/*
 * UNG's Not GNU
 *
 * Copyright (c) 2022, Jakob Kaivo <jkk@ung.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#define _POSIX_C_SOURCE 200809L
#include <errno.h>
#include <fcntl.h>
#include <locale.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>

enum times {
	ACCESS = (1<<0),
	MODIFY = (1<<1),
};

static int touch(const char *path, struct timespec times[2], int create)
{
	int fd = open(path, (create ? O_CREAT : 0), 0644);
	if (fd == -1) {
		if (!create && errno == ENOENT) {
			return 0;
		}
		fprintf(stderr, "touch: %s: %s\n", path, strerror(errno));
		return 1;
	}
	if (futimens(fd, times) != 0) {
		fprintf(stderr, "touch: %s: %s\n", path, strerror(errno));
		close(fd);
		return 1;
	}
	close(fd);
	return 0;
}

int main(int argc, char *argv[])
{
	setlocale(LC_ALL, "");
	enum times which = 0;
	int create = 1;
	enum { CURRENT, TIME, DATE, FILE } how = CURRENT;
	char *source = NULL;

	int c;
	while ((c = getopt(argc, argv, "acmr:t:d:")) != -1) {
		switch(c) {
		case 'a':
			which |= ACCESS;
			break;

		case 'c':
			create = 0;
			break;

		case 'm':
			which |= MODIFY;
			break;

		case 'd':
			if (how != CURRENT) {
				fprintf(stderr, "touch: only one of -d, -r, and -t is allowed\n");
				return 1;
			}
			how = DATE;
			source = optarg;
			break;

		case 'r':
			if (how != CURRENT) {
				fprintf(stderr, "touch: only one of -d, -r, and -t is allowed\n");
				return 1;
			}
			how = FILE;
			source = optarg;
			break;

		case 't':
			if (how != CURRENT) {
				fprintf(stderr, "touch: only one of -d, -r, and -t is allowed\n");
				return 1;
			}
			how = TIME;
			source = optarg;
			break;

		default:
			return 1;
		}
	}

	struct timespec times[2] = { { 0 } };
	struct stat st;

	switch (how) {
	case CURRENT:
		times[0].tv_nsec = UTIME_NOW;
		times[0].tv_nsec = UTIME_NOW;
		break;
	case DATE:
		/* TODO */
		break;
	case TIME:
		/* TODO */
		break;
	case FILE:
		if (stat(source, &st) != 0) {
			fprintf(stderr, "touch: %s: %s\n", source, strerror(errno));
			return 1;
		}
		times[0] = st.st_atim;
		times[1] = st.st_mtim;
	}

	if (which == 0) {
		which = ACCESS | MODIFY;
	}

	if (!(which & ACCESS)) {
		times[0].tv_nsec = UTIME_OMIT;
	}

	if (!(which & MODIFY)) {
		times[1].tv_nsec = UTIME_OMIT;
	}

	int ret = 0;
	do {
		ret |= touch(argv[optind++], times, create);
	} while (optind < argc);
	return ret;
}