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

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

#define DISP_WIDTH 960
#define DISP_HEIGHT 480

#define FPS 60.0

#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)) );
}

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

	uint8_t bits[DISP_HEIGHT][DISP_WIDTH / 8];

	uint8_t automaton = 0;
	unsigned x, y;

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

	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);
	goframes = 0;

reset:

	al_clear_to_color(al_map_rgb(0, 0, 0));
	memset(bits, 0, DISP_HEIGHT * DISP_WIDTH / 8);

	/* seed bit */
	bit_set(bits[0], DISP_WIDTH / 2);

	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);
			}
		}
	}

	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:
				goframes = DISP_HEIGHT;
				goto reset;

			default:
				continue;

			}

		case ALLEGRO_EVENT_TIMER:
			if (goframes == 0) {
				al_flip_display();
				break;
			}

			/* draw line */
			for (x = 0; x < DISP_WIDTH; x++) {
				if (bit_get(bits[DISP_HEIGHT - goframes], x)) {
					al_draw_filled_rectangle(
						(float)x, (float)(DISP_HEIGHT - goframes),
						(float)(x + 1), (float)(DISP_HEIGHT - goframes + 1),
						al_map_rgb(255, 255, 255)
					);
				}
			}

			al_flip_display();

			goframes--;

			if (goframes == 0)
				puts("next");
		}
	}


done:

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