some refactoring and modularizing locale

modules/nixos/services/system/greetd/default.nix

@@ -0,0 +1,58 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}: let
+  inherit (lib) mkIf mkEnableOption mkMerge mkOption types;
+  cfg = config.nixos.services.system.greetd;
+in {
+  options = {
+    nixos.services.system.greetd = {
+      enable = mkEnableOption {
+        type = types.bool;
+        default = false;
+        description = "Enables the greetd service.";
+      };
+      gnomeKeyring.enable = mkEnableOption {
+        type = types.bool;
+        default = false;
+        description = "Enables GnomeKeyring PAM service for greetd.";
+      };
+      autologin.enable = mkEnableOption {
+        type = types.bool;
+        default = false;
+        description = "Enables autologin for a specified user.";
+      };
+      autologin.user = mkOption {
+        type = types.str;
+        default = "cnst";
+        description = "The username to auto-login when autologin is enabled.";
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    services.greetd = {
+      enable = true;
+      settings = mkMerge [
+        # Conditionally include initial_session if autologin is enabled
+        (mkIf cfg.autologin.enable {
+          initial_session = {
+            command = "${pkgs.hyprland}/bin/Hyprland";
+            user = cfg.autologin.user;
+          };
+        })
+        {
+          default_session = {
+            command = "${pkgs.greetd.tuigreet}/bin/tuigreet -r --remember-session --asterisks";
+            user = "greeter";
+          };
+        }
+      ];
+    };
+
+    # Apply GnomeKeyring PAM Service based on user configuration
+    security.pam.services.greetd.enableGnomeKeyring = cfg.gnomeKeyring.enable;
+  };
+}