# SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
# SPDX-License-Identifier: Apache-2.0

export_or_unset()
{
	local var=$1

	if [ -z "${!var+x}" ]; then
		return
	fi

	if [ -n "$2" ]; then
		export $var="$2"
	else
		unset $var
	fi

}

if direnv_version "2.30.0" \
&& has nix \
&& nix show-config experimental-features 2>/dev/null | grep -wqF flakes
then
	local oldtmp="$TMP"
	local oldtemp="$TEMP"
	local oldtmpdir="$TMPDIR"
	local oldtempdir="$TEMPDIR"

	watch_file ./packaging/nix/*.nix
	use flake ./packaging/nix

	export_or_unset TMP "$oldtmp"
	export_or_unset TEMP "$oldtemp"
	export_or_unset TMPDIR "$oldtmpdir"
	export_or_unset TEMPDIR "$oldtempdir"
fi