#!@BASH_PATH@

watchman_version='@VERSION@'

msg() { printf '%s\n' "$*"; }
err() { printf '%s\n' "$*" >&2; }

usage() {
	while read; do msg "$REPLY"; done <<- 'EOF'
		Usage: watchman-svc <-p pidfile> [options] command
		Flags:
		       -p <pidfile>
		       -l <logfile>
		       -r           # Respawn the process if it dies.
		       -h           # Show this message.
		       -v           # Show version.
	EOF
}

cleanup() {
	for i in "$respawn_pid" "$job_pid"; do
		kill_wait "$i" || {
			err "Failed to stop child: $i"
			exit 13
		}
	done

	rm -f "$job_pidfile"
}

respawn_cleanup() {
	kill_wait "$job_pid" || {
		err "Failed to stop child: $i"
		exit 13
	}

	return 0
}

respawn_passthrough() {
	kill -"$1" "$job_pid"
}

kill_wait() {
	kill "$1" &>/dev/null

	counter=0
	while kill -0 "$1" &>/dev/null; do
		sleep 1
		(( counter >= 10 )) && { return 1; }
		(( counter++ ))
	done

	return 0
}

job_run() {
	"${cmd[@]}" >&3 2>&3 & job_pid=$!
	export job_pid
	return 0
}


job_respawn() {
	trap 'respawn_cleanup; return' INT TERM

	trap 'respawn_passthrough 1' HUP
	trap 'respawn_passthrough 10' USR1
	trap 'respawn_passthrough 12' USR2

	while job_run; do
		last_run=$SECONDS
		if kill -0 "$job_pid"; then
			wait "$job_pid"
		fi

		curtime=$SECONDS
		if (( last_run + 1 > ( curtime - 2 ) )); then
			err "The job exists right as we start it. Bailing."
			return 1
		fi
	done
}

job_wait() {
	trap cleanup INT TERM

	if (( flag_respawn )); then
		job_respawn & respawn_pid=$!
		
		printf '%s' "$respawn_pid" > "$job_pidfile"

		wait "$respawn_pid"
	else
		job_run

		printf '%s' "$job_pid" > "$job_pidfile"

		wait "$job_pid"
	fi

	cleanup
}

main() {
	while (( $# )); do
		case "$1" in
			(-h) usage; return 0;;

			(-p) job_pidfile="$2"; shift;;
			(-l) job_logfile="$2"; shift;;

			(-r) flag_respawn=1;;

			(-v)
				printf '%s\n' "$watchman_version"
				exit 0
			;;

			(--) shift; break;;
			(-*)
				err "Unknown key: $1"
				usage
				return 1
			;;

			(*) break;;
		esac
		shift
	done

	if [[ -z "$job_pidfile" ]]; then
		usage
		return 1
	fi

	cmd=( "$@" )

	if [[ "$job_logfile" ]]; then
		exec 3>"$job_logfile"
	else
		exec 3>&1
	fi

	job_wait &

	return 0
}

main "$@"