#!/usr/bin/env bash

set -euo pipefail

ALLOW_REBOOT=
BRANCH="main"
BINARY_CACHE=
HOST_NAME=$HOSTNAME
NO_DELAY=

while [[ $# -gt 0 ]]; do
  case $1 in
    --allow-reboot)
      ALLOW_REBOOT=1
      shift
    ;;
    --branch)
      BRANCH="$2"
      shift
      shift
    ;;
    --cache)
      BINARY_CACHE="$2"
      shift
      shift
    ;;
    --hostname)
      HOST_NAME="$2"
      shift
      shift
    ;;
    --no-delay)
      NO_DELAY=1
      shift
    ;;
    *)
      echo "Unknown option $1"
      exit 1
    ;;
  esac
done

HYDRA_URL="https://hydra.kyouma.net/job/nixfiles/${BRANCH}/nixosConfigurations.${HOST_NAME}/latest-finished"

NEW_STORE_PATH="$(curl --fail -s -L -H "Accept: application/json" "${HYDRA_URL}" | jq -r ".buildoutputs.out.path")"

OLD_STORE_PATH="$(readlink -f "/nix/var/nix/profiles/system")"

OLD_STORE_SUFFIX="$(echo -n "$OLD_STORE_PATH" | tail -c 7)"

get_old_path () {
  for system in $(find /nix/var/nix/profiles/ -printf "%f\n" | grep "system-" | sort -nr); do
    local store_path
    store_path="$(readlink -f "/nix/var/nix/profiles/${system}")"
    if [[ "$(echo -n "$store_path" | tail -c 7)" != "pre-git" ]]; then
      OLD_STORE_PATH=$store_path
      break
    fi
  done
}

if [[ "$OLD_STORE_SUFFIX" == "pre-git" ]]; then
  echo "Last update was pushed manually"
  echo "Getting newest system profile that came from Hydra"
  get_old_path
fi

if [[ "$OLD_STORE_PATH" == "$NEW_STORE_PATH" ]]; then
  echo "no update available. exiting"
  exit 0
fi

echo "Downloading ${NEW_STORE_PATH}"
nix copy --from "${BINARY_CACHE}" --to "daemon" "${NEW_STORE_PATH}"

echo "Adding path to system profile"
nix-env -p "/nix/var/nix/profiles/system" --set "${NEW_STORE_PATH}"

echo "Set new profile as boot target"
/nix/var/nix/profiles/system/bin/switch-to-configuration boot 

if [[ -n "$ALLOW_REBOOT" ]]; then
  nixos-needsreboot
fi

if [[ -n "$NO_DELAY" ]]; then
  delay="1"
else
  delay="$(echo -n $RANDOM | tail -c 2)"
fi

if [[ -f "/var/run/reboot-required" ]]; then
  if [[ -n "$ALLOW_REBOOT" ]]; then
    echo "Rebooting system in ${delay} Minutes"
    shutdown -r +"${delay}"
  else
    echo "Unattended reboot not allowed"
    echo "Reboot system manually"
  fi
else
  echo "Activating system now"
  /nix/var/nix/profiles/system/bin/switch-to-configuration switch
  echo "Finished upgrade"
fi