content: 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.search.IndexSearcher;
  import org.apache.lucene.search.TermQuery;
  import org.apache.lucene.store.FSDirectory;
  import org.apache.lucene.store.Directory;
  import org.apache.lucene.store.IndexInput;
  import org.apache.lucene.util.StringHelper;
  import org.apache.lucene.document.AbstractField;  // for javadocs
  import org.apache.lucene.document.Document;
  
  import java.text.NumberFormat;
  import java.io.PrintStream;
  import java.io.IOException;
  import java.io.File;
  import java.util.Collection;
  
  import java.util.Comparator;
  import java.util.List;
  import java.util.ArrayList;
  import java.util.Map;
  
  /**
   * Basic tool and API to check the health of an index and
   * write a new segments file that removes reference to
   * problematic segments.
   * 
   * <p>As this tool checks every byte in the index, on a large
   * index it can take quite a long time to run.
   *
   * @lucene.experimental Please make a complete backup of your
   * index before using this to fix your index!
   */
  public class CheckIndex {
  
    private PrintStream infoStream;
    private Directory dir;
  
    /**
     * Returned from {@link #checkIndex()} detailing the health and status of the index.
     *
     * @lucene.experimental
     **/
  
    public static class Status {
  
      /** True if no problems were found with the index. */
      public boolean clean;
  
      /** True if we were unable to locate and load the segments_N file. */
      public boolean missingSegments;
  
      /** True if we were unable to open the segments_N file. */
      public boolean cantOpenSegments;
  
      /** True if we were unable to read the version number from segments_N file. */
      public boolean missingSegmentVersion;
  
      /** Name of latest segments_N file in the index. */
      public String segmentsFileName;
  
      /** Number of segments in the index. */
      public int numSegments;
  
      /** String description of the version of the index. */
      public String segmentFormat;
  
      /** Empty unless you passed specific segments list to check as optional 3rd argument.
       *  @see CheckIndex#checkIndex(List) */
      public List<String> segmentsChecked = new ArrayList<String>();
    
      /** True if the index was created with a newer version of Lucene than the CheckIndex tool. */
      public boolean toolOutOfDate;
  
      /** List of {@link SegmentInfoStatus} instances, detailing status of each segment. */
      public List<SegmentInfoStatus> segmentInfos = new ArrayList<SegmentInfoStatus>();
    
      /** Directory index is in. */
      public Directory dir;
  
      /** 
       * SegmentInfos instance containing only segments that
       * had no problems (this is used with the {@link CheckIndex#fixIndex} 
       * method to repair the index. 
       */
      SegmentInfos newSegments;
  
      /** How many documents will be lost to bad segments. */
      public int totLoseDocCount;
  
      /** How many bad segments were found. */
      public int numBadSegments;
  
      /** True if we checked only specific segments ({@link
       * #checkIndex(List)}) was called with non-null
       * argument). */
      public boolean partial;
  
      /** The greatest segment name. */
      public int maxSegmentName;
  
      /** Whether the SegmentInfos.counter is greater than any of the segments' names. */
      public boolean validCounter; 
  
      /** Holds the userData of the last commit in the index */
      public Map<String, String> userData;
  
      /** Holds the status of each segment in the index.
       *  See {@link #segmentInfos}.
       *
       * <p><b>WARNING</b>: this API is new and experimental and is
       * subject to suddenly change in the next release.
       */
      public static class SegmentInfoStatus {
        /** Name of the segment. */
        public String name;
  
        /** Document count (does not take deletions into account). */
        public int docCount;
  
        /** True if segment is compound file format. */
        public boolean compound;
  
        /** Number of files referenced by this segment. */
        public int numFiles;
  
        /** Net size (MB) of the files referenced by this
         *  segment. */
        public double sizeMB;
  
        /** Doc store offset, if this segment shares the doc
         *  store files (stored fields and term vectors) with
         *  other segments.  This is -1 if it does not share. */
        public int docStoreOffset = -1;
      
        /** String of the shared doc store segment, or null if
         *  this segment does not share the doc store files. */
        public String docStoreSegment;
  
        /** True if the shared doc store files are compound file
         *  format. */
        public boolean docStoreCompoundFile;
  
        /** True if this segment has pending deletions. */
        public boolean hasDeletions;
  
        /** Name of the current deletions file name. */
        public String deletionsFileName;
      
        /** Number of deleted documents. */
        public int numDeleted;
  
        /** True if we were able to open a SegmentReader on this
         *  segment. */
        public boolean openReaderPassed;
  
        /** Number of fields in this segment. */
        int numFields;
  
        /** True if at least one of the fields in this segment
         *  has position data
         *  @see AbstractField#setIndexOptions(org.apache.lucene.index.FieldInfo.IndexOptions) */
        public boolean hasProx;
  
        /** Map that includes certain
         *  debugging details that IndexWriter records into
         *  each segment it creates */
        public Map<String,String> diagnostics;
  
        /** Status for testing of field norms (null if field norms could not be tested). */
        public FieldNormStatus fieldNormStatus;
  
        /** Status for testing of indexed terms (null if indexed terms could not be tested). */
        public TermIndexStatus termIndexStatus;
  
        /** Status for testing of stored fields (null if stored fields could not be tested). */
        public StoredFieldStatus storedFieldStatus;
  
        /** Status for testing of term vectors (null if term vectors could not be tested). */
        public TermVectorStatus termVectorStatus;
      }
  
      /**
       * Status from testing field norms.
       */
      public static final class FieldNormStatus {
        /** Number of fields successfully tested */
        public long totFields = 0L;
  
        /** Exception thrown during term index test (null on success) */
        public Throwable error = null;
      }
  
      /**
       * Status from testing term index.
       */
      public static final class TermIndexStatus {
        /** Total term count */
        public long termCount = 0L;
  
        /** Total frequency across all terms. */
        public long totFreq = 0L;
        
        /** Total number of positions. */
        public long totPos = 0L;
  
        /** Exception thrown during term index test (null on success) */
        public Throwable error = null;
      }
  
      /**
       * Status from testing stored fields.
       */
      public static final class StoredFieldStatus {
        
        /** Number of documents tested. */
        public int docCount = 0;
        
        /** Total number of stored fields tested. */
        public long totFields = 0;
        
        /** Exception thrown during stored fields test (null on success) */
        public Throwable error = null;
      }
  
      /**
       * Status from testing stored fields.
       */
      public static final class TermVectorStatus {
        
        /** Number of documents tested. */
        public int docCount = 0;
        
        /** Total number of term vectors tested. */
        public long totVectors = 0;
        
        /** Exception thrown during term vector test (null on success) */
        public Throwable error = null;
      }
    }
  
    /** Create a new CheckIndex on the directory. */
    public CheckIndex(Directory dir) {
      this.dir = dir;
      infoStream = null;
    }
  
    /** Set infoStream where messages should go.  If null, no
     *  messages are printed */
    public void setInfoStream(PrintStream out) {
      infoStream = out;
    }
  
    private void msg(String msg) {
      if (infoStream != null)
        infoStream.println(msg);
    }
  
    private static class MySegmentTermDocs extends SegmentTermDocs {
  
      int delCount;
  
      MySegmentTermDocs(SegmentReader p) {    
        super(p,-1);
      }
  
      @Override
      public void seek(Term term) throws IOException {
        super.seek(term);
        delCount = 0;
      }
  
      @Override
      protected void skippingDoc() throws IOException {
        delCount++;
      }
    }
  
    /** Returns a {@link Status} instance detailing
     *  the state of the index.
     *
     *  <p>As this method checks every byte in the index, on a large
     *  index it can take quite a long time to run.
     *
     *  <p><b>WARNING</b>: make sure
     *  you only call this when the index is not opened by any
     *  writer. */
    public Status checkIndex() throws IOException {
      return checkIndex(null);
    }
  
    /** Returns a {@link Status} instance detailing
     *  the state of the index.
     * 
     *  @param onlySegments list of specific segment names to check
     *
     *  <p>As this method checks every byte in the specified
     *  segments, on a large index it can take quite a long
     *  time to run.
     *
     *  <p><b>WARNING</b>: make sure
     *  you only call this when the index is not opened by any
     *  writer. */
    public Status checkIndex(List<String> onlySegments) throws IOException {
      NumberFormat nf = NumberFormat.getInstance();
      SegmentInfos sis = new SegmentInfos();
      Status result = new Status();
      result.dir = dir;
      try {
        sis.read(dir);
      } catch (Throwable t) {
        msg("ERROR: could not read any segments file in directory");
        result.missingSegments = true;
        if (infoStream != null)
          t.printStackTrace(infoStream);
        return result;
      }
  
      // find the oldest and newest segment versions
      String oldest = Integer.toString(Integer.MAX_VALUE), newest = Integer.toString(Integer.MIN_VALUE);
      String oldSegs = null;
      boolean foundNonNullVersion = false;
      Comparator<String> versionComparator = StringHelper.getVersionComparator();
      for (SegmentInfo si : sis) {
        String version = si.getVersion();
        if (version == null) {
          // pre-3.1 segment
          oldSegs = "pre-3.1";
        } else if (version.equals("2.x")) {
          // an old segment that was 'touched' by 3.1+ code
          oldSegs = "2.x";
        } else {
          foundNonNullVersion = true;
          if (versionComparator.compare(version, oldest) < 0) {
            oldest = version;
          }
          if (versionComparator.compare(version, newest) > 0) {
            newest = version;
          }
        }
      }
      
      final int numSegments = sis.size();
      final String segmentsFileName = sis.getCurrentSegmentFileName();
      IndexInput input = null;
      try {
        input = dir.openInput(segmentsFileName);
      } catch (Throwable t) {
        msg("ERROR: could not open segments file in directory");
        if (infoStream != null)
          t.printStackTrace(infoStream);
        result.cantOpenSegments = true;
        return result;
      }
      int format = 0;
      try {
        format = input.readInt();
      } catch (Throwable t) {
        msg("ERROR: could not read segment file version in directory");
        if (infoStream != null)
          t.printStackTrace(infoStream);
        result.missingSegmentVersion = true;
        return result;
      } 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_CHECKSUM)
          sFormat = "FORMAT_CHECKSUM [Lucene 2.4]";
        else if (format == SegmentInfos.FORMAT_DEL_COUNT)
          sFormat = "FORMAT_DEL_COUNT [Lucene 2.4]";
        else if (format == SegmentInfos.FORMAT_HAS_PROX)
          sFormat = "FORMAT_HAS_PROX [Lucene 2.4]";
        else if (format == SegmentInfos.FORMAT_USER_DATA)
          sFormat = "FORMAT_USER_DATA [Lucene 2.9]";
        else if (format == SegmentInfos.FORMAT_DIAGNOSTICS)
          sFormat = "FORMAT_DIAGNOSTICS [Lucene 2.9]";
        else if (format == SegmentInfos.FORMAT_HAS_VECTORS)
          sFormat = "FORMAT_HAS_VECTORS [Lucene 3.1]";
        else if (format == SegmentInfos.FORMAT_3_1)
          sFormat = "FORMAT_3_1 [Lucene 3.1+]";
        else if (format == SegmentInfos.CURRENT_FORMAT)
          throw new RuntimeException("BUG: You should update this tool!");
        else if (format < SegmentInfos.CURRENT_FORMAT) {
          sFormat = "int=" + format + " [newer version of Lucene than this tool]";
          skip = true;
        } else {
          sFormat = format + " [Lucene 1.3 or prior]";
        }
      }
  
      result.segmentsFileName = segmentsFileName;
      result.numSegments = numSegments;
      result.segmentFormat = sFormat;
      result.userData = sis.getUserData();
      String userDataString;
      if (sis.getUserData().size() > 0) {
        userDataString = " userData=" + sis.getUserData();
      } else {
        userDataString = "";
      }
  
      String versionString = null;
      if (oldSegs != null) {
        if (foundNonNullVersion) {
          versionString = "versions=[" + oldSegs + " .. " + newest + "]";
        } else {
          versionString = "version=" + oldSegs;
        }
      } else {
        versionString = oldest.equals(newest) ? ( "version=" + oldest ) : ("versions=[" + oldest + " .. " + newest + "]");
      }
      
      msg("Segments file=" + segmentsFileName + " numSegments=" + numSegments
          + " " + versionString + " format=" + sFormat + userDataString);
  
      if (onlySegments != null) {
        result.partial = true;
        if (infoStream != null)
          infoStream.print("\nChecking only these segments:");
        for (String s : onlySegments) {
          if (infoStream != null)
            infoStream.print(" " + s);
        }
        result.segmentsChecked.addAll(onlySegments);
        msg(":");
      }
  
      if (skip) {
        msg("\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");
        result.toolOutOfDate = true;
        return result;
      }
  
  
      result.newSegments = (SegmentInfos) sis.clone();
      result.newSegments.clear();
      result.maxSegmentName = -1;
  
      for(int i=0;i<numSegments;i++) {
        final SegmentInfo info = sis.info(i);
        int segmentName = Integer.parseInt(info.name.substring(1), Character.MAX_RADIX);
        if (segmentName > result.maxSegmentName) {
          result.maxSegmentName = segmentName;
        }
        if (onlySegments != null && !onlySegments.contains(info.name))
          continue;
        Status.SegmentInfoStatus segInfoStat = new Status.SegmentInfoStatus();
        result.segmentInfos.add(segInfoStat);
        msg("  " + (1+i) + " of " + numSegments + ": name=" + info.name + " docCount=" + info.docCount);
        segInfoStat.name = info.name;
        segInfoStat.docCount = info.docCount;
  
        int toLoseDocCount = info.docCount;
  
        SegmentReader reader = null;
  
        try {
          msg("    compound=" + info.getUseCompoundFile());
          segInfoStat.compound = info.getUseCompoundFile();
          msg("    hasProx=" + info.getHasProx());
          segInfoStat.hasProx = info.getHasProx();
          msg("    numFiles=" + info.files().size());
          segInfoStat.numFiles = info.files().size();
          segInfoStat.sizeMB = info.sizeInBytes(true)/(1024.*1024.);
          msg("    size (MB)=" + nf.format(segInfoStat.sizeMB));
          Map<String,String> diagnostics = info.getDiagnostics();
          segInfoStat.diagnostics = diagnostics;
          if (diagnostics.size() > 0) {
            msg("    diagnostics = " + diagnostics);
          }
  
          final int docStoreOffset = info.getDocStoreOffset();
          if (docStoreOffset != -1) {
            msg("    docStoreOffset=" + docStoreOffset);
            segInfoStat.docStoreOffset = docStoreOffset;
            msg("    docStoreSegment=" + info.getDocStoreSegment());
            segInfoStat.docStoreSegment = info.getDocStoreSegment();
            msg("    docStoreIsCompoundFile=" + info.getDocStoreIsCompoundFile());
            segInfoStat.docStoreCompoundFile = info.getDocStoreIsCompoundFile();
          }
          final String delFileName = info.getDelFileName();
          if (delFileName == null){
            msg("    no deletions");
            segInfoStat.hasDeletions = false;
          }
          else{
            msg("    has deletions [delFileName=" + delFileName + "]");
            segInfoStat.hasDeletions = true;
            segInfoStat.deletionsFileName = delFileName;
          }
          if (infoStream != null)
            infoStream.print("    test: open reader.........");
          reader = SegmentReader.get(true, info, IndexReader.DEFAULT_TERMS_INDEX_DIVISOR);
  
          segInfoStat.openReaderPassed = true;
  
          final int numDocs = reader.numDocs();
          toLoseDocCount = numDocs;
          if (reader.hasDeletions()) {
            if (reader.deletedDocs.count() != info.getDelCount()) {
              throw new RuntimeException("delete count mismatch: info=" + info.getDelCount() + " vs deletedDocs.count()=" + reader.deletedDocs.count());
            }
            if (reader.deletedDocs.count() > reader.maxDoc()) {
              throw new RuntimeException("too many deleted docs: maxDoc()=" + reader.maxDoc() + " vs deletedDocs.count()=" + reader.deletedDocs.count());
            }
            if (info.docCount - numDocs != info.getDelCount()){
              throw new RuntimeException("delete count mismatch: info=" + info.getDelCount() + " vs reader=" + (info.docCount - numDocs));
            }
            segInfoStat.numDeleted = info.docCount - numDocs;
            msg("OK [" + (segInfoStat.numDeleted) + " deleted docs]");
          } else {
            if (info.getDelCount() != 0) {
              throw new RuntimeException("delete count mismatch: info=" + info.getDelCount() + " vs reader=" + (info.docCount - numDocs));
            }
            msg("OK");
          }
          if (reader.maxDoc() != info.docCount)
            throw new RuntimeException("SegmentReader.maxDoc() " + reader.maxDoc() + " != SegmentInfos.docCount " + info.docCount);
  
          // Test getFieldNames()
          if (infoStream != null) {
            infoStream.print("    test: fields..............");
          }         
          Collection<String> fieldNames = reader.getFieldNames(IndexReader.FieldOption.ALL);
          msg("OK [" + fieldNames.size() + " fields]");
          segInfoStat.numFields = fieldNames.size();
          
          // Test Field Norms
          segInfoStat.fieldNormStatus = testFieldNorms(fieldNames, reader);
  
          // Test the Term Index
          segInfoStat.termIndexStatus = testTermIndex(info, reader);
  
          // Test Stored Fields
          segInfoStat.storedFieldStatus = testStoredFields(info, reader, nf);
  
          // Test Term Vectors
          segInfoStat.termVectorStatus = testTermVectors(info, reader, nf);
  
          // Rethrow the first exception we encountered
          //  This will cause stats for failed segments to be incremented properly
          if (segInfoStat.fieldNormStatus.error != null) {
            throw new RuntimeException("Field Norm test failed");
          } else if (segInfoStat.termIndexStatus.error != null) {
            throw new RuntimeException("Term Index test failed");
          } else if (segInfoStat.storedFieldStatus.error != null) {
            throw new RuntimeException("Stored Field test failed");
          } else if (segInfoStat.termVectorStatus.error != null) {
            throw new RuntimeException("Term Vector test failed");
          }
  
          msg("");
  
        } catch (Throwable t) {
          msg("FAILED");
          String comment;
          comment = "fixIndex() would remove reference to this segment";
          msg("    WARNING: " + comment + "; full exception:");
          if (infoStream != null)
            t.printStackTrace(infoStream);
          msg("");
          result.totLoseDocCount += toLoseDocCount;
          result.numBadSegments++;
          continue;
        } finally {
          if (reader != null)
            reader.close();
        }
  
        // Keeper
        result.newSegments.add((SegmentInfo) info.clone());
      }
  
      if (0 == result.numBadSegments) {
        result.clean = true;
      } else
        msg("WARNING: " + result.numBadSegments + " broken segments (containing " + result.totLoseDocCount + " documents) detected");
  
      if ( ! (result.validCounter = (result.maxSegmentName < sis.counter))) {
        result.clean = false;
        result.newSegments.counter = result.maxSegmentName + 1; 
        msg("ERROR: Next segment name counter " + sis.counter + " is not greater than max segment name " + result.maxSegmentName);
      }
      
      if (result.clean) {
        msg("No problems were detected with this index.\n");
      }
  
      return result;
    }
  
    /**
     * Test field norms.
     */
    private Status.FieldNormStatus testFieldNorms(Collection<String> fieldNames, SegmentReader reader) {
      final Status.FieldNormStatus status = new Status.FieldNormStatus();
  
      try {
        // Test Field Norms
        if (infoStream != null) {
          infoStream.print("    test: field norms.........");
        }
        final byte[] b = new byte[reader.maxDoc()];
        for (final String fieldName : fieldNames) {
          if (reader.hasNorms(fieldName)) {
            reader.norms(fieldName, b, 0);
            ++status.totFields;
          }
        }
  
        msg("OK [" + status.totFields + " fields]");
      } catch (Throwable e) {
        msg("ERROR [" + String.valueOf(e.getMessage()) + "]");
        status.error = e;
        if (infoStream != null) {
          e.printStackTrace(infoStream);
        }
      }
  
      return status;
    }
  
    /**
     * Test the term index.
     */
    private Status.TermIndexStatus testTermIndex(SegmentInfo info, SegmentReader reader) {
      final Status.TermIndexStatus status = new Status.TermIndexStatus();
  
      final IndexSearcher is = new IndexSearcher(reader);
  
      try {
        if (infoStream != null) {
          infoStream.print("    test: terms, freq, prox...");
        }
  
        final TermEnum termEnum = reader.terms();
        final TermPositions termPositions = reader.termPositions();
  
        // Used only to count up # deleted docs for this term
        final MySegmentTermDocs myTermDocs = new MySegmentTermDocs(reader);
  
        final int maxDoc = reader.maxDoc();
        Term lastTerm = null;
        while (termEnum.next()) {
          status.termCount++;
          final Term term = termEnum.term();
          lastTerm = term;
  
          final int docFreq = termEnum.docFreq();
          if (docFreq <= 0) {
            throw new RuntimeException("docfreq: " + docFreq + " is out of bounds");
          }
          termPositions.seek(term);
          int lastDoc = -1;
          int freq0 = 0;
          status.totFreq += docFreq;
          while (termPositions.next()) {
            freq0++;
            final int doc = termPositions.doc();
            final int freq = termPositions.freq();
            if (doc <= lastDoc)
              throw new RuntimeException("term " + term + ": doc " + doc + " <= lastDoc " + lastDoc);
            if (doc >= maxDoc)
              throw new RuntimeException("term " + term + ": doc " + doc + " >= maxDoc " + maxDoc);
  
            lastDoc = doc;
            if (freq <= 0)
              throw new RuntimeException("term " + term + ": doc " + doc + ": freq " + freq + " is out of bounds");
              
            int lastPos = -1;
            status.totPos += freq;
            for(int j=0;j<freq;j++) {
              final int pos = termPositions.nextPosition();
              if (pos < -1)
                throw new RuntimeException("term " + term + ": doc " + doc + ": pos " + pos + " is out of bounds");
              if (pos < lastPos)
                throw new RuntimeException("term " + term + ": doc " + doc + ": pos " + pos + " < lastPos " + lastPos);
              lastPos = pos;
            }
          }
  
          // Test skipping
          for(int idx=0;idx<7;idx++) {
            final int skipDocID = (int) (((idx+1)*(long) maxDoc)/8);
            termPositions.seek(term);
            if (!termPositions.skipTo(skipDocID)) {
              break;
            } else {
  
              final int docID = termPositions.doc();
              if (docID < skipDocID) {
                throw new RuntimeException("term " + term + ": skipTo(docID=" + skipDocID + ") returned docID=" + docID);
              }
              final int freq = termPositions.freq();
              if (freq <= 0) {
                throw new RuntimeException("termFreq " + freq + " is out of bounds");
              }
              int lastPosition = -1;
              for(int posUpto=0;posUpto<freq;posUpto++) {
                final int pos = termPositions.nextPosition();
                if (pos < 0) {
                  throw new RuntimeException("position " + pos + " is out of bounds");
                }
                // TODO: we should assert when all pos == 0 that positions are actually omitted
                if (pos < lastPosition) {
                  throw new RuntimeException("position " + pos + " is < lastPosition " + lastPosition);
                }
                lastPosition = pos;
              } 
  
              if (!termPositions.next()) {
                break;
              }
              final int nextDocID = termPositions.doc();
              if (nextDocID <= docID) {
                throw new RuntimeException("term " + term + ": skipTo(docID=" + skipDocID + "), then .next() returned docID=" + nextDocID + " vs prev docID=" + docID);
              }
            }
          }
  
          // Now count how many deleted docs occurred in
          // this term:
          final int delCount;
          if (reader.hasDeletions()) {
            myTermDocs.seek(term);
            while(myTermDocs.next()) { }
            delCount = myTermDocs.delCount;
          } else {
            delCount = 0; 
          }
  
          if (freq0 + delCount != docFreq) {
            throw new RuntimeException("term " + term + " docFreq=" + 
                                       docFreq + " != num docs seen " + freq0 + " + num docs deleted " + delCount);
          }
        }
  
        // Test search on last term:
        if (lastTerm != null) {
          is.search(new TermQuery(lastTerm), 1);
        }
  
        try {
          long uniqueTermCountAllFields = reader.getUniqueTermCount();
          if (status.termCount != uniqueTermCountAllFields) {
            throw new RuntimeException("termCount mismatch " + uniqueTermCountAllFields + " vs " + (status.termCount));
          }
        } catch (UnsupportedOperationException ex) {
          // not supported
        }
        
        msg("OK [" + status.termCount + " terms; " + status.totFreq + " terms/docs pairs; " + status.totPos + " tokens]");
  
      } catch (Throwable e) {
        msg("ERROR [" + String.valueOf(e.getMessage()) + "]");
        status.error = e;
        if (infoStream != null) {
          e.printStackTrace(infoStream);
        }
      }
  
      return status;
    }
    
    /**
     * Test stored fields for a segment.
     */
    private Status.StoredFieldStatus testStoredFields(SegmentInfo info, SegmentReader reader, NumberFormat format) {
      final Status.StoredFieldStatus status = new Status.StoredFieldStatus();
  
      try {
        if (infoStream != null) {
          infoStream.print("    test: stored fields.......");
        }
  
        // Scan stored fields for all documents
        for (int j = 0; j < info.docCount; ++j) {
          if (!reader.isDeleted(j)) {
            status.docCount++;
            Document doc = reader.document(j);
            status.totFields += doc.getFields().size();
          }
        }      
  
        // Validate docCount
        if (status.docCount != reader.numDocs()) {
          throw new RuntimeException("docCount=" + status.docCount + " but saw " + status.docCount + " undeleted docs");
        }
  
        msg("OK [" + status.totFields + " total field count; avg " + 
            format.format((((float) status.totFields)/status.docCount)) + " fields per doc]");      
      } catch (Throwable e) {
        msg("ERROR [" + String.valueOf(e.getMessage()) + "]");
        status.error = e;
        if (infoStream != null) {
          e.printStackTrace(infoStream);
        }
      }
  
      return status;
    }
  
    /**
     * Test term vectors for a segment.
     */
    private Status.TermVectorStatus testTermVectors(SegmentInfo info, SegmentReader reader, NumberFormat format) {
      final Status.TermVectorStatus status = new Status.TermVectorStatus();
      
      try {
        if (infoStream != null) {
          infoStream.print("    test: term vectors........");
        }
  
        for (int j = 0; j < info.docCount; ++j) {
          if (!reader.isDeleted(j)) {
            status.docCount++;
            TermFreqVector[] tfv = reader.getTermFreqVectors(j);
            if (tfv != null) {
              status.totVectors += tfv.length;
            }
          }
        }
        
        msg("OK [" + status.totVectors + " total vector count; avg " + 
            format.format((((float) status.totVectors) / status.docCount)) + " term/freq vector fields per doc]");
      } catch (Throwable e) {
        msg("ERROR [" + String.valueOf(e.getMessage()) + "]");
        status.error = e;
        if (infoStream != null) {
          e.printStackTrace(infoStream);
        }
      }
      
      return status;
    }
  
    /** Repairs the index using previously returned result
     *  from {@link #checkIndex}.  Note that this does not
     *  remove any of the unreferenced files after it's done;
     *  you must separately open an {@link IndexWriter}, which
     *  deletes unreferenced files when it's created.
     *
     * <p><b>WARNING</b>: this writes a
     *  new segments file into the index, effectively removing
     *  all documents in broken segments from the index.
     *  BE CAREFUL.
     *
     * <p><b>WARNING</b>: Make sure you only call this when the
     *  index is not opened  by any writer. */
    public void fixIndex(Status result) throws IOException {
      if (result.partial)
        throw new IllegalArgumentException("can only fix an index that was fully checked (this status checked a subset of segments)");
      result.newSegments.changed();
      result.newSegments.commit(result.dir);
    }
  
    private static boolean assertsOn;
  
    private static boolean testAsserts() {
      assertsOn = true;
      return true;
    }
  
    private static boolean assertsOn() {
      assert testAsserts();
      return assertsOn;
    }
  
    /** Command-line interface to check and fix an index.
  
      <p>
      Run it like this:
      <pre>
      java -ea:org.apache.lucene... org.apache.lucene.index.CheckIndex pathToIndex [-fix] [-segment X] [-segment Y]
      </pre>
      <ul>
      <li><code>-fix</code>: actually write a new segments_N file, removing any problematic segments
  
      <li><code>-segment X</code>: only check the specified
      segment(s).  This can be specified multiple times,
      to check more than one segment, eg <code>-segment _2
      -segment _a</code>.  You can't use this with the -fix
      option.
      </ul>
  
      <p><b>WARNING</b>: <code>-fix</code> should only be used on an emergency basis as it will cause
                         documents (perhaps many) to be permanently removed from the index.  Always make
                         a backup copy of your index before running this!  Do not run this tool on an index
                         that is actively being written to.  You have been warned!
  
      <p>                Run without -fix, this tool will open the index, report version information
                         and report any exceptions it hits and what action it would take if -fix were
                         specified.  With -fix, this tool will remove any segments that have issues and
                         write a new segments_N file.  This means all documents contained in the affected
                         segments will be removed.
  
      <p>
                         This tool exits with exit code 1 if the index cannot be opened or has any
                         corruption, else 0.
     */
    public static void main(String[] args) throws IOException, InterruptedException {
  
      boolean doFix = false;
      List<String> onlySegments = new ArrayList<String>();
      String indexPath = null;
      int i = 0;
      while(i < args.length) {
        if (args[i].equals("-fix")) {
          doFix = true;
          i++;
        } else if (args[i].equals("-segment")) {
          if (i == args.length-1) {
            System.out.println("ERROR: missing name for -segment option");
            System.exit(1);
          }
          onlySegments.add(args[i+1]);
          i += 2;
        } else {
          if (indexPath != null) {
            System.out.println("ERROR: unexpected extra argument '" + args[i] + "'");
            System.exit(1);
          }
          indexPath = args[i];
          i++;
        }
      }
  
      if (indexPath == null) {
        System.out.println("\nERROR: index path not specified");
        System.out.println("\nUsage: java org.apache.lucene.index.CheckIndex pathToIndex [-fix] [-segment X] [-segment Y]\n" +
                           "\n" +
                           "  -fix: actually write a new segments_N file, removing any problematic segments\n" +
                           "  -segment X: only check the specified segments.  This can be specified multiple\n" + 
                           "              times, to check more than one segment, eg '-segment _2 -segment _a'.\n" +
                           "              You can't use this with the -fix option\n" +
                           "\n" + 
                           "**WARNING**: -fix should only be used on an emergency basis as it will cause\n" +
                           "documents (perhaps many) to be permanently removed from the index.  Always make\n" +
                           "a backup copy of your index before running this!  Do not run this tool on an index\n" +
                           "that is actively being written to.  You have been warned!\n" +
                           "\n" +
                           "Run without -fix, this tool will open the index, report version information\n" +
                           "and report any exceptions it hits and what action it would take if -fix were\n" +
                           "specified.  With -fix, this tool will remove any segments that have issues and\n" + 
                           "write a new segments_N file.  This means all documents contained in the affected\n" +
                           "segments will be removed.\n" +
                           "\n" +
                           "This tool exits with exit code 1 if the index cannot be opened or has any\n" +
                           "corruption, else 0.\n");
        System.exit(1);
      }
  
      if (!assertsOn())
        System.out.println("\nNOTE: testing will be more thorough if you run java with '-ea:org.apache.lucene...', so assertions are enabled");
  
      if (onlySegments.size() == 0)
        onlySegments = null;
      else if (doFix) {
        System.out.println("ERROR: cannot specify both -fix and -segment");
        System.exit(1);
      }
  
      System.out.println("\nOpening index @ " + indexPath + "\n");
      Directory dir = null;
      try {
        dir = FSDirectory.open(new File(indexPath));
      } catch (Throwable t) {
        System.out.println("ERROR: could not open directory \"" + indexPath + "\"; exiting");
        t.printStackTrace(System.out);
        System.exit(1);
      }
  
      CheckIndex checker = new CheckIndex(dir);
      checker.setInfoStream(System.out);
  
      Status result = checker.checkIndex(onlySegments);
      if (result.missingSegments) {
        System.exit(1);
      }
  
      if (!result.clean) {
        if (!doFix) {
          System.out.println("WARNING: would write new segments file, and " + result.totLoseDocCount + " documents would be lost, if -fix were specified\n");
        } else {
          System.out.println("WARNING: " + result.totLoseDocCount + " documents will be lost\n");
          System.out.println("NOTE: will write new segments file in 5 seconds; this will remove " + result.totLoseDocCount + " docs from the index. THIS IS YOUR LAST CHANCE TO CTRL+C!");
          for(int s=0;s<5;s++) {
            Thread.sleep(1000);
            System.out.println("  " + (5-s) + "...");
          }
          System.out.println("Writing...");
          checker.fixIndex(result);
          System.out.println("OK");
          System.out.println("Wrote new segments file \"" + result.newSegments.getCurrentSegmentFileName() + "\"");
        }
      }
      System.out.println("");
  
      final int exitCode;
      if (result.clean == true)
        exitCode = 0;
      else
        exitCode = 1;
      System.exit(exitCode);
    }
  }
  