Optifine dev wrapper must be written in Java

src/main/java/optifine/OptifineTransformerDevWrapper.java

@@ -0,0 +1,65 @@
+package optifine;
+
+import net.minecraft.launchwrapper.IClassTransformer;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.Arrays;
+import java.util.Optional;
+import java.util.stream.Stream;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+
+public class OptifineTransformerDevWrapper implements IClassTransformer {
+
+    public static String OPTIFINE_CLASSNAME = "optifine/OptiFineClassTransformer.class";
+    private ZipFile ofZip = null;
+
+    public  OptifineTransformerDevWrapper() {
+        Stream<URL> loaderSources = Arrays.stream(((URLClassLoader) getClass().getClassLoader()).getURLs());
+        Optional<URL> optifineURL = loaderSources.filter(this::isOptifineJar).findFirst();
+        optifineURL.ifPresent(url -> ofZip = getZip(url));
+    }
+
+    private ZipFile getZip(URL url) {
+        try {
+            return new ZipFile(new File(url.toURI()));
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    private boolean isOptifineJar(URL url) {
+        ZipFile zip = getZip(url);
+        return zip != null && zip.getEntry(OPTIFINE_CLASSNAME) != null;
+    }
+
+    @Override
+    public byte[] transform(String name, String transformedName, byte[] basicClass) {
+        if (ofZip == null) return basicClass;
+        ZipEntry replacement = ofZip.getEntry(name.replace(".", "/") + ".class");
+        if (replacement == null) return basicClass;
+
+        try {
+            return readAll(ofZip.getInputStream(replacement));
+        } catch (IOException e) {
+            return basicClass;
+        }
+    }
+
+    private byte[] readAll(InputStream is) throws IOException {
+        byte[] buf = new byte[4096];
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        int len;
+        do {
+            len = is.read(buf, 0, 4096);
+            if (len > 0) bos.write(buf, 0, len);
+        } while (len > -1);
+        is.close();
+        return bos.toByteArray();
+    }
+}

src/main/java/optifine/OptifineTweakerDevWrapper.java

@@ -0,0 +1,28 @@
+package optifine;
+
+import net.minecraft.launchwrapper.ITweaker;
+import net.minecraft.launchwrapper.LaunchClassLoader;
+
+import java.io.File;
+import java.util.List;
+
+public class OptifineTweakerDevWrapper implements ITweaker {
+    @Override
+    public void acceptOptions(List<String> args, File gameDir, File assetsDir, String profile) {
+    }
+
+    @Override
+    public void injectIntoClassLoader(LaunchClassLoader classLoader) {
+        classLoader.registerTransformer("optifine.OptifineTransformerDevWrapper");
+    }
+
+    @Override
+    public String getLaunchTarget() {
+        return "net.minecraft.client.main.Main";
+    }
+
+    @Override
+    public String[] getLaunchArguments() {
+        return new String[0];
+    }
+}