#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 20.0

#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)) );
}

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, randomness = 4, framerate = 2;
	unsigned goframes = 1;
	unsigned x, y;

	bool pause = 0;

	ALLEGRO_DISPLAY *d = NULL;
	ALLEGRO_BITMAP *b = 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_set_new_bitmap_flags(ALLEGRO_MEMORY_BITMAP);
	DO_INIT(b = al_create_bitmap(DISP_WIDTH, DISP_HEIGHT), "buffer");

	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_1:
				randomness = (randomness == 64 ? 4 : randomness * 2);
				break;

			case ALLEGRO_KEY_2:
				framerate = (framerate == 1 ? 8 : framerate / 2);
				break;

			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;

			if (goframes > 1) {
				goframes--;
				break;
			}

			/* seed bits */

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

			for (x = 1; x < DISP_WIDTH - 1; x++) {
				if (! (randombytes_random() % randomness) )
					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_lock_bitmap(b, ALLEGRO_PIXEL_FORMAT_ANY, ALLEGRO_LOCK_WRITEONLY);

			al_set_target_bitmap(b);

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

			al_unlock_bitmap(b);

			al_set_target_backbuffer(d);
			al_draw_bitmap(b, 0, 0, 0);
			al_flip_display();

			goframes = framerate;
		}
	}


done:

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