Deferred default

- BackendManager.defaultBackend now dynamically computes the result every time it is invoked
- Forge backend config value now uses a supplier to provide the default backend
- Fix Fabric backend config being saved to "flw_backends" but loaded from "flw_backend"

common/src/main/java/dev/engine_room/flywheel/impl/BackendManagerImpl.java

@@ -17,8 +17,6 @@ public final class BackendManagerImpl {
 			.supported(() -> true)
 			.register(Flywheel.rl("off"));
 
-	public static final Backend DEFAULT_BACKEND = findDefaultBackend();
-
 	private static Backend backend = OFF_BACKEND;
 
 	private BackendManagerImpl() {
@@ -41,7 +39,7 @@ private static ArrayList<Backend> backendsByPriority() {
 		return backends;
 	}
 
-	private static Backend findDefaultBackend() {
+	public static Backend defaultBackend() {
 		var backendsByPriority = backendsByPriority();
 		if (backendsByPriority.isEmpty()) {
 			// This probably shouldn't happen, but fail gracefully.

common/src/main/java/dev/engine_room/flywheel/impl/FlwApiLinkImpl.java

@@ -42,7 +42,7 @@ public Backend getOffBackend() {
 
 	@Override
 	public Backend getDefaultBackend() {
-		return BackendManagerImpl.DEFAULT_BACKEND;
+		return BackendManagerImpl.defaultBackend();
 	}
 
 	@Override

fabric/src/main/java/dev/engine_room/flywheel/impl/FabricFlwConfig.java

@@ -100,17 +100,7 @@ public void fromJson(JsonElement json) {
 		readBackend(object);
 		readLimitUpdates(object);
 		readWorkerThreads(object);
-		readFlwBackend(object);
-	}
-
-	private void readFlwBackend(JsonObject object) {
-		var flwBackendJson = object.get("flw_backend");
-
-		if (flwBackendJson instanceof JsonObject flwBackendObject) {
-			backendConfig.fromJson(flwBackendObject);
-		} else {
-			FlwImpl.CONFIG_LOGGER.warn("'flw_backend' value must be an object");
-		}
+		readFlwBackends(object);
 	}
 
 	private void readBackend(JsonObject object) {
@@ -174,6 +164,16 @@ private void readWorkerThreads(JsonObject object) {
 		workerThreads = WORKER_THREADS_DEFAULT;
 	}
 
+	private void readFlwBackends(JsonObject object) {
+		var flwBackendsJson = object.get("flw_backends");
+
+		if (flwBackendsJson instanceof JsonObject flwBackendsObject) {
+			backendConfig.fromJson(flwBackendsObject);
+		} else {
+			FlwImpl.CONFIG_LOGGER.warn("'flw_backends' value must be an object");
+		}
+	}
+
 	public JsonObject toJson() {
 		JsonObject object = new JsonObject();
 		object.addProperty("backend", Backend.REGISTRY.getIdOrThrow(backend).toString());
@@ -206,10 +206,10 @@ public void fromJson(JsonObject object) {
 		}
 
 		private void readLightSmoothness(JsonObject object) {
-			var backendJson = object.get("lightSmoothness");
+			var lightSmoothnessJson = object.get("lightSmoothness");
 			String msg = null;
 
-			if (backendJson instanceof JsonPrimitive primitive && primitive.isString()) {
+			if (lightSmoothnessJson instanceof JsonPrimitive primitive && primitive.isString()) {
 				var value = primitive.getAsString();
 
 				for (var item : LightSmoothness.values()) {
@@ -221,7 +221,7 @@ private void readLightSmoothness(JsonObject object) {
 				}
 
 				msg = "Unknown 'lightSmoothness' value: " + value;
-			} else if (backendJson != null) {
+			} else if (lightSmoothnessJson != null) {
 				msg = "'lightSmoothness' value must be a string";
 			}
 

forge/src/main/java/dev/engine_room/flywheel/impl/ForgeFlwConfig.java

@@ -83,7 +83,7 @@ public static class ClientConfig {
 
 		private ClientConfig(ForgeConfigSpec.Builder builder) {
 			backend = builder.comment("Select the backend to use.")
-					.define("backend", Backend.REGISTRY.getIdOrThrow(BackendManager.defaultBackend()).toString());
+					.define("backend", () -> Backend.REGISTRY.getIdOrThrow(BackendManager.defaultBackend()).toString(), o -> o != null && String.class.isAssignableFrom(o.getClass()));
 
 			limitUpdates = builder.comment("Enable or disable instance update limiting with distance.")
 					.define("limitUpdates", true);