/*
    * 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.utils;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  
  import org.apache.giraph.factories.MessageValueFactory;
  import org.apache.hadoop.io.Writable;
  import org.apache.hadoop.io.WritableComparable;
  
  /**
   * Stores vertex id and message pairs in a single byte array.
   *
   * @param <I> Vertex id
   * @param <M> Message data
   */
  @SuppressWarnings("unchecked")
  public class ByteArrayVertexIdMessages<I extends WritableComparable,
    M extends Writable> extends ByteArrayVertexIdData<I, M>
    implements VertexIdMessages<I, M> {
    /** Message value class */
    private final MessageValueFactory<M> messageValueFactory;
    /** Add the message size to the stream? (Depends on the message store) */
    private boolean useMessageSizeEncoding = false;
  
    /**
     * Constructor
     *
     * @param messageValueFactory Class for messages
     */
    public ByteArrayVertexIdMessages(
        MessageValueFactory<M> messageValueFactory) {
      this.messageValueFactory = messageValueFactory;
    }
  
    /**
     * Set whether message sizes should be encoded.  This should only be a
     * possibility when not combining.  When combining, all messages need to be
     * de-serialized right away, so this won't help.
     */
    private void setUseMessageSizeEncoding() {
      if (!getConf().useOutgoingMessageCombiner()) {
        useMessageSizeEncoding = getConf().useMessageSizeEncoding();
      } else {
        useMessageSizeEncoding = false;
      }
    }
  
    @Override
    public M createData() {
      return messageValueFactory.newInstance();
    }
  
    @Override
    public void writeData(ExtendedDataOutput out, M message) throws IOException {
      message.write(out);
    }
  
    @Override
    public void readData(ExtendedDataInput in, M message) throws IOException {
      message.readFields(in);
    }
  
    @Override
    public void initialize() {
      super.initialize();
      setUseMessageSizeEncoding();
    }
  
    @Override
    public void initialize(int expectedSize) {
      super.initialize(expectedSize);
      setUseMessageSizeEncoding();
    }
  
    @Override
    public ByteStructVertexIdMessageIterator<I, M> getVertexIdMessageIterator() {
      return new ByteStructVertexIdMessageIterator<>(this);
    }
  
    @Override
   public void add(I vertexId, M message) {
     if (!useMessageSizeEncoding) {
       super.add(vertexId, message);
     } else {
       try {
         vertexId.write(extendedDataOutput);
         writeMessageWithSize(message);
       } catch (IOException e) {
         throw new IllegalStateException("add: IOException occurred");
       }
     }
   }
 
   @Override
   public void add(byte[] serializedId, int idPos, M message) {
     if (!useMessageSizeEncoding) {
       super.add(serializedId, idPos, message);
     } else {
       try {
         extendedDataOutput.write(serializedId, 0, idPos);
         writeMessageWithSize(message);
       } catch (IOException e) {
         throw new IllegalStateException("add: IOException occurred");
       }
     }
   }
 
   /**
    * Write a size of the message and message
    *
    * @param message Message to write
    */
   private void writeMessageWithSize(M message) throws IOException {
     int pos = extendedDataOutput.getPos();
     extendedDataOutput.skipBytes(4);
     writeData(extendedDataOutput, message);
     extendedDataOutput.writeInt(
         pos, extendedDataOutput.getPos() - pos - 4);
   }
 
   @Override
   public ByteStructVertexIdMessageBytesIterator<I, M>
   getVertexIdMessageBytesIterator() {
     if (!useMessageSizeEncoding) {
       return null;
     }
     return new ByteStructVertexIdMessageBytesIterator<I, M>(this) {
       @Override
       public void writeCurrentMessageBytes(DataOutput dataOutput) {
         try {
           dataOutput.write(extendedDataOutput.getByteArray(),
             messageOffset, messageBytes);
         } catch (NegativeArraySizeException e) {
           VerboseByteStructMessageWrite.handleNegativeArraySize(vertexId);
         } catch (IOException e) {
           throw new IllegalStateException("writeCurrentMessageBytes: Got " +
               "IOException", e);
         }
       }
     };
   }
 
   @Override
   public void write(DataOutput dataOutput) throws IOException {
     dataOutput.writeBoolean(useMessageSizeEncoding);
     super.write(dataOutput);
   }
 
   @Override
   public void readFields(DataInput dataInput) throws IOException {
     useMessageSizeEncoding = dataInput.readBoolean();
     super.readFields(dataInput);
   }
 }