nixup: add module: nixup-tools

nixup/modules/module-list.nix

@@ -5,6 +5,7 @@
   ./misc/legacy-nixpkgs-config.nix
   ./nixup/activation.nix
   ./nixup/build.nix
+  ./nixup/nixup-tools.nix
   ./nixup/resource-files.nix
   ./nixup/switch-to-configuration.nix
   ./nixup/systemd.nix

nixup/modules/nixup/nixup-tools.nix

@@ -0,0 +1,53 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.nixup-tools;
+
+  managed-packages =
+    let
+      packagesString = if cfg.managed-packages-path == null
+                       then let xdg_config_home_ = builtins.getEnv "XDG_CONFIG_HOME";
+                                xdg_config_home = if xdg_config_home_ == "" then "${builtins.getEnv "HOME"}/.config" else xdg_config_home_;
+                            in
+                            if builtins.pathExists "${xdg_config_home}/nixup/packages.nix"
+                            then readFile (builtins.toPath "${xdg_config_home}/nixup/packages.nix")
+                            else ""
+                       else if builtins.pathExists (builtins.toPath cfg.managed-packages-path)
+                            then readFile (builtins.toPath cfg.managed-packages-path)
+                            else "";
+    in
+      map (x : getAttr x pkgs) (remove "" (map (x: replaceChars ["\n"] [""] x) (splitString "\n" packagesString)));
+
+in
+
+{
+  options = {
+
+    nixup-tools = {
+      enable = mkOption {
+        default = false;
+        type = types.bool;
+        description = ''
+          Enable special tooling for NixUP.
+        '';
+      };
+      managed-packages-path = mkOption {
+        default = null;
+        type = types.nullOr types.path;
+        description = ''
+          Path of file to include into "user.packages".
+          "null" uses "$XDG_CONFIG_HOME/nixup/packages.nix".
+        '';
+      };
+    };
+  };
+
+  config = {
+
+    user.packages = mkIf cfg.enable ([ pkgs.nixup-tools ] ++ managed-packages);
+
+  };
+}