content: /*
   * 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.camel.component.hl7;
  
  import java.nio.charset.Charset;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.Unpooled;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.handler.codec.DecoderException;
  import io.netty.handler.codec.DelimiterBasedFrameDecoder;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * HL7 MLLP Decoder for Netty
   */
  class HL7MLLPNettyDecoder extends DelimiterBasedFrameDecoder {
  
      private static final Logger LOG = LoggerFactory.getLogger(HL7MLLPNettyDecoder.class);
      private static final int MAX_FRAME_LENGTH = Integer.MAX_VALUE;
      private final HL7MLLPConfig config;
  
      /**
       * Creates a decoder instance using a default HL7MLLPConfig
       */
      HL7MLLPNettyDecoder() {
          this(new HL7MLLPConfig());
      }
  
      /**
       * Creates a decoder instance
       *
       * @param  config                         HL7MLLPConfig to be used for decoding
       * @throws java.lang.NullPointerException is config is null
       */
      HL7MLLPNettyDecoder(HL7MLLPConfig config) {
          super(MAX_FRAME_LENGTH, true, Unpooled.copiedBuffer(
                  new char[] { config.getEndByte1(), config.getEndByte2() },
                  Charset.defaultCharset()));
          this.config = config;
      }
  
      @Override
      protected Object decode(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception {
          ByteBuf buf = (ByteBuf) super.decode(ctx, buffer);
          if (buf != null) {
              try {
                  int pos = buf.bytesBefore((byte) config.getStartByte());
                  if (pos >= 0) {
                      ByteBuf msg = buf.readerIndex(pos + 1).slice();
                      LOG.debug("Message ends with length {}", msg.readableBytes());
                      return config.isProduceString() ? asString(msg) : asByteArray(msg);
                  } else {
                      throw new DecoderException("Did not find start byte " + (int) config.getStartByte());
                  }
              } finally {
                  // We need to release the buf here to avoid the memory leak
                  buf.release();
              }
          }
          // Message not complete yet - return null to be called again
          LOG.debug("No complete messages yet at position {}", buffer.readableBytes());
          return null;
      }
  
      private byte[] asByteArray(ByteBuf msg) {
          byte[] bytes = new byte[msg.readableBytes()];
          msg.getBytes(0, bytes);
          if (config.isConvertLFtoCR()) {
              for (int i = 0; i < bytes.length; i++) {
                  if (bytes[i] == (byte) '\n') {
                      bytes[i] = (byte) '\r';
                  }
              }
          }
          return bytes;
      }
  
      private String asString(ByteBuf msg) {
          String s = msg.toString(config.getCharset());
          if (config.isConvertLFtoCR()) {
              return s.replace('\n', '\r');
          }
          return s;
      }
  }
  