{ lib }:
let
  collectNixFiles =
    dir:
    lib.flatten (
      lib.mapAttrsToList (
        name: type:
        let
          path = dir + "/${name}";
        in
        if type == "directory" then
          collectNixFiles path
        else if type == "regular" && lib.hasSuffix ".nix" name then
          [ path ]
        else
          [ ]
      ) (builtins.readDir dir)
    );
in
{
  inherit collectNixFiles;

  removeNixSuffix = path: lib.removeSuffix ".nix" (builtins.baseNameOf path);

  registry.predicates.uniqueValue =
    value: entries: builtins.length (lib.unique (map value entries)) == builtins.length entries;

  bridgeName = id: "br-vlan${toString id}";

  deriveMac =
    name:
    let
      hash = builtins.hashString "sha256" name;
    in
    lib.concatStringsSep ":" (
      [ "02" ]
      ++ map (i: builtins.substring (i * 2) 2 hash) [
        0
        1
        2
        3
        4
      ]
    );
}