using System;
using System.Collections.Generic;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Text;

namespace DevComponents.DotNetBar.Charts
{
    internal static class MathHelper
    {
        #region ToDegrees

        public static double ToDegrees(double radians)
        {
            return (radians * 180 / Math.PI);
        }

        #endregion

        #region ToRadians

        public static double ToRadians(double degrees)
        {
            return (degrees * Math.PI / 180);
        }

        #endregion

        #region GetPointAngle

        public static int GetPointAngle(Point pt)
        {
            double theta = Math.Atan2(pt.X, -pt.Y);
            int angle = (int)(MathHelper.ToDegrees(theta) + 270) % 360;

            return (angle);
        }

        #endregion

        #region GetPointRadius

        public static int GetPointRadius(ref Point pt, Point cpt)
        {
            pt.X -= cpt.X;
            pt.Y -= cpt.Y;

            return ((int)Math.Sqrt(pt.X * pt.X + pt.Y * pt.Y));
        }

        #endregion

        #region GetOffsetPoint

        public static Point GetOffsetPoint(
            Point pt, Point cpt, out int radius, out int angle)
        {
            radius = MathHelper.GetPointRadius(ref pt, cpt);
            angle = MathHelper.GetPointAngle(pt);

            return (pt);
        }

        #endregion

        #region Clamp

        public static T Clamp<T>(T value, T min, T max)
            where T : IComparable<T>
        {
            T result = value;

            if (result.CompareTo(max) > 0)
                result = max;

            if (result.CompareTo(min) < 0)
                result = min;

            return (result);
        }

        #endregion

        #region ToScalar

        public static double ToScalar(double x)
        {
            return (MathHelper.Sqrt((float)(x / Math.PI)) * 2);
        }

        #endregion

        #region Sqrt

        [StructLayout(LayoutKind.Explicit)]
        private struct FloatIntUnion
        {
            [FieldOffset(0)]
            public float f;

            [FieldOffset(0)]
            public int tmp;
        }

        public static float Sqrt(float x)
        {
            if (x != 0)
            {
                FloatIntUnion u;

                u.tmp = 0;
                u.f = x;

                u.tmp -= 1 << 23;   // Subtract 2^m
                u.tmp >>= 1;        // Divide by 2
                u.tmp += 1 << 29;   // Add ((b + 1) / 2) * 2^m

                return (u.f);
            }

            return (0);
        }

        #endregion
    }
}