{ sources, system ? builtins.currentSystem, ... }@args:

let
  pkgs = import sources.nixpkgs args;
  unstable = import sources.nixpkgs-unstable args;

  callPackage = pkgs.lib.callPackageWith (pkgs // newpkgs);

  newpkgs = {

    mattermost = callPackage ./mattermost {inherit sources;};

    tracktrain = import sources.tracktrain {
      nixpkgs = pkgs;
    };

    # a version of the lounge with some extra css that
    # hides things the hacc-voc doesn't need
    thelounge-hacked = pkgs.stdenv.mkDerivation {
      name = "thelounge-hacked";
      src = pkgs.thelounge;

      phases = [ "buildPhase" "installPhase" ];
      buildPhase = ''
        cp $src/* -r .
        chmod 777 lib/node_modules/thelounge/public/css/style.css
        cat ${./thelounge/css-patch.css} >> lib/node_modules/thelounge/public/css/style.css
      '';

      installPhase = ''
        mkdir -p $out
        cp * -r $out
      '';
    };

    uffd = callPackage ./uffd {};

    # netbox takes a python3, then overrides stuff on it before using it.
    # since overrides don't accumulate, this does both the override we want
    # and the one the netbox package would otherwise do, then disables overrides
    netbox = pkgs.netbox.override rec {
      python3 = (pkgs.python3.override {
        packageOverrides = self: super: {
          django = super.django_4;
          social-auth-core = super.social-auth-core.overrideAttrs ( old: {
            patches = [ ./netbox/0001-add-uffd-oauth2-backend.patch ];
          } );
        };
      }) // { override = ignored: python3; };
    };

    inherit (unstable) vaultwarden vaultwarden-vault;
  };

in pkgs.extend(_: _: newpkgs)