/*

 * HEIF codec.

 * Copyright (c) 2024 Dirk Farin <dirk.farin@gmail.com>

 *

 * This file is part of libheif.

 *

 * libheif is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as

 * published by the Free Software Foundation, either version 3 of

 * the License, or (at your option) any later version.

 *

 * libheif 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with libheif.  If not, see <http://www.gnu.org/licenses/>.

 */

#include "jpeg_dec.h"

#include "jpeg_boxes.h"

#include "error.h"

#include "context.h"

#include <string>

#include <algorithm>

Result<std::vector<uint8_t>> Decoder_JPEG::read_bitstream_configuration_data() const

{

  if (m_jpgC) {

    return m_jpgC->get_data();

  }

  else {

    return std::vector<uint8_t>{};

  }

}

// This checks whether a start code FFCx with nibble 'x' is a SOF marker.

// E.g. FFC0-FFC3 are, while FFC4 is not.

static bool isSOF[16] = {true, true, true, true, false, true, true, true,

                         false, true, true, true, false, true, true, true};

Error Decoder_JPEG::parse_SOF()

{

  if (m_config) {

    return Error::Ok;

  }

  // image data, usually from 'mdat'

  auto dataResult = get_compressed_data();

  if (dataResult.error) {

    return dataResult.error;

  }

  const std::vector<uint8_t>& data = dataResult.value;

  const Error error_invalidSOF{heif_error_Invalid_input,

                               heif_suberror_Unspecified,

                               "Invalid JPEG SOF header"};

  for (size_t i = 0; i + 1 < data.size(); i++) {

    if (data[i] == 0xFF && (data[i + 1] & 0xF0) == 0xC0 && isSOF[data[i + 1] & 0x0F]) {

      if (i + 9 >= data.size()) {

        return error_invalidSOF;

      }

      ConfigInfo info;

      info.sample_precision = data[i + 4];

      info.nComponents = data[i + 9];

      if (i + 11 + 3 * info.nComponents >= data.size()) {

        return error_invalidSOF;

      }

      for (int c = 0; c < std::min(info.nComponents, uint8_t(3)); c++) {

        int ss = data[i + 11 + 3 * c];

        info.h_sampling[c] = (ss >> 4) & 0xF;

        info.v_sampling[c] = ss & 0xF;

      }

      if (info.nComponents == 1) {

        info.chroma = heif_chroma_monochrome;

      }

      else if (info.nComponents != 3) {

        return error_invalidSOF;

      }

      else {

        if (info.h_sampling[1] != info.h_sampling[2] ||

            info.v_sampling[1] != info.v_sampling[2]) {

          return error_invalidSOF;

        }

        if (info.h_sampling[0] == 2 && info.v_sampling[0] == 2 &&

            info.h_sampling[1] == 1 && info.v_sampling[1] == 1) {

          info.chroma = heif_chroma_420;

        }

        else if (info.h_sampling[0] == 2 && info.v_sampling[0] == 1 &&

                 info.h_sampling[1] == 1 && info.v_sampling[1] == 1) {

          info.chroma = heif_chroma_422;

        }

        else if (info.h_sampling[0] == 1 && info.v_sampling[0] == 1 &&

                 info.h_sampling[1] == 1 && info.v_sampling[1] == 1) {

          info.chroma = heif_chroma_444;

        }

        else {

          return error_invalidSOF;

        }

      }

      m_config = info;

      return Error::Ok;

    }

  }

  return error_invalidSOF;

}

int Decoder_JPEG::get_luma_bits_per_pixel() const

{

  Error err = const_cast<Decoder_JPEG*>(this)->parse_SOF();

  if (err) {

    return -1;

  }

  else {

    return m_config->sample_precision;

  }

}

int Decoder_JPEG::get_chroma_bits_per_pixel() const

{

  return get_luma_bits_per_pixel();

}

Error Decoder_JPEG::get_coded_image_colorspace(heif_colorspace* out_colorspace, heif_chroma* out_chroma) const

{

  Error err = const_cast<Decoder_JPEG*>(this)->parse_SOF();

  if (err) {

    return err;

  }

  *out_chroma = m_config->chroma;

  if (*out_chroma == heif_chroma_monochrome) {

    *out_colorspace = heif_colorspace_monochrome;

  }

  else {

    *out_colorspace = heif_colorspace_YCbCr;

  }

  return Error::Ok;

}