Refactor modules style

nixosModules/services/system/default.nix

@@ -0,0 +1,61 @@
+{ config, pkgs, lib, ... }:
+
+{
+  options = {
+    user.name = lib.mkOption { default = "pan"; };
+    user.timezone = lib.mkOption { default = "America/Los_Angeles"; };
+    font.extraFonts = lib.mkOption { default = []; };
+  };
+
+  config = {
+    # Use the systemd-boot EFI boot loader.
+    boot.kernelPackages = pkgs.linuxPackages_latest;
+    boot.loader.systemd-boot.enable = true;
+    boot.loader.timeout = 1;
+    boot.loader.efi.canTouchEfiVariables = true;
+
+    time.timeZone = config.user.timezone;
+
+    i18n.defaultLocale = "en_US.UTF-8";
+
+    # "Essential" Packages
+    environment.systemPackages = with pkgs; [
+      git
+      neovim
+      nnn
+      xdg-user-dirs
+    ];
+
+    # XDG Compliance
+    xdg.portal.config.common.default = "*";
+    environment.sessionVariables = rec {
+      XDG_CONFIG_HOME = "\${HOME}/.config";
+      XDG_CACHE_HOME  = "\${HOME}/.cache";
+      XDG_STATE_HOME  = "\${HOME}/.local/state";
+      XDG_DATA_HOME   = "\${HOME}/.local/share";
+      XDG_BIN_HOME    = "\${HOME}/.local/bin";
+      PATH            = [
+        "\${HOME}/prog/scripts"
+      ];
+    };
+
+    users.groups = {
+      wheel = { };
+      network = { };
+    };
+
+    users.users.defaultUser = {
+      name = config.user.name;
+      isNormalUser = true;
+      extraGroups = [ "wheel" "network" ];
+    };
+
+    fonts = {
+      enableDefaultPackages = true;
+      packages = with pkgs; [
+        cascadia-code
+        source-han-sans # Pan-CJK font
+      ] ++ config.system.extraFonts;
+    };
+  };
+}