#!/bin/bash
set -euo pipefail
LOCK=/tmp/after-lock.lock
INITIAL_DELAY=3
LOOP_DELAY=17

if ! mkdir "${LOCK}" &> /dev/null; then
    exit 0
fi
cleanup() {
    rmdir "${LOCK}"
}
trap cleanup INT TERM EXIT

screensaver_isactive() {
    [[ $(qdbus org.kde.screensaver /ScreenSaver org.freedesktop.ScreenSaver.GetActive) = "true" ]]
}

display_shouldsleep() {
    if ! xset q | grep -q Monitor; then
        return 0
    elif [[ "$(xset q | grep -oP '(?<=Monitor is )\w+')" = 'On' ]]; then
        return 0
    fi
    return 1
}

sleep "${INITIAL_DELAY}"
while screensaver_isactive; do
    if display_shouldsleep; then
        xset dpms force suspend
    fi
    sleep "${LOOP_DELAY}"
done