/*
    *  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.directory.api.ldap.codec.protocol.mina;
  
  
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.directory.api.asn1.DecoderException;
  import org.apache.directory.api.asn1.ber.Asn1Decoder;
  import org.apache.directory.api.asn1.ber.tlv.TLVStateEnum;
  import org.apache.directory.api.ldap.codec.api.LdapDecoder;
  import org.apache.directory.api.ldap.codec.api.LdapMessageContainer;
  import org.apache.directory.api.ldap.codec.api.MessageDecorator;
  import org.apache.directory.api.ldap.codec.api.ResponseCarryingException;
  import org.apache.directory.api.ldap.model.constants.Loggers;
  import org.apache.directory.api.ldap.model.exception.ResponseCarryingMessageException;
  import org.apache.directory.api.ldap.model.message.Message;
  import org.apache.directory.api.util.Strings;
  import org.apache.mina.core.buffer.IoBuffer;
  import org.apache.mina.core.session.IoSession;
  import org.apache.mina.filter.codec.ProtocolDecoder;
  import org.apache.mina.filter.codec.ProtocolDecoderOutput;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * A LDAP message decoder. It is based on api-ldap decoder.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class LdapProtocolDecoder implements ProtocolDecoder
  {
      /** The logger */
      private static final Logger CODEC_LOG = LoggerFactory.getLogger( Loggers.CODEC_LOG.getName() );
  
      /** A speedup for logger */
      private static final boolean IS_DEBUG = CODEC_LOG.isDebugEnabled();
  
      /** The ASN 1 decoder instance */
      private Asn1Decoder asn1Decoder;
  
  
      /**
       * Creates a new instance of LdapProtocolEncoder.
       */
      public LdapProtocolDecoder()
      {
          asn1Decoder = new Asn1Decoder();
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
      public void decode( IoSession session, IoBuffer in, ProtocolDecoderOutput out ) throws Exception
      {
          @SuppressWarnings("unchecked")
          LdapMessageContainer<MessageDecorator<? extends Message>> messageContainer =
              ( LdapMessageContainer<MessageDecorator<? extends Message>> )
              session.getAttribute( LdapDecoder.MESSAGE_CONTAINER_ATTR );
  
          if ( session.containsAttribute( LdapDecoder.MAX_PDU_SIZE_ATTR ) )
          {
              int maxPDUSize = ( Integer ) session.getAttribute( LdapDecoder.MAX_PDU_SIZE_ATTR );
  
              messageContainer.setMaxPDUSize( maxPDUSize );
          }
  
          List<Message> decodedMessages = new ArrayList<>();
          ByteBuffer buf = in.buf();
  
          decode( buf, messageContainer, decodedMessages );
  
          for ( Message message : decodedMessages )
          {
              out.write( message );
          }
      }
 
 
     /**
      * Decode an incoming buffer into LDAP messages. The result can be 0, 1 or many
      * LDAP messages, which will be stored into the array the caller has created.
      * 
      * @param buffer The incoming byte buffer
      * @param messageContainer The LdapMessageContainer which will be used to store the
      * message being decoded. If the message is not fully decoded, the ucrrent state
      * is stored into this container
      * @param decodedMessages The list of decoded messages
      * @throws Exception If the decoding failed
      */
     private void decode( ByteBuffer buffer, LdapMessageContainer<MessageDecorator<? extends Message>> messageContainer,
         List<Message> decodedMessages ) throws DecoderException
     {
         buffer.mark();
 
         while ( buffer.hasRemaining() )
         {
             try
             {
                 if ( IS_DEBUG )
                 {
                     CODEC_LOG.debug( "Decoding the PDU : " );
 
                     int size = buffer.limit();
                     int position = buffer.position();
                     int pduLength = size - position;
 
                     byte[] array = new byte[pduLength];
 
                     System.arraycopy( buffer.array(), position, array, 0, pduLength );
 
                     if ( array.length == 0 )
                     {
                         CODEC_LOG.debug( "NULL buffer, what the HELL ???" );
                     }
                     else
                     {
                         CODEC_LOG.debug( Strings.dumpBytes( array ) );
                     }
                 }
 
                 asn1Decoder.decode( buffer, messageContainer );
 
                 if ( messageContainer.getState() == TLVStateEnum.PDU_DECODED )
                 {
                     if ( IS_DEBUG )
                     {
                         CODEC_LOG.debug( "Decoded LdapMessage : " + messageContainer.getMessage() );
                     }
 
                     Message message = messageContainer.getMessage();
 
                     decodedMessages.add( message );
 
                     messageContainer.clean();
                 }
             }
             catch ( ResponseCarryingException rce )
             {
                 buffer.clear();
                 messageContainer.clean();
                 
                 // Transform the DecoderException message to a MessageException
                 ResponseCarryingMessageException rcme = new ResponseCarryingMessageException( rce.getMessage(), rce );
                 rcme.setResponse( rce.getResponse() );
 
                 throw rcme;
             }
             catch ( DecoderException de )
             {
                 buffer.clear();
                 messageContainer.clean();
 
                 // TODO : This is certainly not the way we should handle such an exception !
                 throw new ResponseCarryingException( de.getMessage(), de );
             }
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void finishDecode( IoSession session, ProtocolDecoderOutput out ) throws Exception
     {
         // Nothing to do
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void dispose( IoSession session ) throws Exception
     {
         // Nothing to do
     }
 }