xscreensaver: add option settings

modules/services/xscreensaver.nix

@@ -2,19 +2,41 @@
 
 with lib;
 
+let
+
+  cfg = config.services.xscreensaver;
+
+in
+
 {
   meta.maintainers = [ maintainers.rycee ];
 
   options = {
     services.xscreensaver = {
       enable = mkEnableOption "XScreenSaver";
+
+      settings = mkOption {
+        type = with types; attrsOf (either bool (either int str));
+        default = {};
+        example = {
+          mode = "blank";
+          lock = false;
+          fadeTicks = 20;
+        };
+        description = ''
+          The settings to use for XScreenSaver.
+        '';
+      };
     };
   };
 
-  config = mkIf config.services.xscreensaver.enable {
+  config = mkIf cfg.enable {
     # To make the xscreensaver-command tool available.
     home.packages = [ pkgs.xscreensaver ];
 
+    xresources.properties =
+      mapAttrs' (n: nameValuePair "xscreensaver.${n}") cfg.settings;
+
     systemd.user.services.xscreensaver = {
         Unit = {
           Description = "XScreenSaver";