#!/usr/bin/env sh

### nodes.txt
# localhost 22 <this host's root zfs> <this host's user>
# <remote host 1 address> <host 1 port> <host 1 root zfs>
# <remote host 2 address> <host 2 port> <host 2 root zfs>
# ...

### datasets.txt (Only required for aggregator setup.)
# <dataset 1>
# <dataset 1>/<dataset 1a>
# <dataset 1>/<dataset 1b>
# <dataset 2>
# <dataset 2>/<dataset 2a>
# <dataset 3>
# ...

if [ ! -f nodes.txt ]; then echo "No nodes specified."; exit 2; fi

read BR_HOST BR_PORT BR_ROOT BR_USER < nodes.txt

list_filesets()
{
    zfs list | tail -n +2 | cut -d' ' -f1|grep ${BR_ROOT}
}

get_latest_snapshot()
{
    zfs list -t snapshot |
        grep ${BR_ROOT} |
        tail -n1 |
        cut -d'@' -f2 |
        cut -d' ' -f 1
}

setup_aggregator()
{
    zfs allow -u ${BR_USER} send,snapshot,hold ${BR_ROOT}
    for dataset in `cat datasets.txt`; do
	    zfs create $dataset
    done
}

setup_mirror()
{
    zfs allow -u ${BR_USER} send,snapshot,hold ${BR_ROOT}
    zfs allow -du ${BR_USER} \
        compression,mountpoint,receive,create,mount ${BR_ROOT}
}

create_snapshot()
{
    id="`date -I`-`date +%s`"
    zfs snapshot -r ${BR_ROOT}@${id}
}

send_single_snapshot()
{
    BR_NEW_SNAPSHOT=`get_latest_snapshot`
    while read BR_REMOTE_ADDR BR_REMOTE_PORT BR_REMOTE_ROOT BR_REMOTE_USER; do
        zfs send -R ${BR_ROOT}@${BR_NEW_SNAPSHOT} |
            ssh -i ~/.ssh/id_rsa -o port=${BR_REMOTE_PORT} \
            ${BR_REMOTE_USER}@${BR_REMOTE_ADDR} \
            zfs receive -dvu ${BR_REMOTE_ROOT}@${BR_NEW_SNAPSHOT}
    done
    echo $BR_NEW_SNAPSHOT > "old-snapshot.txt"
}

send_incremental_snapshot()
{
    BR_NEW_SNAPSHOT=`get_latest_snapshot`
    while read BR_REMOTE_ADDR BR_REMOTE_PORT BR_REMOTE_ROOT BR_REMOTE_USER; do
        zfs send -R -i `cat old-snapshot.txt` ${BR_ROOT}@${BR_NEW_SNAPSHOT} |
            ssh -i ~/.ssh/id_rsa -o port=${BR_REMOTE_PORT} \
            ${BR_REMOTE_USER}@${BR_REMOTE_ADDR} \
            zfs receive -dvu ${BR_REMOTE_ROOT}@${BR_NEW_SNAPSHOT}
    done
    echo $BR_NEW_SNAPSHOT > "old-snapshot.txt"
}

create_snapshot

if [ -f "old-snapshot.txt" ]; then
    send_incremental_snapshot
else
    send_single_snapshot
fi