package net.minecraft.world.attribute;

import net.minecraft.util.Mth;
import net.minecraft.world.phys.Vec3;

public class GaussianSampler {
	private static final int GAUSSIAN_SAMPLE_RADIUS = 2;
	private static final int GAUSSIAN_SAMPLE_BREADTH = 6;
	private static final double[] GAUSSIAN_SAMPLE_KERNEL = new double[]{0.0, 1.0, 4.0, 6.0, 4.0, 1.0, 0.0};

	public static <V> void sample(Vec3 position, final GaussianSampler.Sampler<V> sampler, final GaussianSampler.Accumulator<V> accumulator) {
		position = position.subtract(0.5, 0.5, 0.5);
		int integralX = Mth.floor(position.x());
		int integralY = Mth.floor(position.y());
		int integralZ = Mth.floor(position.z());
		double relativeX = position.x() - integralX;
		double relativeY = position.y() - integralY;
		double relativeZ = position.z() - integralZ;

		for (int z = 0; z < 6; z++) {
			double weightZ = Mth.lerp(relativeZ, GAUSSIAN_SAMPLE_KERNEL[z + 1], GAUSSIAN_SAMPLE_KERNEL[z]);
			int sampleZ = integralZ - 2 + z;

			for (int x = 0; x < 6; x++) {
				double weightX = Mth.lerp(relativeX, GAUSSIAN_SAMPLE_KERNEL[x + 1], GAUSSIAN_SAMPLE_KERNEL[x]);
				int sampleX = integralX - 2 + x;

				for (int y = 0; y < 6; y++) {
					double weightY = Mth.lerp(relativeY, GAUSSIAN_SAMPLE_KERNEL[y + 1], GAUSSIAN_SAMPLE_KERNEL[y]);
					int sampleY = integralY - 2 + y;
					double sampleWeight = weightX * weightY * weightZ;
					V value = sampler.get(sampleX, sampleY, sampleZ);
					accumulator.accumulate(sampleWeight, value);
				}
			}
		}
	}

	@FunctionalInterface
	public interface Accumulator<V> {
		void accumulate(double weight, V value);
	}

	@FunctionalInterface
	public interface Sampler<V> {
		V get(int x, int y, int z);
	}
}