/* -----------------------------------------------------------------------------
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the Software are granted under this license.

The Clear BSD License

Copyright (c) 2018-2026, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. & The VVdeC Authors.
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     this list of conditions and the following disclaimer.

     * Redistributions in binary form must reproduce the above copyright
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     software without specific prior written permission.

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------------------------------------------------------------------------------------------- */

#pragma once

#include "MD5.h"

#include <streambuf>
#include <array>
#include <vector>

namespace vvdecoderapp
{

const int MD5_DIGEST_LENGTH = 128/8;

static inline std::string MD5ToHexString(unsigned char hash[MD5_DIGEST_LENGTH])
{
  static const char* hex = "0123456789abcdef";
  std::string result;

  for(unsigned pos=0; pos < MD5_DIGEST_LENGTH; ++pos)
  {
    result += hex[hash[pos] >> 4];
    result += hex[hash[pos] & 0xf];
  }

  return result;
}

class MD5StreamBuf : public std::streambuf
{
public:
  explicit MD5StreamBuf( size_t buf_size = 64 )
    : m_buffer( buf_size )
  {
    std::streambuf::setp( &m_buffer.front(), &m_buffer.back() + 1 );
  }

  int_type overflow(int_type ch) override
  {
    m_md5_ctx.update( (unsigned char*)m_buffer.data(), (unsigned int)m_buffer.size() );

    // reset start & end-pointers
    std::streambuf::setp( &m_buffer.front(), &m_buffer.back() + 1 );
    return std::streambuf::sputc(ch);
  }

  int sync() override
  {
    const auto fillLen = std::streambuf::pptr() - std::streambuf::pbase();
    if( fillLen )
      m_md5_ctx.update( (unsigned char*)std::streambuf::pbase(), (unsigned int)fillLen );
    return 0;
  }

  void finalize(unsigned char digest[16])
  {
    sync();
    m_md5_ctx.finalize( digest);
  }

  std::string finalizeHex()
  {
    unsigned char digest[MD5_DIGEST_LENGTH];
    finalize(digest);
    return MD5ToHexString(digest);
  }

private:
  vvdec::libmd5::MD5     m_md5_ctx;
  std::vector<char_type> m_buffer;
};

}   // namespace vvdecoderapp
