/*
 * 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 org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.CommandLineUtil;
import org.apache.lucene.util.InfoStream;
import org.apache.lucene.util.PrintStreamInfoStream;
import org.apache.lucene.util.SuppressForbidden;
import org.apache.lucene.util.Version;

import java.io.IOException;
import java.nio.file.Paths;
import java.nio.file.Path;
import java.util.Collection;

This is an easy-to-use tool that upgrades all segments of an index from previous Lucene versions
to the current segment file format. It can be used from command line:
 java -cp lucene-core.jar org.apache.lucene.index.IndexUpgrader [-delete-prior-commits] [-verbose] indexDir
 Alternatively this class can be instantiated and upgrade invoked. It uses UpgradeIndexMergePolicy and triggers the upgrade via an forceMerge request to IndexWriter. 
This tool keeps only the last commit in an index; for this reason, if the incoming index has more than one commit, the tool refuses to run by default. Specify -delete-prior-commits to override this, allowing the tool to delete all but the last commit. From Java code this can be enabled by passing true to IndexUpgrader(Directory, InfoStream, boolean). 
Warning: This tool may reorder documents if the index was partially upgraded before execution (e.g., documents were added). If your application relies on "monotonicity" of doc IDs (which means that the order in which the documents were added to the index is preserved), do a full forceMerge instead. The MergePolicy set by IndexWriterConfig may also reorder documents. /**
  * This is an easy-to-use tool that upgrades all segments of an index from previous Lucene versions
  * to the current segment file format. It can be used from command line:
  * <pre>
  *  java -cp lucene-core.jar org.apache.lucene.index.IndexUpgrader [-delete-prior-commits] [-verbose] indexDir
  * </pre>
  * Alternatively this class can be instantiated and {@link #upgrade} invoked. It uses {@link UpgradeIndexMergePolicy}
  * and triggers the upgrade via an forceMerge request to {@link IndexWriter}.
  * <p>This tool keeps only the last commit in an index; for this
  * reason, if the incoming index has more than one commit, the tool
  * refuses to run by default. Specify {@code -delete-prior-commits}
  * to override this, allowing the tool to delete all but the last commit.
  * From Java code this can be enabled by passing {@code true} to
  * {@link #IndexUpgrader(Directory,InfoStream,boolean)}.
  * <p><b>Warning:</b> This tool may reorder documents if the index was partially
  * upgraded before execution (e.g., documents were added). If your application relies
  * on &quot;monotonicity&quot; of doc IDs (which means that the order in which the documents
  * were added to the index is preserved), do a full forceMerge instead.
  * The {@link MergePolicy} set by {@link IndexWriterConfig} may also reorder
  * documents.
  */
public final class IndexUpgrader {
  
  private static final String LOG_PREFIX = "IndexUpgrader";

  @SuppressForbidden(reason = "System.out required: command line tool")
  private static void printUsage() {
    System.err.println("Upgrades an index so all segments created with a previous Lucene version are rewritten.");
    System.err.println("Usage:");
    System.err.println("  java " + IndexUpgrader.class.getName() + " [-delete-prior-commits] [-verbose] [-dir-impl X] indexDir");
    System.err.println("This tool keeps only the last commit in an index; for this");
    System.err.println("reason, if the incoming index has more than one commit, the tool");
    System.err.println("refuses to run by default. Specify -delete-prior-commits to override");
    System.err.println("this, allowing the tool to delete all but the last commit.");
    System.err.println("Specify a " + FSDirectory.class.getSimpleName() + 
        " implementation through the -dir-impl option to force its use. If no package is specified the " 
        + FSDirectory.class.getPackage().getName() + " package will be used.");
    System.err.println("WARNING: This tool may reorder document IDs!");
    System.exit(1);
  }

  
Main method to run {code IndexUpgrader} from the
 command-line. /** Main method to run {code IndexUpgrader} from the
   *  command-line. */
  @SuppressWarnings("deprecation")
  public static void main(String[] args) throws IOException {
    parseArgs(args).upgrade();
  }
  
  @SuppressForbidden(reason = "System.out required: command line tool")
  static IndexUpgrader parseArgs(String[] args) throws IOException {
    String path = null;
    boolean deletePriorCommits = false;
    InfoStream out = null;
    String dirImpl = null;
    int i = 0;
    while (i<args.length) {
      String arg = args[i];
      if ("-delete-prior-commits".equals(arg)) {
        deletePriorCommits = true;
      } else if ("-verbose".equals(arg)) {
        out = new PrintStreamInfoStream(System.out);
      } else if ("-dir-impl".equals(arg)) {
        if (i == args.length - 1) {
          System.out.println("ERROR: missing value for -dir-impl option");
          System.exit(1);
        }
        i++;
        dirImpl = args[i];
      } else if (path == null) {
        path = arg;
      } else {
        printUsage();
      }
      i++;
    }
    if (path == null) {
      printUsage();
    }
    
    Path p = Paths.get(path);
    Directory dir = null;
    if (dirImpl == null) {
      dir = FSDirectory.open(p);
    } else {
      dir = CommandLineUtil.newFSDirectory(dirImpl, p);
    }
    return new IndexUpgrader(dir, out, deletePriorCommits);
  }
  
  private final Directory dir;
  private final IndexWriterConfig iwc;
  private final boolean deletePriorCommits;
  
  
Creates index upgrader on the given directory, using an IndexWriter using the given matchVersion. The tool refuses to upgrade indexes with multiple commit points. /** Creates index upgrader on the given directory, using an {@link IndexWriter} using the given
   * {@code matchVersion}. The tool refuses to upgrade indexes with multiple commit points. */
  public IndexUpgrader(Directory dir) {
    this(dir, new IndexWriterConfig(null), false);
  }
  
  
Creates index upgrader on the given directory, using an IndexWriter using the given matchVersion. You have the possibility to upgrade indexes with multiple commit points by removing all older ones. If infoStream is not null, all logging output will be sent to this stream. /** Creates index upgrader on the given directory, using an {@link IndexWriter} using the given
   * {@code matchVersion}. You have the possibility to upgrade indexes with multiple commit points by removing
   * all older ones. If {@code infoStream} is not {@code null}, all logging output will be sent to this stream. */
  public IndexUpgrader(Directory dir, InfoStream infoStream, boolean deletePriorCommits) {
    this(dir, new IndexWriterConfig(null), deletePriorCommits);
    if (null != infoStream) {
      this.iwc.setInfoStream(infoStream);
    }
  }
  
  
Creates index upgrader on the given directory, using an IndexWriter using the given config. You have the possibility to upgrade indexes with multiple commit points by removing all older ones. /** Creates index upgrader on the given directory, using an {@link IndexWriter} using the given
   * config. You have the possibility to upgrade indexes with multiple commit points by removing
   * all older ones. */
  public IndexUpgrader(Directory dir, IndexWriterConfig iwc, boolean deletePriorCommits) {
    this.dir = dir;
    this.iwc = iwc;
    this.deletePriorCommits = deletePriorCommits;
  }

  
Perform the upgrade. /** Perform the upgrade. */
  public void upgrade() throws IOException {
    if (!DirectoryReader.indexExists(dir)) {
      throw new IndexNotFoundException(dir.toString());
    }
  
    if (!deletePriorCommits) {
      final Collection<IndexCommit> commits = DirectoryReader.listCommits(dir);
      if (commits.size() > 1) {
        throw new IllegalArgumentException("This tool was invoked to not delete prior commit points, but the following commits were found: " + commits);
      }
    }
    
    iwc.setMergePolicy(new UpgradeIndexMergePolicy(iwc.getMergePolicy()));
    iwc.setIndexDeletionPolicy(new KeepOnlyLastCommitDeletionPolicy());
    
    try (final IndexWriter w = new IndexWriter(dir, iwc)) {
      InfoStream infoStream = iwc.getInfoStream();
      if (infoStream.isEnabled(LOG_PREFIX)) {
        infoStream.message(LOG_PREFIX, "Upgrading all pre-" + Version.LATEST + " segments of index directory '" + dir + "' to version " + Version.LATEST + "...");
      }
      w.forceMerge(1);
      if (infoStream.isEnabled(LOG_PREFIX)) {
        infoStream.message(LOG_PREFIX, "All segments upgraded to version " + Version.LATEST);
        infoStream.message(LOG_PREFIX, "Enforcing commit to rewrite all index metadata...");
      }
      w.setLiveCommitData(w.getLiveCommitData()); // fake change to enforce a commit (e.g. if index has no segments)
      assert w.hasUncommittedChanges();
      w.commit();
      if (infoStream.isEnabled(LOG_PREFIX)) {
        infoStream.message(LOG_PREFIX, "Committed upgraded metadata to index.");
      }
    }
  }
  
}