#include <complex.h>
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <SDL2/SDL.h>

// Some polyfills for complex numbers
#if !defined(CMPLX)
#define CMPLX(x, y) ((double complex)((double)(x) + I * (double)(y)))
#define CMPLXF(x, y) ((float complex)((float)(x) + I * (float)(y)))
#define CMPLXL(x, y)                                                           \
	((long double complex)((long double)(x) + I * (long double)(y)))
#endif

static uintmax_t mandle(long double complex const c)
{
	const uintmax_t max = UINTMAX_MAX;
	if ((pow(creal(c) - 0.25, 2) + pow(cimag(c), 2)) *
		    (pow(creal(c), 2) + (creal(c) / 2) + pow(cimag(c), 2) -
		     0.1875) <
		pow(cimag(c), 2) / 4 ||
	    pow(creal(c) + 1, 2) + pow(cimag(c), 2) < 0.0625) {
		return 0;
	}
	long double complex z = c;
	long double complex dz = CMPLXL(1, 0);

	for (uintmax_t iteration = 0; iteration <= max; iteration++) {
		if (pow(creal(dz), 2) + pow(cimag(dz), 2) * pow(cimag(dz), 2) <
		    1e-300) {
			break;
		}
		if (pow(creal(z), 2) + pow(cimag(z), 2) > 4.0) {
			return iteration;
		}

		z = z * z + c;
		dz *= 2 * z;
	}
	return 0;
}

static inline void putpixel(SDL_Surface *surface, SDL_Point const point,
			    SDL_Color color)
{
	if (surface->w <= point.x || surface->h <= point.y) {
		return;
	}
	uint32_t const pixel =
	    SDL_MapRGBA(surface->format, color.r, color.g, color.b, color.a);
	int bpp = surface->format->BytesPerPixel;
	if (SDL_MUSTLOCK(surface)) {
		SDL_LockSurface(surface);
	}

	uint8_t *p = (uint8_t *)surface->pixels + point.y * surface->pitch +
		     point.x * bpp;

	switch (bpp) {
	case 1:
		*p = pixel;
		break;
	case 2:
		*(uint16_t *)p = pixel;
		break;
	case 3:
		if (SDL_BYTEORDER == SDL_BIG_ENDIAN) {
			p[0] = pixel >> 16 & UINT8_MAX;
			p[1] = pixel >> 8 & UINT8_MAX;
			p[2] = pixel & UINT8_MAX;
		} else {
			p[0] = pixel & UINT8_MAX;
			p[1] = (pixel >> 8) & UINT8_MAX;
			p[2] = (pixel >> 16) & UINT8_MAX;
		}
		break;
	case 4:
		*(uint32_t *)p = pixel;
		break;
	}

	if (SDL_MUSTLOCK(surface)) {
		SDL_UnlockSurface(surface);
	}
}

static inline SDL_Color color_scheme(uintmax_t iteration)
{
	uint8_t color_scale = iteration & UINT8_MAX;
	unsigned type = iteration >> 8;
	unsigned color_mask = 255 * (type % 5) / 4;
	SDL_Color color = {.r = 0, .b = 0, .g = 0, .a = 255};
	switch ((type / 5) % 19) {
	case 0:
		color = (SDL_Color){
		    .r = 0, .b = color_mask, .g = color_scale, .a = 255};
		break;
	case 1:
		color = (SDL_Color){
		    .r = 255, .b = color_mask, .g = color_scale, .a = 255};
		break;
	case 2:
		color = (SDL_Color){
		    .r = color_mask, .b = 0, .g = color_scale, .a = 255};
		break;
	case 3:
		color = (SDL_Color){
		    .r = color_mask, .b = 255, .g = color_scale, .a = 255};
		break;
	case 4:
		color = (SDL_Color){.r = color_mask,
				    .b = color_mask,
				    .g = color_scale,
				    .a = 255};
		break;
	case 5:
		color = (SDL_Color){
		    .r = 0, .b = color_scale, .g = color_mask, .a = 255};
		break;
	case 6:
		color = (SDL_Color){
		    .r = 255, .b = color_scale, .g = color_mask, .a = 255};
		break;
	case 7:
		color = (SDL_Color){
		    .r = color_mask, .b = color_scale, .g = 0, .a = 255};
		break;
	case 8:
		color = (SDL_Color){
		    .r = color_mask, .b = color_scale, .g = 255, .a = 255};
		break;
	case 9:
		color = (SDL_Color){.r = color_mask,
				    .b = color_scale,
				    .g = color_mask,
				    .a = 255};
		break;
	case 10:
		color = (SDL_Color){
		    .r = color_scale, .b = 0, .g = color_mask, .a = 255};
		break;
	case 11:
		color = (SDL_Color){
		    .r = color_scale, .b = 255, .g = color_mask, .a = 255};
		break;
	case 12:
		color = (SDL_Color){
		    .r = color_scale, .b = color_mask, .g = 0, .a = 255};
		break;
	case 13:
		color = (SDL_Color){
		    .r = color_scale, .b = color_mask, .g = 255, .a = 255};
		break;
	case 14:
		color = (SDL_Color){.r = color_scale,
				    .b = color_mask,
				    .g = color_mask,
				    .a = 255};
		break;
	case 15:
		color = (SDL_Color){.r = color_scale,
				    .b = color_scale,
				    .g = color_mask,
				    .a = 255};
		break;
	case 16:
		color = (SDL_Color){.r = color_scale,
				    .b = color_mask,
				    .g = color_scale,
				    .a = 255};
		break;
	case 17:
		color = (SDL_Color){.r = color_mask,
				    .b = color_scale,
				    .g = color_scale,
				    .a = 255};
		break;
	case 18:
		color = (SDL_Color){.r = color_scale,
				    .b = color_scale,
				    .g = color_scale,
				    .a = 255};
		break;
	}
	return (type / (5 * 19)) % 2 ? color
				     : (SDL_Color){.r = ~color.r,
						   .b = ~color.b,
						   .g = ~color.g,
						   .a = color.a};
}

struct mandle_thr {
	SDL_Surface *surface;
	SDL_Point point;
	SDL_mutex *mutex;
	SDL_cond *cond;
	SDL_mutex *cond_mutex;
	uint32_t job_id;
	char sleep_no;
	bool quit;
	long double complex centre;
	long double scale;
};

static int mandle_thr(void *ptr)
{
	struct mandle_thr *data = ptr;
	uint32_t id = 0;
	SDL_LockMutex(data->cond_mutex);
	data->sleep_no++;
	SDL_CondWait(data->cond, data->cond_mutex);
	data->sleep_no--;
	SDL_UnlockMutex(data->cond_mutex);
	SDL_LockMutex(data->mutex);
	while (true) {
		if (data->quit) {
			SDL_UnlockMutex(data->mutex);
			return 0;
		}
		if (id != data->job_id) {
			id = data->job_id;
		}
		SDL_Point point = data->point;
		if (data->point.x < data->surface->w) {
			data->point.x++;
		} else if (data->point.y < data->surface->h) {
			data->point.y++;
			data->point.x = 0;
		} else {
			SDL_UnlockMutex(data->mutex);
			SDL_LockMutex(data->cond_mutex);
			data->sleep_no++;
			SDL_CondWait(data->cond, data->cond_mutex);
			data->sleep_no--;
			SDL_UnlockMutex(data->cond_mutex);
			SDL_LockMutex(data->mutex);
			id = data->job_id;
		}
		long double complex z =
		    data->scale * 2.50 *
			CMPLXL((long double)point.x + 1e-10 - (long double)data->surface->w/2,
			       (long double)point.y + 1e-10 - (long double)data->surface->h/2) /
			(long double)data->surface->w +
		    data->centre;
		SDL_UnlockMutex(data->mutex);

		SDL_Color color = color_scheme(mandle(z));

		SDL_LockMutex(data->mutex);
		putpixel(data->surface, point, color);
	}
}

static uint32_t update_screen(uint32_t interval, void *param)
{
	SDL_Event event;
	event.type = SDL_USEREVENT;
	event.user = (SDL_UserEvent){
	    .type = SDL_USEREVENT,
	    .code = *(uint32_t *)param,
	    .data1 = NULL,
	    .data2 = NULL,
	};

	SDL_PushEvent(&event);
	return interval;
}

int main(int argc, char *argv[argc + 1])
{
	(void)argv;
	SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER);
	SDL_Window *window = SDL_CreateWindow("Mandle", SDL_WINDOWPOS_CENTERED,
					      SDL_WINDOWPOS_CENTERED, 640, 480,
					      SDL_WINDOW_RESIZABLE);
	if (!window) {
		SDL_LogMessage(SDL_LOG_CATEGORY_ERROR, SDL_LOG_PRIORITY_ERROR,
			       "Unable to create window: %s", SDL_GetError());
		return EXIT_FAILURE;
	}

	long double complex centre = CMPLXL(-0.765, 0);
	long double scale = 1;
	long double complex const org_centre = centre;

	uint32_t TimeEvent = SDL_RegisterEvents(1);
	SDL_TimerID timer = SDL_AddTimer(40, update_screen, &TimeEvent);
	SDL_Event event;
	bool render = true;

	struct mandle_thr data = {
	    .mutex = SDL_CreateMutex(),
	    .cond_mutex = SDL_CreateMutex(),
	    .cond = SDL_CreateCond(),
	    .quit = false,
	    .job_id = 0,
	};

	SDL_Thread *thread[SDL_GetCPUCount()];
	for (size_t i = 0; i < sizeof thread / sizeof thread[0]; ++i) {
		thread[i] = SDL_CreateThread(mandle_thr, "Renderer", &data);
		if (!thread[i]) {
			SDL_LogMessage(
			    SDL_LOG_CATEGORY_RENDER, SDL_LOG_PRIORITY_ERROR,
			    "SDL_CreateThread failed: %s\n", SDL_GetError());
		}
	}

	while (!data.quit) {
		SDL_WaitEvent(&event);
		switch (event.type) {
		case SDL_QUIT:
			data.quit = true;
			break;
		case SDL_WINDOWEVENT:
			switch (event.window.event) {
			case SDL_WINDOWEVENT_SIZE_CHANGED:
				render = true;
				break;
			}
			break;
		case SDL_KEYDOWN:
			switch (event.key.keysym.sym) {
			case SDLK_UP:
				centre -= CMPLXL(0, 0.1 * scale);
				render = true;
				break;
			case SDLK_DOWN:
				centre += CMPLXL(0, 0.1 * scale);
				render = true;
				break;
			case SDLK_RIGHT:
				centre += CMPLXL(0.1 * scale, 0);
				render = true;
				break;
			case SDLK_LEFT:
				centre -= CMPLXL(0.1 * scale, 0);
				render = true;
				break;
			case SDLK_EQUALS:
			case SDLK_KP_PLUS:
				scale /= 2;
				render = true;
				break;
			case SDLK_MINUS:
				scale *= 2;
				render = true;
				break;
			case SDLK_0:
				centre = org_centre;
				scale = 1;
				render = true;
				break;
			case SDLK_q: {
				data.quit = true;
				break;
			}
			case SDLK_F11: {
				bool flag = SDL_GetWindowFlags(window) &
					    SDL_WINDOW_FULLSCREEN_DESKTOP;
				SDL_SetWindowFullscreen(
				    window,
				    flag ? 0 : SDL_WINDOW_FULLSCREEN_DESKTOP);
				break;
			}
			}
			break;
		case SDL_USEREVENT: {
			SDL_UpdateWindowSurface(window);
			break;
		}
		}
		if (render) {
			char title[50] = {0};
			snprintf(title, sizeof title, "Mandle %LG%+LGi x%Lf",
				 creall(centre), cimagl(centre), 1 / scale);
			SDL_SetWindowTitle(window, title);
			SDL_LockMutex(data.mutex);
			data.job_id++;
			data.point = (SDL_Point){.x = 0, .y = 0};
			data.centre = centre;
			data.surface = SDL_GetWindowSurface(window);
			data.scale = scale;
			SDL_FillRect(data.surface, NULL,
				     SDL_MapRGB(data.surface->format, 0, 0, 0));
			SDL_UnlockMutex(data.mutex);
			SDL_CondBroadcast(data.cond);
			render = false;
		}
	}
	SDL_CondBroadcast(data.cond);
	for (size_t i = 0; i < sizeof thread / sizeof thread[0]; ++i) {
		SDL_WaitThread(thread[i], NULL);
	}
	SDL_RemoveTimer(timer);
	SDL_DestroyMutex(data.mutex);
	SDL_DestroyMutex(data.cond_mutex);
	SDL_DestroyCond(data.cond);

	SDL_DestroyWindow(window);
	SDL_Quit();
	return EXIT_SUCCESS;
}