/*
    * 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.db.protocol.mysql.packet.handshake;
  
  import lombok.Getter;
  import lombok.RequiredArgsConstructor;
  import lombok.Setter;
  import org.apache.shardingsphere.db.protocol.mysql.constant.MySQLAuthenticationMethod;
  import org.apache.shardingsphere.db.protocol.mysql.constant.MySQLCapabilityFlag;
  import org.apache.shardingsphere.db.protocol.mysql.packet.MySQLPacket;
  import org.apache.shardingsphere.db.protocol.mysql.packet.command.admin.MySQLComSetOptionPacket;
  import org.apache.shardingsphere.db.protocol.mysql.payload.MySQLPacketPayload;
  
  /**
   * Handshake response above MySQL 4.1 packet protocol.
   * 
   * @see <a href="https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_connection_phase_packets_protocol_handshake_response.html">HandshakeResponse41</a>
   */
  @RequiredArgsConstructor
  @Getter
  @Setter
  public final class MySQLHandshakeResponse41Packet extends MySQLPacket {
      
      private final int maxPacketSize;
      
      private final int characterSet;
      
      private final String username;
      
      private byte[] authResponse;
      
      private int capabilityFlags;
      
      private String database;
      
      private String authPluginName;
      
      private int multiStatementsOption;
      
      public MySQLHandshakeResponse41Packet(final MySQLPacketPayload payload) {
          capabilityFlags = payload.readInt4();
          multiStatementsOption = readMultiStatementsOption(capabilityFlags);
          maxPacketSize = payload.readInt4();
          characterSet = payload.readInt1();
          payload.skipReserved(23);
          username = payload.readStringNul();
          authResponse = readAuthResponse(payload);
          database = readDatabase(payload);
          authPluginName = readAuthPluginName(payload);
      }
      
      private int readMultiStatementsOption(final int capabilityFlags) {
          return 0 == (capabilityFlags & MySQLCapabilityFlag.CLIENT_MULTI_STATEMENTS.getValue()) ? MySQLComSetOptionPacket.MYSQL_OPTION_MULTI_STATEMENTS_OFF
                  : MySQLComSetOptionPacket.MYSQL_OPTION_MULTI_STATEMENTS_ON;
      }
      
      private byte[] readAuthResponse(final MySQLPacketPayload payload) {
          if (0 != (capabilityFlags & MySQLCapabilityFlag.CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA.getValue())) {
              return payload.readStringLenencByBytes();
          }
          if (0 != (capabilityFlags & MySQLCapabilityFlag.CLIENT_SECURE_CONNECTION.getValue())) {
              int length = payload.readInt1();
              return payload.readStringFixByBytes(length);
          }
          return payload.readStringNulByBytes();
      }
      
      private String readDatabase(final MySQLPacketPayload payload) {
          return 0 == (capabilityFlags & MySQLCapabilityFlag.CLIENT_CONNECT_WITH_DB.getValue()) ? null : payload.readStringNul();
      }
      
      private String readAuthPluginName(final MySQLPacketPayload payload) {
          return 0 == (capabilityFlags & MySQLCapabilityFlag.CLIENT_PLUGIN_AUTH.getValue()) ? null : payload.readStringNul();
      }
      
      /**
       * Set database.
       *
       * @param database database
       */
      public void setDatabase(final String database) {
          this.database = database;
          capabilityFlags |= MySQLCapabilityFlag.CLIENT_CONNECT_WITH_DB.getValue();
      }
     
     /**
      * Set authentication plugin name.
      *
      * @param authenticationMethod authentication method of MySQL
      */
     public void setAuthPluginName(final MySQLAuthenticationMethod authenticationMethod) {
         authPluginName = authenticationMethod.getMethodName();
         capabilityFlags |= MySQLCapabilityFlag.CLIENT_PLUGIN_AUTH.getValue();
     }
     
     @Override
     protected void write(final MySQLPacketPayload payload) {
         payload.writeInt4(capabilityFlags);
         payload.writeInt4(maxPacketSize);
         payload.writeInt1(characterSet);
         payload.writeReserved(23);
         payload.writeStringNul(username);
         writeAuthResponse(payload);
         writeDatabase(payload);
         writeAuthPluginName(payload);
     }
     
     private void writeAuthResponse(final MySQLPacketPayload payload) {
         if (0 != (capabilityFlags & MySQLCapabilityFlag.CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA.getValue())) {
             payload.writeStringLenenc(new String(authResponse));
         } else if (0 != (capabilityFlags & MySQLCapabilityFlag.CLIENT_SECURE_CONNECTION.getValue())) {
             payload.writeInt1(authResponse.length);
             payload.writeBytes(authResponse);
         } else {
             payload.writeStringNul(new String(authResponse));
         }
     }
     
     private void writeDatabase(final MySQLPacketPayload payload) {
         if (0 != (capabilityFlags & MySQLCapabilityFlag.CLIENT_CONNECT_WITH_DB.getValue())) {
             payload.writeStringNul(database);
         }
     }
     
     private void writeAuthPluginName(final MySQLPacketPayload payload) {
         if (0 != (capabilityFlags & MySQLCapabilityFlag.CLIENT_PLUGIN_AUTH.getValue())) {
             payload.writeStringNul(authPluginName);
         }
     }
 }