#!/usr/bin/env bash

backup() {
    local volume
    local target
    local target_dir
    local target_name
    volume="$1"
    target="$(realpath "$2")"
    target_dir="$(dirname "$target")"
    target_name="$(basename "$target")"

    test -z "$(docker volume ls | grep "$volume")" && { echo "Error: No such volume, aborting" >&2; exit 1; }
    test -z "$target_dir" && { echo "Error: No base folder found for target=$target" >&2; exit 2; }
    test -z "$target_name" && { echo "Error: No target name found for target=$target" >&2; exit 3; }

    set -x
    docker run --rm --user="$(id -u):$(id -g)" --mount="type=volume,source=$volume,destination=/data,ro=true" --mount="type=bind,source=$target_dir,destination=/data2" busybox tar cvf "/data2/$target_name" "/data"
    set +x
}

restore() {
    local volume
    local target
    local target_dir
    local target_name
    target="$(realpath "$1")"
    target_dir="$(dirname "$target")"
    target_name="$(basename "$target")"
    volume="$2"

    test -z "$(docker volume ls | grep "$volume")" && { echo "Error: No such volume, aborting" >&2; exit 1; }
    test -z "$target_dir" && { echo "Error: No base folder found for target=$target" >&2; exit 2; }
    test -z "$target_name" && { echo "Error: No target name found for target=$target" >&2; exit 3; }

    set -x
    docker run --rm --user="$(id -u):$(id -g)" --mount="type=volume,source=$volume,destination=/data" --mount="type=bind,source=$target_dir,destination=/data2" busybox /bin/sh -c "rm -rf /data/* && cd / && tar xvf '/data2/$target_name'"
    set +x
}

main() {
    local volumes
    volumes="$(docker volume ls | tail -n+2 | egrep -v '[a-z]+\s+[0-9a-f]+$' | egrep -o '\s.+$' | sed 's/\s//g')"
    while read -r line; do
        echo "$line -> $line.tar"
        backup "$line" "$line.tar"
    done <<< "$volumes"
}

"$@"