package org.galagosearch.core.index;
   
   import java.io.IOException;
   import java.io.OutputStream;
   
   public class ExtentListBuffer implements IndexElement {
       public ExtentListBuffer() {
           super();
           documentCount = 0;
          extentCount = 0;
          endCount = 0;
          data = new CompressedByteBuffer();
          header = new CompressedByteBuffer();
          documentExtents = new CompressedByteBuffer();
      }
  
      public long dataLength() {
          long listLength = 0;
          listLength += header.length();
          listLength += data.length();
          return listLength;
      }
  
      public void write(final OutputStream output) throws IOException {
          output.write(header.getBytes(), 0, header.length());
          output.write(data.getBytes(), 0, data.length());
      }
  
      public byte[] key() {
          return word;
      }
  
      public void setWord(byte[] word) {
          this.word = word;
          this.lastDocument = 0;
          this.lastPosition = 0;
          this.extentCount = 0;
      }
  
      void setValue(long value) {
          this.value = value;
      }
  
      private void storePreviousDocument() {
          if (data.position > 0) {
              data.add(extentCount);
              data.add(documentExtents);
              documentExtents.clear();
          }
      }
  
      public void addDocument(long documentID) {
          storePreviousDocument();
          data.add(documentID - lastDocument);
          lastDocument = documentID;
          lastStartExtent = 0;
          extentCount = 0;
          endCount = 0;
          value = 0;
          documentCount++;
      }
  
      public void addBegin(int begin) {
          extentCount++;
          documentExtents.add(begin - lastStartExtent);
          lastStartExtent = begin;
      }
  
      public void addEnd(int end) {
          endCount++;
          // Record multiple extents at the same begin location
          if (endCount > extentCount) {
              documentExtents.add(0);
              extentCount++;
          }
          documentExtents.add(end - lastStartExtent);
          documentExtents.add(value);
      }
  
      public void close() {
          int options = 0;
          storePreviousDocument();
          header.add(options);
          header.add(documentCount);
      }
  
      private long value;
      private long lastDocument;
      private int lastStartExtent;
      private int lastPosition;
      private int extentCount;
      private int endCount;
      private int documentCount;
      public byte[] word;
      public CompressedByteBuffer header;
      public CompressedByteBuffer data;
      public CompressedByteBuffer documentExtents;
  }