#include "DisplaySDL.hpp"
#include "Peripherals.hpp"

#include <stdexcept>

DisplaySDL::DisplaySDL(int w, int h, uint32_t fgColor, uint32_t bgColor):
  mpFramebuffer{std::make_unique<Framebuffer>()} {
  // Create SDL Window
  mpWindow = SDL_CreateWindow(
    "ChocoChip-8",
    SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
    w, h,
    0
  );
  if(mpWindow == NULL) {
    throw std::runtime_error(SDL_GetError());
  }

  // Convert our foreground/background colors to the format expected by SDL
  SDL_PixelFormat *fmt = SDL_AllocFormat(SDL_GetWindowPixelFormat(mpWindow));
  mFgColor = SDL_MapRGB(
      fmt,
      (fgColor & 0x00FF0000) >> 16,
      (fgColor & 0x0000FF00) >> 8,
      (fgColor & 0x000000FF)
  );
  mBgColor = SDL_MapRGB(
      fmt,
      (bgColor & 0x00FF0000) >> 16,
      (bgColor & 0x0000FF00) >> 8,
      (bgColor & 0x000000FF)
  );
  SDL_FreeFormat(fmt);
};

DisplaySDL::~DisplaySDL() {
  SDL_DestroyWindow(mpWindow);
}

void DisplaySDL::clear() {
  for(auto &scanline : *mpFramebuffer) {
    scanline.reset();
  }
  SDL_FillRect(SDL_GetWindowSurface(mpWindow), nullptr, mBgColor);
}

int DisplaySDL::blit(const chocochip8::Scanline &spriteScanline, int y) {
  using chocochip8::Scanline;
  Scanline &targetScanline = mpFramebuffer->at(y);
  Scanline bitsToSet = spriteScanline & ~targetScanline;
  Scanline bitsToReset = spriteScanline & targetScanline;
  targetScanline ^= spriteScanline;

  SDL_Surface *pSurface = SDL_GetWindowSurface(mpWindow);
  SDL_Rect rect;
  // Map framebuffer pixel to SDL surface rectangle
  auto mapChipxelToPixel = [&rect, pSurface](int x, int y) {
      // Note that the MSB of an scanline's bitset is the leftmost pixel.
      x = (chocochip8::gcWidth - 1) - x;
      int x1 = (      x * pSurface->w) / chocochip8::gcWidth;
      int x2 = ((x + 1) * pSurface->w) / chocochip8::gcWidth;
      int y1 = (      y * pSurface->h) / chocochip8::gcHeight;
      int y2 = ((y + 1) * pSurface->h) / chocochip8::gcHeight;
      rect.x = x1;
      rect.y = y1;
      rect.w = x2 - x1;
      rect.h = y2 - y1;
  };

  for(int x = bitsToReset._Find_first(); x < bitsToReset.size(); x = bitsToReset._Find_next(x)) {
    mapChipxelToPixel(x, y);
    SDL_FillRect(pSurface, &rect, mBgColor);
  }
  for(int x = bitsToSet._Find_first(); x < bitsToSet.size(); x = bitsToSet._Find_next(x)) {
    mapChipxelToPixel(x, y);
    SDL_FillRect(pSurface, &rect, mFgColor);
  }

  return bitsToReset.any();
}

void DisplaySDL::updateWindow() const {
  SDL_UpdateWindowSurface(mpWindow);
}