/* Copyright (C) 2019  C. 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/>.
 */

#import <Cocoa/Cocoa.h>
#import <err.h>
#import <signal.h>
#import <stdlib.h>
#import <sysexits.h>
#import <unistd.h>

static volatile sig_atomic_t sleeping;

static void sigchld(int sig) {
	(void)sig;
	int status;
	pid_t pid = wait(&status);
	if (pid < 0) _exit(EX_OSERR);
	if (WIFSIGNALED(status) && WTERMSIG(status) != SIGHUP) {
		_exit(128 + WTERMSIG(status));
	} else if (!sleeping) {
		_exit(WEXITSTATUS(status));
	}
}

static pid_t spawn(char *argv[]) {
	pid_t pid = fork();
	if (pid < 0) err(EX_OSERR, "fork");
	if (pid) return pid;
	execvp(argv[0], argv);
	err(EX_NOINPUT, "%s", argv[0]);
}

static pid_t pid;

int main(int argc, char *argv[]) {
	if (argc < 2) return EX_USAGE;

	sigset_t mask;
	sigemptyset(&mask);
	struct sigaction action = {
		.sa_handler = sigchld,
		.sa_mask = mask,
		.sa_flags = SA_NOCLDSTOP | SA_RESTART,
	};
	sigaction(SIGCHLD, &action, NULL);

	pid = spawn(&argv[1]);

	[
		[[NSWorkspace sharedWorkspace] notificationCenter]
		addObserverForName: NSWorkspaceWillSleepNotification
		object: nil
		queue: nil
		usingBlock: ^(NSNotification *note) {
			(void)note;
			sleeping = 1;
			int error = kill(pid, SIGHUP);
			if (error) err(EX_UNAVAILABLE, "kill %d", pid);
		}
	];

	[
		[[NSWorkspace sharedWorkspace] notificationCenter]
		addObserverForName: NSWorkspaceDidWakeNotification
		object: nil
		queue: nil
		usingBlock: ^(NSNotification *note) {
			(void)note;
			sleeping = 0;
			pid = spawn(&argv[1]);
		}
	];

	[[NSApplication sharedApplication] run];
}