#!/bin/bash

## Wrapper script running "btrbk" and sending email with results

set -uf
declare -A rsync_src rsync_dst rsync_log rsync_key rsync_opt
now=$(date +%Y%m%d)


#####  start config section  #####

# Email recipients, separated by whitespace:
mailto=$MAILTO

# List of mountpoints to be mounted/unmounted (whitespace-separated)
# mount_targets="/mnt/btr_pool /mnt/backup"
mount_targets=
umount_targets=$mount_targets

# btrbk configuration file:
config="/etc/btrbk/btrbk.conf"

# Uncomment this if you only want to receive error messages:
#btrbk_opts="-q"
#skip_empty_mail=yes

# Email subject:
mail_subject_prefix="btrbk <${HOSTNAME:-localhost}>"

# rsync declarations (repeat complete block for more declarations):
rsync_src[example_data]=user@example.com:/data/
rsync_dst[example_data]=/mnt/backup/example.com/data/
rsync_log[example_data]=/mnt/backup/example.com/data-${now}.log
rsync_key[example_data]=/mnt/backup/ssh_keys/id_rsa
rsync_opt[example_data]="-az --delete"

# Enabled rsync declarations (space separated list)
#rsync_enable="example_data"
rsync_enable=

# Log level (1=error, 2=warn, 3=info)
loglevel=2


#####  end config section  #####

mail_body=""

die()
{
    echo "$0 FATAL: $1"      1>&2
    echo "$0 FATAL: exiting" 1>&2
    exit 1
}
log_error()   { [ $loglevel -ge 1 ] && echo "$0 ERROR: $1"   1>&2 ; }
log_warning() { [ $loglevel -ge 2 ] && echo "$0 WARNING: $1" 1>&2 ; }
log_info()    { [ $loglevel -ge 3 ] && echo "$0 INFO: $1"    1>&2 ; }


#
# mount all mountpoints listed in $mount_targets
#
for mountpoint in $mount_targets; do
    $(findmnt -r -n -t btrfs $mountpoint 1>&2)
    if [ $? = 0 ]; then
	log_warning "btrfs filesystem already mounted: $mountpoint"
    else
	log_info "mount $mountpoint"
	$(mount --target $mountpoint 1>&2)
	[ $? = 0 ] || log_error "mount failed: $mountpoint"
    fi
done


#
# run rsync for all $rsync_enable
#
for key in $rsync_enable; do
    log_info "starting rsync: $key"

    [ -n "${rsync_src[$key]}" ] || die "rsync_src is not set for \"$key\""
    [ -n "${rsync_dst[$key]}" ] || die "rsync_dst is not set for \"$key\""
    [ -n "${rsync_log[$key]}" ] || die "rsync_log is not set for \"$key\""
    [ -n "${rsync_key[$key]}" ] || die "rsync_key is not set for \"$key\""
    [ -n "${rsync_opt[$key]}" ] || die "rsync_opt is not set for \"$key\""

    rsync_header="### rsync ${rsync_opt[$key]} ${rsync_src[$key]} ${rsync_dst[$key]}"

    if [ -d ${rsync_dst[$key]} ]; then
	echo "$rsync_header" >> ${rsync_log[$key]}
	ret=$(rsync ${rsync_opt[$key]} --info=STATS --log-file=${rsync_log[$key]} -e "ssh -i ${rsync_key[$key]}" ${rsync_src[$key]} ${rsync_dst[$key]})
	if [ $? != 0 ]; then
	    log_error "rsync failed: $key"
	    ret+="\nERROR: rsync failed with exit code $?\n"
	fi
	mail_body+="$rsync_header$ret\n\n"
    else
	ret="rsync destination directory not found for \"$key\", skipping: ${rsync_dst[$key]}"
	mail_body+="$rsync_header\n$ret\n\n"
	log_error "$ret"
    fi
done


#
# run btrbk
#
log_info "running btrbk"
ret=$(btrbk -c "$config" ${btrbk_opts:-} run 2>&1)
exitcode=$?
case $exitcode in
    0)  status="All backups successful"
	;;
    10) status="ERROR: At least one backup task aborted!"
	;;
    *)  status="ERROR: btrbk failed with error code $exitcode"
	;;
esac

mail_body+=$ret

if [ "${skip_empty_mail:-no}" = "yes" ] && [ -z "$mail_body" ] && [ $exitcode -eq 0 ]; then
    : # skip email sending if skip_empty_mail=yes
else
    # send email
    echo -e "$mail_body" | mail -s "$mail_subject_prefix - $status" $mailto
    if [ $? != 0 ]; then
	log_error "failed to send btrbk mail to \"$mailto\", dumping mail body:"
	echo -e "$mail_body" 1>&2
    fi
fi


#
# sync all mountpoints listed in $umount_targets
#
# exit on failure!
#for mountpoint in $umount_targets; do
#    log_info "btrfs filesystem sync $mountpoint"
#    $(btrfs filesystem sync $mountpoint 1>&2)
#    [ $? = 0 ] || die "btrfs filesystem sync failed: $mountpoint"
#    sleep 1
#done


#
# unmount all mountpoints listed in $umount_targets
#
for mountpoint in $umount_targets; do
    log_info "umount $mountpoint"
    $(umount $mountpoint 1>&2)
    [ $? = 0 ] || log_error "umount failed: $mountpoint"
done