/*
    * 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.requests;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.IOException;
  
  import org.apache.giraph.conf.ImmutableClassesGiraphConfigurable;
  import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;
  import org.apache.hadoop.io.Writable;
  import org.apache.hadoop.io.WritableComparable;
  
  /**
   * Interface for requests to implement
   *
   * @param <I> Vertex id
   * @param <V> Vertex data
   * @param <E> Edge data
   */
  public abstract class WritableRequest<I extends WritableComparable,
      V extends Writable, E extends Writable> implements Writable,
      ImmutableClassesGiraphConfigurable<I, V, E> {
    /**
     * Value to use when size of the request in serialized form is not known
     * or too expensive to calculate
     */
    public static final int UNKNOWN_SIZE = -1;
  
    /** Configuration */
    protected ImmutableClassesGiraphConfiguration<I, V, E> conf;
    /** Client id */
    private int clientId = -1;
    /** Request id */
    private long requestId = -1;
  
    public int getClientId() {
      return clientId;
    }
  
    public void setClientId(int clientId) {
      this.clientId = clientId;
    }
  
    public long getRequestId() {
      return requestId;
    }
  
    public void setRequestId(long requestId) {
      this.requestId = requestId;
    }
  
    /**
     * Get the size of the request in serialized form. The number returned by
     * this function can't be less than the actual size - if the size can't be
     * calculated correctly return WritableRequest.UNKNOWN_SIZE.
     *
     * @return The size (in bytes) of serialized request,
     * or WritableRequest.UNKNOWN_SIZE if the size is not known
     * or too expensive to calculate.
     */
    public int getSerializedSize() {
      // 4 for clientId, 8 for requestId
      return 4 + 8;
    }
  
    /**
     * Get the type of the request
     *
     * @return Request type
     */
    public abstract RequestType getType();
  
    /**
     * Serialize the request
     *
     * @param input Input to read fields from
     */
    abstract void readFieldsRequest(DataInput input) throws IOException;
  
    /**
     * Deserialize the request
     *
    * @param output Output to write the request to
    */
   abstract void writeRequest(DataOutput output) throws IOException;
 
   @Override
   public final ImmutableClassesGiraphConfiguration<I, V, E> getConf() {
     return conf;
   }
 
   @Override
   public final void setConf(ImmutableClassesGiraphConfiguration<I, V, E> conf) {
     this.conf = conf;
   }
 
   @Override
   public final void readFields(DataInput input) throws IOException {
     clientId = input.readInt();
     requestId = input.readLong();
     readFieldsRequest(input);
   }
 
   @Override
   public final void write(DataOutput output) throws IOException {
     output.writeInt(clientId);
     output.writeLong(requestId);
     writeRequest(output);
   }
 }