//	Spludlow Software
//	Copyright © Samuel P. Ludlow 2020 All Rights Reserved
//	Distributed under the terms of the GNU General Public License version 3
//	Distributed WITHOUT ANY WARRANTY; without implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
//	https://www.spludlow.co.uk/LICENCE.TXT
//	The Spludlow logo is a registered trademark of Samuel P. Ludlow and may not be used without permission
//	v1.14

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Drawing;

namespace Spludlow.Drawing
{
	/// <summary>
	/// Maths used in drawing
	/// </summary>
	public class Maths
	{
		public static PointF ArcPoint(float x, float y, float xRadius, float yRadius, float angle)
		{
			angle += 90;
			angle *= (float)(Math.PI / 180);

			float x1 = x + xRadius * (float)Math.Cos(angle);
			float y1 = y + yRadius * (float)Math.Sin(angle);

			return new PointF(x1, y1);
		}

		public static PointF[] Polygon(float x, float y, float xRadius, float yRadius, int sides, float rotateAngle)
		{
			float whole = (float)(2 * Math.PI);		// convert to arcPoint
			float step = whole / sides;

			rotateAngle += 90;

			rotateAngle *= (float)(Math.PI / 180);
			
			List<PointF> points = new List<PointF>();

			for (int side = 0; side < sides; ++side)
			{
				float angle = side * step - rotateAngle;
				float x1 = x + xRadius * (float)Math.Cos(angle);
				float y1 = y + yRadius * (float)Math.Sin(angle);

				points.Add(new System.Drawing.PointF(x1, y1));
			}

			return points.ToArray();
		}

		public static PointF[] ArcSector(float x, float y, float xOuterRadius, float yOuterRadius, float xInnerRadius, float yInnerRadius, float startAngle, float endAngle)
		{
			startAngle += 180;
			endAngle += 180;

			List<PointF> points = new List<PointF>();

			float sweepAngle = endAngle - startAngle;

			int totalSteps = (int)(sweepAngle);	//	equal to degrees ????

			float stepAngle = sweepAngle / (float)totalSteps;

			PointF point;

			for (int stepIndex = 0; stepIndex < totalSteps; ++stepIndex)
			{
				float angleA = startAngle + (float)stepIndex * stepAngle;
				float angleB = startAngle + (float)(stepIndex + 1) * stepAngle;

				point = ArcPoint(x, y, xOuterRadius, yOuterRadius, angleA);
				points.Add(point);

				point = ArcPoint(x, y, xOuterRadius, yOuterRadius, angleB);
				points.Add(point);
			}

			for (int stepIndex = totalSteps; stepIndex > 0; --stepIndex)
			{
				float angleA = startAngle + (float)stepIndex * stepAngle;
				float angleB = startAngle + (float)(stepIndex - 1) * stepAngle;

				point = ArcPoint(x, y, xInnerRadius, yInnerRadius, angleA);
				points.Add(point);

				point = ArcPoint(x, y, xInnerRadius, yInnerRadius, angleB);
				points.Add(point);
			}

			point = ArcPoint(x, y, xOuterRadius, yOuterRadius, startAngle);
			points.Add(point);

			return points.ToArray();
		}

		public static PointF TransformPoint(PointF point, float scale, float angle, PointF origin)
		{
			angle = (angle / 180.0F) * (float)Math.PI;

			float x = point.X - origin.X;
			float y = point.Y - origin.Y;

			x *= scale;
			y *= scale;

			float rotatedX = x * (float)Math.Cos(angle) - y * (float)Math.Sin(angle);
			float rotatedY = x * (float)Math.Sin(angle) + y * (float)Math.Cos(angle);

			return new PointF(rotatedX + origin.X, rotatedY + origin.Y);
		}
	}
}