#/bin/bash

set -x

# Usage: replicate <hostname> <zfs filesystem>
remote=$1
remote_fs=$2

# The ssh connection doesn't find zfs without this.
zfs=/usr/sbin/zfs

# List the snapshots on the remote machine.
remote_list=$(mktemp /tmp/replicate.XXXXXX)
ssh $remote \
    $zfs list -H -t snapshot |
    grep ^${remote_fs}@ |
    awk '{print$1}' > $remote_list

# List the snapshots on the local machine.
local_list=$(mktemp /tmp/replicate.XXXXXX)
$zfs list -H -t snapshot |
    grep ^backups/${remote_fs}@ |
    awk '{gsub(/^backups./,"",$1); print$1}' > $local_list

# See what the most recent snapshot on the remote end is.
latest=$(tail -n 1 $remote_list)

# I did this to make sure that diff would always display the most recent common
echo bogus.remote >> $remote_list
echo bogus.local  >> $local_list
common=$(diff -u $remote_list $local_list | grep '^ ' | tail -n 1)

ssh $remote $zfs send -R -I${common/*@/@} $latest |
    $zfs receive -vF -d backups/${remote_fs%/*}

rm -f $local_list $remote_list