/*
 * Copyright (C) 2022 Camden Dixie O'Brien
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this program.  If not, see
 * <https://www.gnu.org/licenses/>.
 */

#include "solve.h"
#include "sud.h"

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define PROG_UPDATEPRD 20
#define NPUZZLES 1024U

static uint32_t getseed(void)
{
	FILE *urandom = fopen("/dev/urandom", "rb");
	if (urandom == NULL)
		fprintf(stderr, "Failed to open /dev/urandom\n");

	uint32_t seed = 0;
	for (unsigned i = 0; i < 4; ++i)
		seed = seed << 8 | fgetc(urandom);

	fclose(urandom);

	return seed;
}

int main(void)
{
	uint32_t seed = getseed();
	printf("Seed: %u\n\n", seed);
	srand(seed);

	struct sudoku puzzles[NPUZZLES];
	unsigned i, j, bslen = 0;
	fputs("Generating... ", stdout);
	for (i = 0; i < NPUZZLES; ++i) {
		if (i % PROG_UPDATEPRD == 0) {
			for (j = 0; j < bslen; ++j)
				putchar('\b');
			bslen = (unsigned)printf("%u%%", 100 * i / NPUZZLES);
			fflush(stdout);
		}

		gen(&puzzles[i]);
	}
	for (j = 0; j < bslen; ++j)
		putchar('\b');
	puts("100%");

	bool res[NPUZZLES];
	struct timespec start, end;
	fputs("Solving... ", stdout);
	fflush(stdout);
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start);
	for (i = 0; i < NPUZZLES; ++i)
		res[i] = solve(&puzzles[i]);
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end);
	puts("done");

	long secs = end.tv_sec - start.tv_sec;
	long nanos = end.tv_nsec - start.tv_nsec;
	if (nanos < 0) {
		--secs;
		nanos += 1000000000;
	}
	const double tot_micros = 1e6 * (double)secs + (double)nanos / 1e3;
	const double avg_micros = tot_micros / NPUZZLES;

	unsigned solved = 0;
	for (i = 0; i < NPUZZLES; ++i) {
		if (res[i] && check(&puzzles[i]) == SOLVED)
			++solved;
	}

	puts("\n       SUMMARY\n       =======");
	printf("Success rate: %.0lf%%\n", 1e2 * (double)solved / NPUZZLES);
	printf("Average time: %.3lf µs\n", avg_micros);

	return 0;
}