/**
 * 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.master.procedure;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.MetaTableAccessor;
import org.apache.hadoop.hbase.TableExistsException;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.client.TableDescriptorBuilder;
import org.apache.hadoop.hbase.errorhandling.ForeignException;
import org.apache.hadoop.hbase.errorhandling.ForeignExceptionDispatcher;
import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
import org.apache.hadoop.hbase.master.MasterFileSystem;
import org.apache.hadoop.hbase.master.MetricsSnapshot;
import org.apache.hadoop.hbase.master.RegionState;
import org.apache.hadoop.hbase.master.assignment.AssignmentManager;
import org.apache.hadoop.hbase.master.procedure.CreateTableProcedure.CreateHdfsRegions;
import org.apache.hadoop.hbase.mob.MobUtils;
import org.apache.hadoop.hbase.monitoring.MonitoredTask;
import org.apache.hadoop.hbase.monitoring.TaskMonitor;
import org.apache.hadoop.hbase.procedure2.ProcedureStateSerializer;
import org.apache.hadoop.hbase.snapshot.ClientSnapshotDescriptionUtils;
import org.apache.hadoop.hbase.snapshot.RestoreSnapshotException;
import org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper;
import org.apache.hadoop.hbase.snapshot.SnapshotDescriptionUtils;
import org.apache.hadoop.hbase.snapshot.SnapshotManifest;
import org.apache.hadoop.hbase.util.FSTableDescriptors;
import org.apache.hadoop.hbase.util.FSUtils;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos;
import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos;
import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos.CloneSnapshotState;
import org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription;

@InterfaceAudience.Private
public class CloneSnapshotProcedure
    extends AbstractStateMachineTableProcedure<CloneSnapshotState> {
  private static final Logger LOG = LoggerFactory.getLogger(CloneSnapshotProcedure.class);

  private TableDescriptor tableDescriptor;
  private SnapshotDescription snapshot;
  private boolean restoreAcl;
  private List<RegionInfo> newRegions = null;
  private Map<String, Pair<String, String> > parentsToChildrenPairMap = new HashMap<>();

  // Monitor
  private MonitoredTask monitorStatus = null;

  /**
   * Constructor (for failover)
   */
  public CloneSnapshotProcedure() {
  }

  public CloneSnapshotProcedure(final MasterProcedureEnv env,
      final TableDescriptor tableDescriptor, final SnapshotDescription snapshot) {
    this(env, tableDescriptor, snapshot, false);
  }

  /**
   * Constructor
   * @param env MasterProcedureEnv
   * @param tableDescriptor the table to operate on
   * @param snapshot snapshot to clone from
   */
  public CloneSnapshotProcedure(final MasterProcedureEnv env,
      final TableDescriptor tableDescriptor, final SnapshotDescription snapshot,
      final boolean restoreAcl) {
    super(env);
    this.tableDescriptor = tableDescriptor;
    this.snapshot = snapshot;
    this.restoreAcl = restoreAcl;

    getMonitorStatus();
  }

  /**
   * Set up monitor status if it is not created.
   */
  private MonitoredTask getMonitorStatus() {
    if (monitorStatus == null) {
      monitorStatus = TaskMonitor.get().createStatus("Cloning  snapshot '" + snapshot.getName() +
        "' to table " + getTableName());
    }
    return monitorStatus;
  }

  private void restoreSnapshotAcl(MasterProcedureEnv env) throws IOException {
    Configuration conf = env.getMasterServices().getConfiguration();
    if (restoreAcl && snapshot.hasUsersAndPermissions() && snapshot.getUsersAndPermissions() != null
        && SnapshotDescriptionUtils.isSecurityAvailable(conf)) {
      RestoreSnapshotHelper.restoreSnapshotAcl(snapshot, tableDescriptor.getTableName(), conf);
    }
  }

  @Override
  protected Flow executeFromState(final MasterProcedureEnv env, final CloneSnapshotState state)
      throws InterruptedException {
    LOG.trace("{} execute state={}", this, state);
    try {
      switch (state) {
        case CLONE_SNAPSHOT_PRE_OPERATION:
          // Verify if we can clone the table
          prepareClone(env);

          preCloneSnapshot(env);
          setNextState(CloneSnapshotState.CLONE_SNAPSHOT_WRITE_FS_LAYOUT);
          break;
        case CLONE_SNAPSHOT_WRITE_FS_LAYOUT:
          newRegions = createFilesystemLayout(env, tableDescriptor, newRegions);
          setNextState(CloneSnapshotState.CLONE_SNAPSHOT_ADD_TO_META);
          break;
        case CLONE_SNAPSHOT_ADD_TO_META:
          addRegionsToMeta(env);
          setNextState(CloneSnapshotState.CLONE_SNAPSHOT_ASSIGN_REGIONS);
          break;
        case CLONE_SNAPSHOT_ASSIGN_REGIONS:
          CreateTableProcedure.setEnablingState(env, getTableName());

          // Separate newRegions to split regions and regions to assign
          List<RegionInfo> splitRegions = new ArrayList<>();
          List<RegionInfo> regionsToAssign = new ArrayList<>();
          newRegions.forEach(ri -> {
            if (ri.isOffline() && (ri.isSplit() || ri.isSplitParent())) {
              splitRegions.add(ri);
            } else {
              regionsToAssign.add(ri);
            }
          });

          // For split regions, add them to RegionStates
          AssignmentManager am = env.getAssignmentManager();
          splitRegions.forEach(ri ->
            am.getRegionStates().updateRegionState(ri, RegionState.State.SPLIT)
          );

          addChildProcedure(env.getAssignmentManager()
            .createRoundRobinAssignProcedures(regionsToAssign));
          setNextState(CloneSnapshotState.CLONE_SNAPSHOT_UPDATE_DESC_CACHE);
          break;
        case CLONE_SNAPSHOT_UPDATE_DESC_CACHE:
          CreateTableProcedure.setEnabledState(env, getTableName());
          CreateTableProcedure.updateTableDescCache(env, getTableName());
          setNextState(CloneSnapshotState.CLONE_SNAPHOST_RESTORE_ACL);
          break;
        case CLONE_SNAPHOST_RESTORE_ACL:
          restoreSnapshotAcl(env);
          setNextState(CloneSnapshotState.CLONE_SNAPSHOT_POST_OPERATION);
          break;
        case CLONE_SNAPSHOT_POST_OPERATION:
          postCloneSnapshot(env);

          MetricsSnapshot metricsSnapshot = new MetricsSnapshot();
          metricsSnapshot.addSnapshotClone(
            getMonitorStatus().getCompletionTimestamp() - getMonitorStatus().getStartTime());
          getMonitorStatus().markComplete("Clone snapshot '"+ snapshot.getName() +"' completed!");
          return Flow.NO_MORE_STATE;
        default:
          throw new UnsupportedOperationException("unhandled state=" + state);
      }
    } catch (IOException e) {
      if (isRollbackSupported(state)) {
        setFailure("master-clone-snapshot", e);
      } else {
        LOG.warn("Retriable error trying to clone snapshot=" + snapshot.getName() +
          " to table=" + getTableName() + " state=" + state, e);
      }
    }
    return Flow.HAS_MORE_STATE;
  }

  @Override
  protected void rollbackState(final MasterProcedureEnv env, final CloneSnapshotState state)
      throws IOException {
    if (state == CloneSnapshotState.CLONE_SNAPSHOT_PRE_OPERATION) {
      DeleteTableProcedure.deleteTableStates(env, getTableName());
      // TODO-MAYBE: call the deleteTable coprocessor event?
      return;
    }

    // The procedure doesn't have a rollback. The execution will succeed, at some point.
    throw new UnsupportedOperationException("unhandled state=" + state);
  }

  @Override
  protected boolean isRollbackSupported(final CloneSnapshotState state) {
    switch (state) {
      case CLONE_SNAPSHOT_PRE_OPERATION:
        return true;
      default:
        return false;
    }
  }

  @Override
  protected CloneSnapshotState getState(final int stateId) {
    return CloneSnapshotState.valueOf(stateId);
  }

  @Override
  protected int getStateId(final CloneSnapshotState state) {
    return state.getNumber();
  }

  @Override
  protected CloneSnapshotState getInitialState() {
    return CloneSnapshotState.CLONE_SNAPSHOT_PRE_OPERATION;
  }

  @Override
  public TableName getTableName() {
    return tableDescriptor.getTableName();
  }

  @Override
  public TableOperationType getTableOperationType() {
    return TableOperationType.CREATE; // Clone is creating a table
  }

  @Override
  public void toStringClassDetails(StringBuilder sb) {
    sb.append(getClass().getSimpleName());
    sb.append(" (table=");
    sb.append(getTableName());
    sb.append(" snapshot=");
    sb.append(snapshot);
    sb.append(")");
  }

  @Override
  protected void serializeStateData(ProcedureStateSerializer serializer)
      throws IOException {
    super.serializeStateData(serializer);

    MasterProcedureProtos.CloneSnapshotStateData.Builder cloneSnapshotMsg =
      MasterProcedureProtos.CloneSnapshotStateData.newBuilder()
        .setUserInfo(MasterProcedureUtil.toProtoUserInfo(getUser()))
        .setSnapshot(this.snapshot)
        .setTableSchema(ProtobufUtil.toTableSchema(tableDescriptor));
    if (newRegions != null) {
      for (RegionInfo hri: newRegions) {
        cloneSnapshotMsg.addRegionInfo(ProtobufUtil.toRegionInfo(hri));
      }
    }
    if (!parentsToChildrenPairMap.isEmpty()) {
      final Iterator<Map.Entry<String, Pair<String, String>>> it =
        parentsToChildrenPairMap.entrySet().iterator();
      while (it.hasNext()) {
        final Map.Entry<String, Pair<String, String>> entry = it.next();

        MasterProcedureProtos.RestoreParentToChildRegionsPair.Builder parentToChildrenPair =
          MasterProcedureProtos.RestoreParentToChildRegionsPair.newBuilder()
          .setParentRegionName(entry.getKey())
          .setChild1RegionName(entry.getValue().getFirst())
          .setChild2RegionName(entry.getValue().getSecond());
        cloneSnapshotMsg.addParentToChildRegionsPairList(parentToChildrenPair);
      }
    }
    serializer.serialize(cloneSnapshotMsg.build());
  }

  @Override
  protected void deserializeStateData(ProcedureStateSerializer serializer)
      throws IOException {
    super.deserializeStateData(serializer);

    MasterProcedureProtos.CloneSnapshotStateData cloneSnapshotMsg =
        serializer.deserialize(MasterProcedureProtos.CloneSnapshotStateData.class);
    setUser(MasterProcedureUtil.toUserInfo(cloneSnapshotMsg.getUserInfo()));
    snapshot = cloneSnapshotMsg.getSnapshot();
    tableDescriptor = ProtobufUtil.toTableDescriptor(cloneSnapshotMsg.getTableSchema());
    if (cloneSnapshotMsg.getRegionInfoCount() == 0) {
      newRegions = null;
    } else {
      newRegions = new ArrayList<>(cloneSnapshotMsg.getRegionInfoCount());
      for (HBaseProtos.RegionInfo hri: cloneSnapshotMsg.getRegionInfoList()) {
        newRegions.add(ProtobufUtil.toRegionInfo(hri));
      }
    }
    if (cloneSnapshotMsg.getParentToChildRegionsPairListCount() > 0) {
      parentsToChildrenPairMap = new HashMap<>();
      for (MasterProcedureProtos.RestoreParentToChildRegionsPair parentToChildrenPair:
        cloneSnapshotMsg.getParentToChildRegionsPairListList()) {
        parentsToChildrenPairMap.put(
          parentToChildrenPair.getParentRegionName(),
          new Pair<>(
            parentToChildrenPair.getChild1RegionName(),
            parentToChildrenPair.getChild2RegionName()));
      }
    }
    // Make sure that the monitor status is set up
    getMonitorStatus();
  }

  /**
   * Action before any real action of cloning from snapshot.
   * @param env MasterProcedureEnv
   * @throws IOException
   */
  private void prepareClone(final MasterProcedureEnv env) throws IOException {
    final TableName tableName = getTableName();
    if (MetaTableAccessor.tableExists(env.getMasterServices().getConnection(), tableName)) {
      throw new TableExistsException(getTableName());
    }
  }

  /**
   * Action before cloning from snapshot.
   * @param env MasterProcedureEnv
   * @throws IOException
   * @throws InterruptedException
   */
  private void preCloneSnapshot(final MasterProcedureEnv env)
      throws IOException, InterruptedException {
    if (!getTableName().isSystemTable()) {
      // Check and update namespace quota
      final MasterFileSystem mfs = env.getMasterServices().getMasterFileSystem();

      SnapshotManifest manifest = SnapshotManifest.open(
        env.getMasterConfiguration(),
        mfs.getFileSystem(),
        SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshot, mfs.getRootDir()),
        snapshot);

      ProcedureSyncWait.getMasterQuotaManager(env)
        .checkNamespaceTableAndRegionQuota(getTableName(), manifest.getRegionManifestsMap().size());
    }

    final MasterCoprocessorHost cpHost = env.getMasterCoprocessorHost();
    if (cpHost != null) {
      cpHost.preCreateTableAction(tableDescriptor, null, getUser());
    }
  }

  /**
   * Action after cloning from snapshot.
   * @param env MasterProcedureEnv
   * @throws IOException
   * @throws InterruptedException
   */
  private void postCloneSnapshot(final MasterProcedureEnv env)
      throws IOException, InterruptedException {
    final MasterCoprocessorHost cpHost = env.getMasterCoprocessorHost();
    if (cpHost != null) {
      final RegionInfo[] regions = (newRegions == null) ? null :
        newRegions.toArray(new RegionInfo[newRegions.size()]);
      cpHost.postCompletedCreateTableAction(tableDescriptor, regions, getUser());
    }
  }

  /**
   * Create regions in file system.
   * @param env MasterProcedureEnv
   * @throws IOException
   */
  private List<RegionInfo> createFilesystemLayout(
    final MasterProcedureEnv env,
    final TableDescriptor tableDescriptor,
    final List<RegionInfo> newRegions) throws IOException {
    return createFsLayout(env, tableDescriptor, newRegions, new CreateHdfsRegions() {
      @Override
      public List<RegionInfo> createHdfsRegions(
        final MasterProcedureEnv env,
        final Path tableRootDir, final TableName tableName,
        final List<RegionInfo> newRegions) throws IOException {

        final MasterFileSystem mfs = env.getMasterServices().getMasterFileSystem();
        final FileSystem fs = mfs.getFileSystem();
        final Path rootDir = mfs.getRootDir();
        final Configuration conf = env.getMasterConfiguration();
        final ForeignExceptionDispatcher monitorException = new ForeignExceptionDispatcher();

        getMonitorStatus().setStatus("Clone snapshot - creating regions for table: " + tableName);

        try {
          // 1. Execute the on-disk Clone
          Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshot, rootDir);
          SnapshotManifest manifest = SnapshotManifest.open(conf, fs, snapshotDir, snapshot);
          RestoreSnapshotHelper restoreHelper = new RestoreSnapshotHelper(
            conf, fs, manifest, tableDescriptor, tableRootDir, monitorException, monitorStatus);
          RestoreSnapshotHelper.RestoreMetaChanges metaChanges = restoreHelper.restoreHdfsRegions();

          // Clone operation should not have stuff to restore or remove
          Preconditions.checkArgument(
            !metaChanges.hasRegionsToRestore(), "A clone should not have regions to restore");
          Preconditions.checkArgument(
            !metaChanges.hasRegionsToRemove(), "A clone should not have regions to remove");

          // At this point the clone is complete. Next step is enabling the table.
          String msg =
            "Clone snapshot="+ snapshot.getName() +" on table=" + tableName + " completed!";
          LOG.info(msg);
          monitorStatus.setStatus(msg + " Waiting for table to be enabled...");

          // 2. Let the next step to add the regions to meta
          return metaChanges.getRegionsToAdd();
        } catch (Exception e) {
          String msg = "clone snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot) +
            " failed because " + e.getMessage();
          LOG.error(msg, e);
          IOException rse = new RestoreSnapshotException(msg, e,
              ProtobufUtil.createSnapshotDesc(snapshot));

          // these handlers aren't futures so we need to register the error here.
          monitorException.receive(new ForeignException("Master CloneSnapshotProcedure", rse));
          throw rse;
        }
      }
    });
  }

  /**
   * Create region layout in file system.
   * @param env MasterProcedureEnv
   * @throws IOException
   */
  private List<RegionInfo> createFsLayout(
    final MasterProcedureEnv env,
    final TableDescriptor tableDescriptor,
    List<RegionInfo> newRegions,
    final CreateHdfsRegions hdfsRegionHandler) throws IOException {
    final MasterFileSystem mfs = env.getMasterServices().getMasterFileSystem();
    final Path tempdir = mfs.getTempDir();

    // 1. Create Table Descriptor
    // using a copy of descriptor, table will be created enabling first
    final Path tempTableDir = FSUtils.getTableDir(tempdir, tableDescriptor.getTableName());
    ((FSTableDescriptors)(env.getMasterServices().getTableDescriptors()))
      .createTableDescriptorForTableDirectory(tempTableDir,
              TableDescriptorBuilder.newBuilder(tableDescriptor).build(), false);

    // 2. Create Regions
    newRegions = hdfsRegionHandler.createHdfsRegions(
      env, tempdir, tableDescriptor.getTableName(), newRegions);

    // 3. Move Table temp directory to the hbase root location
    CreateTableProcedure.moveTempDirectoryToHBaseRoot(env, tableDescriptor, tempTableDir);
    // Move Table temp mob directory to the hbase root location
    Path tempMobTableDir = MobUtils.getMobTableDir(tempdir, tableDescriptor.getTableName());
    if (mfs.getFileSystem().exists(tempMobTableDir)) {
      moveTempMobDirectoryToHBaseRoot(mfs, tableDescriptor, tempMobTableDir);
    }
    return newRegions;
  }

  /**
   * Move table temp mob directory to the hbase root location
   * @param mfs The master file system
   * @param tableDescriptor The table to operate on
   * @param tempMobTableDir The temp mob directory of table
   * @throws IOException If failed to move temp mob dir to hbase root dir
   */
  private void moveTempMobDirectoryToHBaseRoot(final MasterFileSystem mfs,
      final TableDescriptor tableDescriptor, final Path tempMobTableDir) throws IOException {
    FileSystem fs = mfs.getFileSystem();
    final Path tableMobDir =
        MobUtils.getMobTableDir(mfs.getRootDir(), tableDescriptor.getTableName());
    if (!fs.delete(tableMobDir, true) && fs.exists(tableMobDir)) {
      throw new IOException("Couldn't delete mob table " + tableMobDir);
    }
    if (!fs.exists(tableMobDir.getParent())) {
      fs.mkdirs(tableMobDir.getParent());
    }
    if (!fs.rename(tempMobTableDir, tableMobDir)) {
      throw new IOException("Unable to move mob table from temp=" + tempMobTableDir
          + " to hbase root=" + tableMobDir);
    }
  }

  /**
   * Add regions to hbase:meta table.
   * @param env MasterProcedureEnv
   * @throws IOException
   */
  private void addRegionsToMeta(final MasterProcedureEnv env) throws IOException {
    newRegions = CreateTableProcedure.addTableToMeta(env, tableDescriptor, newRegions);

    // TODO: parentsToChildrenPairMap is always empty, which makes updateMetaParentRegions()
    // a no-op. This part seems unnecessary. Figure out. - Appy 12/21/17
    RestoreSnapshotHelper.RestoreMetaChanges metaChanges =
        new RestoreSnapshotHelper.RestoreMetaChanges(
                tableDescriptor, parentsToChildrenPairMap);
    metaChanges.updateMetaParentRegions(env.getMasterServices().getConnection(), newRegions);
  }

}