#!/bin/bash

function print_help_and_exit() {
  printf "Usage: rebuild ACTION [HOST]\n"
  printf "\n"
  printf "Arguments:\n"
  printf "  ACTION\n"
  printf "          See 'man 8 nixos-rebuild'\n"
  printf "  [HOST]\n"
  printf "          Host to build on\n"
  printf "\n"
  printf "Options:\n"
  printf "  -x, --external\n"
  printf "          Assume that the target host is outside my realm of my home\n"
  printf "  -b, --build <host>\n"
  printf "          Host to build on, or 'local' for localhost\n"
  exit 1
}

POSITIONAL_ARGS=()
EXTERNAL=
BUILD_HOST=

while [[ $# -gt 0 ]]; do
  case $1 in
  -h | --help)
    print_help_and_exit
    ;;
  -x | --external)
    EXTERNAL=yes
    shift # past argument
    ;;
  -b | --build)
    shift # past argument
    BUILD_HOST=$1
    shift # past value
    ;;
  -*)
    echo "Unknown option $1"
    print_help_and_exit
    ;;
  *)
    POSITIONAL_ARGS+=("$1") # save positional arg
    shift                   # past argument
    ;;
  esac
done

ACTION=${POSITIONAL_ARGS[0]:-}
if [ -z "${ACTION+x}" ]; then
  print_help_and_exit
fi

TARGET_HOST=${POSITIONAL_ARGS[1]:-}

case "$ACTION" in
"switch" | "boot" | "test")
  SUDO=sudo
  ;;
*)
  SUDO=
  ;;
esac

ARGS=("$ACTION")

# Only use my cache if the host is close to me
if [ -z "$EXTERNAL" ]; then
  # Only use my cache if it's up
  if personal-cache --ping; then
    ARGS+=("--option" "extra-substituters" "$(personal-cache --url)")
    printf "Cache is up and running!\n"
  else
    printf "Cache is down!\n"
  fi
fi

if [ -n "$TARGET_HOST" ]; then
  if [ -z "$BUILD_HOST" ]; then
    ARGS+=("--build-host" "root@$TARGET_HOST")
  fi
  ARGS+=("--target-host" "root@$TARGET_HOST" "--flake" ".#$TARGET_HOST")
else
  ARGS+=("--flake" "." "--show-trace")
fi

if [ -n "$BUILD_HOST" ] && [ "$BUILD_HOST" != "local" ]; then
  ARGS+=("--build-host" "root@$BUILD_HOST")
  printf "Building on root@%s\n" "$BUILD_HOST"
fi

printf " > nixos-rebuild %s\n" "${ARGS[*]}"
$SUDO nixos-rebuild "${ARGS[@]}"