#!/bin/sh

set -eu

if [ $EUID -ne 0 ]; then
	exec sudo "$0" "$@"
fi

if [ $# -lt 1 ]; then
	echo "Usage: $0 hostname" >&2
	exit 1
fi

depot_parent() {
	pd="$(readlink -f "$1")/"
	if [ "${pd#*/depot/}" = "$pd" ]; then
		return
	fi
	pd="$(readlink -f "${pd%/depot/*}/depot")"
	echo "$pd"
}

depot_path() {
	pd="$(depot_parent "$PWD")"
	if [ "$pd" = "" ]; then
		pd="$(depot_parent "$(readlink -f "$0")")"
	fi
	echo "$pd"
}

readonly targethostname="$1"
readonly depot="$(depot_path)"
if [ "$depot" = "" ]; then
	echo "This script needs to be executed in-depot (or the script itself should be in-depot)."
	exit 1
fi
readonly system="$(nix-build -E '(import "'"$(depot_path)"'" {}).ops.nixos.'"${targethostname}" --no-out-link)"
nix-env -p /nix/var/nix/profiles/system --set "$system"
"$system/bin/switch-to-configuration" switch