/*
    * 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.chukwa.util;
  
  import java.nio.charset.Charset;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Calendar;
  import java.util.TimeZone;
  
  import org.apache.hadoop.chukwa.extraction.hbase.AbstractProcessor;
  import org.apache.log4j.Logger;
  import org.mortbay.log.Log;
  
  public class HBaseUtil {
    private static Logger LOG = Logger.getLogger(HBaseUtil.class);
    
    static MessageDigest md5 = null;
    static {
      try {
        md5 = MessageDigest.getInstance("md5");
      } catch (NoSuchAlgorithmException e) {
        LOG.warn(ExceptionUtil.getStackTrace(e));
      }
    }
  
    public HBaseUtil() throws NoSuchAlgorithmException {
    }
  
    public byte[] buildKey(long time, String metricGroup, String metric,
        String source) {
      String fullKey = new StringBuilder(metricGroup).append(".")
          .append(metric).toString();
      return buildKey(time, fullKey, source);
    }
  
    public static byte[] buildKey(long time, String primaryKey) {
      Calendar c = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
      c.setTimeInMillis(time);
      byte[] day = Integer.toString(c.get(Calendar.DAY_OF_YEAR)).getBytes(Charset.forName("UTF-8"));
      byte[] pk = getHash(primaryKey);
      byte[] key = new byte[14];
      System.arraycopy(day, 0, key, 0, day.length);
      System.arraycopy(pk, 0, key, 2, 6);
      return key;
    }
    
    public static byte[] buildKey(long time, String primaryKey, String source) {
      Calendar c = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
      c.setTimeInMillis(time);
      byte[] day = Integer.toString(c.get(Calendar.DAY_OF_YEAR)).getBytes(Charset.forName("UTF-8"));
      byte[] pk = getHash(primaryKey);
      byte[] src = getHash(source);
      byte[] key = new byte[14];
      System.arraycopy(day, 0, key, 0, day.length);
      System.arraycopy(pk, 0, key, 2, 6);
      System.arraycopy(src, 0, key, 8, 6);
      return key;
    }
    
    private static byte[] getHash(String key) {
      byte[] hash = new byte[6];
      System.arraycopy(md5.digest(key.getBytes(Charset.forName("UTF-8"))), 0, hash, 0, 6);
      return hash;
    }
  }