content: /**
   * Copyright 2010 Karthik Kumar
   * 
   * Based off the original code by Lucandra project, (C): Jake Luciani
   * 
   * 
   * 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.
   */
  package org.hbasene.index;
  
  import java.io.IOException;
  import java.io.StringReader;
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.analysis.TokenStream;
  import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
  import org.apache.lucene.analysis.tokenattributes.TermAttribute;
  import org.apache.lucene.document.Document;
  import org.apache.lucene.document.Fieldable;
  import org.apache.lucene.index.CorruptIndexException;
  import org.apache.lucene.store.LockObtainFailedException;
  
  import com.google.common.collect.Lists;
  
  /**
   * Index Writer in the noSQL world.
   * 
   */
  public class HBaseIndexWriter { // TODO: extends IndexWriter {
  
    private static final Log LOG = LogFactory.getLog(HBaseIndexWriter.class);
    
    /**
     * Abstraction of the index store
     */
    private final AbstractIndexStore indexStore;
  
    /**
     * Field representing the primary key in the given search index.
     */
    private final String primaryKeyField;
  
  
    /**
     * List of empty term vectors
     */
    static final List<Integer> EMPTY_TERM_POSITIONS = Arrays
        .asList(new Integer[] { 0 });
  
    /**
     * 
     * @param indexTransactionLog
     * @param primaryKeyField
     *          The primary key field of the lucene Document schema to be used.
     * @throws CorruptIndexException
     * @throws LockObtainFailedException
     * @throws IOException
     */
    public HBaseIndexWriter(final AbstractIndexStore indexTransactionLog,
        final String primaryKeyField) throws IOException {
      // super(d, a, create, deletionPolicy, mfl);
      // TODO: bring super ctor in when we inherit from IndexWriter.
  
      this.indexStore = indexTransactionLog;
      this.primaryKeyField = primaryKeyField;
  
      // Reset the transaction Log.
      // this.indexStore.init();
    }
  
    public void addDocument(Document doc, Analyzer analyzer)
        throws CorruptIndexException, IOException {
      String docId = doc.get(this.primaryKeyField);
      if (docId == null) {
        throw new IllegalArgumentException("Primary Key " + this.primaryKeyField
            + " not present in the document to be added ");
        // TODO: Special type of exception needed ?
  
      }
      int position = 0;
      Map<String, List<Integer>> termPositions = new HashMap<String, List<Integer>>();
      Map<String, byte[]> fieldsToStore = new HashMap<String, byte[]>();
  
      for (Fieldable field : doc.getFields()) {
  
        // Indexed field
        if (field.isIndexed() && field.isTokenized()) {
          TokenStream tokens = field.tokenStreamValue();
  
          if (tokens == null) {
            tokens = analyzer.tokenStream(field.name(), new StringReader(field
                .stringValue()));
          }
          tokens.addAttribute(TermAttribute.class);
          tokens.addAttribute(PositionIncrementAttribute.class);
  
          // collect term frequencies per doc
          if (position > 0) {
            position += analyzer.getPositionIncrementGap(field.name());
          }
  
          // Build the termPositions vector for all terms
          while (tokens.incrementToken()) {
            String term = createColumnName(field.name(), tokens.getAttribute(
                TermAttribute.class).term());
  
            List<Integer> pvec = termPositions.get(term);
  
            if (pvec == null) {
              pvec = Lists.newArrayList();
              termPositions.put(term, pvec);
            }
  
            position += (tokens.getAttribute(PositionIncrementAttribute.class)
                .getPositionIncrement() - 1);
            pvec.add(++position);
  
          }
          tokens.close();
  
        }
  
        // Untokenized fields go in without a termPosition
        if (field.isIndexed() && !field.isTokenized()) {
          String term = this.createColumnName(field.name(), field.stringValue());
          String key = term;
          termPositions.put(key, EMPTY_TERM_POSITIONS);
  
        }
  
        // Stores each field as a column under this doc key
        if (field.isStored()) {
  
          byte[] value = field.isBinary() ? field.getBinaryValue() : Bytes
              .toBytes(field.stringValue());
  
          // first byte flags if binary or not
          final byte[] prefix = Bytes.toBytes((field.isBinary() ? 'B' : 'T'));
  
          fieldsToStore.put(field.name(), Bytes.add(prefix, value));
        }
      }
      indexStore.indexDocument(docId, new DocumentIndexContext(termPositions,
          fieldsToStore));
      termPositions.clear();
      fieldsToStore.clear();
    }
  
    public void commit() throws IOException {
      this.indexStore.commit();
    }
  
    public void close() throws IOException {
      this.indexStore.close();
    }
  
    String createColumnName(final String fieldName, final String term) {
      return fieldName + "/" + term;
    }
  }
  