From e26195169fe63b9dde31eddeb927f9fb98acb20c Mon Sep 17 00:00:00 2001
From: Jozufozu <jozsefaug@gmail.com>
Date: Wed, 22 Jun 2022 13:29:28 -0700
Subject: [PATCH] Closing the blinds

 - Prevent LightUpdater from interacting with invalid levels.
 - Bump version - 0.6.3
---
 gradle.properties                             |  2 +-
 .../flywheel/light/DummyLightUpdater.java     | 50 +++++++++++++++++++
 .../jozufozu/flywheel/light/LightUpdated.java | 32 ++++++++++++
 .../jozufozu/flywheel/light/LightUpdater.java | 15 ++++--
 .../jozufozu/flywheel/util/WorldAttached.java |  2 +-
 5 files changed, 96 insertions(+), 5 deletions(-)
 create mode 100644 src/main/java/com/jozufozu/flywheel/light/DummyLightUpdater.java
 create mode 100644 src/main/java/com/jozufozu/flywheel/light/LightUpdated.java

diff --git a/gradle.properties b/gradle.properties
index 7989201c7..45c6f4660 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -2,7 +2,7 @@ org.gradle.jvmargs = -Xmx3G
 org.gradle.daemon = false
 
 # mod version info
-mod_version = 0.6.2
+mod_version = 0.6.3
 mc_update_version = 1.18
 minecraft_version = 1.18.2
 forge_version = 40.0.15
diff --git a/src/main/java/com/jozufozu/flywheel/light/DummyLightUpdater.java b/src/main/java/com/jozufozu/flywheel/light/DummyLightUpdater.java
new file mode 100644
index 000000000..0cb04f944
--- /dev/null
+++ b/src/main/java/com/jozufozu/flywheel/light/DummyLightUpdater.java
@@ -0,0 +1,50 @@
+package com.jozufozu.flywheel.light;
+
+import java.util.stream.Stream;
+
+import com.jozufozu.flywheel.util.box.ImmutableBox;
+
+import net.minecraft.world.level.LightLayer;
+
+public class DummyLightUpdater extends LightUpdater {
+	public static final DummyLightUpdater INSTANCE = new DummyLightUpdater();
+
+	private DummyLightUpdater() {
+		super(null);
+	}
+
+	@Override
+	public void tick() {
+		// noop
+	}
+
+	@Override
+	public void addListener(LightListener listener) {
+		// noop
+	}
+
+	@Override
+	public void removeListener(LightListener listener) {
+		// noop
+	}
+
+	@Override
+	public void onLightUpdate(LightLayer type, long sectionPos) {
+		// noop
+	}
+
+	@Override
+	public void onLightPacket(int chunkX, int chunkZ) {
+		// noop
+	}
+
+	@Override
+	public Stream<ImmutableBox> getAllBoxes() {
+		return Stream.empty();
+	}
+
+	@Override
+	public boolean isEmpty() {
+		return true;
+	}
+}
diff --git a/src/main/java/com/jozufozu/flywheel/light/LightUpdated.java b/src/main/java/com/jozufozu/flywheel/light/LightUpdated.java
new file mode 100644
index 000000000..4173ef2a8
--- /dev/null
+++ b/src/main/java/com/jozufozu/flywheel/light/LightUpdated.java
@@ -0,0 +1,32 @@
+package com.jozufozu.flywheel.light;
+
+import net.minecraft.client.Minecraft;
+import net.minecraft.world.level.LevelAccessor;
+
+/**
+ * Marker interface for custom/fake levels to indicate that LightUpdater should bother interacting with it.<p>
+ *
+ * Implement this if your custom level has light updates at all. If so, be sure to call
+ * {@link com.jozufozu.flywheel.util.WorldAttached#invalidateWorld} when your level in unloaded.
+ */
+public interface LightUpdated extends LevelAccessor {
+
+	/**
+	 * @return {@code true} if this level is passing light updates into LightUpdater.
+	 */
+	default boolean receivesLightUpdates() {
+		return true;
+	}
+
+	static boolean receivesLightUpdates(LevelAccessor level) {
+		// The client level is guaranteed to receive updates.
+		if (Minecraft.getInstance().level == level) {
+			return true;
+		}
+		// Custom/fake levels need to indicate that LightUpdater has meaning.
+		if (level instanceof LightUpdated c) {
+			return c.receivesLightUpdates();
+		}
+		return false;
+	}
+}
diff --git a/src/main/java/com/jozufozu/flywheel/light/LightUpdater.java b/src/main/java/com/jozufozu/flywheel/light/LightUpdater.java
index c1b3b4f54..4958fd682 100644
--- a/src/main/java/com/jozufozu/flywheel/light/LightUpdater.java
+++ b/src/main/java/com/jozufozu/flywheel/light/LightUpdater.java
@@ -20,14 +20,23 @@ import net.minecraft.world.level.LightLayer;
 
 /**
  * Keeps track of what chunks/sections each listener is in, so we can update exactly what needs to be updated.
+ *
+ * @apiNote Custom/fake levels (that are {@code != Minecraft.getInstance.level}) need to implement
+ *          {@link LightUpdated} for LightUpdater to work with them.
  */
 public class LightUpdater {
 
-	private static final WorldAttached<LightUpdater> light = new WorldAttached<>(LightUpdater::new);
+	private static final WorldAttached<LightUpdater> LEVELS = new WorldAttached<>(LightUpdater::new);
 	private final ParallelTaskEngine taskEngine;
 
-	public static LightUpdater get(LevelAccessor world) {
-		return light.get(world);
+	public static LightUpdater get(LevelAccessor level) {
+		if (LightUpdated.receivesLightUpdates(level)) {
+			// The level is valid, add it to the map.
+			return LEVELS.get(level);
+		} else {
+			// Fake light updater for a fake level.
+			return DummyLightUpdater.INSTANCE;
+		}
 	}
 
 	private final LightProvider provider;
diff --git a/src/main/java/com/jozufozu/flywheel/util/WorldAttached.java b/src/main/java/com/jozufozu/flywheel/util/WorldAttached.java
index 408b54e51..45b989f2f 100644
--- a/src/main/java/com/jozufozu/flywheel/util/WorldAttached.java
+++ b/src/main/java/com/jozufozu/flywheel/util/WorldAttached.java
@@ -28,7 +28,7 @@ public class WorldAttached<T> {
 	}
 
 	public static void invalidateWorld(LevelAccessor world) {
-		Iterator<WeakReference<Map<LevelAccessor, ?>>> i = allMaps.iterator();
+		var i = allMaps.iterator();
 		while (i.hasNext()) {
 			Map<LevelAccessor, ?> map = i.next()
 					.get();