#!/usr/local/bin/bash

# DO NOT USE THIS SCRIPT
# It is in a state of hot garbage and will probably be deleted soon


print_help_and_exit() {
    echo "Please run this program with a source and a target dataset name as arguments"
    echo "e.g. $0 zpool/dataset1 zpool/dataset2"
    exit
}

SIMULATION=0

args=$(getopt n $*)
test $? == 0 || print_help_and_exit

set -- $args

while :; do
    sleep 1
    echo $1
    case "$1" in
        --) shift; break ;;
        -n) SIMULATION=1 ; shift ;;
    esac
done

DATASET_ROOT=$1
DATASET_TARGET=$2

if ! zfs get mountpoint $DATASET_TARGET >/dev/null; then
    echo "Dataset $DATASET_TARGET does not exist and will be created."
    echo "You have 10 seconds to abort this with CTRL-C"
    sleep 10
    if ! $SIMULATION; then
        zfs create $DATASET_TARGET
    fi
fi

if zfs get -H -t filesystem -o name,value -r snapdir zeus/data/projects | grep -v visible >/dev/null; then
    echo Please make all snapdirs visible:
    zfs get -H -t filesystem -o name,value -r snapdir zeus/data/projects
    exit 2
fi


MOUNTPOINT_TARGET=$(zfs get -o value -H mountpoint $DATASET_TARGET)
test ${SIMULATION:0} = 1 && test $MOUNTPOINT_TARGET == "" && MOUNTPOINT_TARGET="datapool/simulation"

test -d "$MOUNTPOINT_TARGET" || print_help_and_exit

# make sure, that ctrl-c also works in the inner loops
trap exit INT

# recursively contains all snapshot names (the part after the @) from root on, sorted and only once
SNAPSHOTS=$(zfs list -H  -oname -tsnap -r $DATASET_ROOT | cut -d@ -f2 | sort -u)
DATASETS=$(zfs list -H -oname -t filesystem -r $DATASET_ROOT)

test "${SIMULATION:-0}" = 1 && echo "SIMULATION MODE"

$DATASETS


echo "We are going to flatten the hierachy of this dataset:"
printf "\t%s\n" $DATASETS
echo -e "into the dataset with the name:"
echo -e "\t$DATASET_TARGET"
echo -e "mounted under:"
echo -e "\t$MOUNTPOINT_TARGET"
echo -e "with the following snapshots:"
printf "\t%s\n" $SNAPSHOTS
echo ""
echo "You have 10 seconds to abort this with CTRL-C"
sleep 10

set -- $SNAPSHOTS
SNAPSHOTS_TOTAL=$#
SNAPSHOT_CURRENT=0

set -- $DATASETS
shift
SUBDATASETS=$@

for SNAPSHOT in $SNAPSHOTS; do
    echo ""
    echo ""
    SNAPSHOT_CURRENT=$((SNAPSHOT_CURRENT + 1))
    echo "[$SNAPSHOT_CURRENT/$SNAPSHOTS_TOTAL] Next snapshot is: $SNAPSHOT"

    for DATASET in $SUBDATASETS; do

        DATASET_RELATIVE=${DATASET##$DATASET_ROOT}

        MOUNTPOINT=$(zfs get -H -o value mountpoint $DATASET)
        echo "RELATIVE=$DATASET_RELATIVE"

        if [[ $MOUNTPOINT == "legacy" ]]; then
            MOUNTPOINT=$(findmnt -n -o target $DATASET)
            if test -d $MOUNTPOINT; then
                >&2 echo "Dataset has a legacy mountpoint, but was not found in the fstab: $DATASET"
                continue
            fi
        fi

        if [[ $MOUNTPOINT == "-" ]]; then
            >&2 echo "Dataset does not have a mount point or is a vdev: $DATASET"
            continue
        fi

        SNAPDIR=$MOUNTPOINT/.zfs/snapshot/$SNAPSHOT
        if test -d $SNAPDIR; then

            TARGET_DIR="${MOUNTPOINT_TARGET}${DATASET_RELATIVE}"

            echo -e \\trsync --info=stats3 --delete -a "$SNAPDIR/" "$TARGET_DIR/"
            if test "${SIMULATION:-0}" = 0; then

                mkdir -p "$TARGET_DIR"

                if ! rsync --info=stats3 --delete -a "$SNAPDIR/" "$TARGET_DIR/" ; then
                    >&2 echo "rsync could not entirely copy from $SNAPDIR to $DATASET_TARGET"
                fi
            fi
        else
            echo -e "\tSKIP: Snapshot $SNAPSHOT does not exist for dataset $DATASET"
        fi
    done

    NEW_SNAPSHOT="$DATASET_TARGET@$SNAPSHOT"
    echo ""
    echo -e "\t> Concluding snapshot: ${NEW_SNAPSHOT} <"
    echo ""

    if test "${SIMULATION:-0}" = 0; then
        zfs snap $NEW_SNAPSHOT
    fi
done