/*
    * 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.apache.hadoop.chukwa.datacollection.writer.gora;
  
  import java.nio.ByteBuffer;
  import java.util.List;
  
  import org.apache.gora.store.DataStore;
  import org.apache.gora.store.DataStoreFactory;
  import org.apache.gora.util.GoraException;
  import org.apache.hadoop.chukwa.Chunk;
  import org.apache.hadoop.chukwa.datacollection.agent.ChukwaAgent;
  import org.apache.hadoop.chukwa.datacollection.writer.ChukwaWriter;
  import org.apache.hadoop.chukwa.datacollection.writer.PipelineableWriter;
  import org.apache.hadoop.chukwa.datacollection.writer.WriterException;
  import org.apache.hadoop.chukwa.datacollection.writer.solr.SolrWriter;
  import org.apache.hadoop.chukwa.util.ExceptionUtil;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.log4j.Logger;
  
  /**
   * This class leverages <a href="http://gora.apache.org">Apache Gora</a>
   * as a pipeline writer implementation for mapping Chukwa data chunks and 
   * metadata as {@link org.apache.hadoop.chukwa.datacollection.writer.gora.ChukwaChunk}'s. 
   *
   */
  public class GoraWriter extends PipelineableWriter {
    
    private static Logger log = Logger.getLogger(SolrWriter.class);
    
    DataStore<String, ChukwaChunk> chunkStore;
  
    /**
     * Default constructor for this class.
     * @throws WriterException if error writing
     */
    public GoraWriter() throws WriterException {
      log.debug("Initializing configuration for GoraWriter pipeline...");
      init(ChukwaAgent.getStaticConfiguration());
    }
  
    /**
     * {@link org.apache.gora.store.DataStore} objects are created from a factory. It is necessary to 
     * provide the key and value class. The datastore class parameters is optional, 
     * and if not specified it will be read from the <code>gora.properties</code> file.
     * @throws WriterException if error occurs
     * @see org.apache.hadoop.chukwa.datacollection.writer.ChukwaWriter#init(org.apache.hadoop.conf.Configuration)
     */
    @Override
    public void init(Configuration c) throws WriterException {
      try {
        chunkStore = DataStoreFactory.getDataStore(String.class, ChukwaChunk.class, c);
      } catch (GoraException e) {
        log.error(ExceptionUtil.getStackTrace(e));
        e.printStackTrace();
      } 
    }
  
    /**
     * <p>
     * If the {@link org.apache.gora.store.DataStore} instance is not null, we
     * execute a {@link org.apache.gora.store.DataStore#flush()}. This forces 
     * the write caches to be flushed. DataStore implementations may optimize 
     * their writing by deferring the actual put / delete operations until 
     * this moment.
     * </p>
     * <p>Otherwise, we utilize {@link org.apache.gora.store.DataStore#close()}
     * which closes the DataStore. This should release any resources held by 
     * the implementation, so that the instance is ready for GC. All other 
     * DataStore methods cannot be used after this method was called. 
     * Subsequent calls of this method are ignored.
     * </p>  
     * @see org.apache.hadoop.chukwa.datacollection.writer.ChukwaWriter#close()
     */
    @Override
    public void close() throws WriterException {
      if (chunkStore != null) {
        chunkStore.flush();
      } else {
        chunkStore.close();
      }
      log.debug("Gora datastore successfully closed.");
    }
  
   @Override
   public CommitStatus add(List<Chunk> chunks) throws WriterException {
     CommitStatus cStatus = ChukwaWriter.COMMIT_OK;
     for(Chunk chunk : chunks) {
       try {
         ChukwaChunk chukwaChunk = ChukwaChunk.newBuilder().build();
         chukwaChunk.setSource(chunk.getSource());
         chukwaChunk.setDatatype(chunk.getDataType());
         chukwaChunk.setSequenceID(chunk.getSeqID());
         chukwaChunk.setName(chunk.getStreamName());
         chukwaChunk.setTags(chunk.getTags());
         chukwaChunk.setData(ByteBuffer.wrap(chunk.getData()));
       } catch (Exception e) {
         log.error(ExceptionUtil.getStackTrace(e));
         throw new WriterException("Failed to store data to Solr Cloud.");
       }
     }
     if (next != null) {
       cStatus = next.add(chunks); //pass data through
     }
     return cStatus;
   }
 }