#include <hilbert/kernel/application.hpp>
#include <hilbert/kernel/framebuffer.hpp>
#include <hilbert/kernel/syscall.hpp>

namespace hilbert::kernel::framebuffer {

  static uint64_t paddr;
  static uint32_t *vaddr;
  int width;
  int height;
  static int dword_pitch;

  void encode_color_syscall(
    uint64_t &rax, uint64_t &rdi, uint64_t &rsi, uint64_t &rdx
  ) {
    rax = (uint64_t)encode_color(
      rdi & 0xff, (rdi >> 8) & 0xff, (rdi >> 16) & 0xff);
    rdi = 0;
    rsi = 0;
    rdx = 0;
  }

  void get_framebuffer_syscall(
    uint64_t &rax, uint64_t &rdi, uint64_t &rsi, uint64_t &rdx
  ) {

    auto *app = application::running_app;
    if (app->framebuffer_vaddr == 0) {
      uint64_t pages_needed = (dword_pitch * height * 4 - 1) / 4096 + 1;
      uint64_t vaddr = app->get_free_vaddr_pages(pages_needed);
      for (uint64_t i = 0; i < pages_needed; ++i)
        app->map_page(vaddr + i * 4096, paddr + i * 4096, true, false, false);
      app->framebuffer_vaddr = vaddr;
    }

    rax = app->framebuffer_vaddr;
    rdi = (uint64_t)(uint32_t)width | ((uint64_t)(uint32_t)height << 32);
    rsi = (uint32_t)dword_pitch;
    rdx = 0;

  }

  void init_framebuffer(uint64_t paddr, uint64_t vaddr,
    uint64_t width, uint64_t height, uint64_t pitch
  ) {

    //TODO: assumes 32-bpp rgb

    framebuffer::paddr = paddr;
    framebuffer::vaddr = (uint32_t *)vaddr;
    framebuffer::width = width;
    framebuffer::height = height;
    dword_pitch = pitch / 4;

    syscall::add_syscall(0, &encode_color_syscall);
    syscall::add_syscall(1, &get_framebuffer_syscall);

  }

  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;
  }

}