#define _USE_MATH_DEFINES
#define SDL_MAIN_USE_CALLBACKS

#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
#include <cmath>

static SDL_Window* window = nullptr;
static SDL_Renderer* renderer = nullptr;
static SDL_Texture* texture = nullptr;

constexpr int WIDTH = 160;
constexpr int HEIGHT = 160;
constexpr int SIZE = WIDTH * HEIGHT;
constexpr int ZOOM = 4;

static Uint8 surface_buffer[SIZE];
static Uint32 palette[2] = { 0xFF000000, 0xFFFFFFFF };

SDL_AppResult SDL_AppInit(void **appstate, int argc, char **argv)
{
    if (!SDL_Init(SDL_INIT_VIDEO)) {
        return SDL_APP_FAILURE;
    }

    window = SDL_CreateWindow("pixels", WIDTH * ZOOM, HEIGHT * ZOOM, 0);
    renderer = SDL_CreateRenderer(window, nullptr);
    SDL_SetRenderLogicalPresentation(renderer, WIDTH, HEIGHT, SDL_LOGICAL_PRESENTATION_INTEGER_SCALE);

    texture = SDL_CreateTexture(renderer,
                                SDL_PIXELFORMAT_ARGB8888,
                                SDL_TEXTUREACCESS_STREAMING,
                                WIDTH, HEIGHT);
    SDL_SetTextureScaleMode(texture, SDL_SCALEMODE_NEAREST);

    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
{
    if (event->type == SDL_EVENT_QUIT ||
        (event->type == SDL_EVENT_KEY_DOWN && event->key.key == SDLK_ESCAPE))
    {
        return SDL_APP_SUCCESS;
    }

    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppIterate(void *appstate)
{
    Uint32* pixels;
    int pitch;

    SDL_LockTexture(texture, nullptr, (void**)&pixels, &pitch);

    // limpiar surface
    for (int i = 0; i < SIZE; ++i)
        surface_buffer[i] = 0;

    // dibujar efecto
    float time = SDL_GetTicks() / 1000.0f;
    int rad = 96;
    int dx = (WIDTH - (rad * 2)) / 2;
    int dy = (HEIGHT - (rad * 2)) / 2;

    for (int j = -rad; j <= rad; j += 3)
    {
        for (int i = -rad; i <= rad; i += 2)
        {
            float dist = sqrt(i * i + j * j);
            float z = cos((dist / 40 - time) * M_PI * 2) * 6;

            int X = rad + i + dx;
            int Y = rad + j - z + dy;

            if (X >= 0 && X < WIDTH && Y >= 0 && Y < HEIGHT)
                surface_buffer[X + Y * WIDTH] = 1;
        }
    }

    int pixel_pitch = pitch / sizeof(Uint32);
    for (int y = 0; y < HEIGHT; ++y)
    {
        for (int x = 0; x < WIDTH; ++x)
        {
            int idx = x + y * WIDTH;
            pixels[x + y * pixel_pitch] = palette[surface_buffer[idx]];
        }
    }

    SDL_UnlockTexture(texture);

    SDL_RenderTexture(renderer, texture, nullptr, nullptr);
    SDL_RenderPresent(renderer);

    return SDL_APP_CONTINUE;
}

void SDL_AppQuit(void *appstate, SDL_AppResult result)
{
    SDL_DestroyTexture(texture);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();
}