/**
 * 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.apex.malhar.flume.storage;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.HashMap;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.flume.Event;
import org.apache.flume.event.EventBuilder;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.io.Input;
import com.esotericsoftware.kryo.io.Output;

import com.datatorrent.api.StreamCodec;
import com.datatorrent.netlet.util.Slice;

/**
 * <p>EventCodec class.</p>
 *
 * @since 0.9.4
 */
public class EventCodec implements StreamCodec<Event>
{
  private final transient Kryo kryo;

  public EventCodec()
  {
    this.kryo = new Kryo();
    this.kryo.setClassLoader(Thread.currentThread().getContextClassLoader());
  }

  @Override
  public Object fromByteArray(Slice fragment)
  {
    ByteArrayInputStream is = new ByteArrayInputStream(fragment.buffer, fragment.offset, fragment.length);
    Input input = new Input(is);

    @SuppressWarnings("unchecked")
    HashMap<String, String> headers = kryo.readObjectOrNull(input, HashMap.class);
    byte[] body = kryo.readObjectOrNull(input, byte[].class);
    return EventBuilder.withBody(body, headers);
  }

  @Override
  public Slice toByteArray(Event event)
  {
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    Output output = new Output(os);

    Map<String, String> headers = event.getHeaders();
    if (headers != null && headers.getClass() != HashMap.class) {
      HashMap<String, String> tmp = new HashMap<String, String>(headers.size());
      tmp.putAll(headers);
      headers = tmp;
    }
    kryo.writeObjectOrNull(output, headers, HashMap.class);
    kryo.writeObjectOrNull(output, event.getBody(), byte[].class);
    output.flush();
    final byte[] bytes = os.toByteArray();
    return new Slice(bytes, 0, bytes.length);
  }

  @Override
  public int getPartition(Event o)
  {
    return o.hashCode();
  }

  private static final Logger logger = LoggerFactory.getLogger(EventCodec.class);
}