#! /bin/bash

total_cargo_build_space() {
    local -r dir="$1"

    local cargo_toml_path
    local target_path

    find "$dir" -type f -name Cargo.toml \
    | while read -r cargo_toml_path
    do
        target_path=$(dirname "$cargo_toml_path")/target;
        if test -d "$target_path"
        then
            du -s "$target_path"; fi
        done \
    | awk '{tot += $1} END {print tot * 1024}' \
    | numfmt --to=iec
}

main() {
    local -r dir="${1-$HOME}"

    total_cargo_build_space "$dir"
}

main "$@"