{ host, pkgs, config, lib, ...}:
let cfg = config.system-nix; in {
  options.system-nix = {
    enable = lib.mkOption {
      type = lib.types.bool;
      default = true;
    };
  };

  config = lib.mkIf cfg.enable {
    programs = {
      nix-index = {
        enableBashIntegration = false;
        enableZshIntegration = false;
      };
      nix-index-database.comma.enable = true;
    };
    nix = {
      package = pkgs.nixVersions.nix_2_31; # https://github.com/serokell/deploy-rs/issues/340
      settings = {
        auto-optimise-store = true;
        substituters = [
          "https://install.determinate.systems"
          "https://nvim-treesitter-main.cachix.org"
        ];
        trusted-public-keys = [
          "cache.flakehub.com-3:hJuILl5sVK4iKm86JzgdXW12Y2Hwd5G07qKtHTOcDCM="
          "nvim-treesitter-main.cachix.org-1:cbwE6blfW5+BkXXyeAXoVSu1gliqPLHo2m98E4hWfZQ="
        ];
        trusted-users = [ host.username ];
        experimental-features = [
          "nix-command"
          "flakes"
        ];
        # lazy-trees = true; # https://github.com/serokell/deploy-rs/issues/340
      };
      channel.enable = false;
      nixPath = [ "nixpkgs=flake:nixpkgs" ];
      gc = {
        automatic = true;
        dates = "00:00";
        options = "--delete-older-than 14d";
      };
    };
  };
}