/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2011 Blender Foundation. */

#include "COM_CalculateMeanOperation.h"

#include "COM_ExecutionSystem.h"

#include "IMB_colormanagement.h"

namespace blender::compositor {

CalculateMeanOperation::CalculateMeanOperation()
{
  this->add_input_socket(DataType::Color, ResizeMode::Align);
  this->add_output_socket(DataType::Value);
  image_reader_ = nullptr;
  iscalculated_ = false;
  setting_ = 1;
  flags_.complex = true;
}
void CalculateMeanOperation::init_execution()
{
  image_reader_ = this->get_input_socket_reader(0);
  iscalculated_ = false;
  NodeOperation::init_mutex();
}

void CalculateMeanOperation::execute_pixel(float output[4], int /*x*/, int /*y*/, void * /*data*/)
{
  output[0] = result_;
}

void CalculateMeanOperation::deinit_execution()
{
  image_reader_ = nullptr;
  NodeOperation::deinit_mutex();
}

bool CalculateMeanOperation::determine_depending_area_of_interest(
    rcti * /*input*/, ReadBufferOperation *read_operation, rcti *output)
{
  rcti image_input;
  if (iscalculated_) {
    return false;
  }
  NodeOperation *operation = get_input_operation(0);
  image_input.xmax = operation->get_width();
  image_input.xmin = 0;
  image_input.ymax = operation->get_height();
  image_input.ymin = 0;
  if (operation->determine_depending_area_of_interest(&image_input, read_operation, output)) {
    return true;
  }
  return false;
}

void *CalculateMeanOperation::initialize_tile_data(rcti *rect)
{
  lock_mutex();
  if (!iscalculated_) {
    MemoryBuffer *tile = (MemoryBuffer *)image_reader_->initialize_tile_data(rect);
    calculate_mean(tile);
    iscalculated_ = true;
  }
  unlock_mutex();
  return nullptr;
}

void CalculateMeanOperation::calculate_mean(MemoryBuffer *tile)
{
  result_ = 0.0f;
  float *buffer = tile->get_buffer();
  int size = tile->get_width() * tile->get_height();
  int pixels = 0;
  float sum = 0.0f;
  for (int i = 0, offset = 0; i < size; i++, offset += 4) {
    if (buffer[offset + 3] > 0) {
      pixels++;

      switch (setting_) {
        case 1: {
          sum += IMB_colormanagement_get_luminance(&buffer[offset]);
          break;
        }
        case 2: {
          sum += buffer[offset];
          break;
        }
        case 3: {
          sum += buffer[offset + 1];
          break;
        }
        case 4: {
          sum += buffer[offset + 2];
          break;
        }
        case 5: {
          float yuv[3];
          rgb_to_yuv(buffer[offset],
                     buffer[offset + 1],
                     buffer[offset + 2],
                     &yuv[0],
                     &yuv[1],
                     &yuv[2],
                     BLI_YUV_ITU_BT709);
          sum += yuv[0];
          break;
        }
      }
    }
  }
  result_ = sum / pixels;
}

void CalculateMeanOperation::set_setting(int setting)
{
  setting_ = setting;
  switch (setting) {
    case 1: {
      setting_func_ = IMB_colormanagement_get_luminance;
      break;
    }
    case 2: {
      setting_func_ = [](const float *elem) { return elem[0]; };
      break;
    }
    case 3: {
      setting_func_ = [](const float *elem) { return elem[1]; };
      break;
    }
    case 4: {
      setting_func_ = [](const float *elem) { return elem[2]; };
      break;
    }
    case 5: {
      setting_func_ = [](const float *elem) {
        float yuv[3];
        rgb_to_yuv(elem[0], elem[1], elem[2], &yuv[0], &yuv[1], &yuv[2], BLI_YUV_ITU_BT709);
        return yuv[0];
      };
      break;
    }
  }
}

void CalculateMeanOperation::get_area_of_interest(int input_idx,
                                                  const rcti & /*output_area*/,
                                                  rcti &r_input_area)
{
  BLI_assert(input_idx == 0);
  r_input_area = get_input_operation(input_idx)->get_canvas();
}

void CalculateMeanOperation::update_memory_buffer_started(MemoryBuffer * /*output*/,
                                                          const rcti & /*area*/,
                                                          Span<MemoryBuffer *> inputs)
{
  if (!iscalculated_) {
    MemoryBuffer *input = inputs[0];
    result_ = calc_mean(input);
    iscalculated_ = true;
  }
}

void CalculateMeanOperation::update_memory_buffer_partial(MemoryBuffer *output,
                                                          const rcti &area,
                                                          Span<MemoryBuffer *> /*inputs*/)
{
  output->fill(area, &result_);
}

float CalculateMeanOperation::calc_mean(const MemoryBuffer *input)
{
  PixelsSum total = {0};
  exec_system_->execute_work<PixelsSum>(
      input->get_rect(),
      [=](const rcti &split) { return calc_area_sum(input, split); },
      total,
      [](PixelsSum &join, const PixelsSum &chunk) {
        join.sum += chunk.sum;
        join.num_pixels += chunk.num_pixels;
      });
  return total.num_pixels == 0 ? 0.0f : total.sum / total.num_pixels;
}

using PixelsSum = CalculateMeanOperation::PixelsSum;
PixelsSum CalculateMeanOperation::calc_area_sum(const MemoryBuffer *input, const rcti &area)
{
  PixelsSum result = {0};
  for (const float *elem : input->get_buffer_area(area)) {
    if (elem[3] <= 0.0f) {
      continue;
    }
    result.sum += setting_func_(elem);
    result.num_pixels++;
  }
  return result;
}

}  // namespace blender::compositor