package net.minecraft.util;

import net.minecraft.world.phys.Vec3;

public class CubicSampler {
	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};

	private CubicSampler() {
	}

	public static Vec3 gaussianSampleVec3(Vec3 vec, CubicSampler.Vec3Fetcher fetcher) {
		int i = Mth.floor(vec.x());
		int j = Mth.floor(vec.y());
		int k = Mth.floor(vec.z());
		double d = vec.x() - i;
		double e = vec.y() - j;
		double f = vec.z() - k;
		double g = 0.0;
		Vec3 vec3 = Vec3.ZERO;

		for (int l = 0; l < 6; l++) {
			double h = Mth.lerp(d, GAUSSIAN_SAMPLE_KERNEL[l + 1], GAUSSIAN_SAMPLE_KERNEL[l]);
			int m = i - 2 + l;

			for (int n = 0; n < 6; n++) {
				double o = Mth.lerp(e, GAUSSIAN_SAMPLE_KERNEL[n + 1], GAUSSIAN_SAMPLE_KERNEL[n]);
				int p = j - 2 + n;

				for (int q = 0; q < 6; q++) {
					double r = Mth.lerp(f, GAUSSIAN_SAMPLE_KERNEL[q + 1], GAUSSIAN_SAMPLE_KERNEL[q]);
					int s = k - 2 + q;
					double t = h * o * r;
					g += t;
					vec3 = vec3.add(fetcher.fetch(m, p, s).scale(t));
				}
			}
		}

		return vec3.scale(1.0 / g);
	}

	@FunctionalInterface
	public interface Vec3Fetcher {
		Vec3 fetch(int i, int j, int k);
	}
}