#!/bin/bash
# Copyright (C) 2019 Ian Kelling
# SPDX-License-Identifier: AGPL-3.0-or-later

source /a/bin/errhandle/err

[[ $EUID == 0 ]] || exec sudo -E "${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' | egrep '^[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 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 $svp 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