#!/bin/bash

set -eE -o pipefail
trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR

# keep it short so we don't delay too much wnen we don't have networking.
NETWORK_TIMOUT_SECS=10
fai_check=false
check-fai() {
    # we could just as well check if last_boot != /debianstable_boostrap
    # the intent with this one is just a little clearer.
    if [[ $did_fai_check == true ]]; then
        fai_check=true
        # ref: https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/
        deadline=$(( `date +%s` + NETWORK_TIMOUT_SECS ))
        while ! systemctl status network-online.target && \
                (( `date +%s` < deadline )); do
            sleep 1
        done
        pxe-kexec -n --ignore-whitelist -l fai-generated faiserver ||:
    else
        return 0
    fi
}

first=true
for dev in $(btrfs fi show / | sed -rn 's#^\s*devid\s.*\s([^0-9 ]+)\S+$#\1#p' \
                 |sort); do
    dev+=4
    mount $dev /mnt
    if $first; then
        if [[ -e /mnt/grubenv ]]; then
            source <(grub-editenv /mnt/grubenv list)
        fi
        first=false
        check-fai
    else
        # we make sure there is only 1 grubenv,
        # so grub can just find the first one, in whatever order
        # if looks at them, which may not be the same as us.
        # If the disk dies, we just lose the default boot option,
        # we will have to do manual steps to replace it anyways.
        rm -f /mnt/gruvenv
    fi
    umount /mnt
done

if $fai_check && [[ $last_boot != /debianstable_boostrap ]]; then
    # no need to reboot if we actually want to boot into this os.
    reboot
fi