/*
    * 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.giraph.comm.messages.primitives.long_id;
  
  import it.unimi.dsi.fastutil.longs.LongArrayList;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  
  import org.apache.giraph.comm.messages.MessageStore;
  import org.apache.giraph.comm.messages.PartitionSplitInfo;
  import org.apache.giraph.comm.messages.PointerListMessagesIterable;
  import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;
  import org.apache.giraph.factories.MessageValueFactory;
  import org.apache.giraph.utils.EmptyIterable;
  import org.apache.giraph.utils.ExtendedByteArrayOutputBuffer;
  import org.apache.giraph.utils.ExtendedByteArrayOutputBuffer.IndexAndDataOut;
  import org.apache.giraph.utils.ExtendedDataOutput;
  import org.apache.giraph.utils.VertexIdMessageIterator;
  import org.apache.giraph.utils.VertexIdMessages;
  import org.apache.hadoop.io.LongWritable;
  import org.apache.hadoop.io.Writable;
  
  /**
   * This stores messages in
   * {@link org.apache.giraph.utils.ExtendedByteArrayOutputBuffer}
   * and stores long pointers that point to serialized messages
   *
   * @param <M> message type
   */
  public class LongPointerListPerVertexStore<M extends Writable>
    extends LongAbstractListStore<M, LongArrayList>
    implements MessageStore<LongWritable, M> {
  
    /** Buffers of byte array outputs used to store messages - thread safe */
    private final ExtendedByteArrayOutputBuffer bytesBuffer;
  
    /**
     * Constructor
     *
     * @param messageValueFactory Factory for creating message values
     * @param partitionInfo       Partition split info
     * @param config              Hadoop configuration
     */
    public LongPointerListPerVertexStore(
      MessageValueFactory<M> messageValueFactory,
      PartitionSplitInfo<LongWritable> partitionInfo,
      ImmutableClassesGiraphConfiguration<LongWritable,
      Writable, Writable> config) {
      super(messageValueFactory, partitionInfo, config);
      bytesBuffer = new ExtendedByteArrayOutputBuffer(config);
    }
  
    @Override
    public boolean isPointerListEncoding() {
      return true;
    }
  
    @Override
    protected LongArrayList createList() {
      return new LongArrayList();
    }
  
    @Override
    public void addPartitionMessages(
      int partitionId,
      VertexIdMessages<LongWritable, M> messages
    ) {
      try {
        VertexIdMessageIterator<LongWritable, M> iterator =
            messages.getVertexIdMessageIterator();
        long pointer = 0;
        LongArrayList list;
        while (iterator.hasNext()) {
          iterator.next();
          M msg = iterator.getCurrentMessage();
          list = getList(iterator.getCurrentVertexId());
  
          if (iterator.isNewMessage()) {
            IndexAndDataOut indexAndDataOut = bytesBuffer.getIndexAndDataOut();
            pointer = indexAndDataOut.getIndex();
            pointer <<= 32;
           ExtendedDataOutput dataOutput = indexAndDataOut.getDataOutput();
           pointer += dataOutput.getPos();
           msg.write(dataOutput);
         }
         synchronized (list) { // TODO - any better way?
           list.add(pointer);
         }
       }
     } catch (IOException e) {
       throw new RuntimeException("addPartitionMessages: IOException while" +
           " adding messages for a partition: " + e);
     }
   }
 
   @Override
   public void addMessage(LongWritable vertexId, M message) throws IOException {
     LongArrayList list = getList(vertexId);
     IndexAndDataOut indexAndDataOut = bytesBuffer.getIndexAndDataOut();
     long pointer = indexAndDataOut.getIndex();
     pointer <<= 32;
     ExtendedDataOutput dataOutput = indexAndDataOut.getDataOutput();
     pointer += dataOutput.getPos();
     message.write(dataOutput);
 
     synchronized (list) {
       list.add(pointer);
     }
   }
 
   @Override
   public Iterable<M> getVertexMessages(LongWritable vertexId) {
     LongArrayList list = getPartitionMap(vertexId).get(
         vertexId.get());
     if (list == null) {
       return EmptyIterable.get();
     } else {
       return new PointerListMessagesIterable<>(messageValueFactory,
         list, bytesBuffer);
     }
   }
 
   // FIXME -- complete these for check-pointing
   @Override
   public void writePartition(DataOutput out, int partitionId)
     throws IOException {
   }
 
   @Override
   public void readFieldsForPartition(DataInput in, int partitionId)
     throws IOException {
   }
 }