/**
    *
    * 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.coprocessor;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertTrue;
  
  import java.io.IOException;
  import java.util.Collections;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.SynchronousQueue;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  import org.apache.hadoop.hbase.HColumnDescriptor;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.testclassification.MediumTests;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.client.Admin;
  import org.apache.hadoop.hbase.client.Durability;
  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.regionserver.wal.WALEdit;
  import org.apache.hadoop.hbase.util.Threads;
  import org.junit.After;
  import org.junit.AfterClass;
  import org.junit.BeforeClass;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  /**
   * Test that a coprocessor can open a connection and write to another table, inside a hook.
   */
  @Category(MediumTests.class)
  public class TestOpenTableInCoprocessor {
  
    private static final TableName otherTable = TableName.valueOf("otherTable");
    private static final TableName primaryTable = TableName.valueOf("primary");
    private static final byte[] family = new byte[] { 'f' };
  
    private static boolean[] completed = new boolean[1];
    /**
     * Custom coprocessor that just copies the write to another table.
     */
    public static class SendToOtherTableCoprocessor extends BaseRegionObserver {
  
      @Override
      public void prePut(final ObserverContext<RegionCoprocessorEnvironment> e, final Put put,
          final WALEdit edit, final Durability durability) throws IOException {
        Table table = e.getEnvironment().getTable(otherTable);
        table.put(put);
        completed[0] = true;
        table.close();
      }
  
    }
  
    private static boolean[] completedWithPool = new boolean[1];
    /**
     * Coprocessor that creates an HTable with a pool to write to another table
     */
    public static class CustomThreadPoolCoprocessor extends BaseRegionObserver {
  
      /**
       * @return a pool that has one thread only at every time. A second action added to the pool (
       *         running concurrently), will cause an exception.
       */
      private ExecutorService getPool() {
        int maxThreads = 1;
        long keepAliveTime = 60;
        ThreadPoolExecutor pool =
            new ThreadPoolExecutor(1, maxThreads, keepAliveTime, TimeUnit.SECONDS,
                new SynchronousQueue<Runnable>(), Threads.newDaemonThreadFactory("hbase-table"));
        pool.allowCoreThreadTimeOut(true);
        return pool;
      }
  
      @Override
     public void prePut(final ObserverContext<RegionCoprocessorEnvironment> e, final Put put,
         final WALEdit edit, final Durability durability) throws IOException {
       Table table = e.getEnvironment().getTable(otherTable, getPool());
       Put p = new Put(new byte[] { 'a' });
       p.add(family, null, new byte[] { 'a' });
       try {
         table.batch(Collections.singletonList(put));
       } catch (InterruptedException e1) {
         throw new IOException(e1);
       }
       completedWithPool[0] = true;
       table.close();
     }
   }
 
   private static HBaseTestingUtility UTIL = new HBaseTestingUtility();
 
   @BeforeClass
   public static void setupCluster() throws Exception {
     UTIL.startMiniCluster();
   }
 
   @After
   public void cleanupTestTable() throws Exception {
     UTIL.getHBaseAdmin().disableTable(primaryTable);
     UTIL.getHBaseAdmin().deleteTable(primaryTable);
 
     UTIL.getHBaseAdmin().disableTable(otherTable);
     UTIL.getHBaseAdmin().deleteTable(otherTable);
 
   }
 
   @AfterClass
   public static void teardownCluster() throws Exception {
     UTIL.shutdownMiniCluster();
   }
 
   @Test
   public void testCoprocessorCanCreateConnectionToRemoteTable() throws Throwable {
     runCoprocessorConnectionToRemoteTable(SendToOtherTableCoprocessor.class, completed);
   }
 
   @Test
   public void testCoprocessorCanCreateConnectionToRemoteTableWithCustomPool() throws Throwable {
     runCoprocessorConnectionToRemoteTable(CustomThreadPoolCoprocessor.class, completedWithPool);
   }
 
   private void runCoprocessorConnectionToRemoteTable(Class<? extends BaseRegionObserver> clazz,
       boolean[] completeCheck) throws Throwable {
     HTableDescriptor primary = new HTableDescriptor(primaryTable);
     primary.addFamily(new HColumnDescriptor(family));
     // add our coprocessor
     primary.addCoprocessor(clazz.getName());
 
     HTableDescriptor other = new HTableDescriptor(otherTable);
     other.addFamily(new HColumnDescriptor(family));
 
 
     Admin admin = UTIL.getHBaseAdmin();
     admin.createTable(primary);
     admin.createTable(other);
 
     Table table = new HTable(UTIL.getConfiguration(), TableName.valueOf("primary"));
     Put p = new Put(new byte[] { 'a' });
     p.add(family, null, new byte[] { 'a' });
     table.put(p);
     table.close();
 
     Table target = new HTable(UTIL.getConfiguration(), otherTable);
     assertTrue("Didn't complete update to target table!", completeCheck[0]);
     assertEquals("Didn't find inserted row", 1, getKeyValueCount(target));
     target.close();
   }
 
   /**
    * Count the number of keyvalue in the table. Scans all possible versions
    * @param table table to scan
    * @return number of keyvalues over all rows in the table
    * @throws IOException
    */
   private int getKeyValueCount(Table table) throws IOException {
     Scan scan = new Scan();
     scan.setMaxVersions(Integer.MAX_VALUE - 1);
 
     ResultScanner results = table.getScanner(scan);
     int count = 0;
     for (Result res : results) {
       count += res.listCells().size();
       System.out.println(count + ") " + res);
     }
     results.close();
 
     return count;
   }
 }