using System;

namespace Sarand.Net.Standard.Base.Utils
{
	public static class MathUtil
	{
		//-------------------------------------------------------------------
		//                        C o m p a r i s o n
		//-------------------------------------------------------------------
		/// <summary>Compare double values within tollerance.</summary>
		public static bool Equals (this double value, double compareValue, double tollerance)
		{
			return (Math.Abs(value - compareValue) <= tollerance);
		}
		/// <summary>Compare float values within tollerance.</summary>
		public static bool Equals (this float value, float compareValue, float tollerance)
		{
			return (Math.Abs(value - compareValue) <= tollerance);
		}
		/// <summary>Compare decimal values within tollerance.</summary>
		public static bool Equals (this decimal value, decimal compareValue, decimal tollerance)
		{
			return (Math.Abs(value - compareValue) <= tollerance);
		}

		//-------------------------------------------------------------------
		//                         C o n s t r a i n
		//-------------------------------------------------------------------
		/// <summary>
		/// Constrain integer value by maximum and minimum values.
		/// </summary>
		/// <param name="value"></param>
		/// <param name="min"></param>
		/// <param name="max"></param>
		/// <returns></returns>
		public static int Constrain (this int value, int min, int max)
		{
			// Ref. Math.Clamp() in .Net Core 2.0.
			return Math.Min(max, Math.Max(min, value));
		}
		/// <summary>
		/// Constrain decimal value by maximum and minimum values.
		/// </summary>
		/// <param name="value"></param>
		/// <param name="min"></param>
		/// <param name="max"></param>
		/// <returns></returns>
		public static decimal Constrain (this decimal value, decimal min, decimal max)
		{
			return Math.Min(max, Math.Max(min, value));
		}

		//-------------------------------------------------------------------
		//                   S o l v e   Q u a d r a t i c
		//-------------------------------------------------------------------
		// Ref. https://en.wikipedia.org/wiki/Quadratic_formula
		//    ax² + bx + c = 0
		//    x            = (-b ± Sqrt(b²-4ac)) / 2a
		// NB c must be <= b² / 4a
		public static double SolveQuadratic (double valueA, double valueB, double valueC, bool maxValue = true)
		{
			double result = 0;
			double result1 = (-valueB + Math.Sqrt(Math.Pow(valueB, 2) - (4 * valueA * valueC))) / (2 * valueA);
			double result2 = (-valueB - Math.Sqrt(Math.Pow(valueB, 2) - (4 * valueA * valueC))) / (2 * valueA);
			if (maxValue)
				result = Math.Max(result1, result2);
			else result = Math.Min(result1, result2);
			return result;
		}

		//-------------------------------------------------------------------
		/// <summary>
		/// Test for near zero values (<1e-10).
		/// </summary>
		/// <param name="d"></param>
		/// <returns></returns>
		public static bool IsZero (this double d, double zeroEpsilon = 1e-10)
		{
			return Math.Abs(d) < zeroEpsilon;
		}

		//-------------------------------------------------------------------
		// Convert degress to radians.
		public static double DegreesToRadians (double degrees)
		{
			return (Math.PI / 180) * AdjustDegrees(degrees);
		}
		// Convert radians to degrees.
		public static double RadiansToDegrees (double radians)
		{
			return AdjustDegrees((180 / Math.PI) * radians);
		}
		public static double AdjustDegrees (double degrees)
		{
			while (degrees < 0.0) degrees += 360.0;
			while (degrees >= 360.0) degrees -= 360.0;
			return degrees;
		}

		//-------------------------------------------------------------------
		// Calculate hypotenuse lenfth from the other two sides.
		public static double GetHypotenuseLength (double side1, double side2)
		{
			return Math.Sqrt(Math.Pow(side1, 2.0) + Math.Pow(side2, 2.0));
		}

		//-------------------------------------------------------------------
        /*
		/// <summary>
		/// Offset size by specified distance and angle (anti-clockwise from vertical).
		///   angle = 0: straight up; angle = 90: to left; angle = -90: to right, etc.
		/// </summary>
		/// <param name="distance"></param>
		/// <param name="angleDegrees"></param>
		/// <returns></returns>
		public static SizeF GetSizeOffsetByDegrees (float distance, double angleDegrees)
		{
			double angleRadians = MathUtil.DegreesToRadians(angleDegrees);
			return GetSizeOffsetByRadians(distance, angleRadians);
		}
		public static SizeF GetSizeOffsetByRadians (float distance, double angleRadians)
		{
			return new SizeF(-Convert.ToSingle(Math.Sin(angleRadians) * distance), Convert.ToSingle(Math.Cos(angleRadians) * distance));
		}
        */

		//-------------------------------------------------------------------
        /*
		/// <summary>
		/// Rotate a point about the specified center point by the number of degrees.
		/// </summary>
		public static PointF RotatePointDegrees (PointF point, PointF center, double angleDegrees)
		{
			return RotatePointRadians(point, center, MathUtil.DegreesToRadians(angleDegrees));
		}
		public static PointF RotatePointRadians (PointF point, PointF center, double angleRadians)
		{
			double cosTheta = Math.Cos(angleRadians);
			double sinTheta = Math.Sin(angleRadians);
			float x = Convert.ToSingle(cosTheta * (point.X - center.X) - sinTheta * (point.Y - center.Y) + center.X);
			float y = Convert.ToSingle(sinTheta * (point.X - center.X) + cosTheta * (point.Y - center.Y) + center.Y);
			return new PointF(x, y);
		}
        */

		//-------------------------------------------------------------------
	}
}