#include "window/window.h"
#include "c_cpp_aliases/aliases.h"
#include <SDL2/SDL.h>
#include <SDL2/SDL_error.h>
#include <SDL2/SDL_pixels.h>
#include <SDL2/SDL_surface.h>
#include <stdbool.h>
#include <stdio.h>

#define NORMALISED_MIN -1.0f
#define NORMALISED_MAX 1.0f

u32 colour_to_u32(colour_t colour);
u32 index_from_coordinates(window_t *wnd, u32 x, u32 y);
i32 denormalise(f32 value, u32 max);
void set_screen_pixel(window_t *wnd, u32 x, u32 y, colour_t colour);

bool init_window(window_t *wnd, u64 width, u64 height, const char *title) {
  if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
    printf("Failed to initialise SDL: %s\n", SDL_GetError());

    return false;
  }

  wnd->window = SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED,
                                 SDL_WINDOWPOS_CENTERED, width, height, 0);
  if (!(wnd->window)) {
    printf("Failed to create window: %s\n", SDL_GetError());

    close_window(wnd);

    return false;
  }

  wnd->front_buffer = SDL_GetWindowSurface(wnd->window);
  if (!(wnd->front_buffer)) {
    printf("Failed to get front buffer: %s\n", SDL_GetError());

    close_window(wnd);

    return false;
  }

  wnd->back_buffer = SDL_CreateRGBSurfaceWithFormat(0, width, height, 32,
                                                    SDL_PIXELFORMAT_ABGR32);
  if (!(wnd->back_buffer)) {
    printf("Failed to create back buffer: %s\n", SDL_GetError());

    close_window(wnd);

    return false;
  }

  wnd->width = width;
  wnd->height = height;
  wnd->title = title;

  return true;
}

void close_window(window_t *wnd) {
  if (wnd) {
    wnd->width = 0;
    wnd->height = 0;
    wnd->title = "";

    if (wnd->window) {
      SDL_DestroyWindow(wnd->window);

      wnd->window = NULL;
    }

    if (wnd->back_buffer) {
      SDL_FreeSurface(wnd->back_buffer);

      wnd->back_buffer = NULL;
    }
  }

  SDL_Quit();
}

void clear_window(window_t *wnd, colour_t colour) {
  SDL_LockSurface(wnd->back_buffer);

  u32 c = colour_to_u32(colour);

  u32 *pixels = (u32 *)(wnd->back_buffer->pixels);
  u32 count = wnd->back_buffer->w * wnd->back_buffer->h;

  for (u32 i = 0; i < count; ++i) {
    pixels[i] = c;
  }

  SDL_UnlockSurface(wnd->back_buffer);
}

void set_pixel(window_t *wnd, f32 x, f32 y, colour_t colour) {
  i32 screen_x = denormalise(x, wnd->width);
  i32 screen_y = denormalise(-y, wnd->height);

  if (screen_x < 0 || screen_y < 0) {
    return;
  }

  SDL_LockSurface(wnd->back_buffer);

  set_screen_pixel(wnd, screen_x, screen_y, colour);

  SDL_UnlockSurface(wnd->back_buffer);
}

void swap_buffers(window_t *wnd) {
  SDL_BlitSurface(wnd->back_buffer, NULL, wnd->front_buffer, NULL);

  SDL_UpdateWindowSurface(wnd->window);
}

u32 colour_to_u32(colour_t colour) {
  return ((u32)(colour.r) << 24) | ((u32)(colour.g) << 16) |
         ((u32)(colour.b) << 8) | (u32)(colour.a);
}

u32 index_from_coordinates(window_t *wnd, u32 x, u32 y) {
  return y * wnd->width + x;
}

i32 denormalise(f32 value, u32 max) {
  if (max == 0 || value < NORMALISED_MIN || value >= NORMALISED_MAX) {
    return -1;
  }

  return (i32)(((value - NORMALISED_MIN) * max) /
               (NORMALISED_MAX - NORMALISED_MIN));
}

void set_screen_pixel(window_t *wnd, u32 x, u32 y, colour_t colour) {
  u32 index = index_from_coordinates(wnd, x, y);
  u32 c = colour_to_u32(colour);

  u32 *pixels = (u32 *)(wnd->back_buffer->pixels);

  pixels[index] = c;
}