#!/bin/bash
# I, Ian Kelling, follow the GNU license recommendations at
# https://www.gnu.org/licenses/license-recommendations.en.html. They
# recommend that small programs, < 300 lines, be licensed under the
# Apache License 2.0. This file contains or is part of one or more small
# programs. If a small program grows beyond 300 lines, I plan to switch
# its license to GPL.

# Copyright 2024 Ian Kelling

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


source /a/bin/bash-bear-trap/bash-bear

[[ $EUID == 0 ]] || exec sudo -E "${BASH_SOURCE[0]}" "$@"

pre="${0##*/}:"
err() { echo "[$(date +'%Y-%m-%d %H:%M:%S%z')]: $pre: $*" >&2; }

## begin check on syncthing
if ! systemctl show --no-page syncthing@ziva | sed -n 's/^MainPID=//p' | grep -E '^[0-9]+$' &>/dev/null; then
  err no pid for syncthing@ziva. systemctl status:
  systemctl status syncthing@ziva
fi
## end check on syncthing


## begin check on btrbk
age_limit_sec=$(( 60 * 60 * 24 * 7 )) # 7 days.
for prefix in root boot; do
  if [[ $prefix == boot ]]; then
    # its not uncommon for the /boot subvol to have no changes, and thus
    # no new backups for 10 days or so. todo: instead of this error
    # prone check, we should make it so the ziva computer will
    # touch a file on our computer whenever btrbk succeeds
    age_limit_sec=$(( age_limit_sec + 60* 60 * 24 * 35 ))
  fi
  vol=${prefix}_ubuntubionic
  snaps=(/mnt/r7/amy/$prefix/btrbk/${vol}.20*)
  if [[ ! ${snaps[*]} ]]; then
    err no snapshots starting with /mnt/r7/amy/$prefix/btrbk/${vol}.20
    break
  fi

  read -r last_snap_sec last_snap < <(
    for s in ${snaps[@]}; do
      f=${s##*/}
      unix_time=$(date -d "$(sed -r  's/(.{4})(..)(.{5})(..)(.*)/\1-\2-\3:\4:\5/' <<<${f#"$vol".})" +%s)
      printf "%s %s\n" $unix_time $s # part of the pipeline
    done | sort -r | head -n 1 ||:
  )
  if [[ ! $last_snap ]]; then
    # should not happen.
    err "could not find latest snapshot for $vol among ${snaps[*]}"
    exit 1
  fi
  if (( last_snap_sec < EPOCHSECONDS - age_limit_sec )); then
    err vol $vol last backup older than 50 hours: $last_snap
  fi
done
## end check on btrbk