some refactoring and modularizing locale

modules/nixos/boot/kernel/default.nix

@@ -0,0 +1,74 @@
+{
+  pkgs,
+  lib,
+  config,
+  ...
+}: let
+  inherit (lib) mkOption;
+  cfg = config.nixos.boot.kernel;
+in {
+  options = {
+    nixos.boot.kernel = {
+      variant = mkOption {
+        type = lib.types.enum ["stable" "latest" "cachyos"];
+        default = "latest";
+        description = "Kernel variant to use.";
+      };
+
+      hardware = mkOption {
+        type = lib.types.enum ["amd" "nvidia"];
+        default = "amd";
+        description = "Hardware type (GPU) configuration.";
+      };
+
+      extraKernelParams = mkOption {
+        type = lib.types.listOf lib.types.str;
+        default = [];
+        description = "Additional kernel parameters.";
+      };
+
+      extraBlacklistedModules = mkOption {
+        type = lib.types.listOf lib.types.str;
+        default = [];
+        description = "Additional kernel nixos.to blacklist.";
+      };
+    };
+  };
+
+  config = {
+    boot = {
+      consoleLogLevel = 3;
+
+      kernelPackages = let
+        variant = cfg.variant or "latest"; # Ensure a default value
+      in
+        if variant == "stable"
+        then pkgs.linuxPackages
+        else if variant == "latest"
+        then pkgs.linuxPackages_latest
+        else if variant == "cachyos"
+        then pkgs.linuxPackages_cachyos
+        else throw "Unknown kernel variant: ${variant}";
+
+      kernelParams =
+        [
+          "quiet"
+          "splash"
+        ]
+        ++ (
+          if cfg.hardware == "amd"
+          then ["amd_pstate=active"]
+          else []
+        )
+        ++ cfg.extraKernelParams;
+
+      blacklistedKernelModules =
+        (
+          if cfg.hardware == "nvidia"
+          then ["nouveau"]
+          else []
+        )
+        ++ cfg.extraBlacklistedModules;
+    };
+  };
+}