/*
 * 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.lucene.index;

import java.io.IOException;
import org.apache.lucene.index.IndexWriter.IndexReaderWarmer;
import org.apache.lucene.util.InfoStream;

/** A very simple merged segment warmer that just ensures data structures are initialized. */
public class SimpleMergedSegmentWarmer implements IndexReaderWarmer {
  private final InfoStream infoStream;

  /**
   * Creates a new SimpleMergedSegmentWarmer
   *
   * @param infoStream InfoStream to log statistics about warming.
   */
  public SimpleMergedSegmentWarmer(InfoStream infoStream) {
    this.infoStream = infoStream;
  }

  @Override
  public void warm(LeafReader reader) throws IOException {
    long startTime = System.currentTimeMillis();
    int indexedCount = 0;
    int docValuesCount = 0;
    int normsCount = 0;
    for (FieldInfo info : reader.getFieldInfos()) {
      if (info.getIndexOptions() != IndexOptions.NONE) {
        reader.terms(info.name);
        indexedCount++;

        if (info.hasNorms()) {
          reader.getNormValues(info.name);
          normsCount++;
        }
      }

      if (info.getDocValuesType() != DocValuesType.NONE) {
        switch (info.getDocValuesType()) {
          case NUMERIC:
            reader.getNumericDocValues(info.name);
            break;
          case BINARY:
            reader.getBinaryDocValues(info.name);
            break;
          case SORTED:
            reader.getSortedDocValues(info.name);
            break;
          case SORTED_NUMERIC:
            reader.getSortedNumericDocValues(info.name);
            break;
          case SORTED_SET:
            reader.getSortedSetDocValues(info.name);
            break;
          case NONE:
          default:
            assert false; // unknown dv type
        }
        docValuesCount++;
      }
    }

    reader.storedFields().document(0);
    reader.termVectors().get(0);

    if (infoStream.isEnabled("SMSW")) {
      infoStream.message(
          "SMSW",
          "Finished warming segment: "
              + reader
              + ", indexed="
              + indexedCount
              + ", docValues="
              + docValuesCount
              + ", norms="
              + normsCount
              + ", time="
              + (System.currentTimeMillis() - startTime));
    }
  }
}
