feat(bbsteamie): add gaming mode button

devices/bbsteamie/modules/desktop.nix

@@ -1,5 +1,31 @@
-{config, ...}: let
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
   inherit (config.vars) mainUser;
+
+  inherit (lib) getExe;
+
+  switch-session = pkgs.writeShellApplication {
+    name = "switch-session";
+
+    text = ''
+      mkdir -p /etc/sddm.conf.d
+
+      cat <<EOF | tee /etc/sddm.conf.d/autologin.conf
+      [Autologin]
+      User=${mainUser}
+      Session=$1
+      Relogin=true
+      EOF
+    '';
+  };
+
+  gaming-mode = pkgs.writeShellScriptBin "gaming-mode" ''
+    sudo ${pkgs.systemd}/bin/systemctl start to-gaming-mode.service
+  '';
 in {
   # Auto-login to plasma
   services = {
@@ -11,16 +37,59 @@ in {
         wayland.enable = true;
         autoLogin.relogin = true;
       };
-
-      autoLogin = {
-        enable = true;
-        user = mainUser;
-      };
-
-      defaultSession = "plasma";
     };
   };
 
+  systemd.services."set-session" = {
+    wantedBy = ["multi-user.target"];
+    before = ["display-manager.service"];
+
+    path = [switch-session];
+
+    script = ''
+      switch-session "plasma"
+    '';
+  };
+
+  systemd.services."to-gaming-mode" = {
+    wantedBy = lib.mkForce [];
+
+    path = [switch-session];
+
+    script = ''
+      switch-session "gamescope-wayland"
+      systemctl restart display-manager
+      sleep 10
+      switch-session "plasma"
+    '';
+  };
+
+  security.sudo.extraRules = [
+    {
+      users = [mainUser];
+      groups = [100];
+      commands = [
+        {
+          command = "${pkgs.systemd}/bin/systemctl start to-gaming-mode.service";
+          options = ["SETENV" "NOPASSWD"];
+        }
+      ];
+    }
+  ];
+
+  home-manager.users.${mainUser}.xdg.desktopEntries."Gaming Mode" = {
+    name = "Gaming Mode";
+    exec = getExe gaming-mode;
+    icon = "steam";
+    terminal = false;
+    type = "Application";
+  };
+
+  environment.systemPackages = [
+    pkgs.firefox
+    pkgs.wl-clipboard
+  ];
+
   programs = {
     xwayland.enable = true;
     kdeconnect.enable = true;
@@ -29,7 +98,6 @@ in {
   # Enable flatpak support
   services.flatpak.enable = true;
   services.packagekit.enable = true;
-
   jovian.steam = {
     enable = true;
     user = mainUser;