#!/bin/bash

# /lib/systemd/system-sleep/rtcwake

# chmod a+rx

set -e

AWAKE_TIME="01:23:45" # hour:minute:second

GAP="10 seconds"      # precision of awake time in date(1) format

WAIT_TRIGGER='true'   # test to go back to sleep when action is finished 

                      # typically pgrep on user or for specific process

WAIT_TRIGGER_DELAY=60 # sleep duration in seconds between two tests with WAIT_TRIGGER

MAX_TRIGGER=60        # don't go back to sleep if WAIT_TRIGGER isn't true

                      # after WAIT_TRIGGER_DELAY * MAX_TRIGGER seconds

test -r $0.conf && source $0.conf # all previous variables can be set here

NOW=$(date +%_H%M%S)

RTCWAKE_TIME=$([ $NOW -lt ${AWAKE_TIME//:} ] && date +%s -d $AWAKE_TIME || date +%s -d "tomorrow $AWAKE_TIME")

case "$1/$2" in

    pre/suspend)

        rtcwake -m no -t $RTCWAKE_TIME

        ;;

    post/suspend)

        at -M now <<< "$0 post wait-for-trigger" > /dev/null 2>&1

        ;;

    post/wait-for-trigger)

        if test $NOW -ge ${AWAKE_TIME//:} -a $NOW -le $(date +%_H%M%S -d "$AWAKE_TIME $GAP"); then

            COUNT=1

            while sleep $WAIT_TRIGGER_DELAY && eval $WAIT_TRIGGER; do

                let COUNT++ && [ $COUNT -lt $MAX_TRIGGER ] || exit 0

            done

            rtcwake -m mem -t $RTCWAKE_TIME

        else

            rtcwake -m disable

        fi

        ;;

esac