#include <mercury/kernel/framebuffer.hpp>

namespace mercury::kernel::framebuffer {

  uint32_t *vaddr;
  int width;
  int height;
  int dword_pitch;

  void init_framebuffer(
    uint64_t vaddr, uint64_t width, uint64_t height, uint64_t pitch
  ) {
    //TODO: assumes 32-bpp rgb
    framebuffer::vaddr = (uint32_t *)vaddr;
    framebuffer::width = width;
    framebuffer::height = height;
    dword_pitch = pitch / 4;
  }

  color encode_color(uint8_t r, uint8_t g, uint8_t b) {
    return ((uint32_t)r << 16) | ((uint32_t)g << 8) | (uint32_t)b;
  }

  void set_pixel(int x, int y, color c) {
    vaddr[y * dword_pitch + x] = c;
  }

  void move_region(
    int from_start_x, int from_start_y, int from_end_x,
    int from_end_y, int to_start_x, int to_start_y
  ) {

    int region_width = from_end_x - from_start_x;
    int region_height = from_end_y - from_start_y;

    int from_start_offset = from_start_y * dword_pitch + from_start_x;
    int to_start_offset = to_start_y * dword_pitch + to_start_x;

    if (from_start_offset > to_start_offset)
      for (int y = 0; y < region_height; ++y)
        for (int x = 0; x < region_width; ++x)
          vaddr[to_start_offset + y * dword_pitch + x] =
            vaddr[from_start_offset + y * dword_pitch + x];

    else if (from_start_offset < to_start_offset)
      for (int y = region_height - 1; y >= 0; --y)
        for (int x = region_width - 1; x >= 0; --x)
          vaddr[to_start_offset + y * dword_pitch + x] =
            vaddr[from_start_offset + y * dword_pitch + x];

  }

  void fill_region(int start_x, int start_y, int end_x, int end_y, color c) {
    for (int y = start_y; y < end_y; ++y)
      for (int x = start_x; x < end_x; ++x)
        vaddr[y * dword_pitch + x] = c;
  }

}