feat: modularize nixosSystem with hosts

flake.nix

@@ -24,22 +24,12 @@
       inherit username system;
     };
   in {
-    nixosConfigurations.dekomori = nixpkgs.lib.nixosSystem {
-      inherit specialArgs;
-      modules = [
-        ./hosts/dekomori
-        ./modules/desktop
-        ./options/desktop
+    nixosConfigurations = import ./hosts (
+      {inherit specialArgs;} // {isNixOS = true;}
+    );
 
-        home-manager.nixosModules.home-manager
-        {
-          home-manager.useGlobalPkgs = true;
-          home-manager.useUserPackages = true;
-
-          home-manager.extraSpecialArgs = specialArgs;
-          home-manager.users."${username}" = ./home/desktop;
-        }
-      ];
-    };
+    homeConfigurations = import ./hosts (
+      {inherit specialArgs;} // {isNixOS = false;}
+    );
   };
 }

hosts/default.nix

@@ -0,0 +1,54 @@
+{
+  specialArgs,
+  isNixOS,
+  ...
+}: let
+  username = "${specialArgs.username}";
+  mkHost = host: type: let
+    lib = specialArgs.inputs.nixpkgs.lib;
+    home-manager = specialArgs.inputs.home-manager;
+    nixpkgs = specialArgs.inputs.nixpkgs;
+  in
+    if isNixOS
+    then
+      lib.nixosSystem {
+        inherit specialArgs;
+        modules = [
+          ./${host}
+          ../modules/${type}
+          ../options/${type}
+          home-manager.nixosModules.home-manager
+          {
+            home-manager = {
+              # Because we use Home-Manager as a pure configuration manager.
+              useUserPackages = lib.mkForce false;
+              useGlobalPkgs = lib.mkForce true;
+
+              extraSpecialArgs = specialArgs;
+              users."${username}" = {
+                imports = [
+                  ../home/${type}
+                ];
+              };
+            };
+          }
+        ];
+      }
+    else
+      home-manager.lib.homeManagerConfiguration {
+        extraSpecialArgs = specialArgs;
+        pkgs = import nixpkgs {config.allowUnfree = lib.mkForce true;};
+        modules = [
+          ../home/${type}
+        ];
+      };
+in
+  builtins.listToAttrs (builtins.attrValues (builtins.mapAttrs (host: type: {
+      name =
+        if isNixOS
+        then host
+        else "${username}@${host}";
+      value = mkHost host type;
+    }) {
+      "dekomori" = "desktop";
+    }))

modules/core/user.nix

@@ -3,7 +3,7 @@
   users.groups."${username}" = {};
   users.users."${username}" = {
     # TODO: probably not needed
-    #home = "/home/yunfachi";
+    #home = "/home/${username}";
     isNormalUser = true;
     description = "${username}";
     extraGroups = [