/**
 * 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.hdfs.server.protocol;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Comparator;

import org.apache.hadoop.hdfs.server.common.HdfsConstants;
import org.apache.hadoop.hdfs.server.namenode.EditLogInputStream;
import org.apache.hadoop.io.Writable;

import com.google.common.base.Function;
import com.google.common.collect.ComparisonChain;

public class RemoteEditLog implements Writable, Comparable<RemoteEditLog> {
  private long startTxId = HdfsConstants.INVALID_TXID;
  private long endTxId = HdfsConstants.INVALID_TXID;
  private boolean inProgress = false;
  
  static final public Comparator<RemoteEditLog>
  REMOTE_EDIT_LOG_COMPARATOR = new Comparator<RemoteEditLog>() {
    @Override
    public int compare(RemoteEditLog a, RemoteEditLog b) {
      return ComparisonChain.start().
        compare(a.startTxId, b.startTxId).
        compare(b.endTxId, a.endTxId).
        result();
    }
  };
  
  public RemoteEditLog() {
  }

  public RemoteEditLog(long startTxId, long endTxId, boolean ip) {
    this.startTxId = startTxId;
    this.endTxId = endTxId;
    this.inProgress = ip;
  }

  public long getStartTxId() {
    return startTxId;
  }

  public long getEndTxId() {
    return endTxId;
  }
  
  public boolean inProgress(){
    return inProgress;
  }
    
  @Override
  public String toString() {
    return "[" + startTxId + "," + endTxId + "," + (!inProgress) +"]";
  }

  @Override
  public void write(DataOutput out) throws IOException {
    out.writeLong(startTxId);
    out.writeLong(endTxId);
    out.writeBoolean(inProgress);
  }

  @Override
  public void readFields(DataInput in) throws IOException {
    startTxId = in.readLong();
    endTxId = in.readLong();
    inProgress = in.readBoolean();
  }
  
  @Override
  public int compareTo(RemoteEditLog log) {
    return ComparisonChain.start()
      .compare(startTxId, log.startTxId)
      .compare(endTxId, log.endTxId)
      .result();
  }

  @Override
  public boolean equals(Object o) {
    if (!(o instanceof RemoteEditLog)) return false;
    return this.compareTo((RemoteEditLog)o) == 0;
  }
  
  @Override
  public int hashCode() {
    return (int) (startTxId * endTxId);
  }
  
  /**
   * Guava <code>Function</code> which applies {@link #getStartTxId()} 
   */
  public static final Function<RemoteEditLog, Long> GET_START_TXID =
    new Function<RemoteEditLog, Long>() {
      @Override
      public Long apply(RemoteEditLog log) {
        return log.getStartTxId();
      }
    };
}