/*
 * 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 "ds.h"
#include "solve.h"
#include "sud.h"

#include <fcntl.h>
#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>

#define IFNAME "puzzles"
#define OFNAME "results"
#define FSIZE (NPUZZ * NCELLS)

#define NTHREADS 8U
#define PUZZPT (NPUZZ / NTHREADS)
#define CELLPT (PUZZPT * NCELLS)

static char *ibuf;
static char *obuf;

void *threadproc(void *arg)
{
	unsigned start = CELLPT * (uintptr_t)arg, o;
	const char *libuf = ibuf + start;
	char *lobuf = obuf + start;
	struct sudoku sud;

	for (o = 0; o < CELLPT; o += NCELLS) {
		load(&sud, libuf + o);
		solve(&sud);
		save(&sud, lobuf + o);
	}

	return NULL;
}

int main(void)
{
	int fd;
	pthread_t pool[NTHREADS];
	uintptr_t i;

	fd = open(IFNAME, O_RDONLY);
	if (fd == -1) {
		fputs("Failed to open puzzles file\n", stderr);
		return EXIT_FAILURE;
	}
	ibuf = mmap(NULL, FSIZE, PROT_READ, MAP_PRIVATE, fd, 0);
	if (ibuf == MAP_FAILED) {
		fputs("Failed to mmap() puzzles file\n", stderr);
		return EXIT_FAILURE;
	}
	close(fd);

	fd = open(OFNAME, O_RDWR);
	if (fd == -1) {
		fputs("Failed to open results file\n", stderr);
		return EXIT_FAILURE;
	}
	obuf = mmap(NULL, FSIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (obuf == MAP_FAILED) {
		fputs("Failed to mmap() results file\n", stderr);
		return EXIT_FAILURE;
	}
	close(fd);

	for (i = 0; i < NTHREADS; ++i) {
		if (pthread_create(&pool[i], NULL, threadproc, (void *)i) != 0)
			fprintf(stderr, "Failed to create thread #%lu\n", i);
	}
	for (i = 0; i < NTHREADS; ++i) {
		if (pthread_join(pool[i], NULL) != 0)
			fprintf(stderr, "Failed to join thread #%lu\n", i);
	}

	munmap(ibuf, FSIZE);
	munmap(obuf, FSIZE);
	return EXIT_SUCCESS;
}