/*
    * 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.shardingsphere.proxy.frontend.postgresql.command;
  
  import lombok.AccessLevel;
  import lombok.NoArgsConstructor;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.shardingsphere.db.protocol.packet.sql.SQLReceivedPacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.PostgreSQLCommandPacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.PostgreSQLCommandPacketType;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.PostgreSQLAggregatedCommandPacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.bind.PostgreSQLComBindPacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.close.PostgreSQLComClosePacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.describe.PostgreSQLComDescribePacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.execute.PostgreSQLComExecutePacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.parse.PostgreSQLComParsePacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.simple.PostgreSQLComQueryPacket;
  import org.apache.shardingsphere.proxy.backend.session.ConnectionSession;
  import org.apache.shardingsphere.proxy.frontend.command.executor.CommandExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.generic.PostgreSQLComTerminationExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.generic.PostgreSQLUnsupportedCommandExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.PostgreSQLAggregatedBatchedStatementsCommandExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.PostgreSQLAggregatedCommandExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.bind.PostgreSQLComBindExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.close.PostgreSQLComCloseExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.describe.PostgreSQLComDescribeExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.execute.PostgreSQLComExecuteExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.flush.PostgreSQLComFlushExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.parse.PostgreSQLComParseExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.sync.PostgreSQLComSyncExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.simple.PostgreSQLComQueryExecutor;
  
  import java.sql.SQLException;
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Command executor factory for PostgreSQL.
   */
  @NoArgsConstructor(access = AccessLevel.PRIVATE)
  @Slf4j
  public final class PostgreSQLCommandExecutorFactory {
      
      /**
       * Create new instance of command executor.
       *
       * @param commandPacketType command packet type for PostgreSQL
       * @param commandPacket command packet for PostgreSQL
       * @param connectionSession connection session
       * @param portalContext PostgreSQL portal context
       * @return created instance
       * @throws SQLException SQL exception
       */
      public static CommandExecutor newInstance(final PostgreSQLCommandPacketType commandPacketType, final PostgreSQLCommandPacket commandPacket,
                                                final ConnectionSession connectionSession, final PortalContext portalContext) throws SQLException {
          if (commandPacket instanceof SQLReceivedPacket) {
              log.debug("Execute packet type: {}, sql: {}", commandPacketType, ((SQLReceivedPacket) commandPacket).getSQL());
          } else {
              log.debug("Execute packet type: {}", commandPacketType);
          }
          if (!(commandPacket instanceof PostgreSQLAggregatedCommandPacket)) {
              return getCommandExecutor(commandPacketType, commandPacket, connectionSession, portalContext);
          }
          PostgreSQLAggregatedCommandPacket aggregatedCommandPacket = (PostgreSQLAggregatedCommandPacket) commandPacket;
          if (aggregatedCommandPacket.isContainsBatchedStatements()) {
              return new PostgreSQLAggregatedCommandExecutor(getExecutorsOfAggregatedBatchedStatements(aggregatedCommandPacket, connectionSession, portalContext));
          }
          List<CommandExecutor> result = new ArrayList<>(aggregatedCommandPacket.getPackets().size());
          for (PostgreSQLCommandPacket each : aggregatedCommandPacket.getPackets()) {
              result.add(getCommandExecutor((PostgreSQLCommandPacketType) each.getIdentifier(), each, connectionSession, portalContext));
          }
          return new PostgreSQLAggregatedCommandExecutor(result);
      }
      
      private static List<CommandExecutor> getExecutorsOfAggregatedBatchedStatements(final PostgreSQLAggregatedCommandPacket aggregatedCommandPacket,
                                                                                     final ConnectionSession connectionSession, final PortalContext portalContext) throws SQLException {
          List<PostgreSQLCommandPacket> packets = aggregatedCommandPacket.getPackets();
          int batchPacketBeginIndex = aggregatedCommandPacket.getBatchPacketBeginIndex();
          int batchPacketEndIndex = aggregatedCommandPacket.getBatchPacketEndIndex();
          List<CommandExecutor> result = new ArrayList<>(batchPacketBeginIndex + packets.size() - batchPacketEndIndex);
          for (int i = 0; i < batchPacketBeginIndex; i++) {
              PostgreSQLCommandPacket each = packets.get(i);
              result.add(getCommandExecutor((PostgreSQLCommandPacketType) each.getIdentifier(), each, connectionSession, portalContext));
          }
         result.add(new PostgreSQLAggregatedBatchedStatementsCommandExecutor(connectionSession, packets.subList(batchPacketBeginIndex, batchPacketEndIndex + 1)));
         for (int i = batchPacketEndIndex + 1; i < packets.size(); i++) {
             PostgreSQLCommandPacket each = packets.get(i);
             result.add(getCommandExecutor((PostgreSQLCommandPacketType) each.getIdentifier(), each, connectionSession, portalContext));
         }
         return result;
     }
     
     private static CommandExecutor getCommandExecutor(final PostgreSQLCommandPacketType commandPacketType, final PostgreSQLCommandPacket commandPacket,
                                                       final ConnectionSession connectionSession, final PortalContext portalContext) throws SQLException {
         switch (commandPacketType) {
             case SIMPLE_QUERY:
                 return new PostgreSQLComQueryExecutor(portalContext, (PostgreSQLComQueryPacket) commandPacket, connectionSession);
             case PARSE_COMMAND:
                 return new PostgreSQLComParseExecutor((PostgreSQLComParsePacket) commandPacket, connectionSession);
             case BIND_COMMAND:
                 return new PostgreSQLComBindExecutor(portalContext, (PostgreSQLComBindPacket) commandPacket, connectionSession);
             case DESCRIBE_COMMAND:
                 return new PostgreSQLComDescribeExecutor(portalContext, (PostgreSQLComDescribePacket) commandPacket, connectionSession);
             case EXECUTE_COMMAND:
                 return new PostgreSQLComExecuteExecutor(portalContext, (PostgreSQLComExecutePacket) commandPacket);
             case SYNC_COMMAND:
                 return new PostgreSQLComSyncExecutor(connectionSession);
             case CLOSE_COMMAND:
                 return new PostgreSQLComCloseExecutor(portalContext, (PostgreSQLComClosePacket) commandPacket, connectionSession);
             case FLUSH_COMMAND:
                 return new PostgreSQLComFlushExecutor();
             case TERMINATE:
                 return new PostgreSQLComTerminationExecutor();
             default:
                 return new PostgreSQLUnsupportedCommandExecutor();
         }
     }
 }