#!/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 $MAX_TRIGGER ] || {
                    if test -n "$MAIL_ERROR"; then
                        echo -e "WAIT_TRIGGER_DELAY=$WAIT_TRIGGER_DELAY\nMAX_TRIGGER=$MAX_TRIGGER\nWAIT_TRIGGER=$WAIT_TRIGGER\n\n" | mail -s "${0##*/}" $MAIL_ERROR
                    fi
                    exit 0
                }
            done
            rtcwake -m mem -t $RTCWAKE_TIME
        else
            rtcwake -m disable
        fi
        ;;
esac