#!/bin/bash -e

# defaults
HOURLY_DEL=25
DAILY_DEL=8
WEEKLY_DEL=5
MONTHLY_DEL=
SOURCES=()
DESTINATION=

# overwrite defaults in configs
if test -e /etc/lizardfs-snapshots.conf; then
    . /etc/lizardfs-snapshots.conf
fi
if test -e ~/.lizardfs-snapshots; then
    . ~/.lizrdfs-snapshots
fi

# evaluate commandline
del=
dryrun=0
periodity=${0%/*}
periodity=${periodity##*/}
if [[ $periodity =~ ^cron\... ]]; then
    periodity=${periodity#cron}
else
    periodity=
fi

case "$periodity" in
    (.hourly) del=${HOURLY_DEL};;
    (.daily) del=${DAILY_DEL};;
    (.weekly) del=${WEEKLY_DEL};;
    (.monthly) del=${MONTHLY_DEL};;
    (*) periodity=".manual";;
esac
while test $# -gt 0; do
    case "$1" in
        (-h|--help) cat <<EOF
$0 [OPTIONS] [[SOURCES...] DESTINATION]

OPTIONS

  -h, --help           show this help
  -n, --dry-run        execute dry run, do not backup, just show commands
  -d, --del <number>   delete old snapshots beginning at <numbers>-th

CONFIGURATION FILE

You can have a configuration file lizardfs-snapshots.conf either in
/etc or in your home.

This may define the following bash variables:
  HOURLY_DEL, DAILY_DEL, WEEKLY_DEL, MONTHLY_DEL 
                       defining the parameter --del for
                       hourly, daily, weekly, monthly 
  SOURCES              bash array that defines the sources to backup
  DESTINATION          snapshot target path

DESCRIPTION

To create regular snapshots on a daily base, just run:

  sudo cp lizardfs-snapshots.sh /etc/cron.daily/lizardfs-snapshots

If lizardfs-snapshots is run from a cron.daily, cron.hourly,
cron. monthly or cron.weekly directory, the periodity is automatically
appended to the snapshot name, and the expiry is set meaningfull:

  - hourly  → keep only 24 hours, --del 25
  - daily   → keep only 7 days, --del 8
  - weekly  → keep only 4 weeks, --del 5
  - monthly → old snapshots are not deleted

EOF
                    exit;;
        (-n|--dry-run) dryrun=1;;
        (-d|--del) shift; del="$1";;
        (*) break;;
    esac
    if test $# -lt 1; then
        echo "ERROR: missing argument, try $0 --help" 1>&2
        exit 1
    fi
    shift
done
while test $# -gt 1; do
    SOURCES+=("$1")
    shift
done
if test $# -eq 1; then
    DESTINATION="$1"
fi
if test -z "${SOURCES[*]}"; then
    echo "ERROR: no sources specified, try $0 --help" 1>&2
    exit 1
fi
if test -z "${DESTINATION}"; then
    echo "ERROR: no destination specified, try $0 --help" 1>&2
    exit 1
fi
if test "$dryrun" -eq 0 && ! ( test -d "${DESTINATION}" || mkdir -p "${DESTINATION}" ); then
    echo "ERROR:  cannot create destination path '$DESTINATION', try $0 --help" 1>&2
    exit 1
fi
date="-$(date +%Y-%m-%d-%H-%M)"
for src in "${SOURCES[@]}"; do
    target="${src##*/}${periodity}"
    if test $dryrun -eq 1; then
        echo -e "→ \e[1mbackup $src\e[0m"
        echo " " "lizardfs makesnapshot '${src}' '${DESTINATION}/${target}${date}'"
        if test -n "$del"; then
            for f in $(ls -d1 "${DESTINATION}/${target}"-* | sort -r | tail -n +"$del"); do
                echo " " "rm -rf '$f'"
            done
	fi
    else
        echo -e "→ \e[1mbackup $src\e[0m"
        lizardfs makesnapshot "${src}" "${DESTINATION}/${target}${date}"
        if test -n "$del"; then
            for f in $(ls -d1 "${DESTINATION}/${target}"-* | sort -r | tail -n +"$del"); do
                rm -rf "$f"
            done
        fi
    fi
done