#!/bin/bash

while ! ping -c1 -W2 "${server_ip}"
do
  sleep 3
done

set -exu

ssh="ssh -o ConnectTimeout=5 root@${server_ip}"
bookmark_prefix="auto-mirror_"
new_bookmark="$bookmark_prefix$(date +"%Y-%m-%d_%H:%M:%S")"

for dataset in $(zfs list -t filesystem -H -o name)
do
  echo "MIRRORING $dataset"

  if ! $ssh sudo zfs list -t filesystem -H -o name | grep -q "^$dataset$"
  then
    echo "CREATING PARENT DATASET..."
    $ssh sudo zfs create -p -o mountpoint=none "$dataset"
  fi

  zfs snap "$dataset@$new_bookmark"

  if zfs list -t bookmark -H -o name | grep "^$dataset#$bookmark_prefix" | wc -l | grep -q "^0$"
  then
    echo "INITIAL BACKUP"
    # do in subshell, otherwise ctr+c will lead to 0 exitcode
    $(zfs send -v "$dataset@$new_bookmark" | $ssh sudo zfs recv -F "$dataset" -o mountpoint=none)
  else
    echo "INCREMENTAL BACKUP"
    last_bookmark=$(zfs list -t bookmark -H -o name | grep "^$dataset#$bookmark_prefix" | sort | tail -1 | cut -d '#' -f 2)
    [[ -z "$last_bookmark" ]] && echo "ERROR - last_bookmark is empty" && exit 98
    $(zfs send -v -L -i "#$last_bookmark" "$dataset@$new_bookmark" | $ssh sudo zfs recv "$dataset" -o mountpoint=none)
  fi

  if [[ "$?" == "0" ]]
  then

    # delete old local bookmarks
    for destroyable_bookmark in $(zfs list -t bookmark -H -o name "$dataset" | grep "^$dataset#$bookmark_prefix")
    do
      zfs destroy "$destroyable_bookmark"
    done

    # delete snapshots from bookmarks (except newest, even of not necessary; maybe for resuming tho)
    for destroyable_snapshot in $($ssh sudo zfs list -t snapshot -H -o name "$dataset" | grep "^$dataset@$bookmark_prefix" | grep -v "$new_bookmark")
    do
      $ssh sudo zfs destroy "$destroyable_snapshot"
    done

    zfs bookmark "$dataset@$new_bookmark" "$dataset#$new_bookmark"
    zfs destroy "$dataset@$new_bookmark"
    echo "SUCCESS $dataset"
  else
    zfs destroy "$dataset@$new_bookmark"
    echo "ERROR $dataset"
    exit 99
  fi
done