/**
    * 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.InputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.security.PrivilegedExceptionAction;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.TableNotDisabledException;
  import org.apache.hadoop.hbase.TableNotFoundException;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.backup.HFileArchiver;
  import org.apache.hadoop.hbase.MetaTableAccessor;
  import org.apache.hadoop.hbase.client.ClusterConnection;
  import org.apache.hadoop.hbase.client.Delete;
  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.exceptions.HBaseException;
  import org.apache.hadoop.hbase.regionserver.HRegion;
  import org.apache.hadoop.hbase.master.AssignmentManager;
  import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
  import org.apache.hadoop.hbase.master.MasterFileSystem;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
  import org.apache.hadoop.hbase.protobuf.generated.MasterProcedureProtos;
  import org.apache.hadoop.hbase.protobuf.generated.MasterProcedureProtos.DeleteTableState;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.procedure2.StateMachineProcedure;
  import org.apache.hadoop.hbase.util.FSUtils;
  import org.apache.hadoop.security.UserGroupInformation;
  
  @InterfaceAudience.Private
  public class DeleteTableProcedure
      extends StateMachineProcedure<MasterProcedureEnv, DeleteTableState>
      implements TableProcedureInterface {
    private static final Log LOG = LogFactory.getLog(DeleteTableProcedure.class);
  
    private List<HRegionInfo> regions;
    private UserGroupInformation user;
    private TableName tableName;
  
    // used for compatibility with old clients
    private final ProcedurePrepareLatch syncLatch;
  
    public DeleteTableProcedure() {
      // Required by the Procedure framework to create the procedure on replay
      syncLatch = null;
    }
  
    public DeleteTableProcedure(final MasterProcedureEnv env, final TableName tableName) {
      this(env, tableName, null);
    }
  
    public DeleteTableProcedure(final MasterProcedureEnv env, final TableName tableName,
        final ProcedurePrepareLatch syncLatch) {
      this.tableName = tableName;
      this.user = env.getRequestUser().getUGI();
      this.setOwner(this.user.getShortUserName());
  
      // used for compatibility with clients without procedures
      // they need a sync TableNotFoundException, TableNotDisabledException, ...
      this.syncLatch = syncLatch;
    }
  
    @Override
    protected Flow executeFromState(final MasterProcedureEnv env, DeleteTableState state)
        throws InterruptedException {
      if (LOG.isTraceEnabled()) {
        LOG.trace(this + " execute state=" + state);
      }
      try {
        switch (state) {
         case DELETE_TABLE_PRE_OPERATION:
           // Verify if we can delete the table
           boolean deletable = prepareDelete(env);
           ProcedurePrepareLatch.releaseLatch(syncLatch, this);
           if (!deletable) {
             assert isFailed() : "the delete should have an exception here";
             return Flow.NO_MORE_STATE;
           }
 
           // TODO: Move out... in the acquireLock()
           LOG.debug("waiting for '" + getTableName() + "' regions in transition");
           regions = ProcedureSyncWait.getRegionsFromMeta(env, getTableName());
           assert regions != null && !regions.isEmpty() : "unexpected 0 regions";
           ProcedureSyncWait.waitRegionInTransition(env, regions);
 
           // Call coprocessors
           preDelete(env);
 
           setNextState(DeleteTableState.DELETE_TABLE_REMOVE_FROM_META);
           break;
         case DELETE_TABLE_REMOVE_FROM_META:
           LOG.debug("delete '" + getTableName() + "' regions from META");
           DeleteTableProcedure.deleteFromMeta(env, getTableName(), regions);
           setNextState(DeleteTableState.DELETE_TABLE_CLEAR_FS_LAYOUT);
           break;
         case DELETE_TABLE_CLEAR_FS_LAYOUT:
           LOG.debug("delete '" + getTableName() + "' from filesystem");
           DeleteTableProcedure.deleteFromFs(env, getTableName(), regions, true);
           setNextState(DeleteTableState.DELETE_TABLE_UPDATE_DESC_CACHE);
           regions = null;
           break;
         case DELETE_TABLE_UPDATE_DESC_CACHE:
           LOG.debug("delete '" + getTableName() + "' descriptor");
           DeleteTableProcedure.deleteTableDescriptorCache(env, getTableName());
           setNextState(DeleteTableState.DELETE_TABLE_UNASSIGN_REGIONS);
           break;
         case DELETE_TABLE_UNASSIGN_REGIONS:
           LOG.debug("delete '" + getTableName() + "' assignment state");
           DeleteTableProcedure.deleteAssignmentState(env, getTableName());
           setNextState(DeleteTableState.DELETE_TABLE_POST_OPERATION);
           break;
         case DELETE_TABLE_POST_OPERATION:
           postDelete(env);
           LOG.debug("delete '" + getTableName() + "' completed");
           return Flow.NO_MORE_STATE;
         default:
           throw new UnsupportedOperationException("unhandled state=" + state);
       }
     } catch (HBaseException|IOException e) {
       LOG.warn("Retriable error trying to delete table=" + getTableName() + " state=" + state, e);
     }
     return Flow.HAS_MORE_STATE;
   }
 
   @Override
   protected void rollbackState(final MasterProcedureEnv env, final DeleteTableState state) {
     if (state == DeleteTableState.DELETE_TABLE_PRE_OPERATION) {
       // nothing to rollback, pre-delete is just table-state checks.
       // We can fail if the table does not exist or is not disabled.
       ProcedurePrepareLatch.releaseLatch(syncLatch, this);
       return;
     }
 
     // The delete doesn't have a rollback. The execution will succeed, at some point.
     throw new UnsupportedOperationException("unhandled state=" + state);
   }
 
   @Override
   protected DeleteTableState getState(final int stateId) {
     return DeleteTableState.valueOf(stateId);
   }
 
   @Override
   protected int getStateId(final DeleteTableState state) {
     return state.getNumber();
   }
 
   @Override
   protected DeleteTableState getInitialState() {
     return DeleteTableState.DELETE_TABLE_PRE_OPERATION;
   }
 
   @Override
   public TableName getTableName() {
     return tableName;
   }
 
   @Override
   public TableOperationType getTableOperationType() {
     return TableOperationType.DELETE;
   }
 
   @Override
   public boolean abort(final MasterProcedureEnv env) {
     // TODO: We may be able to abort if the procedure is not started yet.
     return false;
   }
 
   @Override
   protected boolean acquireLock(final MasterProcedureEnv env) {
     if (env.waitInitialized(this)) return false;
     return env.getProcedureQueue().tryAcquireTableExclusiveLock(this, getTableName());
   }
 
   @Override
   protected void releaseLock(final MasterProcedureEnv env) {
     env.getProcedureQueue().releaseTableExclusiveLock(this, getTableName());
   }
 
   @Override
   public void toStringClassDetails(StringBuilder sb) {
     sb.append(getClass().getSimpleName());
     sb.append(" (table=");
     sb.append(getTableName());
     sb.append(")");
   }
 
   @Override
   public void serializeStateData(final OutputStream stream) throws IOException {
     super.serializeStateData(stream);
 
     MasterProcedureProtos.DeleteTableStateData.Builder state =
       MasterProcedureProtos.DeleteTableStateData.newBuilder()
         .setUserInfo(MasterProcedureUtil.toProtoUserInfo(this.user))
         .setTableName(ProtobufUtil.toProtoTableName(tableName));
     if (regions != null) {
       for (HRegionInfo hri: regions) {
         state.addRegionInfo(HRegionInfo.convert(hri));
       }
     }
     state.build().writeDelimitedTo(stream);
   }
 
   @Override
   public void deserializeStateData(final InputStream stream) throws IOException {
     super.deserializeStateData(stream);
 
     MasterProcedureProtos.DeleteTableStateData state =
       MasterProcedureProtos.DeleteTableStateData.parseDelimitedFrom(stream);
     user = MasterProcedureUtil.toUserInfo(state.getUserInfo());
     tableName = ProtobufUtil.toTableName(state.getTableName());
     if (state.getRegionInfoCount() == 0) {
       regions = null;
     } else {
       regions = new ArrayList<HRegionInfo>(state.getRegionInfoCount());
       for (HBaseProtos.RegionInfo hri: state.getRegionInfoList()) {
         regions.add(HRegionInfo.convert(hri));
       }
     }
   }
 
   private boolean prepareDelete(final MasterProcedureEnv env) throws IOException {
     try {
       env.getMasterServices().checkTableModifiable(tableName);
     } catch (TableNotFoundException|TableNotDisabledException e) {
       setFailure("master-delete-table", e);
       return false;
     }
     return true;
   }
 
   private boolean preDelete(final MasterProcedureEnv env)
       throws IOException, InterruptedException {
     final MasterCoprocessorHost cpHost = env.getMasterCoprocessorHost();
     if (cpHost != null) {
       final TableName tableName = this.tableName;
       user.doAs(new PrivilegedExceptionAction<Void>() {
         @Override
         public Void run() throws Exception {
           cpHost.preDeleteTableHandler(tableName);
           return null;
         }
       });
     }
     return true;
   }
 
   private void postDelete(final MasterProcedureEnv env)
       throws IOException, InterruptedException {
     deleteTableStates(env, tableName);
 
     final MasterCoprocessorHost cpHost = env.getMasterCoprocessorHost();
     if (cpHost != null) {
       final TableName tableName = this.tableName;
       user.doAs(new PrivilegedExceptionAction<Void>() {
         @Override
         public Void run() throws Exception {
           cpHost.postDeleteTableHandler(tableName);
           return null;
         }
       });
     }
   }
 
   protected static void deleteFromFs(final MasterProcedureEnv env,
       final TableName tableName, final List<HRegionInfo> regions,
       final boolean archive) throws IOException {
     final MasterFileSystem mfs = env.getMasterServices().getMasterFileSystem();
     final FileSystem fs = mfs.getFileSystem();
     final Path tempdir = mfs.getTempDir();
 
     final Path tableDir = FSUtils.getTableDir(mfs.getRootDir(), tableName);
     final Path tempTableDir = FSUtils.getTableDir(tempdir, tableName);
 
     if (fs.exists(tableDir)) {
       // Ensure temp exists
       if (!fs.exists(tempdir) && !fs.mkdirs(tempdir)) {
         throw new IOException("HBase temp directory '" + tempdir + "' creation failure.");
       }
 
       // Ensure parent exists
       if (!fs.exists(tempTableDir.getParent()) && !fs.mkdirs(tempTableDir.getParent())) {
         throw new IOException("HBase temp directory '" + tempdir + "' creation failure.");
       }
 
       // Move the table in /hbase/.tmp
       if (!fs.rename(tableDir, tempTableDir)) {
         if (fs.exists(tempTableDir)) {
           // TODO
           // what's in this dir? something old? probably something manual from the user...
           // let's get rid of this stuff...
           FileStatus[] files = fs.listStatus(tempdir);
           if (files != null && files.length > 0) {
             for (int i = 0; i < files.length; ++i) {
               if (!files[i].isDir()) continue;
               HFileArchiver.archiveRegion(fs, mfs.getRootDir(), tempTableDir, files[i].getPath());
             }
           }
           fs.delete(tempdir, true);
         }
         throw new IOException("Unable to move '" + tableDir + "' to temp '" + tempTableDir + "'");
       }
     }
 
     // Archive regions from FS (temp directory)
     if (archive) {
       for (HRegionInfo hri : regions) {
         LOG.debug("Archiving region " + hri.getRegionNameAsString() + " from FS");
         HFileArchiver.archiveRegion(fs, mfs.getRootDir(),
             tempTableDir, HRegion.getRegionDir(tempTableDir, hri.getEncodedName()));
       }
       LOG.debug("Table '" + tableName + "' archived!");
     }
 
     // Delete table directory from FS (temp directory)
     if (!fs.delete(tempTableDir, true) && fs.exists(tempTableDir)) {
       throw new IOException("Couldn't delete " + tempTableDir);
     }
   }
 
   /**
    * There may be items for this table still up in hbase:meta in the case where the
    * info:regioninfo column was empty because of some write error. Remove ALL rows from hbase:meta
    * that have to do with this table. See HBASE-12980.
    * @throws IOException
    */
   private static void cleanAnyRemainingRows(final MasterProcedureEnv env,
       final TableName tableName) throws IOException {
     ClusterConnection connection = env.getMasterServices().getConnection();
     Scan tableScan = MetaTableAccessor.getScanForTableName(tableName);
     try (Table metaTable =
         connection.getTable(TableName.META_TABLE_NAME)) {
       List<Delete> deletes = new ArrayList<Delete>();
       try (ResultScanner resScanner = metaTable.getScanner(tableScan)) {
         for (Result result : resScanner) {
           deletes.add(new Delete(result.getRow()));
         }
       }
       if (!deletes.isEmpty()) {
         LOG.warn("Deleting some vestigal " + deletes.size() + " rows of " + tableName +
           " from " + TableName.META_TABLE_NAME);
         metaTable.delete(deletes);
       }
     }
   }
 
   protected static void deleteFromMeta(final MasterProcedureEnv env,
       final TableName tableName, List<HRegionInfo> regions) throws IOException {
     MetaTableAccessor.deleteRegions(env.getMasterServices().getConnection(), regions);
 
     // Clean any remaining rows for this table.
     cleanAnyRemainingRows(env, tableName);
 
     // clean region references from the server manager
     env.getMasterServices().getServerManager().removeRegions(regions);
   }
 
   protected static void deleteAssignmentState(final MasterProcedureEnv env,
       final TableName tableName) throws HBaseException, IOException {
     AssignmentManager am = env.getMasterServices().getAssignmentManager();
 
     // Clean up regions of the table in RegionStates.
     LOG.debug("Removing '" + tableName + "' from region states.");
     am.getRegionStates().tableDeleted(tableName);
 
     // If entry for this table states, remove it.
     LOG.debug("Marking '" + tableName + "' as deleted.");
     am.getTableStateManager().setDeletedTable(tableName);
   }
 
   protected static void deleteTableDescriptorCache(final MasterProcedureEnv env,
       final TableName tableName) throws IOException {
     LOG.debug("Removing '" + tableName + "' descriptor.");
     env.getMasterServices().getTableDescriptors().remove(tableName);
   }
 
   protected static void deleteTableStates(final MasterProcedureEnv env, final TableName tableName)
       throws IOException {
     if (!tableName.isSystemTable()) {
       ProcedureSyncWait.getMasterQuotaManager(env).removeTableFromNamespaceQuota(tableName);
     }
   }
 }