/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/*

 * This file is part of the libvisio project.

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/.

 */

#include "VSDInternalStream.h"

#include <string.h>

VSDInternalStream::VSDInternalStream(librevenge::RVNGInputStream *input, unsigned long size, bool compressed) :

  librevenge::RVNGInputStream(),

  m_offset(0),

  m_buffer()

{

  unsigned long tmpNumBytesRead = 0;

  const unsigned char *tmpBuffer = input->read(size, tmpNumBytesRead);

  if (tmpNumBytesRead < 2)

    return;

  if (!compressed)

  {

    m_buffer.assign(tmpBuffer, tmpBuffer + tmpNumBytesRead);

  }

  else

  {

    unsigned char buffer[4096] = { 0 };

    unsigned pos = 0;

    unsigned offset = 0;

    while (offset < tmpNumBytesRead)

    {

      unsigned flag = tmpBuffer[offset++];

      if (offset > tmpNumBytesRead-1)

        break;

      unsigned mask = 1;

      for (unsigned bit = 0; bit < 8 && offset < tmpNumBytesRead; ++bit)

      {

        if (flag & mask)

        {

          buffer[pos&4095] = tmpBuffer[offset++];

          m_buffer.push_back(buffer[pos&4095]);

          pos++;

        }

        else

        {

          if (offset > tmpNumBytesRead-2)

            break;

          unsigned char addr1 = tmpBuffer[offset++];

          unsigned char addr2 = tmpBuffer[offset++];

          unsigned length = (addr2&15) + 3;

          unsigned pointer = (((unsigned)addr2 & 0xF0) << 4) | addr1;

          if (pointer > 4078)

            pointer -= 4078;

          else

            pointer += 18;

          for (unsigned j = 0; j < length; ++j)

          {

            buffer[(pos+j) & 4095] = buffer[(pointer+j) & 4095];

            m_buffer.push_back(buffer[(pointer+j) & 4095]);

          }

          pos += length;

        }

        mask = mask << 1;

      }

    }

  }

}

const unsigned char *VSDInternalStream::read(unsigned long numBytes, unsigned long &numBytesRead)

{

  numBytesRead = 0;

  if (numBytes == 0)

    return nullptr;

  int numBytesToRead;

  if (numBytes < m_buffer.size() - m_offset)

    numBytesToRead = numBytes;

  else

    numBytesToRead = m_buffer.size() - m_offset;

  numBytesRead = numBytesToRead; // about as paranoid as we can be..

  if (numBytesToRead == 0)

    return nullptr;

  long oldOffset = m_offset;

  m_offset += numBytesToRead;

  return &m_buffer[oldOffset];

}

int VSDInternalStream::seek(long offset, librevenge::RVNG_SEEK_TYPE seekType)

{

  if (seekType == librevenge::RVNG_SEEK_CUR)

    m_offset += offset;

  else if (seekType == librevenge::RVNG_SEEK_SET)

    m_offset = offset;

  else if (seekType == librevenge::RVNG_SEEK_END)

    m_offset = long(static_cast<unsigned long>(m_buffer.size())) + offset;

  if (m_offset < 0)

  {

    m_offset = 0;

    return 1;

  }

  if ((long)m_offset > (long)m_buffer.size())

  {

    m_offset = m_buffer.size();

    return 1;

  }

  return 0;

}

long VSDInternalStream::tell()

{

  return m_offset;

}

bool VSDInternalStream::isEnd()

{

  if ((long)m_offset >= (long)m_buffer.size())

    return true;

  return false;

}

/* vim:set shiftwidth=2 softtabstop=2 expandtab: */