFFIX);
  }

  @Override
  public PerDocProducer docsProducer(SegmentReadState state) throws IOException {
    return new Lucene40NormsDocValuesProducer(state, NORMS_SEGMENT_SUFFIX);
  }

  /**
   * Lucene 4.0 PerDocProducer implementation that uses compound file.
   * 
   * @see Lucene40DocValuesFormat
   */
  public static class Lucene40NormsDocValuesProducer extends Lucene40DocValuesProducer {

    /** Sole constructor. */
    public Lucene40NormsDocValuesProducer(SegmentReadState state,
        String segmentSuffix) throws IOException {
      super(state, segmentSuffix);
    }

    @Override
    protected boolean canLoad(FieldInfo info) {
      return info.hasNorms();
    }

    @Override
    protected Type getDocValuesType(FieldInfo info) {
      return info.getNormType();
    }

    @Override
    protected boolean anyDocValuesFields(FieldInfos infos) {
      return infos.hasNorms();
    }
    
  }
  
  /**
   * Lucene 4.0 PerDocConsumer implementation that uses compound file.
   * 
   * @see Lucene40DocValuesFormat
   * @lucene.experimental
   */
  public static class Lucene40NormsDocValuesConsumer extends Lucene40DocValuesConsumer {

    /** Sole constructor. */
    public Lucene40NormsDocValuesConsumer(PerDocWriteState state,
        String segmentSuffix) {
      super(state, segmentSuffix);
    }

    @Override
    protected DocValues getDocValuesForMerge(AtomicReader reader, FieldInfo info)
        throws IOException {
      return reader.normValues(info.name);
    }

    @Override
    protected boolean canMerge(FieldInfo info) {
      return info.hasNorms();
    }

    @Override
    protected Type getDocValuesType(FieldInfo info) {
      return info.getNormType();
    }
  }
}