minecraft-src/net/minecraft/world/level/lighting/SkyLightSectionStorage.java

package net.minecraft.world.level.lighting;

import it.unimi.dsi.fastutil.longs.Long2IntOpenHashMap;
import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
import net.minecraft.core.BlockPos;
import net.minecraft.core.Direction;
import net.minecraft.core.SectionPos;
import net.minecraft.world.level.LightLayer;
import net.minecraft.world.level.chunk.DataLayer;
import net.minecraft.world.level.chunk.LightChunkGetter;

public class SkyLightSectionStorage extends LayerLightSectionStorage<SkyLightSectionStorage.SkyDataLayerStorageMap> {
	protected SkyLightSectionStorage(LightChunkGetter chunkSource) {
		super(
			LightLayer.SKY, chunkSource, new SkyLightSectionStorage.SkyDataLayerStorageMap(new Long2ObjectOpenHashMap<>(), new Long2IntOpenHashMap(), Integer.MAX_VALUE)
		);
	}

	@Override
	protected int getLightValue(long levelPos) {
		return this.getLightValue(levelPos, false);
	}

	protected int getLightValue(long packedPos, boolean updateAll) {
		long l = SectionPos.blockToSection(packedPos);
		int i = SectionPos.y(l);
		SkyLightSectionStorage.SkyDataLayerStorageMap skyDataLayerStorageMap = updateAll ? this.updatingSectionData : this.visibleSectionData;
		int j = skyDataLayerStorageMap.topSections.get(SectionPos.getZeroNode(l));
		if (j != skyDataLayerStorageMap.currentLowestY && i < j) {
			DataLayer dataLayer = this.getDataLayer(skyDataLayerStorageMap, l);
			if (dataLayer == null) {
				for (packedPos = BlockPos.getFlatIndex(packedPos); dataLayer == null; dataLayer = this.getDataLayer(skyDataLayerStorageMap, l)) {
					if (++i >= j) {
						return 15;
					}

					l = SectionPos.offset(l, Direction.UP);
				}
			}

			return dataLayer.get(
				SectionPos.sectionRelative(BlockPos.getX(packedPos)),
				SectionPos.sectionRelative(BlockPos.getY(packedPos)),
				SectionPos.sectionRelative(BlockPos.getZ(packedPos))
			);
		} else {
			return updateAll && !this.lightOnInSection(l) ? 0 : 15;
		}
	}

	@Override
	protected void onNodeAdded(long sectionPos) {
		int i = SectionPos.y(sectionPos);
		if (this.updatingSectionData.currentLowestY > i) {
			this.updatingSectionData.currentLowestY = i;
			this.updatingSectionData.topSections.defaultReturnValue(this.updatingSectionData.currentLowestY);
		}

		long l = SectionPos.getZeroNode(sectionPos);
		int j = this.updatingSectionData.topSections.get(l);
		if (j < i + 1) {
			this.updatingSectionData.topSections.put(l, i + 1);
		}
	}

	@Override
	protected void onNodeRemoved(long sectionPos) {
		long l = SectionPos.getZeroNode(sectionPos);
		int i = SectionPos.y(sectionPos);
		if (this.updatingSectionData.topSections.get(l) == i + 1) {
			long m;
			for (m = sectionPos; !this.storingLightForSection(m) && this.hasLightDataAtOrBelow(i); m = SectionPos.offset(m, Direction.DOWN)) {
				i--;
			}

			if (this.storingLightForSection(m)) {
				this.updatingSectionData.topSections.put(l, i + 1);
			} else {
				this.updatingSectionData.topSections.remove(l);
			}
		}
	}

	@Override
	protected DataLayer createDataLayer(long sectionPos) {
		DataLayer dataLayer = this.queuedSections.get(sectionPos);
		if (dataLayer != null) {
			return dataLayer;
		} else {
			int i = this.updatingSectionData.topSections.get(SectionPos.getZeroNode(sectionPos));
			if (i != this.updatingSectionData.currentLowestY && SectionPos.y(sectionPos) < i) {
				long l = SectionPos.offset(sectionPos, Direction.UP);

				DataLayer dataLayer2;
				while ((dataLayer2 = this.getDataLayer(l, true)) == null) {
					l = SectionPos.offset(l, Direction.UP);
				}

				return repeatFirstLayer(dataLayer2);
			} else {
				return this.lightOnInSection(sectionPos) ? new DataLayer(15) : new DataLayer();
			}
		}
	}

	private static DataLayer repeatFirstLayer(DataLayer dataLayer) {
		if (dataLayer.isDefinitelyHomogenous()) {
			return dataLayer.copy();
		} else {
			byte[] bs = dataLayer.getData();
			byte[] cs = new byte[2048];

			for (int i = 0; i < 16; i++) {
				System.arraycopy(bs, 0, cs, i * 128, 128);
			}

			return new DataLayer(cs);
		}
	}

	protected boolean hasLightDataAtOrBelow(int y) {
		return y >= this.updatingSectionData.currentLowestY;
	}

	protected boolean isAboveData(long sectionPos) {
		long l = SectionPos.getZeroNode(sectionPos);
		int i = this.updatingSectionData.topSections.get(l);
		return i == this.updatingSectionData.currentLowestY || SectionPos.y(sectionPos) >= i;
	}

	protected int getTopSectionY(long sectionPos) {
		return this.updatingSectionData.topSections.get(sectionPos);
	}

	protected int getBottomSectionY() {
		return this.updatingSectionData.currentLowestY;
	}

	protected static final class SkyDataLayerStorageMap extends DataLayerStorageMap<SkyLightSectionStorage.SkyDataLayerStorageMap> {
		int currentLowestY;
		final Long2IntOpenHashMap topSections;

		public SkyDataLayerStorageMap(Long2ObjectOpenHashMap<DataLayer> map, Long2IntOpenHashMap topSections, int currentLowestY) {
			super(map);
			this.topSections = topSections;
			topSections.defaultReturnValue(currentLowestY);
			this.currentLowestY = currentLowestY;
		}

		public SkyLightSectionStorage.SkyDataLayerStorageMap copy() {
			return new SkyLightSectionStorage.SkyDataLayerStorageMap(this.map.clone(), this.topSections.clone(), this.currentLowestY);
		}
	}
}