#!/bin/bash

################################################################################
# Backup Script
# -------------
#
# This script orchestrates and performs system backups with borg according to
# the environment variables in config/backup and .borgenv files per borg
# repository you wish to backup to.  This script assumes two backups for each
# repository, splitting up the base operating system (debian) and the zfs array
# (zfs) which can be custom named in the config file.
#
# EXPECT THESE BACKUP SCRIPTS TO CHANGE IN THE NEAR FUTURE!
#
# Author: Robin Meier - robin@meier.si
################################################################################

# Load configuration
script_dir=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
set -o allexport
source ${script_dir}/config/backup > /dev/null 2>&1
set +o allexport

# Import logging functionality
logfile=${script_dir}/log/backup.log
log_identifier="BACKUP"
source ${script_dir}/functions/logging.sh

# Check if executables installed
EXEC_DEPS="borg grep sed zfs tac mount umount"
if ! which $EXEC_DEPS >/dev/null 2>&1; then
  log_echo "Missing executables! ($EXEC_DEPS)" >&2
  exit 9
fi

log "Backup Script Started"

# Run backup preparations (scripts for db dumps etc.)
${script_dir}/backup_preparations.sh

# Check preparations exit code
prep_exit=$?
if [[ $prep_exit > 0 ]]; then
  log_echo "Preparations failed with exit code $prep_exit"
  echo -n "Preparations failed with exit code $prep_exit" | ${script_dir}/helpers/tg_notify.sh

  # Do not continue with the backup
  exit $prep_exit
fi

SNAPSHOT_TIMESTAMP=$(date +%Y%m%d%H%M%S) # Make sure this is digits only or adapt regex below

# Create ZFS Snapshots
for DS in $BORG_ZFS_DATASETS; do
  zfs snapshot -r "$DS@$SNAPSHOT_TIMESTAMP"
done

# Mount snapshots under $ZFS_SNAPSHOT_MOUNTPOINT
for SNAP in $(zfs list -t snapshot -o name | grep "$SNAPSHOT_TIMESTAMP"); do
  SNAP_MOUNTPOINT="$ZFS_SNAPSHOT_MOUNTPOINT/$(sed 's/@[[:digit:]]\+$//' <<< "$SNAP")"
  log "Mount $SNAP at $SNAP_MOUNTPOINT"
  mkdir -p "$SNAP_MOUNTPOINT"
  mount -t zfs "$SNAP" "$SNAP_MOUNTPOINT"
done

# Run backup script for each configuration
global_exit=0
for BORG_ENV in $BORG_DESTINATION_ENV_FILES; do
  log "BORG Backup for $BORG_ENV"
  if [[ ! -f "$BORG_ENV" ]]; then
    # Exit if given env file does not exist
    exit 8
  fi
  set -o allexport
  source $BORG_ENV
  set +o allexport

  log "Backup debian system..."
  ${script_dir}/backup_borg.sh debian $(date +%Y%m%d%H%M%S) "$BORG_DEBIAN_DIRS" "--exclude=var/tmp/* --exclude=var/lib/docker" &>> $logfile
  system_exit=$?
  log "Backupped debian system (exit code: $system_exit)"
  if [[ $system_exit -gt 1 ]]; then
    log_echo "System backup failed with error code $system_exit"
    echo -n "System backup failed with error code $system_exit" | ${script_dir}/helpers/tg_notify.sh
  fi

  log "Backup zfs array"
  ${script_dir}/backup_borg.sh ${ZFS_ARRAY_NAME:-zfs} $SNAPSHOT_TIMESTAMP "$ZFS_SNAPSHOT_MOUNTPOINT" "" &>> $logfile
  zfs_exit=$?
  log "Backupped zfs array (exit code: $zfs_exit)"
  if [[ $zfs_exit -gt 0 ]]; then
    log_echo "ZFS Array Backup Failed with Warning or Error (Exit Code: $external_exit)"
    echo -n "ZFS Array Backup Failed with Warning or Error (Exit Code: $external_exit)" | ${script_dir}/helpers/tg_notify.sh
  fi

  borg_env_exit=$(( system_exit > zfs_exit ? system_exit : zfs_exit ))
  global_exit=$(( borg_env_exit > global_exit ? borg_env_exit : global_exit ))
done

# # Wait file for inspecting of /mnt/snapshot
# touch /mnt/snapshot/wait_file
# while : ; do
#   [[ ! -f "/mnt/snapshot/wait_file" ]] && break
#   log_echo "Waiting.."
#   sleep 2
# done

# Unmount snapshots in reverse order (tac reverses lines)
for SNAP in $(zfs list -t snapshot -o name | grep "$SNAPSHOT_TIMESTAMP" | tac); do
  log "Unmount $SNAP"
  umount "$SNAP"
done

# Destroy snapshots (recursive) for each dataset
for DS in $BORG_ZFS_DATASETS; do
  log "Destroy snapshot $DS"
  zfs destroy -r "$DS@$SNAPSHOT_TIMESTAMP"
done

log "Backup Script Finished ($global_exit)"

exit $global_exit