#!/bin/sh -e

PROG="${0##*/}"

Fatal()
{
        echo "${0##*/}: $*" >&2
        exit 1
}

export LC_ALL=C

sisyphus=/path/to/Sisyphus
pattern='^/path/to/archive/Sisyphus/[[:digit:]]{4}/[[:digit:]]{2}/[[:digit:]]{2}$'
format='/path/to/archive/Sisyphus/%CY/%Cm/%Cd\n/path/to/archive/Sisyphus/%TY/%Tm/%Td\n'

old="$(find /path/to/archive/Sisyphus/ -type d -mindepth 3 -maxdepth 3 |egrep "$pattern" |sort -r |head -1)" ||
	Fatal "old sisyphus lookup failed."
[ -n "$old" -a -d "$old" ] ||
	Fatal "old sisyphus lookup failed."

new="$(find "$sisyphus"/i?86/base -mindepth 1 -maxdepth 1 -type f -name pkglist.\* -printf "$format")" ||
	Fatal "new sisyphus lookup failed."
new="$(echo "$new" |egrep "$pattern" |sort -r |head -1)"
[ -n "$new" ] ||
	Fatal "new sisyphus lookup failed."

if [ "$old" = "$new" ]; then
	echo "$old: latest snapshot already exists."
	exit 0
fi

if [ -d "$new" ]; then
	echo "$old: NON-latest snapshot already exists."
	exit 0
fi

echo "New snapshot to be created: $new"

mkdir -pv ${new%/*}
cp -al "$old" "$new"

rsync -va --delete-after --stats "$sisyphus"/ "$new"/