/*
 * 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.namespace;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

import java.io.IOException;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.Coprocessor;
import org.apache.hadoop.hbase.CoprocessorEnvironment;
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.MiniHBaseCluster;
import org.apache.hadoop.hbase.NamespaceDescriptor;
import org.apache.hadoop.hbase.StartMiniClusterOption;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.Waiter;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.CompactionState;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.client.RegionLocator;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.coprocessor.CoprocessorHost;
import org.apache.hadoop.hbase.coprocessor.MasterCoprocessor;
import org.apache.hadoop.hbase.coprocessor.MasterCoprocessorEnvironment;
import org.apache.hadoop.hbase.coprocessor.MasterObserver;
import org.apache.hadoop.hbase.coprocessor.ObserverContext;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessor;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
import org.apache.hadoop.hbase.coprocessor.RegionObserver;
import org.apache.hadoop.hbase.coprocessor.RegionServerCoprocessor;
import org.apache.hadoop.hbase.coprocessor.RegionServerObserver;
import org.apache.hadoop.hbase.master.HMaster;
import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
import org.apache.hadoop.hbase.master.TableNamespaceManager;
import org.apache.hadoop.hbase.quotas.MasterQuotaManager;
import org.apache.hadoop.hbase.quotas.QuotaExceededException;
import org.apache.hadoop.hbase.quotas.QuotaUtil;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.hadoop.hbase.regionserver.Store;
import org.apache.hadoop.hbase.regionserver.StoreFile;
import org.apache.hadoop.hbase.regionserver.compactions.CompactionLifeCycleTracker;
import org.apache.hadoop.hbase.regionserver.compactions.CompactionRequest;
import org.apache.hadoop.hbase.snapshot.RestoreSnapshotException;
import org.apache.hadoop.hbase.testclassification.LargeTests;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.CommonFSUtils;
import org.apache.zookeeper.KeeperException;
import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Tag(LargeTests.TAG)
public class TestNamespaceAuditor {

  private static final Logger LOG = LoggerFactory.getLogger(TestNamespaceAuditor.class);
  private static final HBaseTestingUtility UTIL = new HBaseTestingUtility();
  private static Admin ADMIN;
  private String prefix = "TestNamespaceAuditor";

  @BeforeAll
  public static void before() throws Exception {
    Configuration conf = UTIL.getConfiguration();
    conf.set(CoprocessorHost.REGION_COPROCESSOR_CONF_KEY, CustomObserver.class.getName());
    conf.setStrings(CoprocessorHost.MASTER_COPROCESSOR_CONF_KEY, MasterSyncObserver.class.getName(),
      CPMasterObserver.class.getName());
    conf.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, 5);
    conf.setBoolean(QuotaUtil.QUOTA_CONF_KEY, true);
    conf.setClass("hbase.coprocessor.regionserver.classes", CPRegionServerObserver.class,
      RegionServerObserver.class);
    StartMiniClusterOption option = StartMiniClusterOption.builder().numMasters(2).build();
    UTIL.startMiniCluster(option);
    waitForQuotaInitialize(UTIL);
    ADMIN = UTIL.getAdmin();
  }

  @AfterAll
  public static void tearDown() throws Exception {
    UTIL.shutdownMiniCluster();
  }

  @AfterEach
  public void cleanup() throws Exception, KeeperException {
    for (HTableDescriptor table : ADMIN.listTables()) {
      ADMIN.disableTable(table.getTableName());
      deleteTable(table.getTableName());
    }
    for (NamespaceDescriptor ns : ADMIN.listNamespaceDescriptors()) {
      if (ns.getName().startsWith(prefix)) {
        ADMIN.deleteNamespace(ns.getName());
      }
    }
    assertTrue(UTIL.getHBaseCluster().getMaster().getMasterQuotaManager().isQuotaInitialized(),
      "Quota manager not initialized");
  }

  @Test
  public void testTableOperations() throws Exception {
    String nsp = prefix + "_np2";
    NamespaceDescriptor nspDesc =
      NamespaceDescriptor.create(nsp).addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "5")
        .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "2").build();
    ADMIN.createNamespace(nspDesc);
    assertNotNull(ADMIN.getNamespaceDescriptor(nsp), "Namespace descriptor found null.");
    assertEquals(3, ADMIN.listNamespaceDescriptors().length);
    HColumnDescriptor fam1 = new HColumnDescriptor("fam1");

    HTableDescriptor tableDescOne =
      new HTableDescriptor(TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table1"));
    tableDescOne.addFamily(fam1);
    HTableDescriptor tableDescTwo =
      new HTableDescriptor(TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table2"));
    tableDescTwo.addFamily(fam1);
    HTableDescriptor tableDescThree =
      new HTableDescriptor(TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table3"));
    tableDescThree.addFamily(fam1);
    ADMIN.createTable(tableDescOne);
    boolean constraintViolated = false;
    try {
      ADMIN.createTable(tableDescTwo, Bytes.toBytes("AAA"), Bytes.toBytes("ZZZ"), 5);
    } catch (Exception exp) {
      assertTrue(exp instanceof IOException);
      constraintViolated = true;
    } finally {
      assertTrue(constraintViolated,
        "Constraint not violated for table " + tableDescTwo.getTableName());
    }
    ADMIN.createTable(tableDescTwo, Bytes.toBytes("AAA"), Bytes.toBytes("ZZZ"), 4);
    NamespaceTableAndRegionInfo nspState = getQuotaManager().getState(nsp);
    assertNotNull(nspState);
    assertTrue(nspState.getTables().size() == 2);
    assertTrue(nspState.getRegionCount() == 5);
    constraintViolated = false;
    try {
      ADMIN.createTable(tableDescThree);
    } catch (Exception exp) {
      assertTrue(exp instanceof IOException);
      constraintViolated = true;
    } finally {
      assertTrue(constraintViolated,
        "Constraint not violated for table " + tableDescThree.getTableName());
    }
  }

  @Test
  public void testValidQuotas() throws Exception {
    boolean exceptionCaught = false;
    FileSystem fs = UTIL.getHBaseCluster().getMaster().getMasterFileSystem().getFileSystem();
    Path rootDir = UTIL.getHBaseCluster().getMaster().getMasterFileSystem().getRootDir();
    NamespaceDescriptor nspDesc = NamespaceDescriptor.create(prefix + "vq1")
      .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "hihdufh")
      .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "2").build();
    try {
      ADMIN.createNamespace(nspDesc);
    } catch (Exception exp) {
      LOG.warn(exp.toString(), exp);
      exceptionCaught = true;
    } finally {
      assertTrue(exceptionCaught);
      assertFalse(fs.exists(CommonFSUtils.getNamespaceDir(rootDir, nspDesc.getName())));
    }
    nspDesc = NamespaceDescriptor.create(prefix + "vq2")
      .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "-456")
      .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "2").build();
    try {
      ADMIN.createNamespace(nspDesc);
    } catch (Exception exp) {
      LOG.warn(exp.toString(), exp);
      exceptionCaught = true;
    } finally {
      assertTrue(exceptionCaught);
      assertFalse(fs.exists(CommonFSUtils.getNamespaceDir(rootDir, nspDesc.getName())));
    }
    nspDesc = NamespaceDescriptor.create(prefix + "vq3")
      .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "10")
      .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "sciigd").build();
    try {
      ADMIN.createNamespace(nspDesc);
    } catch (Exception exp) {
      LOG.warn(exp.toString(), exp);
      exceptionCaught = true;
    } finally {
      assertTrue(exceptionCaught);
      assertFalse(fs.exists(CommonFSUtils.getNamespaceDir(rootDir, nspDesc.getName())));
    }
    nspDesc = NamespaceDescriptor.create(prefix + "vq4")
      .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "10")
      .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "-1500").build();
    try {
      ADMIN.createNamespace(nspDesc);
    } catch (Exception exp) {
      LOG.warn(exp.toString(), exp);
      exceptionCaught = true;
    } finally {
      assertTrue(exceptionCaught);
      assertFalse(fs.exists(CommonFSUtils.getNamespaceDir(rootDir, nspDesc.getName())));
    }
  }

  @Test
  public void testDeleteTable() throws Exception {
    String namespace = prefix + "_dummy";
    NamespaceDescriptor nspDesc = NamespaceDescriptor.create(namespace)
      .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "100")
      .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "3").build();
    ADMIN.createNamespace(nspDesc);
    assertNotNull(ADMIN.getNamespaceDescriptor(namespace), "Namespace descriptor found null.");
    NamespaceTableAndRegionInfo stateInfo = getNamespaceState(nspDesc.getName());
    assertNotNull(stateInfo, "Namespace state found null for " + namespace);
    HColumnDescriptor fam1 = new HColumnDescriptor("fam1");
    HTableDescriptor tableDescOne =
      new HTableDescriptor(TableName.valueOf(namespace + TableName.NAMESPACE_DELIM + "table1"));
    tableDescOne.addFamily(fam1);
    HTableDescriptor tableDescTwo =
      new HTableDescriptor(TableName.valueOf(namespace + TableName.NAMESPACE_DELIM + "table2"));
    tableDescTwo.addFamily(fam1);
    ADMIN.createTable(tableDescOne);
    ADMIN.createTable(tableDescTwo, Bytes.toBytes("AAA"), Bytes.toBytes("ZZZ"), 5);
    stateInfo = getNamespaceState(nspDesc.getName());
    assertNotNull(stateInfo, "Namespace state found to be null.");
    assertEquals(2, stateInfo.getTables().size());
    assertEquals(5, stateInfo.getRegionCountOfTable(tableDescTwo.getTableName()));
    assertEquals(6, stateInfo.getRegionCount());
    ADMIN.disableTable(tableDescOne.getTableName());
    deleteTable(tableDescOne.getTableName());
    stateInfo = getNamespaceState(nspDesc.getName());
    assertNotNull(stateInfo, "Namespace state found to be null.");
    assertEquals(5, stateInfo.getRegionCount());
    assertEquals(1, stateInfo.getTables().size());
    ADMIN.disableTable(tableDescTwo.getTableName());
    deleteTable(tableDescTwo.getTableName());
    ADMIN.deleteNamespace(namespace);
    stateInfo = getNamespaceState(namespace);
    assertNull(stateInfo, "Namespace state not found to be null.");
  }

  public static class CPRegionServerObserver
    implements RegionServerCoprocessor, RegionServerObserver {
    private volatile boolean shouldFailMerge = false;

    public void failMerge(boolean fail) {
      shouldFailMerge = fail;
    }

    private boolean triggered = false;

    public synchronized void waitUtilTriggered() throws InterruptedException {
      while (!triggered) {
        wait();
      }
    }

    @Override
    public Optional<RegionServerObserver> getRegionServerObserver() {
      return Optional.of(this);
    }
  }

  public static class CPMasterObserver implements MasterCoprocessor, MasterObserver {
    private volatile boolean shouldFailMerge = false;

    public void failMerge(boolean fail) {
      shouldFailMerge = fail;
    }

    @Override
    public Optional<MasterObserver> getMasterObserver() {
      return Optional.of(this);
    }

    @Override
    public synchronized void preMergeRegionsAction(
      final ObserverContext<MasterCoprocessorEnvironment> ctx, final RegionInfo[] regionsToMerge)
      throws IOException {
      notifyAll();
      if (shouldFailMerge) {
        throw new IOException("fail merge");
      }
    }
  }

  @Test
  public void testRegionMerge() throws Exception {
    String nsp1 = prefix + "_regiontest";
    final int initialRegions = 3;
    NamespaceDescriptor nspDesc = NamespaceDescriptor.create(nsp1)
      .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "" + initialRegions)
      .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "2").build();
    ADMIN.createNamespace(nspDesc);
    final TableName tableTwo = TableName.valueOf(nsp1 + TableName.NAMESPACE_DELIM + "table2");
    byte[] columnFamily = Bytes.toBytes("info");
    HTableDescriptor tableDescOne = new HTableDescriptor(tableTwo);
    tableDescOne.addFamily(new HColumnDescriptor(columnFamily));
    ADMIN.createTable(tableDescOne, Bytes.toBytes("0"), Bytes.toBytes("9"), initialRegions);
    Connection connection = ConnectionFactory.createConnection(UTIL.getConfiguration());
    try (Table table = connection.getTable(tableTwo)) {
      UTIL.loadNumericRows(table, Bytes.toBytes("info"), 1000, 1999);
    }
    ADMIN.flush(tableTwo);
    List<RegionInfo> hris = ADMIN.getRegions(tableTwo);
    assertEquals(initialRegions, hris.size());
    Collections.sort(hris, RegionInfo.COMPARATOR);
    Future<?> f = ADMIN.mergeRegionsAsync(hris.get(0).getEncodedNameAsBytes(),
      hris.get(1).getEncodedNameAsBytes(), false);
    f.get(10, TimeUnit.SECONDS);

    hris = ADMIN.getRegions(tableTwo);
    assertEquals(initialRegions - 1, hris.size());
    Collections.sort(hris, RegionInfo.COMPARATOR);
    byte[] splitKey = Bytes.toBytes("3");
    HRegion regionToSplit = UTIL.getMiniHBaseCluster().getRegions(tableTwo).stream()
      .filter(r -> r.getRegionInfo().containsRow(splitKey)).findFirst().get();
    regionToSplit.compact(true);
    // Waiting for compaction to finish
    UTIL.waitFor(30000, new Waiter.Predicate<Exception>() {
      @Override
      public boolean evaluate() throws Exception {
        return (CompactionState.NONE
            == ADMIN.getCompactionStateForRegion(regionToSplit.getRegionInfo().getRegionName()));
      }
    });

    // Cleaning compacted references for split to proceed
    regionToSplit.getStores().stream().forEach(s -> {
      try {
        s.closeAndArchiveCompactedFiles();
      } catch (IOException e1) {
        LOG.error("Error whiling cleaning compacted file");
      }
    });
    // the above compact may quit immediately if there is a compaction ongoing, so here we need to
    // wait a while to let the ongoing compaction finish.
    UTIL.waitFor(10000, regionToSplit::isSplittable);
    ADMIN.splitRegionAsync(regionToSplit.getRegionInfo().getRegionName(), splitKey).get(10,
      TimeUnit.SECONDS);
    hris = ADMIN.getRegions(tableTwo);
    assertEquals(initialRegions, hris.size());
    Collections.sort(hris, RegionInfo.COMPARATOR);

    // Fail region merge through Coprocessor hook
    MiniHBaseCluster cluster = UTIL.getHBaseCluster();
    MasterCoprocessorHost cpHost = cluster.getMaster().getMasterCoprocessorHost();
    Coprocessor coprocessor = cpHost.findCoprocessor(CPMasterObserver.class);
    CPMasterObserver masterObserver = (CPMasterObserver) coprocessor;
    masterObserver.failMerge(true);

    f = ADMIN.mergeRegionsAsync(hris.get(1).getEncodedNameAsBytes(),
      hris.get(2).getEncodedNameAsBytes(), false);
    try {
      f.get(10, TimeUnit.SECONDS);
      fail("Merge was supposed to fail!");
    } catch (ExecutionException ee) {
      // Expected.
    }
    hris = ADMIN.getRegions(tableTwo);
    assertEquals(initialRegions, hris.size());
    Collections.sort(hris, RegionInfo.COMPARATOR);
    // verify that we cannot split
    try {
      ADMIN.splitRegionAsync(hris.get(1).getRegionName(), Bytes.toBytes("6")).get(10,
        TimeUnit.SECONDS);
      fail();
    } catch (ExecutionException e) {
      // Expected
    }
    Thread.sleep(2000);
    assertEquals(initialRegions, ADMIN.getRegions(tableTwo).size());
  }

  /*
   * Create a table and make sure that the table creation fails after adding this table entry into
   * namespace quota cache. Now correct the failure and recreate the table with same name.
   * HBASE-13394
   */
  @Test
  public void testRecreateTableWithSameNameAfterFirstTimeFailure() throws Exception {
    String nsp1 = prefix + "_testRecreateTable";
    NamespaceDescriptor nspDesc =
      NamespaceDescriptor.create(nsp1).addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "20")
        .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "1").build();
    ADMIN.createNamespace(nspDesc);
    final TableName tableOne = TableName.valueOf(nsp1 + TableName.NAMESPACE_DELIM + "table1");
    byte[] columnFamily = Bytes.toBytes("info");
    HTableDescriptor tableDescOne = new HTableDescriptor(tableOne);
    tableDescOne.addFamily(new HColumnDescriptor(columnFamily));
    MasterSyncObserver.throwExceptionInPreCreateTableAction = true;
    try {
      try {
        ADMIN.createTable(tableDescOne);
        fail("Table " + tableOne.toString() + "creation should fail.");
      } catch (Exception exp) {
        LOG.error(exp.toString(), exp);
      }
      assertFalse(ADMIN.tableExists(tableOne));

      NamespaceTableAndRegionInfo nstate = getNamespaceState(nsp1);
      assertEquals(0, nstate.getTables().size(),
        "First table creation failed in namespace so number of tables in namespace should be 0.");

      MasterSyncObserver.throwExceptionInPreCreateTableAction = false;
      try {
        ADMIN.createTable(tableDescOne);
      } catch (Exception e) {
        fail("Table " + tableOne.toString() + "creation should succeed.");
        LOG.error(e.toString(), e);
      }
      assertTrue(ADMIN.tableExists(tableOne));
      nstate = getNamespaceState(nsp1);
      assertEquals(1, nstate.getTables().size(),
        "First table was created successfully so table size in namespace should be one now.");
    } finally {
      MasterSyncObserver.throwExceptionInPreCreateTableAction = false;
      if (ADMIN.tableExists(tableOne)) {
        ADMIN.disableTable(tableOne);
        deleteTable(tableOne);
      }
      ADMIN.deleteNamespace(nsp1);
    }
  }

  private NamespaceTableAndRegionInfo getNamespaceState(String namespace)
    throws KeeperException, IOException {
    return getQuotaManager().getState(namespace);
  }

  public static class CustomObserver implements RegionCoprocessor, RegionObserver {
    volatile CountDownLatch postCompact;

    @Override
    public void postCompact(ObserverContext<RegionCoprocessorEnvironment> e, Store store,
      StoreFile resultFile, CompactionLifeCycleTracker tracker, CompactionRequest request)
      throws IOException {
      postCompact.countDown();
    }

    @Override
    public void start(CoprocessorEnvironment e) throws IOException {
      postCompact = new CountDownLatch(1);
    }

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

  @Test
  public void testStatePreserve() throws Exception {
    final String nsp1 = prefix + "_testStatePreserve";
    NamespaceDescriptor nspDesc =
      NamespaceDescriptor.create(nsp1).addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "20")
        .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "10").build();
    ADMIN.createNamespace(nspDesc);
    TableName tableOne = TableName.valueOf(nsp1 + TableName.NAMESPACE_DELIM + "table1");
    TableName tableTwo = TableName.valueOf(nsp1 + TableName.NAMESPACE_DELIM + "table2");
    TableName tableThree = TableName.valueOf(nsp1 + TableName.NAMESPACE_DELIM + "table3");
    HColumnDescriptor fam1 = new HColumnDescriptor("fam1");
    HTableDescriptor tableDescOne = new HTableDescriptor(tableOne);
    tableDescOne.addFamily(fam1);
    HTableDescriptor tableDescTwo = new HTableDescriptor(tableTwo);
    tableDescTwo.addFamily(fam1);
    HTableDescriptor tableDescThree = new HTableDescriptor(tableThree);
    tableDescThree.addFamily(fam1);
    ADMIN.createTable(tableDescOne, Bytes.toBytes("1"), Bytes.toBytes("1000"), 3);
    ADMIN.createTable(tableDescTwo, Bytes.toBytes("1"), Bytes.toBytes("1000"), 3);
    ADMIN.createTable(tableDescThree, Bytes.toBytes("1"), Bytes.toBytes("1000"), 4);
    ADMIN.disableTable(tableThree);
    deleteTable(tableThree);
    // wait for chore to complete
    UTIL.waitFor(1000, new Waiter.Predicate<Exception>() {
      @Override
      public boolean evaluate() throws Exception {
        return (getNamespaceState(nsp1).getTables().size() == 2);
      }
    });
    NamespaceTableAndRegionInfo before = getNamespaceState(nsp1);
    killActiveMaster();
    NamespaceTableAndRegionInfo after = getNamespaceState(nsp1);
    assertEquals(before.getTables().size(), after.getTables().size(),
      "Expected: " + before.getTables() + " Found: " + after.getTables());
  }

  public static void waitForQuotaInitialize(final HBaseTestingUtility util) throws Exception {
    util.waitFor(60000, new Waiter.Predicate<Exception>() {
      @Override
      public boolean evaluate() throws Exception {
        HMaster master = util.getHBaseCluster().getMaster();
        if (master == null) {
          return false;
        }
        MasterQuotaManager quotaManager = master.getMasterQuotaManager();
        return quotaManager != null && quotaManager.isQuotaInitialized();
      }
    });
  }

  private void killActiveMaster() throws Exception {
    UTIL.getHBaseCluster().getMaster(0).stop("Stopping to start again");
    UTIL.getHBaseCluster().waitOnMaster(0);
    waitForQuotaInitialize(UTIL);
  }

  private NamespaceAuditor getQuotaManager() {
    return UTIL.getHBaseCluster().getMaster().getMasterQuotaManager().getNamespaceQuotaManager();
  }

  public static class MasterSyncObserver implements MasterCoprocessor, MasterObserver {
    volatile CountDownLatch tableDeletionLatch;
    static boolean throwExceptionInPreCreateTableAction;

    @Override
    public Optional<MasterObserver> getMasterObserver() {
      return Optional.of(this);
    }

    @Override
    public void preDeleteTable(ObserverContext<MasterCoprocessorEnvironment> ctx,
      TableName tableName) throws IOException {
      tableDeletionLatch = new CountDownLatch(1);
    }

    @Override
    public void postCompletedDeleteTableAction(
      final ObserverContext<MasterCoprocessorEnvironment> ctx, final TableName tableName)
      throws IOException {
      tableDeletionLatch.countDown();
    }

    @Override
    public void preCreateTableAction(ObserverContext<MasterCoprocessorEnvironment> ctx,
      TableDescriptor desc, RegionInfo[] regions) throws IOException {
      if (throwExceptionInPreCreateTableAction) {
        throw new IOException("Throw exception as it is demanded.");
      }
    }
  }

  private void deleteTable(final TableName tableName) throws Exception {
    // NOTE: We need a latch because admin is not sync,
    // so the postOp coprocessor method may be called after the admin operation returned.
    MasterSyncObserver observer = UTIL.getHBaseCluster().getMaster().getMasterCoprocessorHost()
      .findCoprocessor(MasterSyncObserver.class);
    ADMIN.deleteTable(tableName);
    observer.tableDeletionLatch.await();
  }

  @Test
  public void testExceedTableQuotaInNamespace() throws Exception {
    String nsp = prefix + "_testExceedTableQuotaInNamespace";
    NamespaceDescriptor nspDesc = NamespaceDescriptor.create(nsp)
      .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "1").build();
    ADMIN.createNamespace(nspDesc);
    assertNotNull(ADMIN.getNamespaceDescriptor(nsp), "Namespace descriptor found null.");
    assertEquals(3, ADMIN.listNamespaceDescriptors().length);
    HColumnDescriptor fam1 = new HColumnDescriptor("fam1");
    HTableDescriptor tableDescOne =
      new HTableDescriptor(TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table1"));
    tableDescOne.addFamily(fam1);
    HTableDescriptor tableDescTwo =
      new HTableDescriptor(TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table2"));
    tableDescTwo.addFamily(fam1);
    ADMIN.createTable(tableDescOne);
    assertThrows(QuotaExceededException.class, () -> {
      ADMIN.createTable(tableDescTwo, Bytes.toBytes("AAA"), Bytes.toBytes("ZZZ"), 4);
    });
  }

  @Test
  public void testCloneSnapshotQuotaExceed() throws Exception {
    String nsp = prefix + "_testTableQuotaExceedWithCloneSnapshot";
    NamespaceDescriptor nspDesc = NamespaceDescriptor.create(nsp)
      .addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "1").build();
    ADMIN.createNamespace(nspDesc);
    assertNotNull(ADMIN.getNamespaceDescriptor(nsp), "Namespace descriptor found null.");
    TableName tableName = TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table1");
    TableName cloneTableName = TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table2");
    HColumnDescriptor fam1 = new HColumnDescriptor("fam1");
    HTableDescriptor tableDescOne = new HTableDescriptor(tableName);
    tableDescOne.addFamily(fam1);
    ADMIN.createTable(tableDescOne);
    String snapshot = "snapshot_testTableQuotaExceedWithCloneSnapshot";
    ADMIN.snapshot(snapshot, tableName);
    assertThrows(QuotaExceededException.class, () -> ADMIN.cloneSnapshot(snapshot, cloneTableName));
    ADMIN.deleteSnapshot(snapshot);
  }

  @Test
  public void testCloneSnapshot() throws Exception {
    String nsp = prefix + "_testCloneSnapshot";
    NamespaceDescriptor nspDesc =
      NamespaceDescriptor.create(nsp).addConfiguration(TableNamespaceManager.KEY_MAX_TABLES, "2")
        .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "20").build();
    ADMIN.createNamespace(nspDesc);
    assertNotNull(ADMIN.getNamespaceDescriptor(nsp), "Namespace descriptor found null.");
    TableName tableName = TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table1");
    TableName cloneTableName = TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table2");

    HColumnDescriptor fam1 = new HColumnDescriptor("fam1");
    HTableDescriptor tableDescOne = new HTableDescriptor(tableName);
    tableDescOne.addFamily(fam1);

    ADMIN.createTable(tableDescOne, Bytes.toBytes("AAA"), Bytes.toBytes("ZZZ"), 4);
    String snapshot = "snapshot_testCloneSnapshot";
    ADMIN.snapshot(snapshot, tableName);
    ADMIN.cloneSnapshot(snapshot, cloneTableName);

    int tableLength;
    try (RegionLocator locator = ADMIN.getConnection().getRegionLocator(tableName)) {
      tableLength = locator.getStartKeys().length;
    }
    assertEquals(4, tableLength, tableName.getNameAsString() + " should have four regions.");

    try (RegionLocator locator = ADMIN.getConnection().getRegionLocator(cloneTableName)) {
      tableLength = locator.getStartKeys().length;
    }
    assertEquals(4, tableLength, cloneTableName.getNameAsString() + " should have four regions.");

    NamespaceTableAndRegionInfo nstate = getNamespaceState(nsp);
    assertEquals(2, nstate.getTables().size(), "Total tables count should be 2.");
    assertEquals(8, nstate.getRegionCount(), "Total regions count should be.");

    ADMIN.deleteSnapshot(snapshot);
  }

  @Test
  public void testRestoreSnapshot() throws Exception {
    String nsp = prefix + "_testRestoreSnapshot";
    NamespaceDescriptor nspDesc = NamespaceDescriptor.create(nsp)
      .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "10").build();
    ADMIN.createNamespace(nspDesc);
    assertNotNull(ADMIN.getNamespaceDescriptor(nsp), "Namespace descriptor found null.");
    TableName tableName1 = TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table1");
    HTableDescriptor tableDescOne = new HTableDescriptor(tableName1);
    HColumnDescriptor fam1 = new HColumnDescriptor("fam1");
    tableDescOne.addFamily(fam1);
    ADMIN.createTable(tableDescOne, Bytes.toBytes("AAA"), Bytes.toBytes("ZZZ"), 4);

    NamespaceTableAndRegionInfo nstate = getNamespaceState(nsp);
    assertEquals(4, nstate.getRegionCount(), "Intial region count should be 4.");

    String snapshot = "snapshot_testRestoreSnapshot";
    ADMIN.snapshot(snapshot, tableName1);

    List<HRegionInfo> regions = ADMIN.getTableRegions(tableName1);
    Collections.sort(regions);

    ADMIN.split(tableName1, Bytes.toBytes("JJJ"));
    Thread.sleep(2000);
    assertEquals(5, nstate.getRegionCount(), "Total regions count should be 5.");

    ADMIN.disableTable(tableName1);
    ADMIN.restoreSnapshot(snapshot);

    assertEquals(4, nstate.getRegionCount(), "Total regions count should be 4 after restore.");

    ADMIN.enableTable(tableName1);
    ADMIN.deleteSnapshot(snapshot);
  }

  @Test
  public void testRestoreSnapshotQuotaExceed() throws Exception {
    String nsp = prefix + "_testRestoreSnapshotQuotaExceed";
    NamespaceDescriptor nspDesc = NamespaceDescriptor.create(nsp)
      .addConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "10").build();
    ADMIN.createNamespace(nspDesc);
    NamespaceDescriptor ndesc = ADMIN.getNamespaceDescriptor(nsp);
    assertNotNull(ndesc, "Namespace descriptor found null.");
    TableName tableName1 = TableName.valueOf(nsp + TableName.NAMESPACE_DELIM + "table1");
    HTableDescriptor tableDescOne = new HTableDescriptor(tableName1);
    HColumnDescriptor fam1 = new HColumnDescriptor("fam1");
    tableDescOne.addFamily(fam1);

    ADMIN.createTable(tableDescOne, Bytes.toBytes("AAA"), Bytes.toBytes("ZZZ"), 4);

    NamespaceTableAndRegionInfo nstate = getNamespaceState(nsp);
    assertEquals(4, nstate.getRegionCount(), "Intial region count should be 4.");

    String snapshot = "snapshot_testRestoreSnapshotQuotaExceed";
    // snapshot has 4 regions
    ADMIN.snapshot(snapshot, tableName1);
    // recreate table with 1 region and set max regions to 3 for namespace
    ADMIN.disableTable(tableName1);
    ADMIN.deleteTable(tableName1);
    ADMIN.createTable(tableDescOne);
    ndesc.setConfiguration(TableNamespaceManager.KEY_MAX_REGIONS, "3");
    ADMIN.modifyNamespace(ndesc);

    ADMIN.disableTable(tableName1);
    try {
      ADMIN.restoreSnapshot(snapshot);
      fail("Region quota is exceeded so QuotaExceededException should be thrown but HBaseAdmin"
        + " wraps IOException into RestoreSnapshotException");
    } catch (RestoreSnapshotException ignore) {
      assertTrue(ignore.getCause() instanceof QuotaExceededException);
    }
    assertEquals(1, getNamespaceState(nsp).getRegionCount());
    ADMIN.enableTable(tableName1);
    ADMIN.deleteSnapshot(snapshot);
  }
}
