using System;

namespace slash;

public static class Maths
{
    public static int u_length(int s_len) => (1 + s_len) * 2;
    public static int s_length(int u_len) => (u_len - 1) / 2;

    public static int u_index(int s_index, int s_len) => s_len + s_index;
    public static int s_index(int u_index, int u_len) => u_index - u_len;

    public static float u_scalar(float s_scalar) => (1.0f + s_scalar) * 0.5f;
    public static float s_scalar(float u_scalar) => (u_scalar * 2.0f) - 1.0f;

    public static int min(int a, int b) => Math.Min(a, b);
    public static float min(float a, float b) => Math.Min(a, b);
    public static double min(double a, double b) => Math.Min(a, b);
    public static int max(int a, int b) => Math.Max(a, b);
    public static float max(float a, float b) => Math.Max(a, b);
    public static double max(double a, double b) => Math.Max(a, b);

    public static float u_clamp(float x, float cap = 1.0f) => min(cap, max(0.0f, x));
    public static double u_clamp(double x, double cap = 1.0) => min(cap, max(0.0, x));
    public static float s_clamp(float x, float cap = 1.0f) => min(cap, max(-cap, x));
    public static double s_clamp(double x, double cap = 1.0) => min(cap, max(-cap, x));

    public static int abs(int x) => Math.Abs(x);
    public static float abs(float x) => Math.Abs(x);
    public static double abs(double x) => Math.Abs(x);

    public static int sign(float x) => x < 0 ? -1 : +1;

    public static float round(float x) => MathF.Round(x);
    // public static int roundi(float value) => MathF.Round(value)

    public static float precision(float x, float p)
        => round(x * p) / p;

    public static float smooth_start(float t) => (t * t * t);
    public static float smooth_stop(float t)
    {
        float s = sign(t);
        return (s - ((s - t) * (s - t) * (s - t)));
    }

    public static float lerp(float a, float b, float t) => a + (b - a) * t;
}

public class DeltaBool
{
    public int delta = 0;
    public bool state = false;

    public DeltaBool(bool state)
    {
        this.state = state;
    }

    public void Step(bool next_state)
    {
        delta = 0;
        if (next_state != state)
        {
            delta = next_state ? +1 : -1;
            state = next_state;
        }
    }
}

public struct XYZi
{
    public int x { get; set; }
    public int y { get; set; }
    public int z { get; set; }

    public XYZi(int x, int y, int z)
    {
        this.x = x;
        this.y = y;
        this.z = z;
    }

    public static XYZi operator -(XYZi a, XYZi b)
        => new(a.x - b.x, a.y - b.y, a.z - b.z);
    public static XYZi operator +(XYZi a, XYZi b)
        => new(a.x + b.x, a.y + b.y, a.z + b.z);

    public static bool operator ==(XYZi a, XYZi b)
        => (a.x == b.x && a.y == b.y && a.z == b.z);
    public static bool operator !=(XYZi a, XYZi b)
        => (a.x != b.x || a.y != b.y || a.z != b.z);
    public override bool Equals(object obj)
    {
        if (obj is XYZi other)
        {
            return this == other;
        }
        return false;
    }
    public override int GetHashCode()
        => HashCode.Combine(x, y, z);

    public StereoKit.Vec3 ToVec3
        => StereoKit.V.XYZ(x, y, z);

    public override string ToString()
        => string.Format("[{0:0.##}, {1:0.##}, {2:0.##}]", x, y, z);
}

// public class SignedArray<T>

public class SpatialArray<T>
{
    private T[,,] u_array;
    private T default_value;
    private int x_slen; // length past signed zero
    private int y_slen;
    private int z_slen;
    public int Xslen => x_slen;
    public int Yslen => y_slen;
    public int Zslen => z_slen;

    public SpatialArray(
        int x_slen,
        int y_slen,
        int z_slen,
        T default_value = default(T)
    )
    {
        this.u_array = new T[
            Maths.u_length(x_slen),
            Maths.u_length(y_slen),
            Maths.u_length(z_slen)
        ];
        this.x_slen = x_slen;
        this.y_slen = y_slen;
        this.z_slen = z_slen;
        this.default_value = default_value;

        // initialize the arrays with the default value
        Clear(default_value);
    }

    public T this[XYZi sv]
    {
        get
        {
            if (InRange(sv))
            {
                return u_array[
                    Maths.u_index(sv.x, x_slen),
                    Maths.u_index(sv.y, y_slen),
                    Maths.u_index(sv.z, z_slen)
                ];
            }
            else
            {
                return default_value;
            }
        }
        set
        {
            if (InRange(sv))
            {
                u_array[
                    Maths.u_index(sv.x, x_slen),
                    Maths.u_index(sv.y, y_slen),
                    Maths.u_index(sv.z, z_slen)
                ] = value;
            }
            else
            {
                // throw new IndexOutOfRangeException("set index is out of range.");
            }
        }
    }

    public bool InX(int sx) => !(Math.Abs(sx) > x_slen);
    public bool InY(int sy) => !(Math.Abs(sy) > y_slen);
    public bool InZ(int sz) => !(Math.Abs(sz) > z_slen);
    public bool InRange(int sx, int sy, int sz) => InX(sx) && InY(sy) && InZ(sz);
    public bool InRange(XYZi sv) => InRange(sv.x, sv.y, sv.z);

    public void Clear(T value)
    {
        for (int ux = 0; ux < u_array.GetLength(0); ux++)
        {
            for (int uy = 0; uy < u_array.GetLength(1); uy++)
            {
                for (int uz = 0; uz < u_array.GetLength(2); uz++)
                {
                    u_array[ux, uy, uz] = value;
                }
            }
        }
    }
}