#!/bin/sh

## Configuration

# Backup
backup_host=___HOST___           # e.g. hostname.local, 192.168.123.45
backup_host_user=___USERNAME__   # e.g. borg
backup_path=___PATH___           # e.g. /mnt/backup/Borg
backup_repo=___REPO___           # e.g. default
backup_passcommand=___COMMAND___ # e.g. "pass show backup"

# Notifications
notify_user=___USERNAME___       # e.g. myname
notify_uid=___USER_ID___         # e.g. 1000

## Backup

print_info() { printf "\n%s %s\n\n" "$( date '+%a, %Y-%m-%d %H:%M:%S' )" "$*" >&2; }

# Check if the backup host is up
host_up=`ping -c 1 $backup_host &> /dev/null; echo $?`
if [ $host_up = 0 ]; then
  # Setting this, so the repo does not need to be given on the commandline:
  export BORG_REPO=ssh://$backup_host_user@$backup_host$backup_path/$backup_repo

  # Setting this, so you won't be asked for your repository passphrase:
  #export BORG_PASSPHRASE='XYZl0ngandsecurepa_55_phrasea&&123'
  # or this to ask an external program to supply the passphrase:
  export BORG_PASSCOMMAND=$backup_passcommand

  # some helpers and error handling:
  trap 'echo $( date ) Backup interrupted >&2; exit 2' INT TERM

  print_info "Starting backup"

  # Backup the most important directories into an archive named after
  # the machine this script is currently running on:

  borg create                       \
    --verbose                       \
    --filter AME                    \
    --list                          \
    --stats                         \
    --show-rc                       \
    --compression lz4               \
    --exclude-caches                \
    --exclude '/home/*/.cache/*'    \
    --exclude '/var/cache/*'        \
    --exclude '/var/tmp/*'          \
    \
    ::'{hostname}-{now}'            \
    /etc                            \
    /home                           \
    /root                           \
    /var                            \

  backup_exit=$?

  print_info "Pruning repository"

  # Use the `prune` subcommand to maintain 7 daily, 4 weekly and 6 monthly
  # archives of THIS machine. The '{hostname}-' prefix is very important to
  # limit prune's operation to this machine's archives and not apply to
  # other machines' archives also:

  borg prune                        \
    --list                          \
    --prefix '{hostname}-'          \
    --show-rc                       \
    --keep-hourly   24              \
    --keep-daily    7               \
    --keep-weekly   4               \
    --keep-monthly  6               \

    prune_exit=$?

  # use highest exit code as global exit code
  global_exit=$(( backup_exit > prune_exit ? backup_exit : prune_exit ))

  if [ ${global_exit} -eq 0 ]; then
    notify_message="Backup and Prune finished successfully."
  else
    notify_icon=dialog-warning
    notify_level=critical

    if [ ${global_exit} -eq 1 ]; then
      notify_message="Backup and/or Prune finished with warnings."
    else
      notify_message="Backup and/or Prune finished with errors."
    fi

    sudo -u $notify_user DISPLAY=:0 DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/$notify_uid/bus notify-send 'BorgBackup' "$notify_message" --icon=$notify_icon --urgency=$notify_level
  fi
else
  global_exit=$host_up
  notify_message="Host is down. Skipped backup."
fi

print_info "${notify_message}"

exit ${global_exit}