/*
 * 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 256U

struct bench_res {
	double succ_rate;
	double avg_time_us;
	double avg_passes;
};

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;
}

static void genpuzzles(struct sudoku puzzles_out[NPUZZLES],
    double fill_prop,
    bool print_progress)
{
	unsigned i, j, bslen = 0;

	if (print_progress)
		fputs("Generating... ", stdout);

	for (i = 0; i < NPUZZLES; ++i) {
		if (print_progress && i % PROG_UPDATEPRD == 0) {
			for (j = 0; j < bslen; ++j)
				putchar('\b');
			bslen = (unsigned)printf("%u%%", 100 * i / NPUZZLES);
			fflush(stdout);
		}

		gen(&puzzles_out[i], fill_prop);
	}

	if (print_progress) {
		for (i = 0; i < bslen; ++i)
			putchar('\b');
		puts("100%");
	}
}

static void runbench(struct sudoku puzzles[NPUZZLES], struct bench_res *res_out)
{
	int res[NPUZZLES];
	unsigned i;
	struct timespec start, end;

	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);

	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;

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

	res_out->succ_rate = (double)solved / NPUZZLES;
	res_out->avg_time_us = tot_micros / NPUZZLES;
	res_out->avg_passes = (double)tot_passes / NPUZZLES;
}

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

	struct sudoku puzzles[NPUZZLES];
	struct bench_res res;
	genpuzzles(puzzles, 0.33, true);
	runbench(puzzles, &res);

	puts("\n       SUMMARY\n       =======");
	printf("Success rate: %.0lf%%\n", 1e2 * res.succ_rate);
	printf("Average time: %.3lf µs\n", res.avg_time_us);
	printf("Average n.o. passes: %0.3lf\n", res.avg_passes);

	return 0;
}