using System.Drawing;
using System.Numerics;

namespace AutoAgent.Domain.Utils
{
    public class Perlin2D : BaseRandom
    {
        byte[] _mTable = new byte[1024];

        public Perlin2D(int seed = 0)
            : base(seed)
        {
            Generate(_mTable);
        }

        private double[] GetPseudoRandomGradientVector(int x, int y)
        {
            int v = (int)(((x * 1836311903) ^ (y * 2971215073) + 4807526976) & 1023);
            v = _mTable[v] & 3;

            switch (v)
            {
                case 0: return new double[] { 1, 0 };
                case 1: return new double[] { -1, 0 };
                case 2: return new double[] { 0, 1 };
                default: return new double[] { 0, -1 };
            }
        }

        static double QunticCurve(double t)
        {
            return t * t * t * (t * (t * 6 - 15) + 10);
        }

        static double Lerp(double a, double b, double t)
        {
            return a + (b - a) * t;
        }

        static double Dot(double[] a, double[] b)
        {
            return a[0] * b[0] + a[1] * b[1];
        }

        public double Noise(double fx, double fy)
        {
            int left = (int)System.Math.Floor(fx);
            int top = (int)System.Math.Floor(fy);
            double pointInQuadX = fx - left;
            double pointInQuadY = fy - top;

            double[] topLeftGradient = GetPseudoRandomGradientVector(left, top);
            double[] topRightGradient = GetPseudoRandomGradientVector(left + 1, top);
            double[] bottomLeftGradient = GetPseudoRandomGradientVector(left, top + 1);
            double[] bottomRightGradient = GetPseudoRandomGradientVector(left + 1, top + 1);

            double[] distanceToTopLeft = { pointInQuadX, pointInQuadY };
            double[] distanceToTopRight = { pointInQuadX - 1, pointInQuadY };
            double[] distanceToBottomLeft = { pointInQuadX, pointInQuadY - 1 };
            double[] distanceToBottomRight = { pointInQuadX - 1, pointInQuadY - 1 };

            double tx1 = Dot(distanceToTopLeft, topLeftGradient);
            double tx2 = Dot(distanceToTopRight, topRightGradient);
            double bx1 = Dot(distanceToBottomLeft, bottomLeftGradient);
            double bx2 = Dot(distanceToBottomRight, bottomRightGradient);

            pointInQuadX = QunticCurve(pointInQuadX);
            pointInQuadY = QunticCurve(pointInQuadY);

            double tx = Lerp(tx1, tx2, pointInQuadX);
            double bx = Lerp(bx1, bx2, pointInQuadX);
            double tb = Lerp(tx, bx, pointInQuadY);

            return tb;
        }

        public double Noise(double fx, double fy, int octaves, double persistence = 0.5)
        {
            double amplitude = 1;
            double max = 0;
            double result = 0;

            while (octaves-- > 0)
            {
                max += amplitude;
                result += Noise(fx, fy) * amplitude;
                amplitude *= persistence;
                fx *= 2;
                fy *= 2;
            }

            return result / max;
        }
    }

    public abstract class PerlinGenerator<T> : BaseGenerator<T>
    {
        private Perlin2D _perlin;
        private double _amplitude = 100.0;
        public double Amplitude { get => _amplitude; protected set => _amplitude = Math.Abs(value); }
        public double Persistance { get; protected set; } = 0.5;
        public double Frequency { get; protected set; } = 5.0;
        public int Octaves { get; protected set; } = 4;
        public double Seed { get; private set; }
        public override double Step { get; protected set; }
        protected double Noise { get => _perlin.Noise(Progress * Frequency, Seed, Octaves, Persistance); }
        public PerlinGenerator(T min, T max, double seed)
            : base(min, max)
        {
            Seed = seed;
            _perlin = new Perlin2D((int)(Seed * 0x000fffff));
        }
    }

    public sealed class PerlinNumberGenerator<T> : PerlinGenerator<T>, INumberGenerator<T> where T : struct, INumber<T>
    {
        public INumberGenerator<T> Self { get => this; }
        public PerlinNumberGenerator<T> SetShapeFactor(double fShape) { FShape = fShape; return this; }
        public PerlinNumberGenerator<T> SetFadeFactor(double fade) { FFade = fade; return this; }
        public PerlinNumberGenerator<T> SetOctaves(int octaves) { Octaves = octaves; return this; }
        public PerlinNumberGenerator<T> SetPersistence(double peristance) { Persistance = peristance; return this; }
        public PerlinNumberGenerator<T> SetFrequency(double frequency) { Frequency = frequency; return this; }
        public PerlinNumberGenerator<T> SetAmplitude(double amplitude) { Amplitude = amplitude; return this; }
        protected override T Calc()
        {
            var offs = Noise * Scale * ((Self.DMax - Self.DMin) / 2.0);

            return T.CreateChecked(Math.Clamp(Self.Mean + offs, Self.DMin, Self.DMax));
        }
        private static double GetSeed(T min, T max, double seed)
        {
            if (Double.IsNormal(seed)) return seed;
            return (Double.CreateChecked(min) + Double.CreateChecked(max)) / 1000.0;
        }
        public PerlinNumberGenerator(T min, T max, int count = 10, double seed = Double.NaN) : base(min, max, GetSeed(min, max, seed))
        {
            Step = CalcStepByCount(count);
            Amplitude = 1.0; // Set default
        }
    }

    public sealed class PerlinPointGenerator : PerlinGenerator<Point>, IPointGenerator
    {
        private readonly double _pAngle;
        public IPointGenerator Self { get => this; }
        public PerlinPointGenerator SetShapeFactor(double fShape) { FShape = fShape; return this; }
        public PerlinPointGenerator SetFadeFactor(double fade) { FFade = fade; return this; }
        public PerlinPointGenerator SetOctaves(int octaves) { Octaves = octaves; return this; }
        public PerlinPointGenerator SetPersistence(double peristance) { Persistance = peristance; return this; }
        public PerlinPointGenerator SetFrequency(double frequency) { Frequency = frequency; return this; }
        public PerlinPointGenerator SetAmplitude(double amplitude) { Amplitude = amplitude; return this; }
        protected override Point Calc()
        {
            return IPointGenerator.CalcPoint(Self.LinearX, Self.LinearY, Noise * Amplitude * Scale, _pAngle);
        }

        private static double GetSeed(Point start, Point end, double seed)
        {
            if (Double.IsNormal(seed)) return seed;
            return (start.X + end.Y) / 1000.0;
        }

        public static PerlinPointGenerator CreateByCount(Point start, Point end, int count, double seed = Double.NaN)
        {
            return new PerlinPointGenerator(start, end, seed)
            {
                Step = CalcStepByCount(count)
            };
        }
        public static PerlinPointGenerator CreateByStepSize(Point start, Point end, double pxPerStep = 5, double seed = Double.NaN)
        {
            return new PerlinPointGenerator(start, end, pxPerStep, seed);
        }

        public PerlinPointGenerator(Point start, Point end, double pxPerStep = 5, double seed = Double.NaN)
            : this(start, end, seed)
        {
            Step = pxPerStep / IPointGenerator.CalcDistance(start, end);
        }

        private PerlinPointGenerator(Point start, Point end, double seed)
            : base(start, end, GetSeed(start, end, seed))
        {
            _pAngle = IPointGenerator.CalcAngle(start, end) + Math.PI / 2.0;
        }
    }
}