#!/bin/bash

[ -z "$2" ] && echo "usage: $0 <src> <dst> <dir> [<dir> ...]" && exit 1

OPTIONS="
--archive
--update
--delete
--numeric-ids
--verbose
--one-file-system
--progress
--rsh=ssh
"

# Destination will have a data prefix, and will use the most recent
# (time stamp) backup directory as a hard link base.

HERE=$(readlink -f .)
DST=$(readlink -f "$2")
SRC="$1"
DST=$(readlink -f $2)
shift
shift

TAG=$(date +%Y%m%d-%H%M%S)

# Get last tag and make a new one.
cd $DST
rm -f last
LAST_TAG=$(ls -t |head -n1)
mkdir $TAG
ln -s $TAG last

fail () {
    echo rsync returned error
    echo removing $DST/$TAG
    rm -rf $DST/$TAG
    exit 1
}

debug () {
    echo "$@"
    "$@" || fail
}

# Transfer dirs
cd $HERE
for dir in "$@"; do
    [ -z "$LAST_TAG" ] || LINK_DEST_OPTIONS="--link-dest=$DST/$LAST_TAG/$dir"
    debug mkdir -p "$DST/$TAG/$dir"
    debug rsync $OPTIONS $LINK_DEST_OPTIONS "$SRC/$dir/" "$DST/$TAG/$dir/"

    # FIXME: If this fails or gets interrupted in in any way, the
    # directory needs to be removed.  Otherwise it will trigger a full
    # download next time.
done