{ config, pkgs, unstable, unstable-small, nixpkgs-master, nixpkgs-2311, lib, ... }:

let
  base = "/etc/nixpkgs/channels";
  nixpkgsPath = "${base}/nixpkgs";
  nixpkgsSmallPath = "${base}/nixpkgsSmall";
  nixpkgsMasterPath = "${base}/nixpkgsMaster";
  nixpkgs2311Path = "${base}/nixpkgs2311";
in
{
  options.nix.flakes.enable = lib.mkEnableOption "nix flakes";

  config = lib.mkIf config.nix.flakes.enable {
    nix = {
      package = pkgs.nixVersions.latest;
      experimentalFeatures = "nix-command flakes";

      registry.nixpkgs.flake = unstable;
      registry.nixpkgsSmall.flake = unstable-small;
      registry.nixpkgsMaster.flake = nixpkgs-master;
      registry.nixpkgs2311.flake = nixpkgs-2311;

      nixPath = [
        "nixpkgs=${nixpkgsPath}"
        "nixpkgsSmall=${nixpkgsSmallPath}"
        "nixpkgs2311=${nixpkgs2311Path}"
        "/nix/var/nix/profiles/per-user/root/channels"
      ];
    };

    systemd.tmpfiles.rules = [
      "L+ ${nixpkgsPath}         - - - - ${unstable}"
      "L+ ${nixpkgsSmallPath} - - - - ${unstable-small}"
      "L+ ${nixpkgsMasterPath} - - - - ${nixpkgs-master}"
      "L+ ${nixpkgs2311Path} - - - - ${nixpkgs-2311}"
    ];
  };
}