Add config file to hide Forge mod presence from Fabric mods

Help disable broken mod integrations of Fabric mods

Relates to #449

README.md

@@ -139,7 +139,7 @@ Here's a minimal configuration example:
       "cloth_config": "cloth-config2",
       "embeddium": [
          "sodium",
-         "rubidium"
+         "magnesium"
       ]
    }
 }
@@ -151,3 +151,25 @@ Let's go over it line-by-line.
 - Secondly, we have `aliases`. This JSON object contains all of our alises for various mods.  
   Keys inside the object represent mod IDs to be aliased. The value can be either a single **string**, or an **array** in case
   we want to provide multiple aliases for one mod.
+
+### Hiding Forge mods presence
+
+Fabric mods tend to integrate with others based on their modid. If you happen to install a Forge version of a mod that
+a Fabric mod wants to integrate with, it might result in a crash, as the two versions' code is different.
+Most of the time, mods provide toggles for integrations in their config. If that's not the case, your other option is
+hiding the Forge mod's presence from Fabric mods entirely, which might help in disabling the problematic integration.
+
+This can be configured in the `connector.json` file, located in your config folder.
+If it doesn't exist yet, Connector will create a new one with empty values.
+
+Inside, the `hiddenMods` field is defined as a list of mod IDs (strings). Forge mod IDs found in this list will be
+excluded from being added to `FabricLoader`, hiding their presence from Fabric mods.
+
+Here's a minimal configuration example:
+```json
+{
+  "hiddenMods": [
+    "examplemod"
+  ]
+}
+```

src/main/java/dev/su5ed/sinytra/connector/loader/ConnectorEarlyLoader.java

@@ -2,6 +2,7 @@
 
 import com.mojang.logging.LogUtils;
 import dev.su5ed.sinytra.connector.ConnectorUtil;
+import dev.su5ed.sinytra.connector.locator.ConnectorConfig;
 import net.fabricmc.loader.api.entrypoint.PreLaunchEntrypoint;
 import net.fabricmc.loader.impl.FabricLoaderImpl;
 import net.fabricmc.loader.impl.entrypoint.EntrypointUtils;
@@ -91,14 +92,18 @@ public static void init() {
         LOGGER.debug("Starting early connector loader setup");
         ProgressMeter progress = StartupNotificationManager.addProgressBar("[Connector] Early Setup", 0);
         try {
+            List<String> hiddenMods = ConnectorConfig.INSTANCE.get().hiddenMods();
             // Find all connector loader mods
-            List<ModInfo> mods = LoadingModList.get().getMods();
-            for (ModInfo mod : mods) {
-                if (mod.getOwningFile().getFileProperties().containsKey(ConnectorUtil.CONNECTOR_MARKER)) {
-                    CONNECTOR_MODIDS.add(mod.getModId());
-                    CONNECTOR_MODS.add(mod);
-                }
-            }
+            List<ModInfo> mods = LoadingModList.get().getMods().stream()
+                .filter(mod -> {
+                    if (mod.getOwningFile().getFileProperties().containsKey(ConnectorUtil.CONNECTOR_MARKER)) {
+                        CONNECTOR_MODIDS.add(mod.getModId());
+                        CONNECTOR_MODS.add(mod);
+                        return true;
+                    }
+                    return !hiddenMods.contains(mod.getModId());
+                })
+                .toList();
             // Propagate mods to fabric
             FabricLoaderImpl.INSTANCE.addFmlMods(mods);
         } catch (Throwable t) {

src/main/java/dev/su5ed/sinytra/connector/locator/ConnectorConfig.java

@@ -0,0 +1,37 @@
+package dev.su5ed.sinytra.connector.locator;
+
+import com.google.common.base.Suppliers;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.mojang.logging.LogUtils;
+import net.minecraftforge.fml.loading.FMLPaths;
+import org.slf4j.Logger;
+
+import java.io.Reader;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.function.Supplier;
+
+public record ConnectorConfig(List<String> hiddenMods) {
+    private static final ConnectorConfig DEFAULT = new ConnectorConfig(List.of());
+    private static final Logger LOGGER = LogUtils.getLogger();
+    public static final Supplier<ConnectorConfig> INSTANCE = Suppliers.memoize(() -> {
+        Path path = FMLPaths.CONFIGDIR.get().resolve("connector.json");
+        try {
+            if (Files.exists(path)) {
+                Gson gson = new Gson();
+                try (Reader reader = Files.newBufferedReader(path)) {
+                    return gson.fromJson(reader, ConnectorConfig.class);
+                }
+            }
+            else {
+                Gson gson = new GsonBuilder().setPrettyPrinting().disableHtmlEscaping().create();
+                Files.writeString(path, gson.toJson(DEFAULT));
+            }
+        } catch (Throwable t) {
+            LOGGER.error("Error loading Connector configuration", t);
+        }
+        return DEFAULT;
+    });
+}

src/main/java/dev/su5ed/sinytra/connector/transformer/jar/JarTransformer.java

@@ -218,8 +218,10 @@ private static void readMixinConfigPackages(File input, JarFile jarFile, ZipEntr
             }
             if (json.has("package")) {
                 String pkg = json.get("package").getAsString();
-                String pkgPath = pkg.replace('.', '/') + '/';
-                packages.add(pkgPath);
+                if (!pkg.isEmpty()) {
+                    String pkgPath = pkg.replace('.', '/') + '/';
+                    packages.add(pkgPath);
+                }
             }
         } catch (IOException e) {
             LOGGER.error("Error reading mixin config entry {} in file {}", entry.getName(), input.getAbsolutePath());