Fix incorrect unloaded chunk lighting

core/src/main/java/com/seibel/distanthorizons/core/api/internal/ServerApi.java

@@ -21,6 +21,7 @@ package com.seibel.distanthorizons.core.api.internal;
 
 import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiLevelLoadEvent;
 import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiLevelUnloadEvent;
+import com.seibel.distanthorizons.core.generation.DhLightingEngine;
 import com.seibel.distanthorizons.core.wrapperInterfaces.misc.IServerPlayerWrapper;
 import com.seibel.distanthorizons.coreapi.DependencyInjection.ApiEventInjector;
 import com.seibel.distanthorizons.core.level.IDhLevel;
@@ -34,6 +35,9 @@ import com.seibel.distanthorizons.core.wrapperInterfaces.world.ILevelWrapper;
 import com.seibel.distanthorizons.core.wrapperInterfaces.world.IServerLevelWrapper;
 import org.apache.logging.log4j.Logger;
 
+import java.util.LinkedList;
+import java.util.List;
+
 /**
  * This holds the methods that should be called by the host mod loader (Fabric,
  * Forge, etc.). Specifically server events.
@@ -153,6 +157,32 @@ public class ServerApi
 			IDhLevel dhLevel = SharedApi.getAbstractDhWorld().getLevel(level);
 			if (dhLevel != null)
 			{
+				
+				// Save or populate the chunk wrapper's lighting
+				// this is done so we don't have to worry about MC unloading the lighting data for this chunk
+				if (chunk.isLightCorrect())
+				{
+					try
+					{
+						chunk.bakeDhLightingUsingMcLightingEngine();
+						chunk.setUseDhLighting(true);
+					}
+					catch (IllegalStateException e)
+					{
+						LOGGER.warn(e.getMessage(), e);
+					}
+				}
+				else
+				{
+					// generate the chunk's lighting, ignoring neighbors.
+					// not a perfect solution, but should prevent chunks from having completely broken lighting
+					List<IChunkWrapper> nearbyChunkList = new LinkedList<>();
+					nearbyChunkList.add(chunk);
+					DhLightingEngine.INSTANCE.lightChunks(chunk, nearbyChunkList, level.hasSkyLight() ? 15 : 0);
+					chunk.setUseDhLighting(true);
+				}
+				
+				
 				dhLevel.updateChunkAsync(chunk);
 			}
 		}

core/src/main/java/com/seibel/distanthorizons/core/wrapperInterfaces/chunk/IChunkWrapper.java

@@ -53,6 +53,7 @@ public interface IChunkWrapper extends IBindable
 	long getLongChunkPos();
 	
 	void setIsDhLightCorrect(boolean isDhLightCorrect);
+	void setUseDhLighting(boolean useDhLighting);
 	boolean isLightCorrect();
 	
 	
@@ -65,6 +66,34 @@ public interface IChunkWrapper extends IBindable
 	int getBlockLight(int relX, int relY, int relZ);
 	int getSkyLight(int relX, int relY, int relZ);
 	
+	/** 
+	 * Populates DH's saved lighting using MC's lighting engine. 
+	 * This is generally done in cases where MC's lighting is correct now, but may not be later (like when a chunk is unloading).
+	 * 
+	 * @throws IllegalStateException if the chunk's lighting isn't valid. This is done to prevent accidentally baking broken lighting.
+	 */
+	default void bakeDhLightingUsingMcLightingEngine() throws IllegalStateException
+	{
+		if (!this.isLightCorrect())
+		{
+			throw new IllegalStateException("Unable to bake lighting for for chunk ["+this.getChunkPos()+"], Minecraft lighting not valid.");
+		}
+		
+		// get the lighting for every relative block pos
+		for (int relX = 0; relX < LodUtil.CHUNK_WIDTH; relX++)
+		{
+			for (int relZ = 0; relZ < LodUtil.CHUNK_WIDTH; relZ++)
+			{
+				for (int y = this.getMinBuildHeight(); y < this.getMaxBuildHeight(); y++)
+				{
+					this.setDhSkyLight(relX, y, relZ, this.getSkyLight(relX, y, relZ));
+					this.setDhBlockLight(relX, y, relZ, this.getBlockLight(relX, y, relZ));
+				}
+			}
+		}
+	}   
+	
+	
 	
 	List<DhBlockPos> getBlockLightPosList();