#!/usr/bin/env bash
# Save every kitty daily session (~/.config/kitty/day_session.py) right before
# shutdown/reboot.
#
# kitty-day-save.service runs this under a logind "delay" inhibitor. When a
# shutdown or reboot starts, logind broadcasts PrepareForShutdown(true) and
# waits (InhibitDelayMaxSec, 5 s by default) for the lock to be released, which
# happens when this script exits. Nothing has been killed yet at that point, so
# every kitty still has all of its windows. The flush also stops further saves
# for a minute, so windows dying during the shutdown can't shrink the saved day.
#
# Usage: kitty-day-save         hold the lock, wait for a shutdown, flush, exit
#        kitty-day-save --now   flush every running kitty immediately
set -u

case "${1-}" in
--now)
    # Every kitty on kitty.conf listens on @kitty-<pid>; ones that don't own
    # a day session ignore the flush.
    for s in $(grep -oE '@kitty-[0-9]+$' /proc/net/unix | sort -u); do
        timeout 3 kitten @ --to "unix:$s" action kitten day_session.py flush >/dev/null 2>&1 &
    done
    wait
    ;;
--wait)
    # grep returns on the first match; gdbus is left to the service's cgroup.
    grep -m1 -q 'PrepareForShutdown (true' < <(
        gdbus monitor --system --dest org.freedesktop.login1 --object-path /org/freedesktop/login1
    ) && exec "$0" --now
    ;;
*)
    exec systemd-inhibit --what=shutdown --mode=delay --who=kitty \
        --why='Saving kitty sessions' "$0" --wait
    ;;
esac