/*
 * 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.benchmark.byTask.tasks;

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import org.apache.lucene.benchmark.byTask.PerfRunData;
import org.apache.lucene.benchmark.byTask.utils.Config;
import org.apache.lucene.codecs.Codec;
import org.apache.lucene.codecs.PostingsFormat;
import org.apache.lucene.codecs.lucene90.Lucene90Codec;
import org.apache.lucene.index.ConcurrentMergeScheduler;
import org.apache.lucene.index.IndexCommit;
import org.apache.lucene.index.IndexDeletionPolicy;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.index.LogMergePolicy;
import org.apache.lucene.index.MergePolicy;
import org.apache.lucene.index.MergeScheduler;
import org.apache.lucene.index.NoDeletionPolicy;
import org.apache.lucene.index.NoMergePolicy;
import org.apache.lucene.index.NoMergeScheduler;

/**
 * Create an index. <br>
 * Other side effects: index writer object in perfRunData is set. <br>
 * Relevant properties: <code>merge.factor (default 10),
 * max.buffered (default no flush), compound (default true), ram.flush.mb [default 0],
 * merge.policy (default org.apache.lucene.index.LogByteSizeMergePolicy),
 * merge.scheduler (default
 * org.apache.lucene.index.ConcurrentMergeScheduler),
 * concurrent.merge.scheduler.max.thread.count and
 * concurrent.merge.scheduler.max.merge.count (defaults per
 * ConcurrentMergeScheduler), default.codec </code>.
 *
 * <p>This task also supports a "writer.info.stream" property with the following values:
 *
 * <ul>
 *   <li>SystemOut - sets {@link IndexWriterConfig#setInfoStream(java.io.PrintStream)} to {@link
 *       System#out}.
 *   <li>SystemErr - sets {@link IndexWriterConfig#setInfoStream(java.io.PrintStream)} to {@link
 *       System#err}.
 *   <li>&lt;file_name&gt; - attempts to create a file given that name and sets {@link
 *       IndexWriterConfig#setInfoStream(java.io.PrintStream)} to that file. If this denotes an
 *       invalid file name, or some error occurs, an exception will be thrown.
 * </ul>
 */
public class CreateIndexTask extends PerfTask {

  public CreateIndexTask(PerfRunData runData) {
    super(runData);
  }

  public static IndexDeletionPolicy getIndexDeletionPolicy(Config config) {
    String deletionPolicyName =
        config.get("deletion.policy", "org.apache.lucene.index.KeepOnlyLastCommitDeletionPolicy");
    if (deletionPolicyName.equals(NoDeletionPolicy.class.getName())) {
      return NoDeletionPolicy.INSTANCE;
    } else {
      try {
        return Class.forName(deletionPolicyName)
            .asSubclass(IndexDeletionPolicy.class)
            .getConstructor()
            .newInstance();
      } catch (Exception e) {
        throw new RuntimeException(
            "unable to instantiate class '" + deletionPolicyName + "' as IndexDeletionPolicy", e);
      }
    }
  }

  @Override
  public int doLogic() throws IOException {
    PerfRunData runData = getRunData();
    Config config = runData.getConfig();
    runData.setIndexWriter(configureWriter(config, runData, OpenMode.CREATE, null));
    return 1;
  }

  public static IndexWriterConfig createWriterConfig(
      Config config, PerfRunData runData, OpenMode mode, IndexCommit commit) {
    IndexWriterConfig iwConf = new IndexWriterConfig(runData.getAnalyzer());
    iwConf.setOpenMode(mode);
    IndexDeletionPolicy indexDeletionPolicy = getIndexDeletionPolicy(config);
    iwConf.setIndexDeletionPolicy(indexDeletionPolicy);
    if (commit != null) {
      iwConf.setIndexCommit(commit);
    }

    final String mergeScheduler =
        config.get("merge.scheduler", "org.apache.lucene.index.ConcurrentMergeScheduler");
    if (mergeScheduler.equals(NoMergeScheduler.class.getName())) {
      iwConf.setMergeScheduler(NoMergeScheduler.INSTANCE);
    } else {
      try {
        iwConf.setMergeScheduler(
            Class.forName(mergeScheduler)
                .asSubclass(MergeScheduler.class)
                .getConstructor()
                .newInstance());
      } catch (Exception e) {
        throw new RuntimeException(
            "unable to instantiate class '" + mergeScheduler + "' as merge scheduler", e);
      }

      if (mergeScheduler.equals("org.apache.lucene.index.ConcurrentMergeScheduler")) {
        ConcurrentMergeScheduler cms = (ConcurrentMergeScheduler) iwConf.getMergeScheduler();
        int maxThreadCount =
            config.get(
                "concurrent.merge.scheduler.max.thread.count",
                ConcurrentMergeScheduler.AUTO_DETECT_MERGES_AND_THREADS);
        int maxMergeCount =
            config.get(
                "concurrent.merge.scheduler.max.merge.count",
                ConcurrentMergeScheduler.AUTO_DETECT_MERGES_AND_THREADS);
        cms.setMaxMergesAndThreads(maxMergeCount, maxThreadCount);
      }
    }

    final String defaultCodec = config.get("default.codec", null);
    if (defaultCodec != null) {
      try {
        Class<? extends Codec> clazz = Class.forName(defaultCodec).asSubclass(Codec.class);
        iwConf.setCodec(clazz.getConstructor().newInstance());
      } catch (Exception e) {
        throw new RuntimeException("Couldn't instantiate Codec: " + defaultCodec, e);
      }
    }

    final String postingsFormat = config.get("codec.postingsFormat", null);
    if (defaultCodec == null && postingsFormat != null) {
      try {
        final PostingsFormat postingsFormatChosen = PostingsFormat.forName(postingsFormat);
        iwConf.setCodec(
            new Lucene90Codec() {
              @Override
              public PostingsFormat getPostingsFormatForField(String field) {
                return postingsFormatChosen;
              }
            });
      } catch (Exception e) {
        throw new RuntimeException("Couldn't instantiate Postings Format: " + postingsFormat, e);
      }
    }

    final String mergePolicy =
        config.get("merge.policy", "org.apache.lucene.index.LogByteSizeMergePolicy");
    boolean isCompound = config.get("compound", true);
    iwConf.setUseCompoundFile(isCompound);
    if (mergePolicy.equals(NoMergePolicy.class.getName())) {
      iwConf.setMergePolicy(NoMergePolicy.INSTANCE);
    } else {
      try {
        iwConf.setMergePolicy(
            Class.forName(mergePolicy)
                .asSubclass(MergePolicy.class)
                .getConstructor()
                .newInstance());
      } catch (Exception e) {
        throw new RuntimeException(
            "unable to instantiate class '" + mergePolicy + "' as merge policy", e);
      }
      iwConf.getMergePolicy().setNoCFSRatio(isCompound ? 1.0 : 0.0);
      if (iwConf.getMergePolicy() instanceof LogMergePolicy) {
        LogMergePolicy logMergePolicy = (LogMergePolicy) iwConf.getMergePolicy();
        logMergePolicy.setMergeFactor(
            config.get("merge.factor", OpenIndexTask.DEFAULT_MERGE_PFACTOR));
      }
    }
    final double ramBuffer = config.get("ram.flush.mb", OpenIndexTask.DEFAULT_RAM_FLUSH_MB);
    final int maxBuffered = config.get("max.buffered", OpenIndexTask.DEFAULT_MAX_BUFFERED);
    if (maxBuffered == IndexWriterConfig.DISABLE_AUTO_FLUSH) {
      iwConf.setRAMBufferSizeMB(ramBuffer);
      iwConf.setMaxBufferedDocs(maxBuffered);
    } else {
      iwConf.setMaxBufferedDocs(maxBuffered);
      iwConf.setRAMBufferSizeMB(ramBuffer);
    }

    return iwConf;
  }

  public static IndexWriter configureWriter(
      Config config, PerfRunData runData, OpenMode mode, IndexCommit commit) throws IOException {
    IndexWriterConfig iwc = createWriterConfig(config, runData, mode, commit);
    String infoStreamVal = config.get("writer.info.stream", null);
    if (infoStreamVal != null) {
      if (infoStreamVal.equals("SystemOut")) {
        iwc.setInfoStream(System.out);
      } else if (infoStreamVal.equals("SystemErr")) {
        iwc.setInfoStream(System.err);
      } else {
        Path f = Paths.get(infoStreamVal);
        iwc.setInfoStream(
            new PrintStream(
                new BufferedOutputStream(Files.newOutputStream(f)),
                false,
                Charset.defaultCharset().name()));
      }
    }
    IndexWriter writer = new IndexWriter(runData.getDirectory(), iwc);
    return writer;
  }
}