package org.apache.lucene.index.codecs;

/**
 * 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.index.SegmentInfo;
import org.apache.lucene.index.SegmentInfos;
import org.apache.lucene.store.ChecksumIndexOutput;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IndexOutput;

/**
 * Default implementation of {@link SegmentInfosWriter}.
 * @lucene.experimental
 */
public class DefaultSegmentInfosWriter extends SegmentInfosWriter {

  /** This format adds optional per-segment String
   *  diagnostics storage, and switches userData to Map */
  public static final int FORMAT_DIAGNOSTICS = -9;

  /** Each segment records whether its postings are written
   *  in the new flex format */
  public static final int FORMAT_4_0 = -10;

  /** This must always point to the most recent file format.
   * whenever you add a new format, make it 1 smaller (negative version logic)! */
  public static final int FORMAT_CURRENT = FORMAT_4_0;
  
  /** This must always point to the first supported file format. */
  public static final int FORMAT_MINIMUM = FORMAT_DIAGNOSTICS;

  @Override
  public IndexOutput writeInfos(Directory dir, String segmentFileName, SegmentInfos infos)
          throws IOException {
    IndexOutput out = createOutput(dir, segmentFileName);
    out.writeInt(FORMAT_CURRENT); // write FORMAT
    out.writeLong(++infos.version); // every write changes
                                 // the index
    out.writeInt(infos.counter); // write counter
    out.writeInt(infos.size()); // write infos
    for (SegmentInfo si : infos) {
      si.write(out);
    }
    out.writeStringStringMap(infos.getUserData());
    return out;
  }
  
  protected IndexOutput createOutput(Directory dir, String segmentFileName)
      throws IOException {
    IndexOutput plainOut = dir.createOutput(segmentFileName);
    ChecksumIndexOutput out = new ChecksumIndexOutput(plainOut);
    return out;
  }

  @Override
  public void prepareCommit(IndexOutput segmentOutput) throws IOException {
    ((ChecksumIndexOutput)segmentOutput).prepareCommit();
  }

  @Override
  public void finishCommit(IndexOutput out) throws IOException {
    ((ChecksumIndexOutput)out).finishCommit();
    out.close();
  }
}