package net.minecraft.world.level.levelgen.synth;

import net.minecraft.util.Mth;
import net.minecraft.util.RandomSource;

public class SimplexNoise {
	protected static final int[][] GRADIENT = new int[][]{
		{1, 1, 0},
		{-1, 1, 0},
		{1, -1, 0},
		{-1, -1, 0},
		{1, 0, 1},
		{-1, 0, 1},
		{1, 0, -1},
		{-1, 0, -1},
		{0, 1, 1},
		{0, -1, 1},
		{0, 1, -1},
		{0, -1, -1},
		{1, 1, 0},
		{0, -1, 1},
		{-1, 1, 0},
		{0, -1, -1}
	};
	private static final double SQRT_3 = Math.sqrt(3.0);
	private static final double F2 = 0.5 * (SQRT_3 - 1.0);
	private static final double G2 = (3.0 - SQRT_3) / 6.0;
	private final int[] p = new int[512];
	public final double xo;
	public final double yo;
	public final double zo;

	public SimplexNoise(final RandomSource random) {
		this.xo = random.nextDouble() * 256.0;
		this.yo = random.nextDouble() * 256.0;
		this.zo = random.nextDouble() * 256.0;
		int i = 0;

		while (i < 256) {
			this.p[i] = i++;
		}

		for (int ix = 0; ix < 256; ix++) {
			int offset = random.nextInt(256 - ix);
			int tmp = this.p[ix];
			this.p[ix] = this.p[offset + ix];
			this.p[offset + ix] = tmp;
		}
	}

	private int p(final int x) {
		return this.p[x & 0xFF];
	}

	protected static double dot(final int[] g, final double x, final double y, final double z) {
		return g[0] * x + g[1] * y + g[2] * z;
	}

	private double getCornerNoise3D(final int index, final double x, final double y, final double z, final double base) {
		double t0 = base - x * x - y * y - z * z;
		double n0;
		if (t0 < 0.0) {
			n0 = 0.0;
		} else {
			t0 *= t0;
			n0 = t0 * t0 * dot(GRADIENT[index], x, y, z);
		}

		return n0;
	}

	public double getValue(final double xin, final double yin) {
		double s = (xin + yin) * F2;
		int i = Mth.floor(xin + s);
		int j = Mth.floor(yin + s);
		double t = (i + j) * G2;
		double X0 = i - t;
		double Y0 = j - t;
		double x0 = xin - X0;
		double y0 = yin - Y0;
		int i1;
		int j1;
		if (x0 > y0) {
			i1 = 1;
			j1 = 0;
		} else {
			i1 = 0;
			j1 = 1;
		}

		double x1 = x0 - i1 + G2;
		double y1 = y0 - j1 + G2;
		double x2 = x0 - 1.0 + 2.0 * G2;
		double y2 = y0 - 1.0 + 2.0 * G2;
		int ii = i & 0xFF;
		int jj = j & 0xFF;
		int gi0 = this.p(ii + this.p(jj)) % 12;
		int gi1 = this.p(ii + i1 + this.p(jj + j1)) % 12;
		int gi2 = this.p(ii + 1 + this.p(jj + 1)) % 12;
		double n0 = this.getCornerNoise3D(gi0, x0, y0, 0.0, 0.5);
		double n1 = this.getCornerNoise3D(gi1, x1, y1, 0.0, 0.5);
		double n2 = this.getCornerNoise3D(gi2, x2, y2, 0.0, 0.5);
		return 70.0 * (n0 + n1 + n2);
	}

	public double getValue(final double xin, final double yin, final double zin) {
		double F3 = 0.3333333333333333;
		double s = (xin + yin + zin) * 0.3333333333333333;
		int i = Mth.floor(xin + s);
		int j = Mth.floor(yin + s);
		int k = Mth.floor(zin + s);
		double G3 = 0.16666666666666666;
		double t = (i + j + k) * 0.16666666666666666;
		double X0 = i - t;
		double Y0 = j - t;
		double Z0 = k - t;
		double x0 = xin - X0;
		double y0 = yin - Y0;
		double z0 = zin - Z0;
		int i1;
		int j1;
		int k1;
		int i2;
		int j2;
		int k2;
		if (x0 >= y0) {
			if (y0 >= z0) {
				i1 = 1;
				j1 = 0;
				k1 = 0;
				i2 = 1;
				j2 = 1;
				k2 = 0;
			} else if (x0 >= z0) {
				i1 = 1;
				j1 = 0;
				k1 = 0;
				i2 = 1;
				j2 = 0;
				k2 = 1;
			} else {
				i1 = 0;
				j1 = 0;
				k1 = 1;
				i2 = 1;
				j2 = 0;
				k2 = 1;
			}
		} else if (y0 < z0) {
			i1 = 0;
			j1 = 0;
			k1 = 1;
			i2 = 0;
			j2 = 1;
			k2 = 1;
		} else if (x0 < z0) {
			i1 = 0;
			j1 = 1;
			k1 = 0;
			i2 = 0;
			j2 = 1;
			k2 = 1;
		} else {
			i1 = 0;
			j1 = 1;
			k1 = 0;
			i2 = 1;
			j2 = 1;
			k2 = 0;
		}

		double x1 = x0 - i1 + 0.16666666666666666;
		double y1 = y0 - j1 + 0.16666666666666666;
		double z1 = z0 - k1 + 0.16666666666666666;
		double x2 = x0 - i2 + 0.3333333333333333;
		double y2 = y0 - j2 + 0.3333333333333333;
		double z2 = z0 - k2 + 0.3333333333333333;
		double x3 = x0 - 1.0 + 0.5;
		double y3 = y0 - 1.0 + 0.5;
		double z3 = z0 - 1.0 + 0.5;
		int ii = i & 0xFF;
		int jj = j & 0xFF;
		int kk = k & 0xFF;
		int gi0 = this.p(ii + this.p(jj + this.p(kk))) % 12;
		int gi1 = this.p(ii + i1 + this.p(jj + j1 + this.p(kk + k1))) % 12;
		int gi2 = this.p(ii + i2 + this.p(jj + j2 + this.p(kk + k2))) % 12;
		int gi3 = this.p(ii + 1 + this.p(jj + 1 + this.p(kk + 1))) % 12;
		double n0 = this.getCornerNoise3D(gi0, x0, y0, z0, 0.6);
		double n1 = this.getCornerNoise3D(gi1, x1, y1, z1, 0.6);
		double n2 = this.getCornerNoise3D(gi2, x2, y2, z2, 0.6);
		double n3 = this.getCornerNoise3D(gi3, x3, y3, z3, 0.6);
		return 32.0 * (n0 + n1 + n2 + n3);
	}
}