package net.minecraft.world.level.biome;

import com.google.common.hash.Hashing;
import net.minecraft.core.BlockPos;
import net.minecraft.core.Holder;
import net.minecraft.core.QuartPos;
import net.minecraft.util.LinearCongruentialGenerator;
import net.minecraft.util.Mth;

public class BiomeManager {
	public static final int CHUNK_CENTER_QUART = QuartPos.fromBlock(8);
	private static final int ZOOM_BITS = 2;
	private static final int ZOOM = 4;
	private static final int ZOOM_MASK = 3;
	private final BiomeManager.NoiseBiomeSource noiseBiomeSource;
	private final long biomeZoomSeed;

	public BiomeManager(final BiomeManager.NoiseBiomeSource noiseBiomeSource, final long seed) {
		this.noiseBiomeSource = noiseBiomeSource;
		this.biomeZoomSeed = seed;
	}

	public static long obfuscateSeed(final long seed) {
		return Hashing.sha256().hashLong(seed).asLong();
	}

	public BiomeManager withDifferentSource(final BiomeManager.NoiseBiomeSource biomeSource) {
		return new BiomeManager(biomeSource, this.biomeZoomSeed);
	}

	public Holder<Biome> getBiome(final BlockPos pos) {
		int absX = pos.getX() - 2;
		int absY = pos.getY() - 2;
		int absZ = pos.getZ() - 2;
		int parentX = absX >> 2;
		int parentY = absY >> 2;
		int parentZ = absZ >> 2;
		double fractX = (absX & 3) / 4.0;
		double fractY = (absY & 3) / 4.0;
		double fractZ = (absZ & 3) / 4.0;
		int minI = 0;
		double minFiddledDistance = Double.POSITIVE_INFINITY;

		for (int i = 0; i < 8; i++) {
			boolean xEven = (i & 4) == 0;
			boolean yEven = (i & 2) == 0;
			boolean zEven = (i & 1) == 0;
			int cornerX = xEven ? parentX : parentX + 1;
			int cornerY = yEven ? parentY : parentY + 1;
			int cornerZ = zEven ? parentZ : parentZ + 1;
			double distanceX = xEven ? fractX : fractX - 1.0;
			double distanceY = yEven ? fractY : fractY - 1.0;
			double distanceZ = zEven ? fractZ : fractZ - 1.0;
			double next = getFiddledDistance(this.biomeZoomSeed, cornerX, cornerY, cornerZ, distanceX, distanceY, distanceZ);
			if (minFiddledDistance > next) {
				minI = i;
				minFiddledDistance = next;
			}
		}

		int biomeX = (minI & 4) == 0 ? parentX : parentX + 1;
		int biomeY = (minI & 2) == 0 ? parentY : parentY + 1;
		int biomeZ = (minI & 1) == 0 ? parentZ : parentZ + 1;
		return this.noiseBiomeSource.getNoiseBiome(biomeX, biomeY, biomeZ);
	}

	public Holder<Biome> getNoiseBiomeAtPosition(final double x, final double y, final double z) {
		int quartX = QuartPos.fromBlock(Mth.floor(x));
		int quartY = QuartPos.fromBlock(Mth.floor(y));
		int quartZ = QuartPos.fromBlock(Mth.floor(z));
		return this.getNoiseBiomeAtQuart(quartX, quartY, quartZ);
	}

	public Holder<Biome> getNoiseBiomeAtPosition(final BlockPos blockPos) {
		int quartX = QuartPos.fromBlock(blockPos.getX());
		int quartY = QuartPos.fromBlock(blockPos.getY());
		int quartZ = QuartPos.fromBlock(blockPos.getZ());
		return this.getNoiseBiomeAtQuart(quartX, quartY, quartZ);
	}

	public Holder<Biome> getNoiseBiomeAtQuart(final int quartX, final int quartY, final int quartZ) {
		return this.noiseBiomeSource.getNoiseBiome(quartX, quartY, quartZ);
	}

	private static double getFiddledDistance(
		final long seed, final int xRandom, final int yRandom, final int zRandom, final double distanceX, final double distanceY, final double distanceZ
	) {
		long rval = LinearCongruentialGenerator.next(seed, xRandom);
		rval = LinearCongruentialGenerator.next(rval, yRandom);
		rval = LinearCongruentialGenerator.next(rval, zRandom);
		rval = LinearCongruentialGenerator.next(rval, xRandom);
		rval = LinearCongruentialGenerator.next(rval, yRandom);
		rval = LinearCongruentialGenerator.next(rval, zRandom);
		double fiddleX = getFiddle(rval);
		rval = LinearCongruentialGenerator.next(rval, seed);
		double fiddleY = getFiddle(rval);
		rval = LinearCongruentialGenerator.next(rval, seed);
		double fiddleZ = getFiddle(rval);
		return Mth.square(distanceZ + fiddleZ) + Mth.square(distanceY + fiddleY) + Mth.square(distanceX + fiddleX);
	}

	private static double getFiddle(final long rval) {
		double uniform = Math.floorMod(rval >> 24, 1024) / 1024.0;
		return (uniform - 0.5) * 0.9;
	}

	public interface NoiseBiomeSource {
		Holder<Biome> getNoiseBiome(final int quartX, final int quartY, final int quartZ);
	}
}