Fix desktop file and move directories around

packages/nix/overlay.nix

@@ -0,0 +1,3 @@
+self: super: rec {
+  polymc = super.libsForQt5.callPackage ./nix/polymc {};
+}

packages/nix/polymc/0001-pick-latest-java-first.patch

@@ -0,0 +1,48 @@
+From 44e1b2a19a869b907b40e56c85c8a47aa6c22097 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Mustafa=20=C3=87al=C4=B1=C5=9Fkan?= <musfay@protonmail.com>
+Date: Tue, 22 Jun 2021 21:50:11 +0300
+Subject: [PATCH] pick latest java first
+
+---
+ launcher/java/JavaInstallList.cpp | 4 ++--
+ launcher/java/JavaUtils.cpp       | 2 +-
+ 2 files changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/launcher/java/JavaInstallList.cpp b/launcher/java/JavaInstallList.cpp
+index 0bded03c..40898e20 100644
+--- a/launcher/java/JavaInstallList.cpp
++++ b/launcher/java/JavaInstallList.cpp
+@@ -120,8 +120,8 @@ void JavaInstallList::updateListData(QList<BaseVersionPtr> versions)
+ 
+ bool sortJavas(BaseVersionPtr left, BaseVersionPtr right)
+ {
+-    auto rleft = std::dynamic_pointer_cast<JavaInstall>(left);
+-    auto rright = std::dynamic_pointer_cast<JavaInstall>(right);
++    auto rleft = std::dynamic_pointer_cast<JavaInstall>(right);
++    auto rright = std::dynamic_pointer_cast<JavaInstall>(left);
+     return (*rleft) > (*rright);
+ }
+ 
+diff --git a/launcher/java/JavaUtils.cpp b/launcher/java/JavaUtils.cpp
+index 5f004a10..6d633631 100644
+--- a/launcher/java/JavaUtils.cpp
++++ b/launcher/java/JavaUtils.cpp
+@@ -350,7 +350,6 @@ QList<QString> JavaUtils::FindJavaPaths()
+     qDebug() << "Linux Java detection incomplete - defaulting to \"java\"";
+ 
+     QList<QString> javas;
+-    javas.append(this->GetDefaultJava()->path);
+     auto scanJavaDir = [&](const QString & dirPath)
+     {
+         QDir dir(dirPath);
+@@ -379,6 +378,7 @@ QList<QString> JavaUtils::FindJavaPaths()
+     // general locations used by distro packaging
+     scanJavaDir("/usr/lib/jvm");
+     scanJavaDir("/usr/lib32/jvm");
++    javas.append(this->GetDefaultJava()->path);
+     // javas stored in MultiMC's folder
+     scanJavaDir("java");
+     return javas;
+-- 
+2.31.1
+

packages/nix/polymc/default.nix

@@ -0,0 +1,49 @@
+{ lib, mkDerivation, fetchFromGitHub, cmake, jdk8, jdk, zlib, file, makeWrapper, xorg, libpulseaudio, qtbase, libGL, msaClientID ? "" }:
+
+let
+  libpath = with xorg; lib.makeLibraryPath [ libX11 libXext libXcursor libXrandr libXxf86vm libpulseaudio libGL ];
+in 
+mkDerivation rec {
+  pname = "polymc";
+  version = "1.0.4";
+  src = fetchFromGitHub {
+    owner = "PolyMC";
+    repo = "PolyMC";
+    rev = "${version}";
+    sha256 = "sha256-8aya0KfV9F+i2qBpweWcR9hwyTSQkqn2wHdtkCEeNvk=";
+    fetchSubmodules = true;
+  };
+  nativeBuildInputs = [ cmake file makeWrapper ];
+  buildInputs = [ qtbase jdk8 zlib ];
+
+  patches = [ ./0001-pick-latest-java-first.patch ];
+
+  postPatch = ''
+    # hardcode jdk paths
+    substituteInPlace launcher/java/JavaUtils.cpp \
+      --replace 'scanJavaDir("/usr/lib/jvm")' 'javas.append("${jdk}/lib/openjdk/bin/java")' \
+      --replace 'scanJavaDir("/usr/lib32/jvm")' 'javas.append("${jdk8}/lib/openjdk/bin/java")'
+  '';
+
+  cmakeFlags = [ "-DLauncher_LAYOUT=lin-system" ];
+
+  postInstall = ''
+    # xorg.xrandr needed for LWJGL [2.9.2, 3) https://github.com/LWJGL/lwjgl/issues/128
+    wrapProgram $out/bin/polymc \
+      --set GAME_LIBRARY_PATH /run/opengl-driver/lib:${libpath} \
+      --prefix PATH : ${lib.makeBinPath [ xorg.xrandr ]}
+
+    substituteInPlace $out/share/applications/org.polymc.PolyMC.desktop --replace 'Exec=' 'Exec=${placeholder "out"}/bin/polymc'
+  '';
+
+  meta = with lib; {
+    homepage = "https://github.com/PolyMC/PolyMC";
+    description = "A free, open source launcher for Minecraft";
+    longDescription = ''
+      Allows you to have multiple, separate instances of Minecraft (each with their own mods, texture packs, saves, etc) and helps you manage them and their associated options with a simple interface.
+    '';
+    platforms = platforms.linux;
+    license = licenses.gpl3;
+    maintainers = with maintainers; [ cidkid ];
+  };
+}