#!/usr/bin/env bash

set -euo pipefail

script_dir=$(dirname "$0")

repository_root="${script_dir}/.."
nix_dir="${repository_root}/nix"
target="${script_dir}/expotools-built"
up_to_date_package="$(nix path-info -f "${nix_dir}" expotools 2>/dev/null || true)"

buildAndLink() {
  nix build -f "${nix_dir}" --out-link "${target}" expotools
}

if ! ls "${target}/bin/expotools" &>/dev/null; then
  echo "No version of expotools linked. Rebuilding..."
  buildAndLink
elif [ -z "${up_to_date_package}" ]; then
  read -r -t 7 -n 1 -p "Linked expotools is out of date. Rebuild (Y/n)? " choice || true
  choice=${choice:-Y}
  case "$choice" in 
    y|Y ) buildAndLink ;;
    * ) echo "Using previously-built expotools." ;;
  esac
elif [ "$(readlink "${target}")" != "${up_to_date_package}" ]; then
  echo "Wrong version of expotools linked. Re-linking..."
  buildAndLink
fi

exec "${target}/bin/expotools" "$@"