{
  config,
  inputs,
  lib,
  ...
}:
with lib;
let
  cfg = config.nixfiles.modules.common.nix;
in
{
  options.nixfiles.modules.common.nix.allowedUnfreePackages = mkOption {
    description = "A list of allowed unfree packages.";
    type = with types; listOf str;
    default = [ ];
  };

  config = {
    nix = {
      daemonCPUSchedPolicy = "idle";
      daemonIOSchedClass = "idle";
      daemonIOSchedPriority = 7;
    };

    nixpkgs.config.allowUnfreePredicate = p: elem (getName p) cfg.allowedUnfreePackages;

    system.stateVersion = with builtins; head (split "\n" (readFile "${inputs.nixpkgs}/.version"));

    environment = {
      sessionVariables.NIX_SHELL_PRESERVE_PROMPT = "1";
      localBinInPath = true;
      defaultPackages = [ ];
    };
  };
}