#!/bin/bash
# Copyright (C) 2009 Herbert Straub mail@straub.co.at
# License: GNU/GPL Version 3
# For details see: http://www.gnu.org/licenses/gpl.html

if [ $# -ne "3" ]; then
	echo $(basename $0) "snapshotcount sourcedir destinationdir"
	cat <<NOWARRANTY

THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.
EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE
PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
NECESSARY SERVICING, REPAIR OR CORRECTION.

NOWARRANTY
	exit 1
fi

TIMESTAMP=$(date +"%Y-%m-%d_%H:%M:%S")
SNAPSHOTDIR=${3}/snapshot_$TIMESTAMP
CURRENTSNAPSHOT=$3/current_snapshot

if [ ! -L $CURRENTSNAPSHOT ]; then
	rsync -a $2/ $SNAPSHOTDIR
else
	rsync -a --delete --link-dest=$CURRENTSNAPSHOT \
		$2/ $SNAPSHOTDIR
	rm $CURRENTSNAPSHOT
fi

ln -s $SNAPSHOTDIR $CURRENTSNAPSHOT

#Cleanup

i=0
for snap in `ls -d -1 $3/snapshot_*`; do
	snaplist[$i]=$snap
	let i=i+1
done

let purgecount=${#snaplist[@]}-$1
i=0
while  [ $i -lt $purgecount ]; do
	echo "purging " ${snaplist[$i]}
	rm -fR ${snaplist[$i]}
	let i=i+1
done