#!/bin/sh

set -eu

ZSYS_SNAPSHOT_UUFILE="/var/run/zsys-snapshot.unattended-upgrades"
ZSYS_UPDATEOOTMENU_UUFILE="/var/run/zsys-bootmenu.unattended-upgrades"
UUPIDFILE="/var/run/unattended-upgrades.pid"

# Return 0 unattended-upgrade isn’t running or if we didn’t proceeded the action for it yet.
can_run() {
    local zsys_uufile="$1"
    local uupid=""

    # Not running under unattended-upgraded (no pid file)
    if [ ! -f "${UUPIDFILE}" ]; then
        rm -f "${zsys_uufile}"
        return 0
    fi

    # Not running under unattended-upgraded (unattended upgrade has a leftover pid file)
    uupid="$(cat $UUPIDFILE)"
    if ! kill -0 $uupid 2>/dev/null; then
        rm -f "${zsys_uufile}"
        return 0
    fi

    # unattended-upgraded is running, do we have a matching pid file stored?
    if [ -f "${zsys_uufile}" ]; then
        zuupid="$(cat ${zsys_uufile})"
        # We took a snapshot on that unattended-upgrades run. Nothing to do
        if [ "$uupid" = "$zuupid" ]; then
            return 1
        fi
    fi

    cp "${UUPIDFILE}" "${zsys_uufile}"
    return 0
}

zsys_uufile="${ZSYS_SNAPSHOT_UUFILE}"
if [ "$1" = "update-menu" ]; then
    zsys_uufile="${ZSYS_UPDATEOOTMENU_UUFILE}"
fi

if ! can_run "${zsys_uufile}"; then
    exit 0
fi

if [ "$1" = "update-menu" ]; then
    zsysctl boot update-menu --auto
else
    zsysctl state save --system --no-update-bootmenu --auto
fi