/**
 * Square Dreams Note
 * This code is grabbed from:
 * https://gist.githubusercontent.com/banksean/304522/raw/8f481c980fe34e6930d44c61c59d7851f4235a3c/perlin-noise-simplex.js
 * And edited to make it work as a class
 */

// Ported from Stefan Gustavson's java implementation
// http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
// Read Stefan's excellent paper for details on how this code works.
//
// Sean McCullough banksean@gmail.com

/**
 * You can pass in a random number generator object if you like.
 * It is assumed to have a random() method.
 */
export default class SimplexNoise {
    constructor() {
        this.grad3 = [
            [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],
        ];
        this.p = [];
        for (var i = 0; i < 256; i++) {
            this.p[i] = Math.floor(Math.random() * 256);
        }
        // To remove the need for index wrapping, double the permutation table length
        this.perm = [];
        for (var i = 0; i < 512; i++) {
            this.perm[i] = this.p[i & 255];
        }
        // A lookup table to traverse the simplex around a given point in 4D.
        // Details can be found where this table is used, in the 4D noise method.
        this.simplex = [
            [0, 1, 2, 3],
            [0, 1, 3, 2],
            [0, 0, 0, 0],
            [0, 2, 3, 1],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [1, 2, 3, 0],
            [0, 2, 1, 3],
            [0, 0, 0, 0],
            [0, 3, 1, 2],
            [0, 3, 2, 1],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [1, 3, 2, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [1, 2, 0, 3],
            [0, 0, 0, 0],
            [1, 3, 0, 2],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [2, 3, 0, 1],
            [2, 3, 1, 0],
            [1, 0, 2, 3],
            [1, 0, 3, 2],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [2, 0, 3, 1],
            [0, 0, 0, 0],
            [2, 1, 3, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [2, 0, 1, 3],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [3, 0, 1, 2],
            [3, 0, 2, 1],
            [0, 0, 0, 0],
            [3, 1, 2, 0],
            [2, 1, 0, 3],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0],
            [3, 1, 0, 2],
            [0, 0, 0, 0],
            [3, 2, 0, 1],
            [3, 2, 1, 0],
        ];
    }
    dot(g, x, y) {
        return g[0] * x + g[1] * y;
    }
    dot3(g, x, y, z) {
        return g[0] * x + g[1] * y + g[2] * z;
    }
    noise(xin, yin) {
            var n0, n1, n2; // Noise contributions from the three corners
            // Skew the input space to determine which simplex cell we're in
            var F2 = 0.5 * (Math.sqrt(3.0) - 1.0);
            var s = (xin + yin) * F2; // Hairy factor for 2D
            var i = Math.floor(xin + s);
            var j = Math.floor(yin + s);
            var G2 = (3.0 - Math.sqrt(3.0)) / 6.0;
            var t = (i + j) * G2;
            var X0 = i - t; // Unskew the cell origin back to (x,y) space
            var Y0 = j - t;
            var x0 = xin - X0; // The x,y distances from the cell origin
            var y0 = yin - Y0;
            // For the 2D case, the simplex shape is an equilateral triangle.
            // Determine which simplex we are in.
            var i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
            if (x0 > y0) {
                i1 = 1;
                j1 = 0;
            } // lower triangle, XY order: (0,0)->(1,0)->(1,1)
            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
            var x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
            var y1 = y0 - j1 + G2;
            var x2 = x0 - 1.0 + 2.0 * G2; // Offsets for last corner in (x,y) unskewed coords
            var y2 = y0 - 1.0 + 2.0 * G2;
            // Work out the hashed gradient indices of the three simplex corners
            var ii = i & 255;
            var jj = j & 255;
            var gi0 = this.perm[ii + this.perm[jj]] % 12;
            var gi1 = this.perm[ii + i1 + this.perm[jj + j1]] % 12;
            var gi2 = this.perm[ii + 1 + this.perm[jj + 1]] % 12;
            // Calculate the contribution from the three corners
            var t0 = 0.5 - x0 * x0 - y0 * y0;
            if (t0 < 0) n0 = 0.0;
            else {
                t0 *= t0;
                n0 = t0 * t0 * this.dot(this.grad3[gi0], x0, y0); // (x,y) of grad3 used for 2D gradient
            }
            var t1 = 0.5 - x1 * x1 - y1 * y1;
            if (t1 < 0) n1 = 0.0;
            else {
                t1 *= t1;
                n1 = t1 * t1 * this.dot(this.grad3[gi1], x1, y1);
            }
            var t2 = 0.5 - x2 * x2 - y2 * y2;
            if (t2 < 0) n2 = 0.0;
            else {
                t2 *= t2;
                n2 = t2 * t2 * this.dot(this.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 70.0 * (n0 + n1 + n2);
        }
        // 3D simplex noise
    noise3d(xin, yin, zin) {
        var n0, n1, n2, n3; // Noise contributions from the four corners
        // Skew the input space to determine which simplex cell we're in
        var F3 = 1.0 / 3.0;
        var s = (xin + yin + zin) * F3; // Very nice and simple skew factor for 3D
        var i = Math.floor(xin + s);
        var j = Math.floor(yin + s);
        var k = Math.floor(zin + s);
        var G3 = 1.0 / 6.0; // Very nice and simple unskew factor, too
        var t = (i + j + k) * G3;
        var X0 = i - t; // Unskew the cell origin back to (x,y,z) space
        var Y0 = j - t;
        var Z0 = k - t;
        var x0 = xin - X0; // The x,y,z distances from the cell origin
        var y0 = yin - Y0;
        var z0 = zin - Z0;
        // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
        // Determine which simplex we are in.
        var i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
        var i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
        if (x0 >= y0) {
            if (y0 >= z0) {
                i1 = 1;
                j1 = 0;
                k1 = 0;
                i2 = 1;
                j2 = 1;
                k2 = 0;
            } // X Y Z order
            else if (x0 >= z0) {
                i1 = 1;
                j1 = 0;
                k1 = 0;
                i2 = 1;
                j2 = 0;
                k2 = 1;
            } // X Z Y order
            else {
                i1 = 0;
                j1 = 0;
                k1 = 1;
                i2 = 1;
                j2 = 0;
                k2 = 1;
            } // Z X Y order
        } else {
            // x0<y0
            if (y0 < z0) {
                i1 = 0;
                j1 = 0;
                k1 = 1;
                i2 = 0;
                j2 = 1;
                k2 = 1;
            } // Z Y X order
            else if (x0 < z0) {
                i1 = 0;
                j1 = 1;
                k1 = 0;
                i2 = 0;
                j2 = 1;
                k2 = 1;
            } // Y Z X order
            else {
                i1 = 0;
                j1 = 1;
                k1 = 0;
                i2 = 1;
                j2 = 1;
                k2 = 0;
            } // Y X Z order
        }
        // 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.
        var x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
        var y1 = y0 - j1 + G3;
        var z1 = z0 - k1 + G3;
        var x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords
        var y2 = y0 - j2 + 2.0 * G3;
        var z2 = z0 - k2 + 2.0 * G3;
        var x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords
        var y3 = y0 - 1.0 + 3.0 * G3;
        var z3 = z0 - 1.0 + 3.0 * G3;
        // Work out the hashed gradient indices of the four simplex corners
        var ii = i & 255;
        var jj = j & 255;
        var kk = k & 255;
        var gi0 = this.perm[ii + this.perm[jj + this.perm[kk]]] % 12;
        var gi1 = this.perm[ii + i1 + this.perm[jj + j1 + this.perm[kk + k1]]] % 12;
        var gi2 = this.perm[ii + i2 + this.perm[jj + j2 + this.perm[kk + k2]]] % 12;
        var gi3 = this.perm[ii + 1 + this.perm[jj + 1 + this.perm[kk + 1]]] % 12;
        // Calculate the contribution from the four corners
        var t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
        if (t0 < 0) n0 = 0.0;
        else {
            t0 *= t0;
            n0 = t0 * t0 * this.dot3(this.grad3[gi0], x0, y0, z0);
        }
        var t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
        if (t1 < 0) n1 = 0.0;
        else {
            t1 *= t1;
            n1 = t1 * t1 * this.dot3(this.grad3[gi1], x1, y1, z1);
        }
        var t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
        if (t2 < 0) n2 = 0.0;
        else {
            t2 *= t2;
            n2 = t2 * t2 * this.dot3(this.grad3[gi2], x2, y2, z2);
        }
        var t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
        if (t3 < 0) n3 = 0.0;
        else {
            t3 *= t3;
            n3 = t3 * t3 * this.dot3(this.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 32.0 * (n0 + n1 + n2 + n3);
    }
}