wesnoth: add darwin app bundle

pkgs/games/wesnoth/default.nix

@@ -1,6 +1,7 @@
 {
   lib,
   stdenv,
+  stdenvNoCC,
   fetchFromGitHub,
   cmake,
   pkg-config,
@@ -91,7 +92,34 @@ stdenv.mkDerivation rec {
     "-DENABLE_SYSTEM_LUA=ON"
   ];
 
-  NIX_LDFLAGS = lib.optionalString stdenv.hostPlatform.isDarwin "-framework AppKit";
+  postInstall = lib.optionalString stdenv.hostPlatform.isDarwin ''
+    app_name="The Battle for Wesnoth"
+    app_bundle="$out/Applications/$app_name.app"
+    app_contents="$app_bundle/Contents"
+    mkdir -p "$app_contents"
+    echo "APPL????" > "$app_contents/PkgInfo"
+    mv $out/bin "$app_contents/MacOS"
+    mv $out/share/wesnoth "$app_contents/Resources"
+    pushd ../projectfiles/Xcode
+    substitute Info.plist "$app_contents/Info.plist" \
+      --replace-fail ''\'''${EXECUTABLE_NAME}' wesnoth \
+      --replace-fail '$(PRODUCT_BUNDLE_IDENTIFIER)' org.wesnoth.Wesnoth \
+      --replace-fail ''\'''${PRODUCT_NAME}' "$app_name"
+    cp -r Resources/SDLMain.nib "$app_contents/Resources/"
+    install -m0644 Resources/{container-migration.plist,icon.icns} "$app_contents/Resources"
+    popd
+
+    # Make the game and dedicated server binary available for shell users
+    mkdir -p "$out/bin"
+    ln -s "$app_contents/MacOS/wesnothd" "$out/bin/wesnothd"
+    # Symlinking the game binary is unsifficient as it would be unable to
+    # find the bundle resources
+    cat << EOF > "$out/bin/wesnoth"
+    #!${stdenvNoCC.shell}
+    open -na "$app_bundle" --args "\$@"
+    EOF
+    chmod +x "$out/bin/wesnoth"
+  '';
 
   meta = with lib; {
     description = "Battle for Wesnoth, a free, turn-based strategy game with a fantasy theme";
@@ -107,5 +135,6 @@ stdenv.mkDerivation rec {
     license = licenses.gpl2Plus;
     maintainers = with maintainers; [ abbradar ];
     platforms = platforms.unix;
+    mainProgram = "wesnoth";
   };
 }