dotfiles/overlays/rolling_datasets/bin/roll_dataset

# -*- mode: shell-script -*-

source @out@/share/functions/get_old_datasets

export "PATH=$PATH:@runtimePath@"

if [[ "$#" != 3 ]] ; then
    echo "This script requires precisely 2 arguments!"
    exit 1
fi

dataset="$1"
to_keep="$2"

generation="$(zfs get :generation "$dataset" -H -o value)"
generation="$(("$generation" + 1))"

zfs set ":generation=$generation" "$dataset"
zfs send "$dataset" | zfs recv "$dataset/$generation"
zfs rollback "$dataset@blank" && echo "rollback complete"

while IFS="\n" read gen
do
    printf "$gen < $(("$generation" - "$to_keep")) => "
    if [ "$gen" -lt "$(("$generation" - "$to_keep"))" ]; then
        zfs destroy -r "$dataset/$gen"
        echo "destroyed"
    else
        echo "kept"
    fi
done <<< "$(get_old_datasets "$dataset")"