/**
    *
    * 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 java.io.IOException;
  
  import org.apache.commons.lang.StringUtils;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.client.Result;
  import org.apache.hadoop.hbase.client.Scan;
  import org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter;
  import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.mapreduce.Job;
  import org.apache.hadoop.mapreduce.lib.output.NullOutputFormat;
  import org.apache.hadoop.util.GenericOptionsParser;
  
  /**
   * A job with a just a map phase to count rows. Map outputs table rows IF the
   * input row has columns that have content.
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class RowCounter {
  
    /** Name of this 'program'. */
    static final String NAME = "rowcounter";
  
    /**
     * Mapper that runs the count.
     */
    static class RowCounterMapper
    extends TableMapper<ImmutableBytesWritable, Result> {
  
      /** Counter enumeration to count the actual rows. */
      public static enum Counters {ROWS}
  
      /**
       * Maps the data.
       *
       * @param row  The current table row key.
       * @param values  The columns.
       * @param context  The current context.
       * @throws IOException When something is broken with the data.
       * @see org.apache.hadoop.mapreduce.Mapper#map(KEYIN, VALUEIN,
       *   org.apache.hadoop.mapreduce.Mapper.Context)
       */
      @Override
      public void map(ImmutableBytesWritable row, Result values,
        Context context)
      throws IOException {
        // Count every row containing data, whether it's in qualifiers or values
        context.getCounter(Counters.ROWS).increment(1);
      }
    }
  
    /**
     * Sets up the actual job.
     *
     * @param conf  The current configuration.
     * @param args  The command line parameters.
     * @return The newly created job.
     * @throws IOException When setting up the job fails.
     */
    public static Job createSubmittableJob(Configuration conf, String[] args)
    throws IOException {
      String tableName = args[0];
      String startKey = null;
      String endKey = null;
      long startTime = 0;
      long endTime = 0;
  
      StringBuilder sb = new StringBuilder();
  
      final String rangeSwitch = "--range=";
      final String startTimeArgKey = "--starttime=";
      final String endTimeArgKey = "--endtime=";
  
      // First argument is table name, starting from second
     for (int i = 1; i < args.length; i++) {
       if (args[i].startsWith(rangeSwitch)) {
         String[] startEnd = args[i].substring(rangeSwitch.length()).split(",", 2);
         if (startEnd.length != 2 || startEnd[1].contains(",")) {
           printUsage("Please specify range in such format as \"--range=a,b\" " +
               "or, with only one boundary, \"--range=,b\" or \"--range=a,\"");
           return null;
         }
         startKey = startEnd[0];
         endKey = startEnd[1];
       }
       if (startTime < endTime) {
         printUsage("--endtime=" + endTime + " needs to be greater than --starttime=" + startTime);
         return null;
       }
       if (args[i].startsWith(startTimeArgKey)) {
         startTime = Long.parseLong(args[i].substring(startTimeArgKey.length()));
         continue;
       }
       if (args[i].startsWith(endTimeArgKey)) {
         endTime = Long.parseLong(args[i].substring(endTimeArgKey.length()));
         continue;
       }
       else {
         // if no switch, assume column names
         sb.append(args[i]);
         sb.append(" ");
       }
     }
 
     Job job = new Job(conf, NAME + "_" + tableName);
     job.setJarByClass(RowCounter.class);
     Scan scan = new Scan();
     scan.setCacheBlocks(false);
     if (startKey != null && !startKey.equals("")) {
       scan.setStartRow(Bytes.toBytesBinary(startKey));
     }
     if (endKey != null && !endKey.equals("")) {
       scan.setStopRow(Bytes.toBytesBinary(endKey));
     }
     if (sb.length() > 0) {
       for (String columnName : sb.toString().trim().split(" ")) {
         String family = StringUtils.substringBefore(columnName, ":");
         String qualifier = StringUtils.substringAfter(columnName, ":");
 
         if (StringUtils.isBlank(qualifier)) {
           scan.addFamily(Bytes.toBytes(family));
         }
         else {
           scan.addColumn(Bytes.toBytes(family), Bytes.toBytes(qualifier));
         }
       }
     }
     scan.setFilter(new FirstKeyOnlyFilter()); 
     scan.setTimeRange(startTime, endTime == 0 ? HConstants.LATEST_TIMESTAMP : endTime);
     job.setOutputFormatClass(NullOutputFormat.class);
     TableMapReduceUtil.initTableMapperJob(tableName, scan,
       RowCounterMapper.class, ImmutableBytesWritable.class, Result.class, job);
     job.setNumReduceTasks(0);
     return job;
   }
 
   /*
    * @param errorMessage Can attach a message when error occurs.
    */
   private static void printUsage(String errorMessage) {
     System.err.println("ERROR: " + errorMessage);
     printUsage();
   }
 
   /*
    * Prints usage without error message
    */
   private static void printUsage() {
     System.err.println("Usage: RowCounter [options] <tablename> " +
         "[--starttime=[start] --endtime=[end] " +
         "[--range=[startKey],[endKey]] [<column1> <column2>...]");
     System.err.println("For performance consider the following options:\n"
         + "-Dhbase.client.scanner.caching=100\n"
         + "-Dmapreduce.map.speculative=false");
   }
 
   /**
    * Main entry point.
    *
    * @param args  The command line parameters.
    * @throws Exception When running the job fails.
    */
   public static void main(String[] args) throws Exception {
     Configuration conf = HBaseConfiguration.create();
     String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
     if (otherArgs.length < 1) {
       printUsage("Wrong number of parameters: " + args.length);
       System.exit(-1);
     }
     Job job = createSubmittableJob(conf, otherArgs);
     if (job == null) {
       System.exit(-1);
     }
     System.exit(job.waitForCompletion(true) ? 0 : 1);
   }
 }