using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Markup;
using System.Windows.Media;
using System.Windows.Shapes;
using Tango.Graphics2D.VisualBinders;

namespace Tango.Graphics2D
{
    [ContentProperty(nameof(Elements))]
    public abstract class Drawing2DHost : FrameworkElement
    {
        private readonly VisualCollection _children;
        private Dictionary<DrawingVisual, FrameworkElement> _elements;
        private List<BindingEventContainer> _containers;
        private FrameworkElement _mouseEnterElement;
        private Dictionary<Type, IVisualBinder> _binders;

        #region Properties

        public ObservableCollection<FrameworkElement> Elements
        {
            get { return (ObservableCollection<FrameworkElement>)GetValue(ElementsProperty); }
            set { SetValue(ElementsProperty, value); }
        }
        public static readonly DependencyProperty ElementsProperty =
            DependencyProperty.Register("Elements", typeof(ObservableCollection<FrameworkElement>), typeof(Drawing2DHost), new PropertyMetadata(null, (d, e) => (d as Drawing2DHost).OnElementsChanged()));

        public Brush Foreground
        {
            get { return (Brush)this.GetValue(ForegroundProperty); }
            set { this.SetValue(ForegroundProperty, value); }
        }
        public static readonly DependencyProperty ForegroundProperty =
               TextBlock.ForegroundProperty.AddOwner(typeof(Drawing2DHost));

        public bool CanResize
        {
            get { return (bool)GetValue(CanResizeProperty); }
            set { SetValue(CanResizeProperty, value); }
        }
        public static readonly DependencyProperty CanResizeProperty =
            DependencyProperty.Register("CanResize", typeof(bool), typeof(Drawing2DHost), new PropertyMetadata(false));


        #endregion

        #region Constructors

        public Drawing2DHost()
        {
            Elements = new ObservableCollection<FrameworkElement>();
            _elements = new Dictionary<DrawingVisual, FrameworkElement>();
            _containers = new List<BindingEventContainer>();
            _binders = new Dictionary<Type, IVisualBinder>();
            _children = new VisualCollection(this);

            RegisterVisualBinder<TextBlock>(new TextBlockBinder());
            RegisterVisualBinder<Rectangle>(new RectangleBinder());
            RegisterVisualBinder<Ellipse>(new EllipseBinder());
            RegisterVisualBinder<Border>(new BorderBinder());
            RegisterVisualBinder<Image>(new ImageBinder());
            RegisterVisualBinder<Line>(new LineBinder());
            RegisterVisualBinder<Path>(new PathBinder());

            Loaded += Drawing2DHost_Loaded;
            SizeChanged += Drawing2DHost_SizeChanged;
        }

        #endregion

        #region Host Events

        private void Drawing2DHost_Loaded(object sender, RoutedEventArgs e)
        {
            DrawElements();
            var size = OnMeasure();

            if (double.IsNaN(Width))
            {
                Width = size.Width;
            }

            if (double.IsNaN(Height))
            {
                Height = size.Height;
            }
        }

        private void Drawing2DHost_SizeChanged(object sender, SizeChangedEventArgs e)
        {
            foreach (var item in _elements)
            {
                InvalidateElement(item.Key, item.Value);
            }
        }

        #endregion

        #region Mouse Interactions

        protected override void OnMouseDown(MouseButtonEventArgs e)
        {
            base.OnMouseDown(e);

            if (e.ChangedButton == MouseButton.Left)
            {
                Point pt = e.GetPosition(this);
                VisualTreeHelper.HitTest(this, null, MouseDownCallback, new PointHitTestParameters(pt));
            }
        }

        private HitTestResultBehavior MouseDownCallback(HitTestResult result)
        {
            if (result.VisualHit.GetType() == typeof(DrawingVisual))
            {
                var visual = result.VisualHit as DrawingVisual;

                if (visual != null)
                {
                    var element = _elements[visual];

                    if (element != null)
                    {
                        element.RaiseEvent(new MouseButtonEventArgs(Mouse.PrimaryDevice, 0, MouseButton.Left)
                        {
                            RoutedEvent = Mouse.MouseDownEvent,
                            Source = element,
                        });
                    }
                }
            }

            return HitTestResultBehavior.Stop;
        }

        protected override void OnMouseUp(MouseButtonEventArgs e)
        {
            base.OnMouseUp(e);

            if (e.ChangedButton == MouseButton.Left)
            {
                Point pt = e.GetPosition(this);
                VisualTreeHelper.HitTest(this, null, MouseUpCallback, new PointHitTestParameters(pt));
            }
        }

        private HitTestResultBehavior MouseUpCallback(HitTestResult result)
        {
            if (result.VisualHit.GetType() == typeof(DrawingVisual))
            {
                var visual = result.VisualHit as DrawingVisual;

                if (visual != null)
                {
                    var element = _elements[visual];

                    if (element != null)
                    {
                        element.RaiseEvent(new MouseButtonEventArgs(Mouse.PrimaryDevice, 0, MouseButton.Left)
                        {
                            RoutedEvent = Mouse.MouseUpEvent,
                            Source = element,
                        });
                    }
                }
            }

            return HitTestResultBehavior.Stop;
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);

            Point pt = e.GetPosition(this);
            VisualTreeHelper.HitTest(this, null, MouseMoveCallback, new PointHitTestParameters(pt));
        }

        private HitTestResultBehavior MouseMoveCallback(HitTestResult result)
        {
            if (result.VisualHit.GetType() == typeof(DrawingVisual))
            {
                var visual = result.VisualHit as DrawingVisual;

                if (visual != null)
                {
                    var element = _elements[visual];

                    if (element != null)
                    {
                        element.RaiseEvent(new MouseEventArgs(Mouse.PrimaryDevice, 0)
                        {
                            RoutedEvent = Mouse.MouseMoveEvent,
                            Source = element,
                        });

                        if (_mouseEnterElement != null && _mouseEnterElement != element)
                        {
                            _mouseEnterElement.RaiseEvent(new MouseEventArgs(Mouse.PrimaryDevice, 0)
                            {
                                RoutedEvent = Mouse.MouseLeaveEvent,
                                Source = _mouseEnterElement,
                            });
                        }

                        if (_mouseEnterElement != element)
                        {
                            _mouseEnterElement = element;

                            element.RaiseEvent(new MouseEventArgs(Mouse.PrimaryDevice, 0)
                            {
                                RoutedEvent = Mouse.MouseEnterEvent,
                                Source = element,
                            });
                        }
                    }
                }
            }

            return HitTestResultBehavior.Stop;
        }

        #endregion

        #region Elements Changed

        private void Elements_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
        {
            if (!IsDesignMode)
            {
                foreach (var element in e.NewItems)
                {
                    (element as FrameworkElement).DataContext = DataContext;
                }
            }
        }

        private void OnElementsChanged()
        {
            if (Elements != null)
            {
                Elements.CollectionChanged += Elements_CollectionChanged;
            }
        }

        #endregion

        #region Drawing Executers

        private void DrawElements()
        {
            foreach (var element in Elements)
            {
                DrawElement(element);
            }
        }

        private void DrawElement(FrameworkElement element)
        {
            DrawingVisual visual = new DrawingVisual();

            IVisualBinder binder = InvalidateElement(visual, element);

            AddVisual(visual, element);

            foreach (var dp in binder.GetRenderProperties())
            {
                var container = BindingEventContainer.Generate(visual, element, dp);
                container.ValueChanged += (sender, e) =>
                {
                    InvalidateElement(e.Visual, e.Element);
                };

                _containers.Add(container);
            }
        }

        private IVisualBinder InvalidateElement(DrawingVisual visual, FrameworkElement element)
        {
            var context = visual.RenderOpen();

            if (!_binders.TryGetValue(element.GetType(), out IVisualBinder binder))
            {
                throw new InvalidOperationException($"No visual binder is registered for element type '{element.GetType()}'");
            }

            binder.DrawVisual(element, this, context);

            visual.Opacity = element.Opacity;

            if (element.Visibility != Visibility.Visible)
            {
                visual.Opacity = 0;
            }

            context.Close();

            return binder;
        }

        private void AddVisual(DrawingVisual visual, FrameworkElement element)
        {
            visual.Opacity = element.Opacity;
            visual.Transform = element.RenderTransform;

            _children.Add(visual);
            _elements.Add(visual, element);
        }

        #endregion

        #region Abstract and Virtual Methods

        protected virtual Size OnMeasure()
        {
            return new Size(double.NaN, double.NaN);
        }

        public abstract Point GetElementLocation(FrameworkElement element);

        public abstract Size GetElementSize(FrameworkElement element);

        #endregion

        #region Binders

        public void RegisterVisualBinder<T>(IVisualBinder instance)
        {
            _binders.Add(typeof(T), instance);
        }

        #endregion

        #region Child Get/Count

        protected override int VisualChildrenCount => _children != null ? _children.Count : 0;

        protected override Visual GetVisualChild(int index)
        {
            if (index < 0 || index >= _children.Count)
            {
                throw new ArgumentOutOfRangeException();
            }

            return _children[index];
        }

        #endregion

        #region Helper Methods

        protected bool IsDesignMode
        {
            get { return (DesignerProperties.GetIsInDesignMode(new DependencyObject())); }
        }

        #endregion

    }
}