/**
 *
 * 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.assertNull;

import java.io.IOException;
import java.util.Collections;
import java.util.List;
import java.util.NavigableSet;
import java.util.concurrent.CountDownLatch;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.Coprocessor;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HBaseTestingUtility;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.MediumTests;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.IsolationLevel;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.FilterBase;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.hadoop.hbase.regionserver.HRegionServer;
import org.apache.hadoop.hbase.regionserver.HStore;
import org.apache.hadoop.hbase.regionserver.InternalScanner;
import org.apache.hadoop.hbase.regionserver.KeyValueScanner;
import org.apache.hadoop.hbase.regionserver.RegionCoprocessorHost;
import org.apache.hadoop.hbase.regionserver.RegionServerServices;
import org.apache.hadoop.hbase.regionserver.ScanType;
import org.apache.hadoop.hbase.regionserver.Store;
import org.apache.hadoop.hbase.regionserver.StoreScanner;
import org.apache.hadoop.hbase.regionserver.compactions.CompactionContext;
import org.apache.hadoop.hbase.regionserver.wal.HLog;
import org.apache.hadoop.hbase.util.Bytes;
import org.junit.Test;
import org.junit.experimental.categories.Category;

@Category(MediumTests.class)
public class TestRegionObserverScannerOpenHook {
  private static HBaseTestingUtility UTIL = new HBaseTestingUtility();
  static final Path DIR = UTIL.getDataTestDir();

  public static class NoDataFilter extends FilterBase {

    @Override
    public ReturnCode filterKeyValue(Cell ignored) throws IOException {
      return ReturnCode.SKIP;
    }

    @Override
    public boolean filterAllRemaining() throws IOException {
      return true;
    }

    @Override
    public boolean filterRow() throws IOException {
      return true;
    }
  }

  /**
   * Do the same logic as the {@link BaseRegionObserver}. Needed since {@link BaseRegionObserver} is
   * an abstract class.
   */
  public static class EmptyRegionObsever extends BaseRegionObserver {
  }

  /**
   * Don't return any data from a scan by creating a custom {@link StoreScanner}.
   */
  public static class NoDataFromScan extends BaseRegionObserver {
    @Override
    public KeyValueScanner preStoreScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
        Store store, Scan scan, NavigableSet<byte[]> targetCols, KeyValueScanner s)
        throws IOException {
      scan.setFilter(new NoDataFilter());
      return new StoreScanner(store, store.getScanInfo(), scan, targetCols,
        ((HStore)store).getHRegion().getReadpoint(IsolationLevel.READ_COMMITTED));
    }
  }

  /**
   * Don't allow any data in a flush by creating a custom {@link StoreScanner}.
   */
  public static class NoDataFromFlush extends BaseRegionObserver {
    @Override
    public InternalScanner preFlushScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
        Store store, KeyValueScanner memstoreScanner, InternalScanner s) throws IOException {
      Scan scan = new Scan();
      scan.setFilter(new NoDataFilter());
      return new StoreScanner(store, store.getScanInfo(), scan,
          Collections.singletonList(memstoreScanner), ScanType.COMPACT_RETAIN_DELETES,
          store.getSmallestReadPoint(), HConstants.OLDEST_TIMESTAMP);
    }
  }

  /**
   * Don't allow any data to be written out in the compaction by creating a custom
   * {@link StoreScanner}.
   */
  public static class NoDataFromCompaction extends BaseRegionObserver {
    @Override
    public InternalScanner preCompactScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
        Store store, List<? extends KeyValueScanner> scanners, ScanType scanType,
        long earliestPutTs, InternalScanner s) throws IOException {
      Scan scan = new Scan();
      scan.setFilter(new NoDataFilter());
      return new StoreScanner(store, store.getScanInfo(), scan, scanners,
          ScanType.COMPACT_RETAIN_DELETES, store.getSmallestReadPoint(),
          HConstants.OLDEST_TIMESTAMP);
    }
  }

  HRegion initHRegion(byte[] tableName, String callingMethod, Configuration conf,
      byte[]... families) throws IOException {
    HTableDescriptor htd = new HTableDescriptor(TableName.valueOf(tableName));
    for (byte[] family : families) {
      htd.addFamily(new HColumnDescriptor(family));
    }
    HRegionInfo info = new HRegionInfo(htd.getTableName(), null, null, false);
    Path path = new Path(DIR + callingMethod);
    HRegion r = HRegion.createHRegion(info, path, conf, htd);
    // this following piece is a hack. currently a coprocessorHost
    // is secretly loaded at OpenRegionHandler. we don't really
    // start a region server here, so just manually create cphost
    // and set it to region.
    RegionCoprocessorHost host = new RegionCoprocessorHost(r, null, conf);
    r.setCoprocessorHost(host);
    return r;
  }

  @Test
  public void testRegionObserverScanTimeStacking() throws Exception {
    byte[] ROW = Bytes.toBytes("testRow");
    byte[] TABLE = Bytes.toBytes(getClass().getName());
    byte[] A = Bytes.toBytes("A");
    byte[][] FAMILIES = new byte[][] { A };

    Configuration conf = HBaseConfiguration.create();
    HRegion region = initHRegion(TABLE, getClass().getName(), conf, FAMILIES);
    RegionCoprocessorHost h = region.getCoprocessorHost();
    h.load(NoDataFromScan.class, Coprocessor.PRIORITY_HIGHEST, conf);
    h.load(EmptyRegionObsever.class, Coprocessor.PRIORITY_USER, conf);

    Put put = new Put(ROW);
    put.add(A, A, A);
    region.put(put);

    Get get = new Get(ROW);
    Result r = region.get(get);
    assertNull(
      "Got an unexpected number of rows - no data should be returned with the NoDataFromScan coprocessor. Found: "
          + r, r.listCells());
  }

  @Test
  public void testRegionObserverFlushTimeStacking() throws Exception {
    byte[] ROW = Bytes.toBytes("testRow");
    byte[] TABLE = Bytes.toBytes(getClass().getName());
    byte[] A = Bytes.toBytes("A");
    byte[][] FAMILIES = new byte[][] { A };

    Configuration conf = HBaseConfiguration.create();
    HRegion region = initHRegion(TABLE, getClass().getName(), conf, FAMILIES);
    RegionCoprocessorHost h = region.getCoprocessorHost();
    h.load(NoDataFromFlush.class, Coprocessor.PRIORITY_HIGHEST, conf);
    h.load(EmptyRegionObsever.class, Coprocessor.PRIORITY_USER, conf);

    // put a row and flush it to disk
    Put put = new Put(ROW);
    put.add(A, A, A);
    region.put(put);
    region.flushcache();
    Get get = new Get(ROW);
    Result r = region.get(get);
    assertNull(
      "Got an unexpected number of rows - no data should be returned with the NoDataFromScan coprocessor. Found: "
          + r, r.listCells());
  }

  /*
   * Custom HRegion which uses CountDownLatch to signal the completion of compaction
   */
  public static class CompactionCompletionNotifyingRegion extends HRegion {
    private static volatile CountDownLatch compactionStateChangeLatch = null;
    
    @SuppressWarnings("deprecation")
    public CompactionCompletionNotifyingRegion(Path tableDir, HLog log,
        FileSystem fs, Configuration confParam, HRegionInfo info,
        HTableDescriptor htd, RegionServerServices rsServices) {
      super(tableDir, log, fs, confParam, info, htd, rsServices);
    }
    
    public CountDownLatch getCompactionStateChangeLatch() {
      if (compactionStateChangeLatch == null) compactionStateChangeLatch = new CountDownLatch(1);
      return compactionStateChangeLatch;
    }
    @Override
    public boolean compact(CompactionContext compaction, Store store) throws IOException {
      boolean ret = super.compact(compaction, store);
      if (ret) compactionStateChangeLatch.countDown();
      return ret;
    }    
  }
  
  /**
   * Unfortunately, the easiest way to test this is to spin up a mini-cluster since we want to do
   * the usual compaction mechanism on the region, rather than going through the backdoor to the
   * region
   */
  @Test
  public void testRegionObserverCompactionTimeStacking() throws Exception {
    // setup a mini cluster so we can do a real compaction on a region
    Configuration conf = UTIL.getConfiguration();
    conf.setClass(HConstants.REGION_IMPL, CompactionCompletionNotifyingRegion.class, HRegion.class);
    conf.setInt("hbase.hstore.compaction.min", 2);
    UTIL.startMiniCluster();
    String tableName = "testRegionObserverCompactionTimeStacking";
    byte[] ROW = Bytes.toBytes("testRow");
    byte[] A = Bytes.toBytes("A");
    HTableDescriptor desc = new HTableDescriptor(TableName.valueOf(tableName));
    desc.addFamily(new HColumnDescriptor(A));
    desc.addCoprocessor(EmptyRegionObsever.class.getName(), null, Coprocessor.PRIORITY_USER, null);
    desc.addCoprocessor(NoDataFromCompaction.class.getName(), null, Coprocessor.PRIORITY_HIGHEST,
      null);

    HBaseAdmin admin = UTIL.getHBaseAdmin();
    admin.createTable(desc);

    HTable table = new HTable(conf, desc.getTableName());

    // put a row and flush it to disk
    Put put = new Put(ROW);
    put.add(A, A, A);
    table.put(put);
    table.flushCommits();

    HRegionServer rs = UTIL.getRSForFirstRegionInTable(desc.getTableName());
    List<HRegion> regions = rs.getOnlineRegions(desc.getTableName());
    assertEquals("More than 1 region serving test table with 1 row", 1, regions.size());
    HRegion region = regions.get(0);
    admin.flush(region.getRegionName());
    CountDownLatch latch = ((CompactionCompletionNotifyingRegion)region)
        .getCompactionStateChangeLatch();
    
    // put another row and flush that too
    put = new Put(Bytes.toBytes("anotherrow"));
    put.add(A, A, A);
    table.put(put);
    table.flushCommits();
    admin.flush(region.getRegionName());

    // run a compaction, which normally would should get rid of the data
    // wait for the compaction checker to complete
    latch.await();
    // check both rows to ensure that they aren't there
    Get get = new Get(ROW);
    Result r = table.get(get);
    assertNull(
      "Got an unexpected number of rows - no data should be returned with the NoDataFromScan coprocessor. Found: "
          + r, r.listCells());

    get = new Get(Bytes.toBytes("anotherrow"));
    r = table.get(get);
    assertNull(
      "Got an unexpected number of rows - no data should be returned with the NoDataFromScan coprocessor Found: "
          + r, r.listCells());

    table.close();
    UTIL.shutdownMiniCluster();
  }
}
