#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>

#include <allegro5/allegro5.h>
#include <allegro5/allegro_primitives.h>

#include <sodium.h>

#define DISP_WIDTH 640
#define DISP_HEIGHT 480

#define FPS 3.3

#define DO_INIT(check, desc) \
	if (!(check)) { \
		fprintf(stderr, "err: can't initialise %s\n", desc); \
		rval = 1; \
		goto done; \
	}

static bool bit_get(uint8_t *bline, unsigned off)
{
	return (bline[off / 8] >> (off % 8)) & 0x01;
}

static void bit_set(uint8_t *bline, unsigned off)
{
	bline[off / 8] = (bline[off / 8] | (0x01 << (off % 8)) );
}

static void bit_toggle(uint8_t *bline, unsigned off)
{
	bline[off / 8] = (bline[off / 8] ^ (0x01 << (off % 8)) );
}

int main(int argc, char **argv)
{
	int rval = 0;

	uint8_t bits[DISP_HEIGHT][DISP_WIDTH / 8];

	uint8_t automaton = 0;
	unsigned x, y;

	bool pause = 0;

	ALLEGRO_DISPLAY* d = NULL;
	ALLEGRO_TIMER* t = NULL;
	ALLEGRO_EVENT_QUEUE* eq = NULL;
	ALLEGRO_EVENT e;


	DO_INIT(sodium_init() >= 0, "sodium");

	DO_INIT(al_init(), "allegro");
	DO_INIT(al_init_primitives_addon(), "primitives");
	DO_INIT(al_install_keyboard(), "keyboard");

	DO_INIT(t = al_create_timer(1.0 / FPS), "timer");
	DO_INIT(eq = al_create_event_queue(), "event queue");

	al_set_new_display_option(ALLEGRO_SINGLE_BUFFER, 1, ALLEGRO_REQUIRE);
	DO_INIT(d = al_create_display(DISP_WIDTH, DISP_HEIGHT), "display");

	al_register_event_source(eq, al_get_keyboard_event_source());
	al_register_event_source(eq, al_get_display_event_source(d));
	al_register_event_source(eq, al_get_timer_event_source(t));


	al_start_timer(t);

	al_clear_to_color(al_map_rgb(0, 0, 0));

	while(true) {
		al_wait_for_event(eq, &e);

		switch (e.type) {

		case ALLEGRO_EVENT_DISPLAY_CLOSE:
			goto done;

		case ALLEGRO_EVENT_KEY_DOWN:
			switch(e.keyboard.keycode) {

			case ALLEGRO_KEY_UP:
				automaton += 10;
				printf("%d\n", automaton);
				break;

			case ALLEGRO_KEY_DOWN:
				automaton -= 10;
				printf("%d\n", automaton);
				break;

			case ALLEGRO_KEY_LEFT:
				automaton -= 1;
				printf("%d\n", automaton);
				break;

			case ALLEGRO_KEY_RIGHT:
				automaton += 1;
				printf("%d\n", automaton);
				break;

			case ALLEGRO_KEY_ENTER:
				pause = !pause;
				printf("%s\n", pause ? "pause" : "play");
				break;

			default:
				break;

			}

			break;

		case ALLEGRO_EVENT_TIMER:

			if (pause)
				break;

			/* seed bits */

			memset(bits[1], 0, (DISP_HEIGHT - 1) * DISP_WIDTH / 8);

			for (x = 1; x < DISP_WIDTH - 1; x++) {
				if (randombytes_random() < 0x20000000)
					bit_toggle(bits[0], x);
			}

			/* propagate */

			for (y = 0; y < DISP_HEIGHT - 1; y++) {
				for (x = 1; x < DISP_WIDTH - 2; x++) {
					if (
						bit_get(&automaton,
							bit_get(bits[y], x + 2)
							+ bit_get(bits[y], x + 1) * 2
							+ bit_get(bits[y], x) * 4
						)
					) {
						bit_set(bits[y + 1], x + 1);
					}
				}
			}

			/* draw frame */

			al_clear_to_color(al_map_rgb(0, 0, 0));

			for (y = 0; y < DISP_HEIGHT; y++) {
				for (x = 0; x < DISP_WIDTH; x++) {
					if (bit_get(bits[y], x)) {
						al_draw_filled_rectangle(
							(float)x, (float)y,
							(float)(x + 1), (float)(y + 1),
							al_map_rgb(255, 255, 255)
						);
					}
				}
			}

			al_flip_display();
		}
	}


done:

	if (d)
		al_destroy_display(d);
	if (t)
		al_destroy_timer(t);
	if (eq)
		al_destroy_event_queue(eq);
	
	return rval;
}