using TriangleNet.Geometry;

namespace TriangleNet.Tools
{
	public static class IntersectionHelper
	{
		public static void IntersectSegments(Point p0, Point p1, Point q0, Point q1, ref Point c0)
		{
			double num = p1.x - p0.x;
			double num2 = p1.y - p0.y;
			double num3 = q1.x - q0.x;
			double num4 = q1.y - q0.y;
			double num5 = p0.x - q0.x;
			double num6 = p0.y - q0.y;
			double num7 = num * num4 - num2 * num3;
			double num8 = (num3 * num6 - num4 * num5) / num7;
			c0.x = p0.X + num8 * num;
			c0.y = p0.Y + num8 * num2;
		}

		public static bool LiangBarsky(Rectangle rect, Point p0, Point p1, ref Point c0, ref Point c1)
		{
			double left = rect.Left;
			double right = rect.Right;
			double bottom = rect.Bottom;
			double top = rect.Top;
			double x = p0.X;
			double y = p0.Y;
			double x2 = p1.X;
			double y2 = p1.Y;
			double num = 0.0;
			double num2 = 1.0;
			double num3 = x2 - x;
			double num4 = y2 - y;
			double num5 = 0.0;
			double num6 = 0.0;
			for (int i = 0; i < 4; i++)
			{
				if (i == 0)
				{
					num5 = 0.0 - num3;
					num6 = 0.0 - (left - x);
				}
				if (i == 1)
				{
					num5 = num3;
					num6 = right - x;
				}
				if (i == 2)
				{
					num5 = 0.0 - num4;
					num6 = 0.0 - (bottom - y);
				}
				if (i == 3)
				{
					num5 = num4;
					num6 = top - y;
				}
				double num7 = num6 / num5;
				if (num5 == 0.0 && num6 < 0.0)
				{
					return false;
				}
				if (num5 < 0.0)
				{
					if (num7 > num2)
					{
						return false;
					}
					if (num7 > num)
					{
						num = num7;
					}
				}
				else if (num5 > 0.0)
				{
					if (num7 < num)
					{
						return false;
					}
					if (num7 < num2)
					{
						num2 = num7;
					}
				}
			}
			c0.X = x + num * num3;
			c0.Y = y + num * num4;
			c1.X = x + num2 * num3;
			c1.Y = y + num2 * num4;
			return true;
		}

		public static bool BoxRayIntersection(Rectangle rect, Point p0, Point p1, ref Point c1)
		{
			double x = p0.X;
			double y = p0.Y;
			double num = p1.x - x;
			double num2 = p1.y - y;
			double left = rect.Left;
			double right = rect.Right;
			double bottom = rect.Bottom;
			double top = rect.Top;
			if (x < left || x > right || y < bottom || y > top)
			{
				return false;
			}
			double num3;
			double x2;
			double y2;
			if (num < 0.0)
			{
				num3 = (left - x) / num;
				x2 = left;
				y2 = y + num3 * num2;
			}
			else if (num > 0.0)
			{
				num3 = (right - x) / num;
				x2 = right;
				y2 = y + num3 * num2;
			}
			else
			{
				num3 = double.MaxValue;
				x2 = (y2 = 0.0);
			}
			double num4;
			double x3;
			double y3;
			if (num2 < 0.0)
			{
				num4 = (bottom - y) / num2;
				x3 = x + num4 * num;
				y3 = bottom;
			}
			else if (num2 > 0.0)
			{
				num4 = (top - y) / num2;
				x3 = x + num4 * num;
				y3 = top;
			}
			else
			{
				num4 = double.MaxValue;
				x3 = (y3 = 0.0);
			}
			if (num3 < num4)
			{
				c1.x = x2;
				c1.y = y2;
			}
			else
			{
				c1.x = x3;
				c1.y = y3;
			}
			return true;
		}
	}
}