namespace Utilities
{
	using System;
	using System.Windows;
	using System.Windows.Media;
	using System.Windows.Shapes;


	public class Arc: Shape
	{
		public static readonly DependencyProperty EndAngleProperty = DependencyProperty.Register("EndAngle", typeof(double), typeof(Arc), new FrameworkPropertyMetadata((double)315, FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure));
		public static readonly DependencyProperty StartAngleProperty = DependencyProperty.Register("StartAngle", typeof(double), typeof(Arc), new FrameworkPropertyMetadata((double)0, FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure));
		public static readonly DependencyProperty IsStrokeClosedProperty = DependencyProperty.Register("IsStrokeClosed", typeof(bool), typeof(Arc), new FrameworkPropertyMetadata(true, FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure));

		static Arc() {
			Shape.StretchProperty.OverrideMetadata(typeof(Arc), new FrameworkPropertyMetadata(Stretch.Uniform));

			// Make *something* appear when first adding it.
			Shape.FillProperty.OverrideMetadata(typeof(Arc), new FrameworkPropertyMetadata(Brushes.Gray));
		}

		public double EndAngle {
			get { return (double)this.GetValue(Arc.EndAngleProperty); }
			set { this.SetValue(Arc.EndAngleProperty, value); }
		}

		public double StartAngle {
			get { return (double)this.GetValue(Arc.StartAngleProperty); }
			set { this.SetValue(Arc.StartAngleProperty, value); }
		}

		public bool IsStrokeClosed {
			get { return (bool)this.GetValue(Arc.IsStrokeClosedProperty); }
			set { this.SetValue(Arc.IsStrokeClosedProperty, value); }
		}


		protected override Geometry DefiningGeometry {
			get {
				PathGeometry geometry = new PathGeometry();
				PathFigure figure = new PathFigure();
				figure.StartPoint = new Point(1, 1);

				double startAngle = this.StartAngle;
				double endAngle = this.EndAngle;

				while (endAngle < startAngle)
					endAngle += 360;

				double startTheta = (startAngle - 90) / 180 * Math.PI;

				double startX = Math.Cos(startTheta) + figure.StartPoint.X;
				double startY = Math.Sin(startTheta) + figure.StartPoint.Y;

				bool isStrokeClosed = this.IsStrokeClosed;

				figure.Segments.Add(new LineSegment(new Point(startX, startY), isStrokeClosed));

				double theta = (endAngle - 90) / 180 * Math.PI;

				double finalX = Math.Cos(theta) + figure.StartPoint.X;
				double finalY = Math.Sin(theta) + figure.StartPoint.Y;

				bool isLargeAngle = (endAngle - startAngle) > 180;

				figure.Segments.Add(new ArcSegment(new Point(finalX, finalY), new Size(1, 1), endAngle, isLargeAngle, SweepDirection.Clockwise, true));
				figure.Segments.Add(new LineSegment(new Point(1, 1), isStrokeClosed));

				geometry.Figures.Add(figure);

				// Shape by default stretches the geometry to fill the area, which is all good,
				// but we want the area to be the full circle, even when only a wedge is shown.
				PathFigure crossbar = new PathFigure();
				crossbar.StartPoint = new Point(0, 0);
				crossbar.Segments.Add(new LineSegment(new Point(2, 2), false));
				geometry.Figures.Add(crossbar);

				return geometry;
			}
		}
	}
}