Add btop theming

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

users/configs/btop/default.nix

@@ -0,0 +1,38 @@
+{ user ? throw "user argument is required", gpu ? false }: { config, lib, pkgs, ... }:
+
+let
+  hmConfig = config.home-manager.users."${user.name}";
+in
+{
+  home-manager.users."${user.name}" = {
+    programs = {
+      btop = {
+        enable = true;
+        settings = {
+          color_theme = "matugen";
+          theme_background = false;
+          presets = "";
+          vim_keys = true;
+          shown_boxes = "cpu mem net proc gpu0 gpu1";
+          update_ms = 1000;
+          proc_tree = true;
+          cpu_single_graph = true;
+          disks_filter = "/ /nix /persist /cache";
+        };
+      };
+
+      matugen.settings.templates.btop = {
+        input_path = ./theme.theme;
+        output_path = "${hmConfig.xdg.configHome}/btop/themes/matugen.theme";
+      };
+    };
+
+    theme.extraConfig = "${lib.meta.getExe (pkgs.writeShellApplication {
+      name = "reload-btop";
+      runtimeInputs = with pkgs; [ procps ];
+      text = ''
+        pkill btop -SIGUSR2
+      '';
+    })} &";
+  };
+}