#!/usr/bin/env sh

nodes_file="nodes.txt"
### nodes.txt
# <local hostname> <local ssh port> <this host's root zfs> <this host's user>
# <remote host 1 address> <host 1 ssh port> <host 1 root zfs>
# <remote host 2 address> <host 2 ssh port> <host 2 root zfs>
# ...

datasets_file="datasets.txt"
### datasets.txt
# <dataset 1>
# <dataset 1>/<dataset 1a>
# <dataset 1>/<dataset 1b>
# <dataset 2>/<dataset 2a>
# <dataset 3>
# ...

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

# compare_datasets()

create_datasets() {
    # should compare_datasets and only create missing or possibly error.
    
    for dataset in `cat ${datasets_file}`; do
        case $dataset in
            \#*) continue;;
        esac
        if [ $BG_TEST_MODE = "TRUE" ]; then
            echo zfs create -p ${BG_ROOT}/$dataset
        else    
	        zfs create -p ${BG_ROOT}/$dataset
        fi
    done
}

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

setup_aggregator()
{
    create_datasets
    if [ $BG_TEST_MODE = "TRUE" ]; then
        echo zfs allow -u ${BG_USER} send,snapshot,hold ${BG_ROOT}
    else
        zfs allow -u ${BG_USER} send,snapshot,hold ${BG_ROOT}
    fi
}

setup_mirror()
{
    if [ $BG_TEST_MODE = "TRUE" ]; then
        echo     zfs allow -u ${BG_USER} send,snapshot,hold ${BG_ROOT}
        echo zfs allow -u ${BG_USER} \
            compression,mountpoint,receive,create,mount ${BG_ROOT}
    else
        zfs allow -u ${BG_USER} send,snapshot,hold ${BG_ROOT}
        zfs allow -u ${BG_USER} \
            compression,mountpoint,receive,create,mount ${BG_ROOT}
    fi
}

create_snapshot()
{
    id="`date -I`-`date +%s`"
    if [ $BG_TEST_MODE = "TRUE" ]; then
        echo zfs snapshot -r ${BG_ROOT}@${id}
    else
        zfs snapshot -r ${BG_ROOT}@${id}
    fi
}

send_single_snapshot()
{
    BG_NEW_SNAPSHOT=`get_latest_snapshot`
    tail -n +2 ${nodes_file} > sendnodes.tmp
    while read BG_REMOTE_ADDR BG_REMOTE_PORT BG_REMOTE_ROOT BG_REMOTE_USER; do
        case $BG_REMOTE_ADDR in
            \#*) continue;;
        esac
        if [ $BG_TEST_MODE = "TRUE" ]; then
            echo zfs send -R ${BG_ROOT}@${BG_NEW_SNAPSHOT} 
            echo ssh -i ~/.ssh/id_rsa -o port=${BG_REMOTE_PORT} \
                ${BG_REMOTE_USER}@${BG_REMOTE_ADDR} \
                zfs receive -dvu ${BG_REMOTE_ROOT}
        else
            zfs send -R ${BG_ROOT}@${BG_NEW_SNAPSHOT} |
                ssh -i ~/.ssh/id_rsa -o port=${BG_REMOTE_PORT} \
                ${BG_REMOTE_USER}@${BG_REMOTE_ADDR} \
                zfs receive -dvu ${BG_REMOTE_ROOT}
        fi
    done < sendnodes.tmp
    rm sendnodes.tmp
    if [ $BG_TEST_MODE = "TRUE" ]; then
        :
    else
        echo $BG_NEW_SNAPSHOT > "old-snapshot.txt"
    fi
}

send_incremental_snapshot()
{
    BG_NEW_SNAPSHOT=`get_latest_snapshot`
    echo Will send $BG_NEW_SNAPSHOT
    #while read BG_REMOTE_ADDR BG_REMOTE_PORT BG_REMOTE_ROOT BG_REMOTE_USER; do
    #    zfs send -R -i `cat old-snapshot.txt` ${BG_ROOT}@${BG_NEW_SNAPSHOT} |
    #        ssh -i ~/.ssh/id_rsa -o port=${BG_REMOTE_PORT} \
    #        ${BG_REMOTE_USER}@${BG_REMOTE_ADDR} \
    #        zfs receive -dvu ${BG_REMOTE_ROOT}@${BG_NEW_SNAPSHOT}
    #done
    echo $BG_NEW_SNAPSHOT > "old-snapshot.txt"
}


################################### MAIN ####################################

### Options
set -- `getopt "tl:" "$@"` || {
    echo "Usage: `basename $0` [-tl] [command]" 1>&2
    exit 1
}
BG_TEST_MODE=FALSE
while :; do
    case "$1" in
        -t)
            BG_TEST_MODE=TRUE
            echo Test mode.
        ;;
        --) shift; break ;;
    esac
    shift
done

read BG_HOST BG_PORT BG_ROOT BG_USER < ${nodes_file}

if [ ! -f ${nodes_file} ]; then echo "No nodes specified."; exit 2; fi

### Command
case "$1" in
    list) list_active_datasets ;;
    create) create_snapshot ;;
    setup-mirror) setup_mirror ;;
    setup-aggregator) setup_aggregator ;;
    send)
        if [ -f "old-snapshot.txt" ]; then
            send_incremental_snapshot
        else
            send_single_snapshot
        fi            
    ;;
esac