#!/bin/sh

pool="tank/vol1"
destination="tank"
remote_pool="tank/vol1"
host="192.168.0.10"

today=`date +"%Y-%m-%d"`
yesterday=`date -v -1d +"$type%Y-%m-%d"`
#yesterday="2017-01-07"

# create today snapshot
snapshot_today="${pool}@${today}"
# look for a snapshot with this name
if zfs list -H -o name -t snapshot | sort | grep "${snapshot_today}" > /dev/null; then
        echo " snapshot, ${snapshot_today}, already exists"
#       exit 1
else
        echo " taking todays snapshot, ${snapshot_today}"
        zfs snapshot -r ${snapshot_today}
fi

# look for yesterday snapshot
snapshot_yesterday="$pool@$yesterday"
snapshot_yesterday_r="$remote_pool@$yesterday"
snapshot_today_r="$remote_pool@${today}"

snapshot_start=""
snapshot_end=""
ss_list_local="`zfs list -H -o name -t snapshot | grep ${pool} | cut -d \"@\" -f2 | sort -r`"
ss_list_remote="`ssh root@${host} \"zfs list -H -o name -t snapshot | grep ${remote_pool} | cut -d \"@\" -f2 | sort -r\"`"

#echo $snapshot_yesterday
if  ssh root@$host "zfs list -H -o name -t filesystem | sort | grep \"${remote_pool}\"" > /dev/null; then
    echo " Pool found on remote"
else
    echo " Pool missing on remote, aborting"
    exit 1;
fi
if zfs list -H -o name -t snapshot | sort | grep "${snapshot_yesterday}" > /dev/null; then
        echo " yesterday snapshot, ${snapshot_yesterday}, exists locally"
        for l in $ss_list_local
        do
                for r in $ss_list_remote
                do
                        if [ "$l" == $r ]; then
                                snapshot_start="$l"
                        fi
                done
                if [ "$snapshot_start" != "" ]; then
                        break
                fi
        done
        if [ "$snapshot_start" != "" ]; then
                echo " found common ss at: ${snapshot_start}"
                if ssh root@$host "zfs list -H -o name -t snapshot | sort | grep \"${snapshot_today_r}\"" > /dev/null; then
                        echo " Remote already has today's snapshot aborting sync"
                        exit 2
                else
                        echo " proceeding with incremental sync"
                        echo "zfs send -R -i ${pool}@${snapshot_start} ${snapshot_today} | lzop | ssh root@$host \"lzop -d | zfs receive -Fduv ${destination}\""
                        zfs send -R -i ${pool}@${snapshot_start} ${snapshot_today} | lzop | ssh root@$host "lzop -d | zfs receive -Fduv ${destination}"
                        echo " sync complete"
                        exit 0;
                fi
        else
                echo " yesterday snapshot, ${snapshot_yesterday_r}, missing on destination"
                if ssh root@$host "zfs list -H -o name -t snapshot | sort | grep \"${snapshot_today_r}\"" > /dev/null; then
                        echo " Remote already has today's snapshot aborting sync"
                        exit 2
                else
                        echo " proceeding with full sync"
                        zfs send ${snapshot_today} | ssh root@$host "zfs receive -Fduv ${destination}"
                        echo " sync complete"
                        exit 0;
                fi
        fi
else
        echo " missing yesterday snapshot aborting, ${snapshot_yesterday}"
        exit 1
fi