/*
    * 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.query.extended;
  
  import lombok.RequiredArgsConstructor;
  import org.apache.shardingsphere.db.protocol.packet.DatabasePacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.PostgreSQLCommandPacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.PostgreSQLNoDataPacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.PostgreSQLColumnType;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.bind.PostgreSQLBindCompletePacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.bind.PostgreSQLComBindPacket;
  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.generic.PostgreSQLCommandCompletePacket;
  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.query.PostgreSQLCommand;
  
  import java.sql.SQLException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.LinkedList;
  import java.util.List;
  
  /**
   * Aggregated batched statements command executor for PostgreSQL.
   */
  @RequiredArgsConstructor
  public final class PostgreSQLAggregatedBatchedStatementsCommandExecutor implements CommandExecutor {
      
      private final ConnectionSession connectionSession;
      
      private final List<PostgreSQLCommandPacket> packets;
      
      @Override
      public Collection<DatabasePacket> execute() throws SQLException {
          PostgreSQLServerPreparedStatement preparedStatement = getPreparedStatement();
          PostgreSQLBatchedStatementsExecutor executor = new PostgreSQLBatchedStatementsExecutor(connectionSession, preparedStatement, readParameterSets(preparedStatement.getParameterTypes()));
          Collection<DatabasePacket> result = new ArrayList<>(packets.size());
          int totalInserted = executor.executeBatch();
          int executePacketCount = executePacketCount();
          for (PostgreSQLCommandPacket each : packets) {
              if (each instanceof PostgreSQLComBindPacket) {
                  result.add(PostgreSQLBindCompletePacket.getInstance());
              }
              if (each instanceof PostgreSQLComDescribePacket) {
                  result.add(preparedStatement.describeRows().orElseGet(PostgreSQLNoDataPacket::getInstance));
              }
              if (each instanceof PostgreSQLComExecutePacket) {
                  String tag = PostgreSQLCommand.valueOf(preparedStatement.getSqlStatementContext().getSqlStatement().getClass()).orElse(PostgreSQLCommand.INSERT).getTag();
                  result.add(new PostgreSQLCommandCompletePacket(tag, 0 == executePacketCount ? 1 : totalInserted / executePacketCount));
              }
          }
          return result;
      }
      
      private PostgreSQLServerPreparedStatement getPreparedStatement() {
          PostgreSQLComBindPacket bindPacket = (PostgreSQLComBindPacket) packets.get(0);
          return connectionSession.getServerPreparedStatementRegistry().getPreparedStatement(bindPacket.getStatementId());
      }
      
      private List<List<Object>> readParameterSets(final List<PostgreSQLColumnType> parameterTypes) {
          List<List<Object>> result = new LinkedList<>();
          for (PostgreSQLCommandPacket each : packets) {
              if (each instanceof PostgreSQLComBindPacket) {
                  result.add(((PostgreSQLComBindPacket) each).readParameters(parameterTypes));
              }
          }
          return result;
      }
      
      private int executePacketCount() {
          int result = 0;
          for (PostgreSQLCommandPacket each : packets) {
              if (each instanceof PostgreSQLComExecutePacket) {
                  result++;
              }
          }
          return result;
      }
  }