{
  buildPythonPackage,
  flask,
  flask_sqlalchemy,
  lib,
  libsass,
  mkYarnModules,
  nodejs,
  pkgconfig,
  pkgs,
  psycopg2,
  python2,
  python3,
  stdenv,
  flask-excel,
  pyexcel-xlsx,
}:

let
  src = fetchGit {
    url = "https://git.clerie.de/clerie/wetter.git";
    ref = "master";
    rev = "bb503828098717825c389fd6f450b395a02dcc6a";
  };
  pname = "wetter";
  version = "0.0.1";

  packageJSON = src + "/package.json";
  yarnLock = src + "/yarn.lock";

  modules = mkYarnModules {
    pname = "${pname}-modules";
    name = "${pname}-modules-${version}";
    inherit version packageJSON yarnLock;

    /* build native node-sass extensions */
    pkgConfig.node-sass = {
      buildInputs = [ python2 libsass pkgconfig ];
      postInstall = ''
        mkdir -p $HOME/.node-gyp/${nodejs.version}
        echo 9 > $HOME/.node-gyp/${nodejs.version}/installVersion
        ln -sfv ${nodejs}/include $HOME/.node-gyp/${nodejs.version}
        LIBSASS_EXT=auto yarn --offline run build
        rm build/config.gypi
      '';
    };
  };

  assets = stdenv.mkDerivation {
    inherit src pname version;

    NODE_ENV = "production";

    buildPhase = ''
      runHook preBuild
      ln -s ${modules}/node_modules
      node_modules/.bin/rollup -c
      runHook postBuild
    '';

    installPhase = ''
      runHook preInstall
      cp -r wetter/static/bundle $out
      runHook postInstall
    '';
  };

in buildPythonPackage rec {
  inherit src pname version;

  propagatedBuildInputs = [
    flask
    flask_sqlalchemy
    psycopg2
    flask-excel
    pyexcel-xlsx
  ];

  postInstall = ''
    mkdir -p $out/${python3.sitePackages}/wetter/static
    cp -r ${assets} $out/${python3.sitePackages}/wetter/static/bundle
    cp -r wetter/templates $out/${python3.sitePackages}/wetter/templates
  '';

  doCheck = false;
}