#!/bin/bash
#
# Borg script for home folder backups.
# Adapted from https://borgbackup.readthedocs.io/en/stable/quickstart.html#automating-backups
#
# Example config to be put at ~/.config/borger/destination-name:
#
#   # Backup destination
#   export SSH_SERVER="user@host"
#   export SSH_PORT="2202"
#
#   # Repository path
#   export BORG_REPO_DIR="/var/backups/users/$USER/borg"
#   export BORG_REPO="ssh://$SSH_SERVER:$SSH_PORT/$BORG_REPO_DIR"
#
#   # Setting this, so you won't be asked for your repository passphrase:
#   #export BORG_PASSPHRASE='HACKME'
#   #export BORG_PASSCOMMAND='pass show backup'
#   #export BORG_PASSCOMMAND='keyringer default decrypt pessoal/backups/borg 2> /dev/null'
#
#   # Backup config
#   keepdaily="7"
#   keepweekly="4"
#   keepmonth="3"
#   encryption="keyfile"

# Parameters
BASENAME="`basename $0`"
DESTINATION="$1"
BASE_CONFIG="$HOME/.config/borger"
CONFIG="$BASE_CONFIG/$DESTINATION"
HOSTNAME=`cat /etc/hostname`

# Some helpers and error handling:
info() { printf "\n%s %s\n\n" "$( date )" "$*" >&2; }
fatal() { info $*; exit 1; }

# Ensure we have our base config folder
mkdir -p $BASE_CONFIG

# List available targets
if [ -z "$DESTINATION" ]; then
  echo "usage: $BASENAME <destination> [--check]"
  echo -n "available destinations from $BASE_CONFIG: "
  ls $BASE_CONFIG
  exit 1
fi

# Ensure we have an username
if [ -z "$USER" ]; then
  USER="`whoami`"
fi

# In case your home folder is a symlink
if [ ! -z "`readlink $HOME`" ]; then
  ORIG="`readlink $HOME`"
else
  ORIG="$HOME"
fi

# Default backup config
keepdaily="7"
keepweekly="4"
keepmonth="3"
encryption="keyfile"

# Config
if [ -e "$CONFIG" ] ; then
  source $CONFIG
else
  fatal "No such config $CONFIG"
fi

# Setting this, so the repo does not need to be given on the commandline:
if [ -z "$BORG_REPO" ]; then
  export BORG_REPO_DIR="/var/backups/users/$USER/borg"
  export BORG_REPO="ssh://$SSH_SERVER:$SSH_PORT/$BORG_REPO_DIR"
fi

# Check
if [ "$2" == "--check" ]; then
  borg list
  exit $?
fi

# Our trap
trap 'info $( date ) Backup interrupted >&2; exit 2' INT TERM

# Initialize
if ! ssh $SSH_SERVER -p $SSH_PORT test -f $BORG_REPO_DIR/config; then
  info "Initializing borg repository at $BORG_REPO..."
  borg init --encryption=$encryption $BORG_REPO

  init_exit=$?

  if [ "$init_exit" != "0" ]; then
    fatal "Error initializing repository"
  fi
fi

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

info "Starting backup..."

borg create                          \
  --verbose                          \
  --filter AME                       \
  --list                             \
  --stats                            \
  --show-rc                          \
  --compression lz4                  \
  --exclude-caches                   \
  ::'{now}'                          \
  $ORIG

  backup_exit=$?

if [ "$backup_exit" != "0" ]; then
  fatal "Error creating snapshot"
fi

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                        \
  --show-rc                     \
  --keep-daily    $keepdaily    \
  --keep-weekly   $keepweekly   \
  --keep-monthly  $keepmonthly  \

  prune_exit=$?

if [ "$prune_exit" != "0" ]; then
  fatal "Error pruning repository"
fi

# use highest exit code as global exit code
#global_exit=$(( backup_exit > prune_exit ? backup_exit : prune_exit ))
#
#if [ ${global_exit} -eq 1 ];
#then
#  info "Backup and/or Prune finished with a warning"
#fi
#
#if [ ${global_exit} -gt 1 ];
#then
#  info "Backup and/or Prune finished with an error"
#fi
#
#exit ${global_exit}