/**
    *
    * 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 static org.junit.Assert.assertTrue;
  import static org.junit.Assert.fail;
  
  import java.io.IOException;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.NavigableMap;
  
  import org.apache.commons.logging.Log;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.CategoryBasedTimeout;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.CellUtil;
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.client.HTable;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.client.Result;
  import org.apache.hadoop.hbase.client.ResultScanner;
  import org.apache.hadoop.hbase.client.Scan;
  import org.apache.hadoop.hbase.client.Table;
  import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.junit.AfterClass;
  import org.junit.BeforeClass;
  import org.junit.Rule;
  import org.junit.Test;
  import org.junit.rules.TestRule;
  
  /**
   * A base class for a test Map/Reduce job over HBase tables. The map/reduce process we're testing
   * on our tables is simple - take every row in the table, reverse the value of a particular cell,
   * and write it back to the table. Implements common components between mapred and mapreduce
   * implementations.
   */
  public abstract class TestTableMapReduceBase {
    @Rule public final TestRule timeout = CategoryBasedTimeout.builder().
        withTimeout(this.getClass()).withLookingForStuckThread(true).build();
    protected static final HBaseTestingUtility UTIL = new HBaseTestingUtility();
    protected static final TableName MULTI_REGION_TABLE_NAME = TableName.valueOf("mrtest");
    protected static final TableName TABLE_FOR_NEGATIVE_TESTS = TableName.valueOf("testfailuretable");
    protected static final byte[] INPUT_FAMILY = Bytes.toBytes("contents");
    protected static final byte[] OUTPUT_FAMILY = Bytes.toBytes("text");
  
    protected static final byte[][] columns = new byte[][] {
      INPUT_FAMILY,
      OUTPUT_FAMILY
    };
  
    /**
     * Retrieve my logger instance.
     */
    protected abstract Log getLog();
  
    /**
     * Handles API-specifics for setting up and executing the job.
     */
    protected abstract void runTestOnTable(HTable table) throws IOException;
  
    @BeforeClass
    public static void beforeClass() throws Exception {
      UTIL.setJobWithoutMRCluster();
      UTIL.startMiniCluster();
      HTable table =
          UTIL.createMultiRegionTable(MULTI_REGION_TABLE_NAME, new byte[][] { INPUT_FAMILY,
              OUTPUT_FAMILY });
      UTIL.loadTable(table, INPUT_FAMILY, false);
      UTIL.createTable(TABLE_FOR_NEGATIVE_TESTS, new byte[][] { INPUT_FAMILY, OUTPUT_FAMILY });
    }
  
    @AfterClass
    public static void afterClass() throws Exception {
      UTIL.deleteTable(TABLE_FOR_NEGATIVE_TESTS);
      UTIL.shutdownMiniCluster();
    }
  
    /**
     * Test a map/reduce against a multi-region table
    * @throws IOException
    */
   @Test
   public void testMultiRegionTable() throws IOException {
     runTestOnTable(new HTable(UTIL.getConfiguration(), MULTI_REGION_TABLE_NAME));
   }
 
   @Test
   public void testCombiner() throws IOException {
     Configuration conf = new Configuration(UTIL.getConfiguration());
     // force use of combiner for testing purposes
     conf.setInt("mapreduce.map.combine.minspills", 1);
     runTestOnTable(new HTable(conf, MULTI_REGION_TABLE_NAME));
   }
 
   /**
    * Implements mapper logic for use across APIs.
    */
   protected static Put map(ImmutableBytesWritable key, Result value) throws IOException {
     if (value.size() != 1) {
       throw new IOException("There should only be one input column");
     }
     Map<byte[], NavigableMap<byte[], NavigableMap<Long, byte[]>>>
       cf = value.getMap();
     if(!cf.containsKey(INPUT_FAMILY)) {
       throw new IOException("Wrong input columns. Missing: '" +
         Bytes.toString(INPUT_FAMILY) + "'.");
     }
 
     // Get the original value and reverse it
 
     String originalValue = Bytes.toString(value.getValue(INPUT_FAMILY, INPUT_FAMILY));
     StringBuilder newValue = new StringBuilder(originalValue);
     newValue.reverse();
 
     // Now set the value to be collected
 
     Put outval = new Put(key.get());
     outval.add(OUTPUT_FAMILY, null, Bytes.toBytes(newValue.toString()));
     return outval;
   }
 
   protected void verify(TableName tableName) throws IOException {
     Table table = new HTable(UTIL.getConfiguration(), tableName);
     boolean verified = false;
     long pause = UTIL.getConfiguration().getLong("hbase.client.pause", 5 * 1000);
     int numRetries = UTIL.getConfiguration().getInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, 5);
     for (int i = 0; i < numRetries; i++) {
       try {
         getLog().info("Verification attempt #" + i);
         verifyAttempt(table);
         verified = true;
         break;
       } catch (NullPointerException e) {
         // If here, a cell was empty. Presume its because updates came in
         // after the scanner had been opened. Wait a while and retry.
         getLog().debug("Verification attempt failed: " + e.getMessage());
       }
       try {
         Thread.sleep(pause);
       } catch (InterruptedException e) {
         // continue
       }
     }
     assertTrue(verified);
   }
 
   /**
    * Looks at every value of the mapreduce output and verifies that indeed
    * the values have been reversed.
    * @param table Table to scan.
    * @throws IOException
    * @throws NullPointerException if we failed to find a cell value
    */
   private void verifyAttempt(final Table table) throws IOException, NullPointerException {
     Scan scan = new Scan();
     TableInputFormat.addColumns(scan, columns);
     ResultScanner scanner = table.getScanner(scan);
     try {
       Iterator<Result> itr = scanner.iterator();
       assertTrue(itr.hasNext());
       while(itr.hasNext()) {
         Result r = itr.next();
         if (getLog().isDebugEnabled()) {
           if (r.size() > 2 ) {
             throw new IOException("Too many results, expected 2 got " +
               r.size());
           }
         }
         byte[] firstValue = null;
         byte[] secondValue = null;
         int count = 0;
          for(Cell kv : r.listCells()) {
           if (count == 0) {
             firstValue = CellUtil.cloneValue(kv);
           }
           if (count == 1) {
             secondValue = CellUtil.cloneValue(kv);
           }
           count++;
           if (count == 2) {
             break;
           }
         }
 
 
         if (firstValue == null) {
           throw new NullPointerException(Bytes.toString(r.getRow()) +
             ": first value is null");
         }
         String first = Bytes.toString(firstValue);
 
         if (secondValue == null) {
           throw new NullPointerException(Bytes.toString(r.getRow()) +
             ": second value is null");
         }
         byte[] secondReversed = new byte[secondValue.length];
         for (int i = 0, j = secondValue.length - 1; j >= 0; j--, i++) {
           secondReversed[i] = secondValue[j];
         }
         String second = Bytes.toString(secondReversed);
 
         if (first.compareTo(second) != 0) {
           if (getLog().isDebugEnabled()) {
             getLog().debug("second key is not the reverse of first. row=" +
                 Bytes.toStringBinary(r.getRow()) + ", first value=" + first +
                 ", second value=" + second);
           }
           fail();
         }
       }
     } finally {
       scanner.close();
     }
   }
 }