#include "Contents/GroundGeometry.h"
#include "Resource/TerrainResource.h"

#include <bit>

// OFFSET: 0x00AC09B0
// FUNCTION: fn_17568
void GroundGeometry::WorldColor(float x, float, float z, std::uint32_t* output) const {
  int column;
  int row;
  this->Spatial().SpatialCell(x, z, column, row);

  if (column < 0 || row < 0 || column >= this->width || row >= this->height) {
    output[1] = 255;
    output[0] = 255;
    output[2] = 255;
    return;
  }

  const GroundCell& cell =
    this->cells[static_cast<unsigned>(column) + static_cast<unsigned>(row) * static_cast<unsigned>(this->width)];
  output[0] = cell.color[0];
  output[1] = cell.color[1];
  output[2] = cell.color[2];
}

// OFFSET: 0x00AC1130
// FUNCTION: fn_17577
void GroundGeometry::Lighting(int column, int row, float& red, float& green, float& blue) const {
  if (column < 0 || (column >> 1) >= this->width || row < 0 || (row >> 1) >= this->height || this->lighting.empty()) {
    red = 1.0f;
    green = 1.0f;
    blue = 1.0f;
    return;
  }

  const unsigned index =
    static_cast<unsigned>(column) + 2u * static_cast<unsigned>(row) * static_cast<unsigned>(this->width);
  red = this->lighting[index][0];
  green = this->lighting[index][1];
  blue = this->lighting[index][2];
}

// OFFSET: 0x00AC11D0
// FUNCTION: fn_17579
void GroundGeometry::LightmapSample(
  int column,
  int row,
  unsigned char& alpha,
  unsigned char& red,
  unsigned char& green,
  unsigned char& blue
) const {
  if (column < 0 || (column >> 1) >= this->width || row < 0 || (row >> 1) >= this->height || this->cells.empty()) {
    alpha = red = green = blue = 255;
    return;
  }

  const unsigned index =
    static_cast<unsigned>(column >> 1) + static_cast<unsigned>(row >> 1) * static_cast<unsigned>(this->width);

  if (!this->cells[index].top || !this->cells[index].top->lightmap) {
    alpha = red = green = blue = 255;
    return;
  }

  const unsigned sample = (static_cast<unsigned>(column) & 1u) + 2u * (static_cast<unsigned>(row) & 1u);
  // Re-read the owner for each output store: outputs can alias sampled bytes.
  const auto read = [&](unsigned shift) {
    return static_cast<unsigned char>(this->cells[index].top->lightmap->unknown_0028[sample] >> shift);
  };
  alpha = read(24);
  red = read(16);
  green = read(8);
  blue = read(0);
}

// OFFSET: 0x00AC0C40
// FUNCTION: fn_17570
bool GroundGeometry::TerrainCellCorners(const C3dAttr& terrain, int column, int row, float* vertices) const {
  const int columns = std::bit_cast<int>(2u * static_cast<unsigned>(this->width));
  const int rows = std::bit_cast<int>(2u * static_cast<unsigned>(this->height));

  if (column < 0 || columns < column || row < 0 || rows < row) {
    return false;
  }

  const float size = this->cellSize * 0.5f;
  const unsigned dx = static_cast<unsigned>(column) - static_cast<unsigned>(this->width);
  const unsigned dz = static_cast<unsigned>(row) - static_cast<unsigned>(this->height);
  const float left = static_cast<float>(std::bit_cast<int>(dx)) * size;
  const float right = static_cast<float>(std::bit_cast<int>(dx + 1u)) * size;
  const float top = static_cast<float>(std::bit_cast<int>(dz)) * size;
  const float bottom = static_cast<float>(std::bit_cast<int>(dz + 1u)) * size;
  vertices[1] = 0.0f;
  vertices[4] = 0.0f;
  vertices[7] = 0.0f;
  vertices[10] = 0.0f;
  vertices[0] = left;
  vertices[2] = top;
  vertices[3] = right;
  vertices[5] = top;
  vertices[6] = left;
  vertices[8] = bottom;
  vertices[9] = right;
  vertices[11] = bottom;
  return this->OverlayHeights(terrain, vertices, column, row);
}