# ByteArrayHandler.java

    /*
    ** Module   : ByteArrayHandler.java
    ** Abstract : Splits input data stream into chunks
    **
    ** Copyright (c) 2016-2023, Golden Code Development Corporation.
    **
    ** -#- -I- --Date--  ---------------------------------------Description---------------------------------------
    ** 001 IAS 20160805  Initial version
    ** 002 IAS 20200729  Process large messages
    ** 003 IAS 20210329  Re-worked logging configuration
    ** 004 GBB 20230512  Logging methods replaced by CentralLogger/ConversionStatus.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.net;

    import com.goldencode.p2j.util.logging.*;

    import java.io.*;
    import java.nio.*;

    /**
     * This class splits input data stream into chunks. Each chunk is a sequence of bytes prepended with an
     * integer length.
     */
    public abstract class ByteArrayHandler
    {
       /** Work buffer. */
       private volatile ByteBuffer bb;

       /** Trace operations' flag */
       private final boolean trace;

       /** The length of the next chunk. */
       private volatile int len = -1;

       /** Bytes to be read in a large message */
       private volatile int remaining = 0;

       /** Large message data holder */
       private volatile ByteArrayOutputStream baos = null;

       /**
        * Constructor
        *
        * @param bufsize
        *        max incoming portion size
        * @param trace
        *        trace operations flag
        */
       public ByteArrayHandler(int bufsize, boolean trace)
       {
          super();
          this.bb = ByteBuffer.allocate(4*bufsize);
          this.trace = trace;
       }

       /**
        * Process the next portion of input
        *
        * @param chunk
        *        input data
        *
        * @return number of chunks found since previous input
        */
       public synchronized int nextChunk(ByteBuffer chunk)
       {
          int parsed = 0;
          if (bb.remaining() < chunk.remaining());
          {
             ByteBuffer nbb = ByteBuffer.allocate(bb.position()+chunk.remaining());
             bb.flip();
             nbb.put(bb);
             bb = nbb;
          }
          try
          {
             bb.put(chunk);
          }
          catch (BufferOverflowException e)
          {
             CentralLogger.get(ByteArrayHandler.class)
                          .warning("Exception in processing the next portion of input:", e);
          }
          while (next())
          {
             parsed++;
          }
          return parsed;
       }

       /**
        * Process the byte portion of the next chunk
        *
        * @param data
        *        the byte portion of the next chunk
        */
       protected abstract void ready(byte[] data);

    /**
        * Try to extract a next chunk from the input
        *
        * @return <code>true</code> if a new chunk was found
        */
       private boolean next()
       {
          if (len == -1)
          {
             if (bb.position() < 4)
             {
                return false;
             }
             int pos = bb.position();
             bb.flip();
             bb.rewind();
             len = bb.getInt();
             bb.position(pos);
          }
          if (len < 0)
          {
             if (trace)
             {
                NetSocketBase.LOG.finest(
                      String.format("Long message to be received, length: %d", -len));
             }
             remaining = -len;
             baos = new ByteArrayOutputStream(remaining);
             len = -1;
             bb.compact();
             return false;
          }

          if (trace && baos != null)
          {
             NetSocketBase.LOG.finest(
                   String.format("Next chunk of long message received, length: %d", len));
          }

          if (bb.position() < len + 4)
          {
             return false;
          }
          byte[] data = new byte[len];
          bb.position(4);
          bb.get(data);

          len = -1;
          bb.compact();
          if (baos != null)
          {
             try
             {
                baos.write(data);
             }
             catch (IOException e) // should never happen
             {
                throw new RuntimeException("Unexpected exception", e);
             }
             remaining -= data.length;
             if (trace)
             {
                NetSocketBase.LOG.finest(
                      String.format("Next chunk of the long message: %d, remaining: %d",
                            data.length, remaining));
             }
             if (remaining < 0)
             {
                throw new RuntimeException("Unexpected value of the 'remaining':" + remaining);
             }
             if (remaining > 0)
             {
                return false;
             }
             if (remaining == 0)
             {
                try
                {
                   baos.close();
                }
                catch (IOException e) // should never happen
                {
                   throw new RuntimeException("Unexpected exception", e);
                }
                data = baos.toByteArray();
                baos = null;
                if (trace)
                {
                   NetSocketBase.LOG.finest(
                         String.format("Long message received, len: %d", len));
                }
             }
          }
          ready(data);
          return true;
       }
    }