make nixos module system-independent

flake.nix

@@ -6,8 +6,8 @@
     utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, utils }: utils.lib.eachDefaultSystem (system:
-    let
+  outputs = { self, nixpkgs, utils }: let
+    packages = utils.lib.eachDefaultSystem (system: let
       pkgs = import nixpkgs { inherit system; };
       mpvScript = { owner, repo, rev, sha256, scriptName }: pkgs.stdenvNoCC.mkDerivation {
         pname = repo;
@@ -21,8 +21,8 @@
         '';
         passthru = { inherit scriptName; };
       };
-    in rec {
-      packages.mpvScripts.sub-select = mpvScript {
+    in {
+      packages.sub-select = mpvScript {
         owner = "CogentRedTester";
         repo = "mpv-sub-select";
         rev = "5d2fb7ab73fc0e36d44109e75c9be26bd42084e2";
@@ -30,30 +30,32 @@
         scriptName = "sub-select.lua";
       };
 
-      packages.mpvScripts.segment-linking = mpvScript {
+      packages.segment-linking = mpvScript {
         owner = "CogentRedTester";
         repo = "mpv-segment-linking";
         rev = "bb0fdb7961859df57c64b42d75dbbd60a4024e97";
         sha256 = "1ykl24p96wwka4fillrzni6i0xkk4s2l9zg1scqypcbs5w491qsj";
         scriptName = "segment-linking.lua";
       };
+    });
+  in
+    packages // rec {
+      overlays.default = final: prev: let
+        newScripts = packages.packages.${prev.system};
+      in {
+        mpv = prev.mpv.override { scripts = builtins.attrValues newScripts; };
+        mpvScripts = prev.mpvScripts // newScripts;
+      };
 
-      nixosModules.default = { ... }: {
-        nixpkgs.overlays = final: prev: {
-          mpv = prev.mpv.override {
-            scripts = with packages.mpvScripts; [
-              sub-select
-              segment-linking
-            ];
-          };
-        };
+      nixosModules.default = { pkgs, lib, ... }: {
+        nixpkgs.overlays = [ overlays.default ];
 
         # needed for mpv segment-linking plugin
         environment.systemPackages = [
           pkgs.mkvtoolnix
         ];
 
-        home-manager.sharedModules = [ ({ config, lib, ... }: {
+        home-manager.sharedModules = [ ({ config, ... }: {
           config = lib.mkIf config.programs.mpv.enable {
             xdg.configFile."mpv/script-opts/sub-select.json".text = builtins.toJSON [
               {
@@ -93,6 +95,5 @@
           };
         }) ];
       };
-    }
-  );
+    };
 }