content: /*
   * Copyright 2022 paxos.cn.
   *
   * Licensed 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 cn.paxos.mysql.codec;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.handler.codec.DecoderException;
  import java.util.List;
  import java.util.Optional;
  
  public class MysqlClientCommandPacketDecoder extends AbstractPacketDecoder
      implements MysqlClientPacketDecoder {
  
    private final String database;
    private final String userName;
    private final byte[] scramble411;
  
    public MysqlClientCommandPacketDecoder(String database, String userName, byte[] scramble411) {
      this(Constants.DEFAULT_MAX_PACKET_SIZE, database, userName, scramble411);
    }
  
    public MysqlClientCommandPacketDecoder(
        int maxPacketSize, String database, String userName, byte[] scramble411) {
      super(maxPacketSize);
  
      this.database = database;
      this.userName = userName;
      this.scramble411 = scramble411;
    }
  
    @Override
    protected void decodePacket(
        ChannelHandlerContext ctx, int sequenceId, ByteBuf packet, List<Object> out) {
      final MysqlCharacterSet clientCharset = MysqlCharacterSet.getClientCharsetAttr(ctx.channel());
  
      final byte commandCode = packet.readByte();
      final Optional<Command> command = Command.findByCommandCode(commandCode);
      if (!command.isPresent()) {
        throw new DecoderException("Unknown command " + commandCode);
      }
      switch (command.get()) {
        case COM_QUERY:
          out.add(
              new QueryCommand(
                  sequenceId,
                  CodecUtils.readFixedLengthString(
                      packet, packet.readableBytes(), clientCharset.getCharset()),
                  database,
                  userName,
                  scramble411));
          break;
        case COM_INIT_DB:
          out.add(
              new InitDbCommand(
                  sequenceId,
                  CodecUtils.readFixedLengthString(
                      packet, packet.readableBytes(), clientCharset.getCharset())));
          break;
        default:
          out.add(new CommandPacket(sequenceId, command.get()));
      }
    }
  }
  