using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;

namespace Tango.Touch.Converters
{
    public class ArcEndPointConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            var actualWidth = values[0].ExtractDouble();
            var value = values[1].ExtractDouble();
            var minimum = values[2].ExtractDouble();
            var maximum = values[3].ExtractDouble();

            if (new[] {actualWidth, value, minimum, maximum}.AnyNan())
                return Binding.DoNothing;

            if (values.Length == 5)
            {
                var fullIndeterminateScaling = values[4].ExtractDouble();
                if (!double.IsNaN(fullIndeterminateScaling) && fullIndeterminateScaling > 0.0)
                {
                    value = (maximum - minimum)*fullIndeterminateScaling;                        
                }
            }

            var percent = maximum <= minimum ? 1.0 : (value - minimum)/(maximum - minimum);
            var degrees = 360*percent;
            var radians = degrees*(Math.PI/180);

            var centre = new Point(actualWidth/2, actualWidth/2);
            var hypotenuseRadius = (actualWidth/2);

            var adjacent = Math.Cos(radians)*hypotenuseRadius;
            var opposite = Math.Sin(radians)*hypotenuseRadius;

            return new Point(centre.X + opposite, centre.Y - adjacent);
        }

        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}