reusable gtk theme config

draft implementation of reusable theme configs

modules/home/themes/gtk/adw-gtk3/default.nix

@@ -0,0 +1,33 @@
+{ pkgs, lib, config, ... }:
+let
+  cfg = config.themes.gtk.adw-gtk3;
+in
+with lib; {
+  options.themes.gtk.adw-gtk3 =
+    {
+      enable = mkEnableOption "Use adw-gtk3 theme";
+      scheme = mkOption {
+        type = with types; (enum [ "light" "dark" ]);
+        description = "Theme colour scheme";
+      };
+    };
+
+  config = mkIf cfg.enable {
+    home.packages = with pkgs; [
+      adw-gtk3
+    ];
+
+    gtk = {
+      enable = true;
+      theme.name =
+        if cfg.scheme == "dark"
+        then "adw-gtk3-dark" else "adw-gtk3-light";
+    };
+
+    dconf.settings."org/gnome/desktop/interface" = {
+      "color-scheme" = mkDefault
+        (if cfg.scheme == "dark"
+        then "prefer-dark" else "prefer-light");
+    };
+  };
+}