/*
 * Copyright (c) Camden Dixie O'Brien
 * SPDX-License-Identifier: AGPL-3.0-only
 */

#include "puzz.h"

#include <assert.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

enum { NO = 0, YES = 1 };

static puzz_t soln;
static puzz_t scanned;

void gen(void)
{
	memset(soln, 0, sizeof(soln));

	for (int i = 0; i < NMINES; ++i) {
		int x, y;
		do {
			x = rand() % WIDTH;
			y = rand() % HEIGHT;
		} while (soln[x][y] == MINE);
		soln[x][y] = MINE;
	}

	for (int y = 0; y < HEIGHT; ++y) {
		for (int x = 0; x < WIDTH; ++x) {
			if (soln[x][y] == MINE)
				continue;
			soln[x][y] = countadj(soln, x, y, MINE);
		}
	}
}

void print(puzz_t puzz)
{
	for (int y = 0; y < HEIGHT; ++y) {
		for (int x = 0; x < WIDTH; ++x) {
			char c;
			switch (puzz[x][y]) {
			case MINE:
				c = 'x';
				break;
			case UNKNOWN:
				c = '.';
				break;
			default:
				c = '0' + puzz[x][y];
				break;
			}
			putchar(c);
		}
		putchar('\n');
	}
	putchar('\n');
}

void printsoln(void)
{
	puts("Solution:");
	print(soln);
}

static void scan_copy(int x, int y, puzz_t out)
{
	assert(x >= 0 && x < WIDTH);
	assert(y >= 0 && y < HEIGHT);

	out[x][y] = soln[x][y];
	scanned[x][y] = YES;

	if (soln[x][y] != 0)
		return;

	for (int yp = y - 1; yp < y + 2; ++yp) {
		for (int xp = x - 1; xp < x + 2; ++xp) {
			if (xp < 0 || xp >= WIDTH || yp < 0 || yp >= HEIGHT
			    || scanned[xp][yp] == YES)
				continue;
			scan_copy(xp, yp, out);
		}
	}
}

status_t probe(int x, int y, puzz_t out)
{
	assert(x >= 0 && x < WIDTH);
	assert(y >= 0 && y < HEIGHT);

	if (soln[x][y] == MINE)
		return DEAD;

	memset(scanned, NO, sizeof(scanned));
	scan_copy(x, y, out);

	return OK;
}

status_t check(puzz_t puzz)
{
	for (int y = 0; y < HEIGHT; ++y) {
		for (int x = 0; x < WIDTH; ++x) {
			if (puzz[x][y] != UNKNOWN && puzz[x][y] != soln[x][y])
				return INCORRECT;
		}
	}
	return OK;
}

int countadj(puzz_t field, int x, int y, uint8_t val)
{
	int n = 0;
	for (int yp = y - 1; yp < y + 2; ++yp) {
		for (int xp = x - 1; xp < x + 2; ++xp) {
			if (xp < 0 || xp >= WIDTH || yp < 0 || yp >= HEIGHT
			    || (xp == x && yp == y))
				continue;
			n += field[xp][yp] == val ? 1 : 0;
		}
	}
	return n;
}