/*
    * Copyright 2014 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.handler.codec.socksx.v5;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufUtil;
  import io.netty.channel.ChannelHandler.Sharable;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.handler.codec.EncoderException;
  import io.netty.handler.codec.MessageToByteEncoder;
  import io.netty.util.internal.ObjectUtil;
  import io.netty.util.internal.StringUtil;
  
  /**
   * Encodes a server-side {@link Socks5Message} into a {@link ByteBuf}.
   */
  @Sharable
  public class Socks5ServerEncoder extends MessageToByteEncoder<Socks5Message> {
  
      public static final Socks5ServerEncoder DEFAULT = new Socks5ServerEncoder(Socks5AddressEncoder.DEFAULT);
  
      private final Socks5AddressEncoder addressEncoder;
  
      /**
       * Creates a new instance with the default {@link Socks5AddressEncoder}.
       */
      protected Socks5ServerEncoder() {
          this(Socks5AddressEncoder.DEFAULT);
      }
  
      /**
       * Creates a new instance with the specified {@link Socks5AddressEncoder}.
       */
      public Socks5ServerEncoder(Socks5AddressEncoder addressEncoder) {
          this.addressEncoder = ObjectUtil.checkNotNull(addressEncoder, "addressEncoder");
      }
  
      /**
       * Returns the {@link Socks5AddressEncoder} of this encoder.
       */
      protected final Socks5AddressEncoder addressEncoder() {
          return addressEncoder;
      }
  
      @Override
      protected void encode(ChannelHandlerContext ctx, Socks5Message msg, ByteBuf out) throws Exception {
          if (msg instanceof Socks5InitialResponse) {
              encodeAuthMethodResponse((Socks5InitialResponse) msg, out);
          } else if (msg instanceof Socks5PasswordAuthResponse) {
              encodePasswordAuthResponse((Socks5PasswordAuthResponse) msg, out);
          } else if (msg instanceof Socks5CommandResponse) {
              encodeCommandResponse((Socks5CommandResponse) msg, out);
          } else {
              throw new EncoderException("unsupported message type: " + StringUtil.simpleClassName(msg));
          }
      }
  
      private static void encodeAuthMethodResponse(Socks5InitialResponse msg, ByteBuf out) {
          out.writeByte(msg.version().byteValue());
          out.writeByte(msg.authMethod().byteValue());
      }
  
      private static void encodePasswordAuthResponse(Socks5PasswordAuthResponse msg, ByteBuf out) {
          out.writeByte(0x01);
          out.writeByte(msg.status().byteValue());
      }
  
      private void encodeCommandResponse(Socks5CommandResponse msg, ByteBuf out) throws Exception {
          out.writeByte(msg.version().byteValue());
          out.writeByte(msg.status().byteValue());
          out.writeByte(0x00);
  
          final Socks5AddressType bndAddrType = msg.bndAddrType();
          out.writeByte(bndAddrType.byteValue());
          addressEncoder.encodeAddress(bndAddrType, msg.bndAddr(), out);
  
          ByteBufUtil.writeShortBE(out, msg.bndPort());
      }
  }