package org.apache.lucene.index;

/**
 * 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 org.apache.lucene.store.FSDirectory;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.document.Document;

import java.text.NumberFormat;
import java.io.PrintStream;
import java.io.IOException;
import java.util.Collection;
import java.util.Iterator;

/**
 * Basic tool to check the health of an index and write a
 * new segments file that removes reference to problematic
 * segments.  There are many more checks that this tool
 * could do but does not yet, eg: reconstructing a segments
 * file by looking for all loadable segments (if no segments
 * file is found), removing specifically specified segments,
 * listing files that exist but are not referenced, etc.
 */

public class CheckIndex {

  public static PrintStream out = System.out;

  private static class MySegmentTermDocs extends SegmentTermDocs {

    int delCount;

    MySegmentTermDocs(SegmentReader p) {    
      super(p);
    }

    public void seek(Term term) throws IOException {
      super.seek(term);
      delCount = 0;
    }

    protected void skippingDoc() throws IOException {
      delCount++;
    }
  }

  /** Returns true if index is clean, else false.*/
  public static boolean check(Directory dir, boolean doFix) throws IOException {
    NumberFormat nf = NumberFormat.getInstance();
    SegmentInfos sis = new SegmentInfos();
    
    try {
      sis.read(dir);
    } catch (Throwable t) {
      out.println("ERROR: could not read any segments file in directory");
      t.printStackTrace(out);
      return false;
    }

    final int numSegments = sis.size();
    final String segmentsFileName = sis.getCurrentSegmentFileName();
    IndexInput input = null;
    try {
      input = dir.openInput(segmentsFileName);
    } catch (Throwable t) {
      out.println("ERROR: could not open segments file in directory");
      t.printStackTrace(out);
      return false;
    }
    int format = 0;
    try {
      format = input.readInt();
    } catch (Throwable t) {
      out.println("ERROR: could not read segment file version in directory");
      t.printStackTrace(out);
      return false;
    } finally {
      if (input != null)
        input.close();
    }

    String sFormat = "";
    boolean skip = false;

    if (format == SegmentInfos.FORMAT)
      sFormat = "FORMAT [Lucene Pre-2.1]";
    if (format == SegmentInfos.FORMAT_LOCKLESS)
      sFormat = "FORMAT_LOCKLESS [Lucene 2.1]";
    else if (format == SegmentInfos.FORMAT_SINGLE_NORM_FILE)
      sFormat = "FORMAT_SINGLE_NORM_FILE [Lucene 2.2]";
    else if (format == SegmentInfos.FORMAT_SHARED_DOC_STORE)
      sFormat = "FORMAT_SHARED_DOC_STORE [Lucene 2.3]";
    else if (format < SegmentInfos.FORMAT_SHARED_DOC_STORE) {
      sFormat = "int=" + format + " [newer version of Lucene than this tool]";
      skip = true;
    } else {
      sFormat = format + " [Lucene 1.3 or prior]";
    }

    out.println("Segments file=" + segmentsFileName + " numSegments=" + numSegments + " version=" + sFormat);

    if (skip) {
      out.println("\nERROR: this index appears to be created by a newer version of Lucene than this tool was compiled on; please re-compile this tool on the matching version of Lucene; exiting");
      return false;
    }

    SegmentInfos newSIS = (SegmentInfos) sis.clone();
    newSIS.clear();
    boolean changed = false;
    int totLoseDocCount = 0;
    int numBadSegments = 0;
    for(int i=0;i