/*
 * 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.hive.ql.parse.repl.load.message;

import org.apache.hadoop.hive.metastore.messaging.AlterTableMessage;
import org.apache.hadoop.hive.ql.exec.Task;
import org.apache.hadoop.hive.ql.exec.TaskFactory;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.plan.AlterTableDesc;
import org.apache.hadoop.hive.ql.plan.DDLWork;

import java.io.Serializable;
import java.util.Collections;
import java.util.List;

public class RenameTableHandler extends AbstractMessageHandler {
  @Override
  public List<Task<? extends Serializable>> handle(Context context)
      throws SemanticException {

    AlterTableMessage msg = deserializer.getAlterTableMessage(context.dmd.getPayload());
    if (!context.isTableNameEmpty()) {
      throw new SemanticException(
          "RENAMES of tables are not supported for table-level replication");
    }
    try {
      String oldDbName = msg.getTableObjBefore().getDbName();
      String newDbName = msg.getTableObjAfter().getDbName();

      if (!context.isDbNameEmpty()) {
        // If we're loading into a db, instead of into the warehouse, then the oldDbName and
        // newDbName must be the same
        if (!oldDbName.equalsIgnoreCase(newDbName)) {
          throw new SemanticException("Cannot replicate an event renaming a table across"
              + " databases into a db level load " + oldDbName + "->" + newDbName);
        } else {
          // both were the same, and can be replaced by the new db we're loading into.
          oldDbName = context.dbName;
          newDbName = context.dbName;
        }
      }

      String oldName = oldDbName + "." + msg.getTableObjBefore().getTableName();
      String newName = newDbName + "." + msg.getTableObjAfter().getTableName();
      AlterTableDesc renameTableDesc = new AlterTableDesc(oldName, newName, false);
      Task<DDLWork> renameTableTask = TaskFactory.get(
          new DDLWork(readEntitySet, writeEntitySet, renameTableDesc), context.hiveConf
      );
      context.log.debug(
          "Added rename table task : {}:{}->{}", renameTableTask.getId(), oldName, newName
      );
      // oldDbName and newDbName *will* be the same if we're here
      databasesUpdated.put(newDbName, context.dmd.getEventTo());
      tablesUpdated.remove(oldName);
      tablesUpdated.put(newName, context.dmd.getEventTo());
      // Note : edge-case here in interaction with table-level REPL LOAD, where that nukes out tablesUpdated
      // However, we explicitly don't support repl of that sort, and error out above if so. If that should
      // ever change, this will need reworking.
      return Collections.singletonList(renameTableTask);
    } catch (Exception e) {
      throw (e instanceof SemanticException)
          ? (SemanticException) e
          : new SemanticException("Error reading message members", e);
    }
  }
}