/**
    *
    * 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.hbase.mapreduce;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.conf.Configurable;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
  import org.apache.hadoop.hbase.util.Base64;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.mapreduce.Partitioner;
  
  /**
   * A partitioner that takes start and end keys and uses bigdecimal to figure
   * which reduce a key belongs to.  Pass the start and end
   * keys in the Configuration using <code>hbase.simpletotalorder.start</code>
   * and <code>hbase.simpletotalorder.end</code>.  The end key needs to be
   * exclusive; i.e. one larger than the biggest key in your key space.
   * You may be surprised at how this class partitions the space; it may not
   * align with preconceptions; e.g. a start key of zero and an end key of 100
   * divided in ten will not make regions whose range is 0-10, 10-20, and so on.
   * Make your own partitioner if you need the region spacing to come out a
   * particular way.
   * @param <VALUE>
   * @see #START
   * @see #END
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class SimpleTotalOrderPartitioner<VALUE> extends Partitioner<ImmutableBytesWritable, VALUE>
  implements Configurable {
    private final static Log LOG = LogFactory.getLog(SimpleTotalOrderPartitioner.class);
  
    @Deprecated
    public static final String START = "hbase.simpletotalorder.start";
    @Deprecated
    public static final String END = "hbase.simpletotalorder.end";
    
    static final String START_BASE64 = "hbase.simpletotalorder.start.base64";
    static final String END_BASE64 = "hbase.simpletotalorder.end.base64";
    
    private Configuration c;
    private byte [] startkey;
    private byte [] endkey;
    private byte [][] splits;
    private int lastReduces = -1;
  
    public static void setStartKey(Configuration conf, byte[] startKey) {
      conf.set(START_BASE64, Base64.encodeBytes(startKey));
    }
    
    public static void setEndKey(Configuration conf, byte[] endKey) {
      conf.set(END_BASE64, Base64.encodeBytes(endKey));
    }
    
    @SuppressWarnings("deprecation")
    static byte[] getStartKey(Configuration conf) {
      return getKeyFromConf(conf, START_BASE64, START);
    }
    
    @SuppressWarnings("deprecation")
    static byte[] getEndKey(Configuration conf) {
      return getKeyFromConf(conf, END_BASE64, END);
    }
    
    private static byte[] getKeyFromConf(Configuration conf,
        String base64Key, String deprecatedKey) {
      String encoded = conf.get(base64Key);
      if (encoded != null) {
        return Base64.decode(encoded);
      }
      String oldStyleVal = conf.get(deprecatedKey);
      if (oldStyleVal == null) {
        return null;
      }
      LOG.warn("Using deprecated configuration " + deprecatedKey +
          " - please use static accessor methods instead.");
      return Bytes.toBytes(oldStyleVal);
    }
    
   @Override
   public int getPartition(final ImmutableBytesWritable key, final VALUE value,
       final int reduces) {
     if (reduces == 1) return 0;
     if (this.lastReduces != reduces) {
       this.splits = Bytes.split(this.startkey, this.endkey, reduces - 1);
       for (int i = 0; i < splits.length; i++) {
         LOG.info(Bytes.toStringBinary(splits[i]));
       }
       this.lastReduces = reduces;
     }
     int pos = Bytes.binarySearch(this.splits, key.get(), key.getOffset(),
       key.getLength(), Bytes.BYTES_RAWCOMPARATOR);
     // Below code is from hfile index search.
     if (pos < 0) {
       pos++;
       pos *= -1;
       if (pos == 0) {
         // falls before the beginning of the file.
         throw new RuntimeException("Key outside start/stop range: " +
           key.toString());
       }
       pos--;
     }
     return pos;
   }
 
   @Override
   public Configuration getConf() {
     return this.c;
   }
 
   @Override
   public void setConf(Configuration conf) {
     this.c = conf;
     this.startkey = getStartKey(conf);
     this.endkey = getEndKey(conf);
     if (startkey == null || endkey == null) {
       throw new RuntimeException(this.getClass() + " not configured");
     }
     LOG.info("startkey=" + Bytes.toStringBinary(startkey) +
         ", endkey=" + Bytes.toStringBinary(endkey));
     // Reset last reduces count on change of Start / End key
     this.lastReduces = -1;
   }
 }