/*
 * 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.apache.hadoop.hbase.coprocessor.CoprocessorHost.REGION_COPROCESSOR_CONF_KEY;
import static org.junit.jupiter.api.Assertions.assertThrows;

import java.io.IOException;
import java.util.Optional;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.client.RegionInfoBuilder;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.client.TableDescriptorBuilder;
import org.apache.hadoop.hbase.regionserver.FlushLifeCycleTracker;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.hadoop.hbase.regionserver.InternalScanner;
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.compactions.CompactionLifeCycleTracker;
import org.apache.hadoop.hbase.regionserver.compactions.CompactionRequest;
import org.apache.hadoop.hbase.testclassification.CoprocessorTests;
import org.apache.hadoop.hbase.testclassification.SmallTests;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;
import org.mockito.Mockito;

/**
 * Test that we fail if a Coprocessor tries to return a null scanner out
 * {@link RegionObserver#preFlush(ObserverContext, Store, InternalScanner, FlushLifeCycleTracker)}
 * or
 * {@link RegionObserver#preCompact(ObserverContext, Store, InternalScanner, ScanType, CompactionLifeCycleTracker, CompactionRequest)}
 * @see <a href=https://issues.apache.org/jira/browse/HBASE-19122>HBASE-19122</a>
 */
@Tag(CoprocessorTests.TAG)
@Tag(SmallTests.TAG)
public class TestRegionObserverPreFlushAndPreCompact {

  /**
   * Coprocessor that returns null when preCompact or preFlush is called.
   */
  public static class TestRegionObserver implements RegionObserver, RegionCoprocessor {
    @Override
    public InternalScanner preFlush(ObserverContext<RegionCoprocessorEnvironment> c, Store store,
      InternalScanner scanner, FlushLifeCycleTracker tracker) throws IOException {
      return null;
    }

    @Override
    public InternalScanner preCompact(ObserverContext<RegionCoprocessorEnvironment> c, Store store,
      InternalScanner scanner, ScanType scanType, CompactionLifeCycleTracker tracker,
      CompactionRequest request) throws IOException {
      return null;
    }

    @Override
    public Optional<RegionObserver> getRegionObserver() {
      return Optional.of(this);
    }
  }

  /**
   * Ensure we get expected exception when we try to return null from a preFlush call.
   * @throws IOException We expect it to throw {@link CoprocessorException}
   */
  @Test
  public void testPreFlushReturningNull() throws IOException {
    RegionCoprocessorHost rch = getRegionCoprocessorHost();
    assertThrows(CoprocessorException.class, () -> rch.preFlush(null, null, null));
  }

  /**
   * Ensure we get expected exception when we try to return null from a preCompact call.
   * @throws IOException We expect it to throw {@link CoprocessorException}
   */
  @Test
  public void testPreCompactReturningNull() throws IOException {
    RegionCoprocessorHost rch = getRegionCoprocessorHost();
    assertThrows(CoprocessorException.class,
      () -> rch.preCompact(null, null, null, null, null, null));
  }

  private RegionCoprocessorHost getRegionCoprocessorHost() {
    // Make up an HRegion instance. Use the hbase:meta first region as our RegionInfo. Use
    // hbase:meta table name for building the TableDescriptor our mock returns when asked schema
    // down inside RegionCoprocessorHost. Pass in mocked RegionServerServices too.
    RegionInfo ri = RegionInfoBuilder.FIRST_META_REGIONINFO;
    HRegion mockedHRegion = Mockito.mock(HRegion.class);
    Mockito.when(mockedHRegion.getRegionInfo()).thenReturn(ri);
    TableDescriptor td = TableDescriptorBuilder.newBuilder(ri.getTable()).build();
    Mockito.when(mockedHRegion.getTableDescriptor()).thenReturn(td);
    RegionServerServices mockedServices = Mockito.mock(RegionServerServices.class);
    Configuration conf = HBaseConfiguration.create();
    // Load our test coprocessor defined above.
    conf.set(REGION_COPROCESSOR_CONF_KEY, TestRegionObserver.class.getName());
    return new RegionCoprocessorHost(mockedHRegion, mockedServices, conf);
  }
}
