/*
 * Druid - a distributed column store.
 * Copyright (C) 2012, 2013  Metamarkets Group Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package io.druid.indexer;

import com.metamx.common.Pair;
import org.joda.time.DateTime;

import java.nio.ByteBuffer;

public class Bucket
{
  public static int PREAMBLE_BYTES = 16;

  /** ID for this bucket, unique for this indexer run. Used for grouping and partitioning. */
  private final int shardNum;

  /** Start time of this bucket's time window. End time can be determined by our GranularitySpec. */
  public final DateTime time;

  /** Partition number of this bucket within our time window (other Buckets may occupy the same window). */
  public final int partitionNum;

  public Bucket(int shardNum, DateTime time, int partitionNum)
  {
    this.shardNum = shardNum;
    this.time = time;
    this.partitionNum = partitionNum;
  }

  public byte[] toGroupKey(byte[]... parts)
  {
    ByteBuffer buf = ByteBuffer.allocate(PREAMBLE_BYTES + sizes(parts));

    buf.putInt(shardNum);
    buf.putLong(time.getMillis());
    buf.putInt(partitionNum);
    for (int i = 0; i < parts.length; i++) {
      buf.put(parts[i]);
    }

    return buf.array();
  }

  @Override
  public String toString()
  {
    return "Bucket{" +
           "time=" + time +
           ", partitionNum=" + partitionNum +
           ", shardNum=" + shardNum +
           '}';
  }

  @Override
  public boolean equals(Object o)
  {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }

    Bucket bucket = (Bucket) o;

    if (partitionNum != bucket.partitionNum) {
      return false;
    }
    if (shardNum != bucket.shardNum) {
      return false;
    }
    if (time != null ? !time.equals(bucket.time) : bucket.time != null) {
      return false;
    }

    return true;
  }

  @Override
  public int hashCode()
  {
    int result = time != null ? time.hashCode() : 0;
    result = 31 * result + partitionNum;
    result = 31 * result + shardNum;
    return result;
  }

  private static int sizes(byte[]... parts)
  {
    int size = 0;
    for (int i = 0; i < parts.length; i++) {
      size += parts[i].length;
    }
    return size;
  }

  public static final Pair<Bucket, byte[]> fromGroupKey(byte[] keyBytes)
  {
    ByteBuffer buf = ByteBuffer.wrap(keyBytes);

    Bucket bucket = new Bucket(buf.getInt(), new DateTime(buf.getLong()), buf.getInt());
    byte[] bytesLeft = new byte[buf.remaining()];
    buf.get(bytesLeft);

    return Pair.of(bucket, bytesLeft);    
  }
}