using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Markup;
using System.Windows.Shapes;
using System.Windows.Threading;
using Tango.Core.Threading;

namespace Tango.Touch.Controls
{
    [ContentProperty(nameof(Content))]
    public class TouchVirtualizedContentControl : Control
    {
        private LightTouchScrollViewer _scrollViewer;
        private ContentPresenter _innerBorder;
        private ActionTimer _updateTimer;
        private Point _location;
        private bool _loaded;

        public UIElement Content
        {
            get { return (UIElement)GetValue(ContentProperty); }
            set { SetValue(ContentProperty, value); }
        }
        public static readonly DependencyProperty ContentProperty =
            DependencyProperty.Register("Content", typeof(UIElement), typeof(TouchVirtualizedContentControl), new PropertyMetadata(null));

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

        public LightTouchDataGrid DataGrid
        {
            get { return (LightTouchDataGrid)GetValue(DataGridProperty); }
            set { SetValue(DataGridProperty, value); }
        }
        public static readonly DependencyProperty DataGridProperty =
            DependencyProperty.Register("DataGrid", typeof(LightTouchDataGrid), typeof(TouchVirtualizedContentControl), new PropertyMetadata(null));

        static TouchVirtualizedContentControl()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(TouchVirtualizedContentControl), new FrameworkPropertyMetadata(typeof(TouchVirtualizedContentControl)));
        }

        public TouchVirtualizedContentControl()
        {
            _updateTimer = new ActionTimer(TimeSpan.FromMilliseconds(100));
            Loaded += TouchVirtualizedContentControl_Loaded;
        }

        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();
            _innerBorder = GetTemplateChild("PART_innerBorder") as ContentPresenter;
        }

        private void TouchVirtualizedContentControl_Loaded(object sender, System.Windows.RoutedEventArgs e)
        {
            _scrollViewer = this.FindAncestor<LightTouchScrollViewer>();
            _scrollViewer.Scrolling += _scrollViewer_Scrolling;

            if (DataGrid != null)
            {
                DataGrid.SortingChanged += DataGrid_SortingChanged;
                DataGrid.FilterChanged += DataGrid_FilterChanged;
            }

            _location = this.TranslatePoint(new Point(0, 0), _scrollViewer.GetContentGrid());

            _scrollViewer.GetContentGrid().SizeChanged += TouchVirtualizedContentControl_SizeChanged;

            ApplyVirtualization();
            _loaded = true;
        }

        private void DataGrid_FilterChanged(object sender, EventArgs e)
        {
            InvalidateVirtualization();
        }

        private void DataGrid_SortingChanged(object sender, EventArgs e)
        {
            InvalidateVirtualization();
        }

        private void TouchVirtualizedContentControl_SizeChanged(object sender, SizeChangedEventArgs e)
        {
            InvalidateVirtualization();
        }

        private void _scrollViewer_Scrolling(object sender, DoubleValueChangedEventArgs e)
        {
            if (_loaded)
            {
                ApplyVirtualization();
            }
        }

        private void InvalidateVirtualization()
        {
            _updateTimer.ResetReplace(() =>
            {
                Dispatcher.BeginInvoke(new Action(() =>
                {
                    _location = this.TranslatePoint(new Point(0, 0), _scrollViewer.GetContentGrid());
                    ApplyVirtualization();
                }));
            });
        }

        private void ApplyVirtualization()
        {
            var _border_viewport = _scrollViewer.GetViewportBorder();

            if (CanMovePosition)
            {
                _location = this.TranslatePoint(new Point(0, 0), _scrollViewer.GetContentGrid());
            }

            Rect bounds = new Rect(_location.X, _location.Y, ActualWidth, ActualHeight);
            Rect rect = new Rect(0.0, _scrollViewer.GetScrollPosition(), _border_viewport.ActualWidth, _border_viewport.ActualHeight);

            if (_innerBorder != null)
            {
                if (bounds.IntersectsWith(rect))
                {
                    if (_innerBorder.Visibility == Visibility.Hidden)
                    {
                        //Debug.WriteLine("Visible");
                        Dispatcher.BeginInvoke(new Action(() =>
                        {
                            _innerBorder.Visibility = Visibility.Visible;
                        }), DispatcherPriority.Background);
                    }
                }
                else
                {
                    if (_innerBorder.Visibility == Visibility.Visible)
                    {
                        Dispatcher.BeginInvoke(new Action(() =>
                        {
                        //Debug.WriteLine("Hidden");
                        _innerBorder.Visibility = Visibility.Hidden;
                        }), DispatcherPriority.Background);
                    }
                }
            }
        }
    }
}