#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 BUF_W 256
#define BUF_H 256

#define DISP_SCALE 3

#define SEED_BITS 4096

#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;

	uint8_t bits1[BUF_H][BUF_W / 8] = {0};
	uint8_t bits2[BUF_H][BUF_W / 8] = {0};

	uint8_t framerate = 8;
	unsigned goframes = 1;
	unsigned x, y, sum;

	bool pause = true;
	bool mouse_down = false;

	ALLEGRO_MOUSE_STATE ms;

	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(al_install_mouse(), "mouse");

	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_SCALE * BUF_W, DISP_SCALE * BUF_H
			), "display"
	);
	al_set_new_bitmap_flags(ALLEGRO_MEMORY_BITMAP);
	DO_INIT(b = al_create_bitmap(BUF_W, BUF_H), "buffer");

	al_register_event_source(eq, al_get_keyboard_event_source());
	al_register_event_source(eq, al_get_mouse_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);

reset:

	memset(bits1, 0, sizeof(bits1));

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

		switch (e.type) {

		case ALLEGRO_EVENT_DISPLAY_CLOSE:
			goto done;

		case ALLEGRO_EVENT_MOUSE_BUTTON_DOWN:
			bit_set(bits1[e.mouse.y / DISP_SCALE], e.mouse.x / DISP_SCALE);
			mouse_down = true;
			break;

		case ALLEGRO_EVENT_MOUSE_BUTTON_UP:
			mouse_down = false;
			break;

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

			case ALLEGRO_KEY_Q:
				goto done;

			case ALLEGRO_KEY_1:
				framerate = (framerate == 2 ? 16 : framerate / 2);
				printf("fps: %.1f\n", FPS / ((float)framerate) );
				break;

			case ALLEGRO_KEY_2:
				memset(bits1, 0, sizeof(bits1));
				for (x = 0; x < SEED_BITS; x++) {
					bit_set(
						bits1[randombytes_random() % BUF_H],
						randombytes_random() % BUF_W
					);
				}
				break;

			case ALLEGRO_KEY_3:
				goto reset;

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

			default:
				break;

			}

			break;

		case ALLEGRO_EVENT_TIMER:

			if (mouse_down) {
				al_get_mouse_state(&ms);
				bit_set(bits1[ms.y / 2], ms.x / 2);
			}

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

			/* step */

			if (!pause) {
				memset(bits2, 0, sizeof(bits1));

				for (y = 0; y < BUF_H; y++) {
					for (x = 0; x < BUF_W; x++) {
						sum =
							  bit_get(bits1[(y-1) % BUF_H], (x-1) % BUF_W)
							+ bit_get(bits1[(y-1) % BUF_H],  x                )
							+ bit_get(bits1[(y-1) % BUF_H], (x+1) % BUF_W)
							+ bit_get(bits1[ y                 ], (x-1) % BUF_W)
							+ bit_get(bits1[ y                 ], (x+1) % BUF_W)
							+ bit_get(bits1[(y+1) % BUF_H], (x-1) % BUF_W)
							+ bit_get(bits1[(y+1) % BUF_H],  x                )
							+ bit_get(bits1[(y+1) % BUF_H], (x+1) % BUF_W)
						;

						if (sum == 3 || (bit_get(bits1[y], x) && sum == 2))
							bit_set(bits2[y], x);
					}
				}

				memcpy(bits1, bits2, sizeof(bits1));
			}

			/* draw frame */

			al_lock_bitmap(b, ALLEGRO_PIXEL_FORMAT_ANY, ALLEGRO_LOCK_WRITEONLY);

			al_set_target_bitmap(b);

			for (y = 0; y < BUF_H; y++) {
				for (x = 0; x < BUF_W; x++) {
					if (bit_get(bits1[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_scaled_bitmap(b,
				0, 0, BUF_W, BUF_H,
				0, 0, DISP_SCALE * BUF_W, DISP_SCALE * BUF_H,
				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;
}