#!/bin/sh

{ # Prevent execution if this script was only partially downloaded
  oops() {
    echo "$0:" "$@" >&2
    exit 1
  }

  umask 0022

  tmpDir="$(mktemp -d -t xip-binary-tarball-unpack.XXXXXXXXXX ||
    oops "Can't create temporary directory for downloading the Xip binary tarball")"
  cleanup() {
    rm -rf "$tmpDir"
  }
  trap cleanup EXIT INT QUIT TERM

  require_util() {
    command -v "$1" >/dev/null 2>&1 ||
      oops "you do not have '$1' installed, which I need to $2"
  }

  case "$(uname -s).$(uname -m)" in
  Darwin.x86_64)
    system=darwin-amd64
    ;;
  Darwin.arm64 | Darwin.aarch64)
    system=darwin-arm64
    ;;
  *) oops "sorry, there is no binary distribution of Nix for your platform" ;;
  esac

  url=$(curl -s https://api.github.com/repos/gordian-jklapacz/xip/releases/latest |
    grep "browser" |
    cut -d : -f 2,3 |
    tr -d \" |
    grep $system |
    grep -v md5 |
    awk '{$1=$1};1')
  path=$(echo "$url" | cut -d / -f 9)

  # Use this command-line option to fetch the tarballs using nar-serve or Cachix
  if [ "${1:-}" = "--tarball-url-prefix" ]; then
    if [ -z "${2:-}" ]; then
      oops "missing argument for --tarball-url-prefix"
    fi
    url=${2}/${path}
    shift 2
  fi

  tarball=$tmpDir/$path

  require_util tar "unpack the binary tarball"
  if [ "$(uname -s)" != "Darwin" ]; then
    require_util xz "unpack the binary tarball"
  fi

  if command -v curl >/dev/null 2>&1; then
    fetch() { curl --fail -L "$1" -o "$2"; }
  elif command -v wget >/dev/null 2>&1; then
    fetch() { wget "$1" -O "$2"; }
  else
    oops "you don't have wget or curl installed, which I need to download the binary tarball"
  fi

  echo "downloading $path binary tarball for $system from '$url' to '$tmpDir'..."
  fetch "$url" "$tarball" || oops "failed to download '$url'"

  unpack=$tmpDir/unpack
  mkdir -p "$unpack"
  tar -xJf "$tarball" -C "$unpack" || oops "failed to unpack '$url'"

  script=$(echo "$unpack"/xip)

  create_dir() {
    dest="$1"
    if ! [ -e "$dest" ]; then
      cmd="mkdir -m 0755 $dest && chown $USER $dest"
      echo "directory $dest does not exist; creating it by running '$cmd' using sudo" >&2
      if ! sudo sh -c "$cmd"; then
        echo "$0: please manually run '$cmd' as root to create $dest" >&2
        exit 1
      fi
    fi
  }
  create_dir /opt
  create_dir /opt/gordian
  create_dir /opt/gordian/bin
  [ -e "/opt/gordian/bin/xip" ] || cp "$unpack"/xip /opt/gordian/bin/xip

  [ -e "$script" ] || oops "installation script is missing from the binary tarball!"
  export INVOKED_FROM_INSTALL_IN=1
  if [ -n "$@" ]; then
    "$script" check all
    "$script" setup
  else
    "$script" "$@"
  fi
} # End of wrapping