using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Shapes;

namespace Tango.Visuals.Components
{
    internal class Arc : Shape
    {
        public double StartAngle
        {
            get { return (double)GetValue(StartAngleProperty); }
            set { SetValue(StartAngleProperty, value); }
        }
        public static readonly DependencyProperty StartAngleProperty =
            DependencyProperty.Register("StartAngle", typeof(double), typeof(Arc), new PropertyMetadata(0.0));

        public double EndAngle
        {
            get { return (double)GetValue(EndAngleProperty); }
            set { SetValue(EndAngleProperty, value); }
        }
        public static readonly DependencyProperty EndAngleProperty =
            DependencyProperty.Register("EndAngle", typeof(double), typeof(Arc), new PropertyMetadata(90.0));

        protected override Geometry DefiningGeometry
        {
            get
            {
                double maxWidth = RenderSize.Width;
                double maxHeight = RenderSize.Height;
                double maxRadius = Math.Min(maxWidth, maxHeight) / 2.0;

                PolarPoint arcStart = new PolarPoint(maxRadius, StartAngle);
                PolarPoint arcFinish = new PolarPoint(maxRadius, EndAngle);

                StreamGeometry geom = new StreamGeometry();
                using (StreamGeometryContext ctx = geom.Open())
                {
                    ctx.BeginFigure(
                        new Point((maxWidth / 2.0) + arcStart.X,
                                   (maxHeight / 2.0) - arcStart.Y),
                        false,
                        false);
                    ctx.ArcTo( 
                        new Point((maxWidth / 2.0) + arcFinish.X,
                                  (maxHeight / 2.0) - arcFinish.Y),
                        new Size(maxRadius, maxRadius),
                        0.0,     // rotationAngle
                        EndAngle > 180 && StartAngle < 180 && (EndAngle - StartAngle) > 180,   // greater than 180 deg?
                        SweepDirection.Counterclockwise,
                        true,    // isStroked
                        true);
                }

                geom.Transform = new RotateTransform((-90 + EndAngle) + StartAngle, maxWidth / 2, maxHeight / 2);

                return geom;
            }
        }
    }
}