#!/bin/sh
#

#set -e

check_stamp()
{
    stamp="$1"
    interval="$2"

    if [ $interval -eq 0 ]; then
        return 1
    fi

    if [ ! -f $stamp ]; then
        return 0
    fi

    # compare midnight today to midnight the day the stamp was updated
    stamp=$(date --date=$(date -r $stamp --iso-8601) +%s)
    now=$(date --date=$(date --iso-8601) +%s)
    delta=$(($now-$stamp))

    if [ $delta -ge $interval ]; then
        return 0
    fi

    return 1
}

update_stamp()
{
    stamp="$1"

    touch $stamp
}

UpdateInterval=0
DownloadUpgradeableInterval=0
eval $(apt-config shell UpdateInterval APT::Periodic::Update-Package-Lists DownloadUpgradeableInterval APT::Periodic::Download-Upgradeable-Packages)
AutocleanInterval=$DownloadUpgradeableInterval
eval $(apt-config shell AutocleanInterval APT::Periodic::Autoclean)

# laptop check, on_ac_power returns:
#       0 (true)    System is on mains power
#       1 (false)   System is not on mains power
#       255 (false) Power status could not be determined
# Desktop systems always return 255 it seems
if which on_ac_power >/dev/null; then
    on_ac_power
    if [ $? -eq 1 ]; then
	exit 0
    fi
fi

UPDATE_STAMP=/var/lib/apt/periodic/update-stamp
if check_stamp $UPDATE_STAMP $UpdateInterval; then
    if apt-get -qq update 2>/dev/null; then
	if which dbus-send >/dev/null; then
	    dbus-send --system / app.apt.dbus.updated boolean:true
	fi
        update_stamp $UPDATE_STAMP
    fi
fi

DOWNLOAD_UPGRADEABLE_STAMP=/var/lib/apt/periodic/download-upgradeable-stamp
if check_stamp $DOWNLOAD_UPGRADEABLE_STAMP $DownloadUpgradeableInterval; then
    apt-get -qq -d dist-upgrade 2>/dev/null
    update_stamp $DOWNLOAD_UPGRADEABLE_STAMP
fi

AUTOCLEAN_STAMP=/var/lib/apt/periodic/autoclean-stamp
if check_stamp $AUTOCLEAN_STAMP $AutocleanInterval; then
    apt-get -qq autoclean
    update_stamp $AUTOCLEAN_STAMP
fi