package net.minecraft.world.level;

import com.google.common.base.Suppliers;
import java.util.List;
import java.util.function.Supplier;
import net.minecraft.core.BlockPos;
import net.minecraft.core.Holder;
import net.minecraft.core.SectionPos;
import net.minecraft.core.registries.Registries;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.level.biome.Biome;
import net.minecraft.world.level.biome.Biomes;
import net.minecraft.world.level.block.Blocks;
import net.minecraft.world.level.block.entity.BlockEntity;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.level.border.WorldBorder;
import net.minecraft.world.level.chunk.ChunkAccess;
import net.minecraft.world.level.chunk.ChunkSource;
import net.minecraft.world.level.chunk.EmptyLevelChunk;
import net.minecraft.world.level.material.FluidState;
import net.minecraft.world.level.material.Fluids;
import net.minecraft.world.phys.AABB;
import net.minecraft.world.phys.shapes.VoxelShape;
import org.jetbrains.annotations.Nullable;

public class PathNavigationRegion implements CollisionGetter {
	protected final int centerX;
	protected final int centerZ;
	protected final ChunkAccess[][] chunks;
	protected boolean allEmpty;
	protected final Level level;
	private final Supplier<Holder<Biome>> plains;

	public PathNavigationRegion(Level level, BlockPos centerPos, BlockPos offsetPos) {
		this.level = level;
		this.plains = Suppliers.memoize(() -> level.registryAccess().lookupOrThrow(Registries.BIOME).getOrThrow(Biomes.PLAINS));
		this.centerX = SectionPos.blockToSectionCoord(centerPos.getX());
		this.centerZ = SectionPos.blockToSectionCoord(centerPos.getZ());
		int i = SectionPos.blockToSectionCoord(offsetPos.getX());
		int j = SectionPos.blockToSectionCoord(offsetPos.getZ());
		this.chunks = new ChunkAccess[i - this.centerX + 1][j - this.centerZ + 1];
		ChunkSource chunkSource = level.getChunkSource();
		this.allEmpty = true;

		for (int k = this.centerX; k <= i; k++) {
			for (int l = this.centerZ; l <= j; l++) {
				this.chunks[k - this.centerX][l - this.centerZ] = chunkSource.getChunkNow(k, l);
			}
		}

		for (int k = SectionPos.blockToSectionCoord(centerPos.getX()); k <= SectionPos.blockToSectionCoord(offsetPos.getX()); k++) {
			for (int l = SectionPos.blockToSectionCoord(centerPos.getZ()); l <= SectionPos.blockToSectionCoord(offsetPos.getZ()); l++) {
				ChunkAccess chunkAccess = this.chunks[k - this.centerX][l - this.centerZ];
				if (chunkAccess != null && !chunkAccess.isYSpaceEmpty(centerPos.getY(), offsetPos.getY())) {
					this.allEmpty = false;
					return;
				}
			}
		}
	}

	private ChunkAccess getChunk(BlockPos pos) {
		return this.getChunk(SectionPos.blockToSectionCoord(pos.getX()), SectionPos.blockToSectionCoord(pos.getZ()));
	}

	private ChunkAccess getChunk(int x, int z) {
		int i = x - this.centerX;
		int j = z - this.centerZ;
		if (i >= 0 && i < this.chunks.length && j >= 0 && j < this.chunks[i].length) {
			ChunkAccess chunkAccess = this.chunks[i][j];
			return (ChunkAccess)(chunkAccess != null ? chunkAccess : new EmptyLevelChunk(this.level, new ChunkPos(x, z), (Holder<Biome>)this.plains.get()));
		} else {
			return new EmptyLevelChunk(this.level, new ChunkPos(x, z), (Holder<Biome>)this.plains.get());
		}
	}

	@Override
	public WorldBorder getWorldBorder() {
		return this.level.getWorldBorder();
	}

	@Override
	public BlockGetter getChunkForCollisions(int chunkX, int chunkZ) {
		return this.getChunk(chunkX, chunkZ);
	}

	@Override
	public List<VoxelShape> getEntityCollisions(@Nullable Entity entity, AABB collisionBox) {
		return List.of();
	}

	@Nullable
	@Override
	public BlockEntity getBlockEntity(BlockPos pos) {
		ChunkAccess chunkAccess = this.getChunk(pos);
		return chunkAccess.getBlockEntity(pos);
	}

	@Override
	public BlockState getBlockState(BlockPos pos) {
		if (this.isOutsideBuildHeight(pos)) {
			return Blocks.AIR.defaultBlockState();
		} else {
			ChunkAccess chunkAccess = this.getChunk(pos);
			return chunkAccess.getBlockState(pos);
		}
	}

	@Override
	public FluidState getFluidState(BlockPos pos) {
		if (this.isOutsideBuildHeight(pos)) {
			return Fluids.EMPTY.defaultFluidState();
		} else {
			ChunkAccess chunkAccess = this.getChunk(pos);
			return chunkAccess.getFluidState(pos);
		}
	}

	@Override
	public int getMinY() {
		return this.level.getMinY();
	}

	@Override
	public int getHeight() {
		return this.level.getHeight();
	}
}