// BSD License (http://www.galagosearch.org/license)

 package org.galagosearch.core.index;

 import java.io.FileNotFoundException;

 import java.io.IOException;

 import java.io.OutputStream;

 import org.galagosearch.core.types.NumberWordProbability;

 import org.galagosearch.tupleflow.TupleFlowParameters;

 /**

  *

  * @author trevor

  */

 public class SparseFloatListWriter implements 

         NumberWordProbability.NumberWordOrder.ShreddedProcessor {

     IndexWriter writer;

     DoubleInvertedList list;

     public class DoubleInvertedList implements IndexElement {

         BackedCompressedByteBuffer data = new BackedCompressedByteBuffer();

         CompressedByteBuffer header = new CompressedByteBuffer();

         int lastDocument;

         int documentCount;

         byte[] word;

         public DoubleInvertedList(byte[] word) {

             this.word = word;

             this.lastDocument = 0;

             this.documentCount = 0;

         }

         public void write(final OutputStream stream) throws IOException {

             header.write(stream);

             data.write(stream);

         }

         public void addDocument(int document) throws IOException {

             data.add(document - lastDocument);

             documentCount++;

             lastDocument = document;

         }

         public void addProbability(double probability) throws IOException {

             data.addFloat((float) probability);

         }

         public byte[] key() {

             return word;

         }

         public long dataLength() {

             return data.length() + header.length();

         }

         public void close() {

             header.add(documentCount);

         }

     }

     /** Creates a new instance of DoubleListWriter */

     public SparseFloatListWriter(TupleFlowParameters parameters) throws FileNotFoundException, IOException {

         writer = new IndexWriter(parameters);

         writer.getManifest().add("readerClass", SparseFloatListReader.class.getName());

         writer.getManifest().add("writerClass", getClass().getName());

     }

     public void processWord(byte[] word) throws IOException {

         if (list != null) {

             list.close();

             writer.add(list);

         }

         list = new DoubleInvertedList(word);

     }

     public void processNumber(int number) throws IOException {

         list.addDocument(number);

     }

     public void processTuple(double probability) throws IOException {

         list.addProbability(probability);

     }

     public void close() throws IOException {

         if (list != null) {

             list.close();

             writer.add(list);

         }

         writer.close();

     }

 }