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

 package org.galagosearch.core.index;

 import java.io.BufferedOutputStream;

 import java.io.DataOutputStream;

 import java.io.FileNotFoundException;

 import java.io.FileOutputStream;

 import java.io.IOException;

 import org.galagosearch.core.types.NumberedDocumentData;

 import org.galagosearch.tupleflow.Counter;

 import org.galagosearch.tupleflow.InputClass;

 import org.galagosearch.tupleflow.Processor;

 import org.galagosearch.tupleflow.TupleFlowParameters;

 import org.galagosearch.tupleflow.execution.ErrorHandler;

 import org.galagosearch.tupleflow.execution.Verification;

 /**

  * Writes the document lengths file based on data in NumberedDocumentData tuples.

  * The document lengths data is used by StructuredIndex because it's a key

  * input to more scoring functions.

  * 

  * @author trevor

  */

 @InputClass(className = "org.galagosearch.core.types.NumberedDocumentData", order = {"+number"})

 public class DocumentLengthsWriter implements Processor<NumberedDocumentData> {

     DataOutputStream output;

     int document = 0;

     Counter documentsWritten = null;

     /** Creates a new instance of DocumentLengthsWriter */

     public DocumentLengthsWriter(TupleFlowParameters parameters) throws FileNotFoundException {

         String filename = parameters.getXML().get("filename");

         output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(filename)));

         documentsWritten = parameters.getCounter("Documents Written");

     }

     public void close() throws IOException {

         output.close();

     }

     public void process(NumberedDocumentData object) throws IOException {

         assert document <= object.number : "d: " + document + " o.d:" + object.number;

         while (document < object.number) {

             output.writeInt(0);

             document++;

         }

         output.writeInt(object.textLength);

         document++;

         if (documentsWritten != null) documentsWritten.increment();

     }

     public static void verify(TupleFlowParameters parameters, ErrorHandler handler) {

         if (!parameters.getXML().containsKey("filename")) {

             handler.addError("DocumentLengthsWriter requires an 'filename' parameter.");

             return;

         }

         String filename = parameters.getXML().get("filename");

         Verification.requireWriteableFile(filename, handler);

     }

 }