using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Media;
using FarseerPhysics.Dynamics;

namespace FarseerTransforms
{
    public class BodyViewModel : INotifyPropertyChanged
    {
        private Fixture _fixture;
        private CompositeTransform _transform = new CompositeTransform();
        private System.Windows.Media.GeneralTransform _worldToCanvas;
        private double _width;
        private double _height;

        public BodyViewModel(Fixture fixture, double width, double height, System.Windows.Media.GeneralTransform worldToCanvas)
        {
            _fixture = fixture;
            _width = width;
            _height = height;
            _worldToCanvas = worldToCanvas;

            // rotate around center
            _transform.CenterX = width / 2;
            _transform.CenterY = height / 2;
            // adjust for center
            var position = _worldToCanvas.Transform(new Point(_fixture.Body.Position.X, _fixture.Body.Position.Y));
            _transform.TranslateX = position.X - width / 2;
            _transform.TranslateY = position.Y - width / 2;
            _transform.Rotation = _fixture.Body.Rotation * 360 / (2 * Math.PI);
        }

        public event PropertyChangedEventHandler PropertyChanged;

        public double Width
        {
            get { return _width; }
        }

        public double Height
        {
            get { return _height; }
        }

        public CompositeTransform RenderTransform
        {
            get { return _transform; }
        }

        internal void Notify()
        {
            var position = _worldToCanvas.Transform(new Point(_fixture.Body.Position.X, _fixture.Body.Position.Y));
            _transform.TranslateX = position.X - Width / 2;
            _transform.TranslateY = position.Y - Height / 2;
            _transform.Rotation = _fixture.Body.Rotation * 360 / (2 * Math.PI);
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("RenderTransform"));
            }
        }
    }
}