#!/bin/sh

set -e

_adopt_conffile() {
    conffile=$1
    pkg=$2

    [ -f "${conffile}.dpkg-bak" ] || return 0

    md5sum="$(md5sum "${conffile}" | sed -e 's/ .*//')"
    old_md5sum="$(dpkg-query -W -f='${Conffiles}' "$pkg" | \
                        sed -n -e "\' ${conffile} ' { s/ obsolete$//; s/.* //; p }")"
    # On new installs, if the policy file was preserved on systemd upgrade
    # by dpkg-maintscript helper, copy it back if the new file has not been modified yet
    if [ "$md5sum" = "$old_md5sum" ]; then
        mv "${conffile}.dpkg-bak" "${conffile}"
    fi
}


if [ "$1" = configure ] && [ -z "$2" ]; then
    _adopt_conffile "${DPKG_ROOT}/etc/systemd/resolved.conf" systemd-resolved
fi

if [ "$1" = configure ] && dpkg --compare-versions "$2" lt 251.4-2; then
    if [ "$(readlink "${DPKG_ROOT}/etc/resolv.conf")" != "../run/systemd/resolve/stub-resolv.conf" ] && [ "$(readlink "${DPKG_ROOT}/etc/resolv.conf")" != "/run/systemd/resolve/stub-resolv.conf" ]; then
        echo "Converting /etc/resolv.conf to a symlink to /run/systemd/resolve/stub-resolv.conf..."
        if [ -f "${DPKG_ROOT}/etc/resolv.conf" ]; then
            mv "${DPKG_ROOT}/etc/resolv.conf" "${DPKG_ROOT}/etc/.resolv.conf.systemd-resolved.bak" || echo "Cannot take a backup of /etc/resolv.conf."
        fi
        ln -sf ../run/systemd/resolve/stub-resolv.conf "${DPKG_ROOT}/etc/resolv.conf" || echo "Cannot install symlink from /etc/resolv.conf to ../run/systemd/resolve/stub-resolv.conf"
    fi
fi

#DEBHELPER#