#! /usr/bin/env nix-shell
#! nix-shell -i bash -p rsync

# shellcheck shell=bash

set -eou pipefail

function show_help() {
  echo "Usage:"
  echo "$0 [--build-local] <host.hq.c3d2.de>"
  echo "--help          Show this help."
  echo "--build-local   Build config locally and copy it to the target system via nix-copy-closure"
  exit 1
}

if [[ $# == 0 ]]; then
  show_help
fi

while [[ $# -gt 0 ]]; do
  case "${1:-}" in
    "" | "-h" | "--help")
      show_help
      ;;
    "--build-local")
      build_local=true
      ;;
    *)
      target=$1
      ;;
  esac
  shift
done

if [[ -v build_local ]]; then
  nix --experimental-features 'nix-command flakes' -Lv build ".#nixosConfigurations.$target.config.system.build.toplevel"
  store_path=$(readlink -f result)
  nix-copy-closure --to root@"$target" -v "$store_path"
  ssh root@"$target" "$store_path/bin/switch-to-configuration" switch
else
  hostname=$(echo "$target" | cut -d . -f 1)

  rsync -az "$(dirname "$0")" root@"$target":nix-config

  echo "$hostname> nixos-rebuild switch"
  exec ssh root@"$target" "nixos-rebuild --flake ./nix-config#$hostname switch"
fi