{
  url ? null,
  hash ? null,
  pkgs,
  lib,
  ...
}: let
  modpack = pkgs.fetchzip {
    inherit url hash;
    stripRoot = false;
  };

  variablesStr = builtins.readFile "${modpack}/variables.txt";
  variableLines =
    builtins.filter (l: l != "" && (lib.strings.elemAt (lib.stringToCharacters l) 0) != "#")
    (lib.strings.splitString "\n" variablesStr);

  stripQuotes = s:
    if builtins.match "^\".*\"$" s != null
    then builtins.substring 1 (builtins.stringLength s - 2) s
    else s;

  parseLine = line: let
    parts = lib.strings.splitString "=" line;
  in {
    name = builtins.elemAt parts 0;
    value = stripQuotes (builtins.concatStringsSep "=" (builtins.tail parts));
  };

  variables = builtins.listToAttrs (map parseLine variableLines);
in {
  inherit variables;
  root = modpack;
  mods = "${modpack}/mods";
  config = "${modpack}/config";
}