#!/bin/bash

# make sure this was run as root
if [ $UID -ne 0 ] ; then
    echo "Need to be root; trying sudo"
    exec sudo env BUILD_CONFIG=$BUILD_CONFIG $0 "$@"
fi
. config || exit 0

# Spawn a systemd container that boots the machine, then run the given
# command.  We can't execute systemd-nspawn directly, because that
# only allows us to either boot the machine, or run a command (not
# both).  Instead let's execute systemd-nspawn in a transient systemd
# unit, then enter it using machinectl.

UNIT=nilmbuntu-run-$VERSION
MACH=nilmbuntu-$VERSION

setup_networking() {
    # We use a virtual ethernet adapter -- this requires that
    # systemd-networkd is installed and running on the host.
    if ! systemctl is-active systemd-networkd ; then
        echo "Starting systemd-networkd"
        systemctl start systemd-networkd
    fi

    # However, the current systemd-networkd from Debian is broken and
    # won't enable masquerading -- so do it manually
    IFACE=$(ip -4 route list default | head -1 | awk '{print $5}')
    echo 1 > /proc/sys/net/ipv4/ip_forward
    iptables -t nat -D POSTROUTING -o $IFACE -j MASQUERADE >/dev/null || true
    iptables -t nat -A POSTROUTING -o $IFACE -j MASQUERADE
}

kill_container() {
    # Kill any running container
    if systemctl --quiet is-active $UNIT ; then
        echo "Stopping container..."
        # We could use "machinectl terminate", but that will wait
        # for a clean shutdown or timeout; we don't need a clean
        # shutdown, so send a SIGTERM twice to get systemd-nspawn
        # to terminate pretty quickly
        systemctl kill $UNIT
        sleep 2
        systemctl kill $UNIT

        # Then wait for it to really stop
        systemctl stop $UNIT
    fi

    # If systemd-nspawn returned with a failure code,
    # the transient service unit file will stick around,
    # so make sure we clear that.
    if systemctl --quiet is-failed $UNIT ; then
        systemctl reset-failed $UNIT
    fi
}

start_container() {
    kill_container
    echo "Starting container..."
    systemd-run --unit=$UNIT systemd-nspawn \
                --quiet \
                --keep-unit \
                --boot \
                --network-veth \
                --directory $(realpath $FS) \
                --machine $MACH
    echo "Waiting..."
    while ! env SYSTEMD_LOG_LEVEL=0 machinectl shell $MACH /bin/true ; do
        sleep 0.1
    done
}

FAILED=0
run() {
    # Run a command inside the container
    echo "+" "$1"

    # machinectl doesn't propagate return codes, so append something
    # to the command that saves the result of what we ran.
    echo "99" > $FS/jim-cmd-result
    CMD="$1 ; echo \$? > /jim-cmd-result"

    # Run it
    env SYSTEMD_LOG_LEVEL=notice machinectl \
        shell $MACH /usr/bin/env IN_CHROOT=1 \
        bash -c "$CMD"

    # Check result
    RET=$(cat $FS/jim-cmd-result)
    rm -f $FS/jim-cmd-result
    if [ $RET -ne 0 ] && [ "$1" != "exec bash" ] ; then
        printf "%s\n" "----------- WARNING: failed with exit code $RET"
        FAILED=$RET
        sleep 5
    fi
}

set -e

setup_networking
start_container

run "resolvconf --disable-updates"
run "echo 'nameserver 8.8.8.8' > /run/resolvconf/resolv.conf"
run "hostnamectl --transient set-hostname nilmbuntu"

#run "dbus-uuidgen > /var/lib/dbus/machine-id"
#run "dpkg-divert --local --rename --add /sbin/initctl"
#run "ln -sf /bin/true /sbin/initctl"
#run "dpkg-divert --local --rename --add /usr/sbin/update-grub"
#run "ln -sf /bin/true /usr/sbin/update-grub"

set +e
if [ -z "$1" ] ; then
    run "exec bash"
else
    run "$1"
fi

echo "Cleaning up..."

# Manually clean up some things that show up after booting an image
# and installing packages.  This doesn't get everything, but what's
# left should be fine.
run "apt-get clean"
run "> /etc/machine-id"
run "rm -f /core /boot/grub/grubenv"
run "rm -f /var/lib/systemd/random-seed"
run "rm -f /var/lib/ubuntu-drivers-common/last_gfx_boot"
run "rm -f /var/lib/NetworkManager/*"
run "rm -f /root/.bash_history"

#run "rm /sbin/initctl"
#run "dpkg-divert --rename --remove /sbin/initctl"
#run "rm /usr/sbin/update-grub"
#run "dpkg-divert --rename --remove /usr/sbin/update-grub"
#run "rm /var/lib/dbus/machine-id"
#run "> /etc/resolv.conf"

kill_container

echo "Done"
if [ $FAILED -ne 0 ] ; then
    exit $FAILED
fi
exit 0