/*
    * 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.apache.solr.util;
  
  import java.io.IOException;
  import java.lang.invoke.MethodHandles;
  import java.util.Map;
  
  import org.apache.lucene.index.IndexWriter;
  import org.apache.lucene.index.MergePolicy;
  import org.apache.lucene.index.MergeTrigger;
  import org.apache.lucene.index.SegmentCommitInfo;
  import org.apache.lucene.index.SegmentInfos;
  import org.apache.lucene.util.LuceneTestCase;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A {@link MergePolicy} with a no-arg constructor that proxies to a 
   * wrapped instance retrieved from {@link LuceneTestCase#newMergePolicy}.
   * Solr tests utilizing the Lucene randomized test framework can refer 
   * to this class in solrconfig.xml to get a fully randomized merge policy.
   */
  public final class RandomMergePolicy extends MergePolicy {
  
    private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
    
    /** 
     * Not private so tests can inspect it, 
     * Not final so it can be set on clone
     */
    final MergePolicy inner;
  
    public RandomMergePolicy() {
      this(LuceneTestCase.newMergePolicy());
    }
  
    private RandomMergePolicy(MergePolicy inner) {
      super(inner.getNoCFSRatio(), 
            (long) (inner.getMaxCFSSegmentSizeMB() * 1024 * 1024));
      this.inner = inner;
      log.info("RandomMergePolicy wrapping {}: {}",
               inner.getClass(), inner);
    }
  
    @Override
    public MergeSpecification findForcedDeletesMerges(SegmentInfos segmentInfos, IndexWriter writer) 
      throws IOException {
  
      return inner.findForcedDeletesMerges(segmentInfos, writer);
    }
  
    @Override
    public MergeSpecification findForcedMerges(SegmentInfos segmentInfos, 
                                               int maxSegmentCount, 
                                               Map<SegmentCommitInfo,Boolean> segmentsToMerge,
                                               IndexWriter writer) 
      throws IOException {
      
      return inner.findForcedMerges(segmentInfos, maxSegmentCount, segmentsToMerge, writer);
    }
  
    @Override
    public MergeSpecification findMerges(MergeTrigger mergeTrigger, 
                                         SegmentInfos segmentInfos,
                                         IndexWriter writer)
      throws IOException {
  
      return inner.findMerges(mergeTrigger, segmentInfos, writer);
    }
  
    @Override
    public boolean useCompoundFile(SegmentInfos infos,
                                   SegmentCommitInfo mergedInfo,
                                   IndexWriter writer)
      throws IOException {
      
      return inner.useCompoundFile(infos, mergedInfo, writer);
    }
  
  }