nix: revert overlay changes and add conditionals to derivation for flake build

flake.nix

@@ -21,14 +21,13 @@
         packages = {
           polymc = pkgs.libsForQt5.callPackage ./packages/nix/polymc {
             inherit self;
+            isFlakeBuild = true;
             submoduleQuazip = quazip;
             submoduleNbt = libnbtplusplus;
           };
         };
 
-        overlay = import ./packages/nix/overlay.nix {
+        overlay = import ./packages/nix/overlay.nix {};
-          inherit self quazip libnbtplusplus;
-        };
 
         apps = {
           polymc = flake-utils.lib.mkApp {

packages/nix/overlay.nix

@@ -1,9 +1,3 @@
-{ self, quazip, libnbtplusplus }:
-
 final: prev: rec {
-  polymc = prev.libsForQt5.callPackage ./polymc {
+  polymc = prev.libsForQt5.callPackage ./polymc {};
-    inherit self;
-    submoduleQuazip = quazip;
-    submoduleNbt = libnbtplusplus;
-  };
 }

packages/nix/polymc/default.nix

@@ -15,9 +15,10 @@
 , qtbase
 , libGL
 # submodules
-, self
+, isFlakeBuild ? false
-, submoduleNbt
+, self ? ""
-, submoduleQuazip
+, submoduleNbt ? ""
+, submoduleQuazip ? ""
 }:
 
 let
@@ -34,19 +35,26 @@ in
 
 mkDerivation rec {
   pname = "polymc";
-  version = "nightly";
+  version = if isFlakeBuild then "nightly" else "1.0.4";
 
-  src = lib.cleanSource self;
+  src = if isFlakeBuild then lib.cleanSource self
+    else fetchFromGitHub {
+    owner = "PolyMC";
+    repo = "PolyMC";
+    rev = "${version}";
+    sha256 = "sha256-8aya0KfV9F+i2qBpweWcR9hwyTSQkqn2wHdtkCEeNvk=";
+    fetchSubmodules = true;
+  };
 
   nativeBuildInputs = [ cmake file makeWrapper ];
   buildInputs = [ qtbase jdk8 zlib ];
 
-  postUnpack = ''
+  postUnpack = if isFlakeBuild then ''
     mkdir source/libraries/{libnbtplusplus,quazip}
     cp -a ${submoduleNbt}/* source/libraries/libnbtplusplus
     cp -a ${submoduleQuazip}/* source/libraries/quazip
     chmod a+r+w source/libraries/{libnbtplusplus,quazip}/*
-  '';
+  '' else "";
 
   cmakeFlags = [
     "-DLauncher_LAYOUT=lin-system"