/* Copyright (C) 2021  June McEnroe <june@causal.agency>
 *
 * 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 <http://www.gnu.org/licenses/>.
 */

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sysexits.h>
#include <unistd.h>

static void run(char *argv[]) {
	pid_t pid = fork();
	if (pid < 0) err(EX_OSERR, "fork");
	if (!pid) {
		execvp(argv[0], argv);
		err(126, "%s", argv[0]);
	}

	int status;
	pid = wait(&status);
	if (pid < 0) err(EX_OSERR, "wait");
	if (WIFEXITED(status)) {
		status = WEXITSTATUS(status);
		if (status) exit(status);
	} else {
		exit(status);
	}
}

int main(int argc, char *argv[]) {
	if (argc < 2) errx(EX_USAGE, "interval required");
	if (argc < 3) errx(EX_USAGE, "command required");

	unsigned interval = 0;
	char *spec = argv[1];
	while (*spec) {
		unsigned num = strtoul(spec, &spec, 10);
		switch (*spec) {
			break; case '\0': interval += num;
			break; case 's': spec++; interval += num;
			break; case 'm': spec++; interval += 60 * num;
			break; case 'h': spec++; interval += 60 * 60 * num;
			break; default: errx(EX_USAGE, "invalid interval unit %c", *spec);
		}
	}
	if (!interval) errx(EX_USAGE, "invalid zero interval");

#ifdef __OpenBSD__
	int error = pledge("stdio proc exec", NULL);
	if (error) err(EX_OSERR, "pledge");
#endif

	for (;;) {
		run(&argv[2]);
		sleep(interval);
	}
}