using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace Dugan.Mathf {
	public class Simplex {

		private static int[][] grad3 = {new int[] {1,1,0},new int[] {-1,1,0},new int[] {1,-1,0},new int[] {-1,-1,0},new int[] {1,0,1},
			new int[] {-1,0,1},new int[] {1,0,-1},new int[] {-1,0,-1},new int[] {0,1,1},
			new int[] {0,-1,1},new int[] {0,1,-1},new int[] {0,-1,-1}
		};

		private static int[][] grad4 =  {new int[]{0,1,1,1}, new int[]{0,1,1,-1}, new int[]{0,1,-1,1}, new int[]{0,1,-1,-1},
			new int[]{0,-1,1,1}, new int[]{0,-1,1,-1}, new int[]{0,-1,-1,1},new int[] {0,-1,-1,-1},
			new int[]{1,0,1,1},new int[] {1,0,1,-1},new int[] {1,0,-1,1},new int[] {1,0,-1,-1},
			new int[]{-1,0,1,1}, new int[]{-1,0,1,-1}, new int[]{-1,0,-1,1},new int[] {-1,0,-1,-1},
			new int[]{1,1,0,1}, new int[]{1,1,0,-1}, new int[]{1,-1,0,1}, new int[]{1,-1,0,-1},
			new int[]{-1,1,0,1}, new int[]{-1,1,0,-1},new int[] {-1,-1,0,1},new int[] {-1,-1,0,-1},
			new int[]{1,1,1,0}, new int[]{1,1,-1,0}, new int[]{1,-1,1,0},new int[] {1,-1,-1,0},
			new int[]{-1,1,1,0}, new int[]{-1,1,-1,0},new int[] {-1,-1,1,0},new int[] {-1,-1,-1,0}
		};

		private static int[] p = {51,160,137,91,90,15,
			131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
			190,6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
			88,237,149,56,87,174,20,125,136,171,168,68,175,74,165,71,134,139,48,27,166,
			77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
			102,143,54,65,25,63,161,1,216,80,73,209,76,132,187,208,89,18,169,200,196,
			135,130,116,188,159,86,164,100,109,198,173,186,3,64,52,217,226,250,124,123,
			5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
			223,183,170,213,119,248,152,2,44,154,163,70,221,153,101,155,167,43,172,9,
			129,22,39,253,19,98,108,110,79,113,224,232,178,185,112,104,218,246,97,228,
			251,34,242,193,238,210,144,12,191,179,162,241,81,51,145,235,249,14,239,107,
			49,192,214,31,181,199,106,157,184,84,204,176,115,121,50,45,127,4,150,254,
			138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180
		};

		private static int[][] simplex = {
			new int[]{0,1,2,3},new int[]{0,1,3,2},new int[]{0,0,0,0},new int[]{0,2,3,1},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{1,2,3,0},
			new int[]{0,2,1,3},new int[]{0,0,0,0},new int[]{0,3,1,2},new int[]{0,3,2,1},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{1,3,2,0},
			new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},
			new int[]{1,2,0,3},new int[]{0,0,0,0},new int[]{1,3,0,2},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{2,3,0,1},new int[]{2,3,1,0},
			new int[]{1,0,2,3},new int[]{1,0,3,2},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{2,0,3,1},new int[]{0,0,0,0},new int[]{2,1,3,0},
			new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},
			new int[]{2,0,1,3},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{3,0,1,2},new int[]{3,0,2,1},new int[]{0,0,0,0},new int[]{3,1,2,0},
			new int[]{2,1,0,3},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{3,1,0,2},new int[]{0,0,0,0},new int[]{3,2,0,1},new int[]{3,2,1,0}};

		private static int[] perm = new int[512];

		private static int fastfloor(double x) {
			return x > 0 ? (int)x : (int)x - 1;
		}

		private static double dot(int[] g, double x, double y) {
			return g[0] * x + g[1] * y;
		}
		private static double dot(int[] g, double x, double y, double z) {
			return g[0] * x + g[1] * y + g[2] * z;
		}
		private static double dot(int[] g, double x, double y, double z, double w) {
			return g[0] * x + g[1] * y + g[2] * z + g[3] * w;
		}

		private static double F2 = 0.5 * (System.Math.Sqrt(3.0) - 1.0);
		private static double F3 = 1.0 / 3.0;
		private static double F4 = (System.Math.Sqrt(5.0) - 1.0) / 4.0;

		private static double G2 = (3.0 - System.Math.Sqrt(3.0)) / 6.0;
		private static double G3 = 1.0 / 6.0;
		private static double G4 = (5.0 - System.Math.Sqrt(5.0)) / 20.0;

		// 2D simplex noise
		public static float Noise(float xin, float yin) {
			double n0, n1, n2; // Noise contributions from the three corners
							   // Skew the input space to determine which simplex cell we're in
			//double F2 = 0.5 * (System.Math.Sqrt(3.0) - 1.0);

			double s = (xin + yin) * F2; // Hairy factor for 2D
			int i = fastfloor(xin + s);

			int j = fastfloor(yin + s);
			//double G2 = (3.0 - System.Math.Sqrt(3.0)) / 6.0;
			double t = (i + j) * G2;

			double X0 = i - t; // Unskew the cell origin back to (x,y) space
			double Y0 = j - t;

			double x0 = xin - X0; // The x,y distances from the cell origin
			double y0 = yin - Y0;
			// For the 2D case, the simplex shape is an equilateral triangle.
			// Determine which simplex we are in.

			int i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
			if (x0 > y0) { // lower triangle, XY order: (0,0)->(1,0)->(1,1)
				 i1 = 1; j1 = 0;
			}
			else {
				i1 = 0; j1 = 1;
			}
			// upper triangle, YX order: (0,0)->(0,1)->(1,1)
			// A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
			// a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where

			// c = (3-sqrt(3))/6
			double x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
			double y1 = y0 - j1 + G2;

			double x2 = x0 - 1.0 + 2.0 * G2; // Offsets for last corner in (x,y) unskewed coords
			double y2 = y0 - 1.0 + 2.0 * G2;
			// Work out the hashed gradient indices of the three simplex corners
			int ii = i & 255;
			int jj = j & 255;
			int gi0 = perm[ii + perm[jj]] % 12;
			int gi1 = perm[ii + i1 + perm[jj + j1]] % 12;
			int gi2 = perm[ii + 1 + perm[jj + 1]] % 12;
			// Calculate the contribution from the three corners
			double t0 = 0.5 - x0 * x0 - y0 * y0;

			if (t0 < 0){
				n0 = 0.0;
			} else {
				t0 *= t0;
				n0 = t0 * t0 * dot(grad3[gi0], x0, y0);  // (x,y) of grad3 used for 2D gradient
			}
			double t1 = 0.5 - x1 * x1 - y1 * y1;
			if (t1 < 0){
				n1 = 0.0;
			} else {
				t1 *= t1;
				n1 = t1 * t1 * dot(grad3[gi1], x1, y1);
			}
			double t2 = 0.5 - x2 * x2 - y2 * y2;
			if (t2 < 0) {
				n2 = 0.0;
			} else {
				t2 *= t2;
				n2 = t2 * t2 * dot(grad3[gi2], x2, y2);
			}
			// Add contributions from each corner to get the final noise value.
			// The result is scaled to return values in the interval [-1,1].

			return (float)(70.0 * (n0 + n1 + n2));

		}
		// 3D simplex noise
		public static float Noise(float xin, float yin, float zin) {
			double n0, n1, n2, n3; // Noise contributions from the four corners
								   // Skew the input space to determine which simplex cell we're in

			//double F3 = 1.0 / 3.0;
			// double G3 = 1.0 / 6.0; // Very nice and simple unskew factor, too

			double s = (xin + yin + zin) * F3; // Very nice and simple skew factor for 3D
			int i = fastfloor(xin + s);
			int j = fastfloor(yin + s);
			int k = fastfloor(zin + s);
			
			double t = (i + j + k) * G3;
			double X0 = i - t; // Unskew the cell origin back to (x,y,z) space
			double Y0 = j - t;
			double Z0 = k - t;
			double x0 = xin - X0; // The x,y,z distances from the cell origin
			double y0 = yin - Y0;

			double z0 = zin - Z0;
			// For the 3D case, the simplex shape is a slightly irregular tetrahedron.
			// Determine which simplex we are in.

			int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
			int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
			if (x0 >= y0) {
				if (y0 >= z0) {// X Y Z order
					i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
				} else if (x0 >= z0) { // X Z Y order
					i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1;
				} else { // Z X Y order
					i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1;
				}
			} else { // x0<y0
				if (y0 < z0) { // Z Y X order
					i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1;
				} else if (x0 < z0) { // Y Z X order
					i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1;
				} else { // Y X Z order
					i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
				}
			}
			// A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
			// a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and

			// a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where

			// c = 1/6.
			double x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
			double y1 = y0 - j1 + G3;
			double z1 = z0 - k1 + G3;
			double x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords
			double y2 = y0 - j2 + 2.0 * G3;
			double z2 = z0 - k2 + 2.0 * G3;
			double x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords
			double y3 = y0 - 1.0 + 3.0 * G3;
			double z3 = z0 - 1.0 + 3.0 * G3;

			// Work out the hashed gradient indices of the four simplex corners
			int ii = i & 255;
			int jj = j & 255;
			int kk = k & 255;
			int gi0 = perm[ii + perm[jj + perm[kk]]] % 12;
			int gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1]]] % 12;
			int gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2]]] % 12;
			int gi3 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1]]] % 12;
			// Calculate the contribution from the four corners
			double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;

			if (t0 < 0) {
				n0 = 0.0;
			} else {
				t0 *= t0;
				n0 = t0 * t0 * dot(grad3[gi0], x0, y0, z0);
			}
			double t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
			if (t1 < 0) {
				n1 = 0.0;
			} else {
				t1 *= t1;
				n1 = t1 * t1 * dot(grad3[gi1], x1, y1, z1);
			}
			double t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
			if (t2 < 0) {
				n2 = 0.0;
			} else {
				t2 *= t2;
				n2 = t2 * t2 * dot(grad3[gi2], x2, y2, z2);
			}
			double t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
			if (t3 < 0){
				n3 = 0.0;
			} else {
				t3 *= t3;
				n3 = t3 * t3 * dot(grad3[gi3], x3, y3, z3);
			}
			// Add contributions from each corner to get the final noise value.
			// The result is scaled to stay just inside [-1,1]

			return (float)(32.0 * (n0 + n1 + n2 + n3));

		}
		// 4D simplex noise
		public static float Noise(float x, float y, float z, float w) {
			// The skewing and unskewing factors are hairy again for the 4D case

			//Made into static variables for speed optimization
			// double F4 = (System.Math.Sqrt(5.0) - 1.0) / 4.0;
			// double G4 = (5.0 - System.Math.Sqrt(5.0)) / 20.0;

			double n0, n1, n2, n3, n4; // Noise contributions from the five corners
									   // Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
			double s = (x + y + z + w) * F4; // Factor for 4D skewing
			int i = fastfloor(x + s);
			int j = fastfloor(y + s);
			int k = fastfloor(z + s);
			int l = fastfloor(w + s);

			double t = (i + j + k + l) * G4; // Factor for 4D unskewing
			double X0 = i - t; // Unskew the cell origin back to (x,y,z,w) space
			double Y0 = j - t;
			double Z0 = k - t;
			double W0 = l - t;
			double x0 = x - X0;  // The x,y,z,w distances from the cell origin
			double y0 = y - Y0;
			double z0 = z - Z0;
			double w0 = w - W0;

			// For the 4D case, the simplex is a 4D shape I won't even try to describe.
			// To find out which of the 24 possible simplices we're in, we need to
			// determine the magnitude ordering of x0, y0, z0 and w0.
			// The method below is a good way of finding the ordering of x,y,z,w and
			// then find the correct traversal order for the simplex we’re in.
			// First, six pair-wise comparisons are performed between each possible pair
			// of the four coordinates, and the results are used to add up binary bits
			// for an integer index.
			int c1 = (x0 > y0) ? 32 : 0;
			int c2 = (x0 > z0) ? 16 : 0;
			int c3 = (y0 > z0) ? 8 : 0;
			int c4 = (x0 > w0) ? 4 : 0;
			int c5 = (y0 > w0) ? 2 : 0;
			int c6 = (z0 > w0) ? 1 : 0;
			int c = c1 + c2 + c3 + c4 + c5 + c6;
			int i1, j1, k1, l1; // The integer offsets for the second simplex corner
			int i2, j2, k2, l2; // The integer offsets for the third simplex corner
			int i3, j3, k3, l3; // The integer offsets for the fourth simplex corner
								// simplex[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order.
								// Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w
			// impossible. Only the 24 indices which have non-zero entries make any sense.
			// We use a thresholding to set the coordinates in turn from the largest magnitude.

			// The number 3 in the "simplex" array is at the position of the largest coordinate.
			i1 = simplex[c][0] >= 3 ? 1 : 0;
			j1 = simplex[c][1] >= 3 ? 1 : 0;
			k1 = simplex[c][2] >= 3 ? 1 : 0;
			l1 = simplex[c][3] >= 3 ? 1 : 0;

			// The number 2 in the "simplex" array is at the second largest coordinate.
			i2 = simplex[c][0] >= 2 ? 1 : 0;
			j2 = simplex[c][1] >= 2 ? 1 : 0;
			k2 = simplex[c][2] >= 2 ? 1 : 0;
			l2 = simplex[c][3] >= 2 ? 1 : 0;

			// The number 1 in the "simplex" array is at the second smallest coordinate.
			i3 = simplex[c][0] >= 1 ? 1 : 0;
			j3 = simplex[c][1] >= 1 ? 1 : 0;
			k3 = simplex[c][2] >= 1 ? 1 : 0;
			l3 = simplex[c][3] >= 1 ? 1 : 0;

			// The fifth corner has all coordinate offsets = 1, so no need to look that up.
			double x1 = x0 - i1 + G4; // Offsets for second corner in (x,y,z,w) coords
			double y1 = y0 - j1 + G4;
			double z1 = z0 - k1 + G4;
			double w1 = w0 - l1 + G4;
			double x2 = x0 - i2 + 2.0 * G4; // Offsets for third corner in (x,y,z,w) coords
			double y2 = y0 - j2 + 2.0 * G4;
			double z2 = z0 - k2 + 2.0 * G4;
			double w2 = w0 - l2 + 2.0 * G4;
			double x3 = x0 - i3 + 3.0f * G4; // Offsets for fourth corner in (x,y,z,w) coords
			double y3 = y0 - j3 + 3.0 * G4;
			double z3 = z0 - k3 + 3.0 * G4;
			double w3 = w0 - l3 + 3.0 * G4;
			double x4 = x0 - 1.0 + 4.0 * G4; // Offsets for last corner in (x,y,z,w) coords
			double y4 = y0 - 1.0 + 4.0 * G4;
			double z4 = z0 - 1.0 + 4.0 * G4;
			double w4 = w0 - 1.0 + 4.0 * G4;
			// Work out the hashed gradient indices of the five simplex corners
			int ii = i & 255;
			int jj = j & 255;
			int kk = k & 255;
			int ll = l & 255;
			int gi0 = perm[ii + perm[jj + perm[kk + perm[ll]]]] % 32;
			int gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1 + perm[ll + l1]]]] % 32;
			int gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2 + perm[ll + l2]]]] % 32;
			int gi3 = perm[ii + i3 + perm[jj + j3 + perm[kk + k3 + perm[ll + l3]]]] % 32;
			int gi4 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1 + perm[ll + 1]]]] % 32;
			// Calculate the contribution from the five corners
			double t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0;

			if (t0 < 0) {
				n0 = 0.0;
			} else {
				t0 *= t0;
				n0 = t0 * t0 * dot(grad4[gi0], x0, y0, z0, w0);
			}
			double t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1 - w1 * w1;
			if (t1 < 0) {
				n1 = 0.0;
			} else {
				t1 *= t1;
				n1 = t1 * t1 * dot(grad4[gi1], x1, y1, z1, w1);
			}
			double t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2 - w2 * w2;
			if (t2 < 0) {
				n2 = 0.0;
			} else {
				t2 *= t2;
				n2 = t2 * t2 * dot(grad4[gi2], x2, y2, z2, w2);
			}
			double t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3 - w3 * w3;
			if (t3 < 0) {
				n3 = 0.0;
			} else {
				t3 *= t3;
				n3 = t3 * t3 * dot(grad4[gi3], x3, y3, z3, w3);
			}
			double t4 = 0.6 - x4 * x4 - y4 * y4 - z4 * z4 - w4 * w4;
			if (t4 < 0) {
				n4 = 0.0;
			} else {
				t4 *= t4;
				n4 = t4 * t4 * dot(grad4[gi4], x4, y4, z4, w4);
			}
			// Sum up and scale the result to cover the range [-1,1]
			return (float)(27.0 * (n0 + n1 + n2 + n3 + n4));
		}

		public static float Noise(Vector2 position) {
			return Noise(position.x, position.y);
		}

		public static float Noise(Vector3 position) {
			return Noise(position.x, position.y, position.z);
		}

		public static float Noise(Vector4 position) {
			return Noise(position.x, position.y, position.z, position.w);
		}

		[RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.AfterAssembliesLoaded)]
		private static void RuntimeInitializationMethod() {
			for (int i = 0; i < perm.Length; i++)
				perm[i] = p[i & 255];
		}
	}
}
