// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#include "lib/extras/hlg.h"

#include <jxl/cms.h>

#include <cmath>

namespace jxl {

float GetHlgGamma(const float peak_luminance, const float surround_luminance) {
  return 1.2f * std::pow(1.111f, std::log2(peak_luminance / 1000.f)) *
         std::pow(0.98f, std::log2(surround_luminance / 5.f));
}

Status HlgOOTF(ImageBundle* ib, const float gamma, ThreadPool* pool) {
  ColorEncoding linear_rec2020;
  linear_rec2020.SetColorSpace(ColorSpace::kRGB);
  JXL_RETURN_IF_ERROR(linear_rec2020.SetPrimariesType(Primaries::k2100));
  JXL_RETURN_IF_ERROR(linear_rec2020.SetWhitePointType(WhitePoint::kD65));
  linear_rec2020.Tf().SetTransferFunction(TransferFunction::kLinear);
  JXL_RETURN_IF_ERROR(linear_rec2020.CreateICC());
  JXL_RETURN_IF_ERROR(
      ib->TransformTo(linear_rec2020, *JxlGetDefaultCms(), pool));

  const auto process_row = [&](const int y, const int thread) -> Status {
    float* const JXL_RESTRICT rows[3] = {ib->color()->PlaneRow(0, y),
                                         ib->color()->PlaneRow(1, y),
                                         ib->color()->PlaneRow(2, y)};
    for (size_t x = 0; x < ib->xsize(); ++x) {
      float& red = rows[0][x];
      float& green = rows[1][x];
      float& blue = rows[2][x];
      const float luminance = 0.2627f * red + 0.6780f * green + 0.0593f * blue;
      const float ratio = std::pow(luminance, gamma - 1);
      if (std::isfinite(ratio)) {
        red *= ratio;
        green *= ratio;
        blue *= ratio;
      }
    }
    return true;
  };

  JXL_RETURN_IF_ERROR(RunOnPool(pool, 0, ib->ysize(), ThreadPool::NoInit,
                                process_row, "HlgOOTF"));
  return true;
}

Status HlgInverseOOTF(ImageBundle* ib, const float gamma, ThreadPool* pool) {
  return HlgOOTF(ib, 1.f / gamma, pool);
}

}  // namespace jxl
