using RealTimeGraphX.EventArguments;
using RealTimeGraphX.WPF.DataSeries;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace RealTimeGraphX.WPF.Surfaces
{
    /// <summary>
    /// Represents a WPF implementation for <see cref="IGraphSurface{TImage}"/>.
    /// This surface expects a graph image of type <see cref="BitmapSource"/>.
    /// </summary>
    /// <seealso cref="System.Windows.Controls.Control" />
    /// <seealso cref="RealTimeGraphX.IGraphSurface{System.Windows.Media.Imaging.BitmapSource}" />
    public class WpfGraphSurface : Control, IGraphSurface<WpfDataSeries, BitmapSource>
    {
        private Rectangle _selection_rectangle;
        private Canvas _selection_canvas;
        private bool _is_selection_mouse_down_zoom;
        private bool _is_selection_mouse_down_pan;
        private Point _selection_start_point;
        private bool _is_scaled;
        private Rect _pan_rect;
        private Point _current_mouse_position;
        private Point _last_mouse_position;
        private Grid _grid;

        #region Events

        /// <summary>
        /// Occurs when <see cref="IGraphPainter{TImage}"/> has changed.
        /// </summary>
        public event EventHandler<InputChangedEventArgs<IGraphPainter<WpfDataSeries, BitmapSource>>> InputChanged;

        /// <summary>
        /// Occurs when the surface size has changed.
        /// </summary>
        public event EventHandler<SurfaceSizeChangedEventArgs> SurfaceSizeChanged;

        /// <summary>
        /// Occurs when the connected input <see cref="IGraphPainter"/> has changed.
        /// </summary>
        event EventHandler<InputChangedEventArgs<IGraphPainter>> IGraphInputComponent<IGraphPainter>.InputChanged
        {
            add
            {
                InputChanged += new EventHandler<InputChangedEventArgs<IGraphPainter<WpfDataSeries, BitmapSource>>>((sender, e) => { value.Invoke(sender, new InputChangedEventArgs<IGraphPainter>(e.Input)); });
            }

            remove
            {
                InputChanged -= new EventHandler<InputChangedEventArgs<IGraphPainter<WpfDataSeries, BitmapSource>>>((sender, e) => { value.Invoke(sender, new InputChangedEventArgs<IGraphPainter>(e.Input)); });
            }
        }

        #endregion

        #region Properties     

        /// <summary>
        /// Gets the current graph image.
        /// </summary>
        public BitmapSource Image
        {
            get { return (BitmapSource)GetValue(ImageProperty); }
            private set { SetValue(ImageProperty, value); }
        }
        public static readonly DependencyProperty ImageProperty =
            DependencyProperty.Register("Image", typeof(BitmapSource), typeof(WpfGraphSurface), new PropertyMetadata(null));

        private double _surfaceWidth;
        /// <summary>
        /// Gets the width of the surface.
        /// </summary>
        public double SurfaceWidth
        {
            get
            {
                return _surfaceWidth;
            }
            private set
            {
                _surfaceWidth = value;
            }
        }

        private double _surfaceHeight;
        /// <summary>
        /// Gets the height of the surface.
        /// </summary>
        public double SurfaceHeight
        {
            get
            {
                return _surfaceHeight;
            }
            private set
            {
                _surfaceHeight = value;
            }
        }

        private IGraphPainter<WpfDataSeries,BitmapSource> _input;
        /// <summary>
        /// Gets the connected input <see cref="IGraphPainter{TImage}"/>.
        /// </summary>
        public IGraphPainter<WpfDataSeries,BitmapSource> Input
        {
            get
            {
                return _input;
            }
            private set
            {
                _input = value;
                OnInputChanged(_input);
            }
        }

        /// <summary>
        /// Gets the connected input <see cref="IGraphPainter"/>.
        /// </summary>
        IGraphPainter IGraphInputComponent<IGraphPainter>.Input
        {
            get
            {
                return Input;
            }
        }

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes the <see cref="WpfGraphSurface"/> class.
        /// </summary>
        static WpfGraphSurface()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(WpfGraphSurface), new FrameworkPropertyMetadata(typeof(WpfGraphSurface)));
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="WpfGraphSurface"/> class.
        /// </summary>
        public WpfGraphSurface()
        {
            SizeChanged += OnSizeChanged;
        }

        #endregion

        #region Protected Methods

        /// <summary>
        /// Called when the mouse moves over the zoom/pan selection canvas.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="MouseEventArgs"/> instance containing the event data.</param>
        protected virtual void OnSelectionCanvasMouseMove(object sender, MouseEventArgs e)
        {
            _current_mouse_position = e.GetPosition(_selection_canvas);

            if (_is_selection_mouse_down_zoom && Keyboard.IsKeyDown(Key.LeftCtrl))
            {
                Canvas.SetLeft(_selection_rectangle, _selection_start_point.X);
                Canvas.SetTop(_selection_rectangle, _selection_start_point.Y);

                Point _selection_current_point = e.GetPosition(_selection_canvas);

                if (_selection_current_point.X - _selection_start_point.X > 1)
                {
                    _selection_rectangle.Width = _selection_current_point.X - _selection_start_point.X;
                }

                if (_selection_current_point.Y - _selection_start_point.Y > 1)
                {
                    _selection_rectangle.Height = _selection_current_point.Y - _selection_start_point.Y;
                }

                if (_selection_current_point.X < _selection_start_point.X)
                {
                    Canvas.SetLeft(_selection_rectangle, _selection_current_point.X);
                    _selection_rectangle.Width = _selection_start_point.X - _selection_current_point.X;
                }

                if (_selection_current_point.Y < _selection_start_point.Y)
                {
                    Canvas.SetTop(_selection_rectangle, _selection_current_point.Y);
                    _selection_rectangle.Height = _selection_start_point.Y - _selection_current_point.Y;
                }
            }
            else if (_is_selection_mouse_down_pan && _is_scaled)
            {
                Point _selection_current_point = e.GetPosition(_selection_canvas);

                double delta_x = _current_mouse_position.X - _last_mouse_position.X;
                double delta_y = _current_mouse_position.Y - _last_mouse_position.Y;

                var renderer = Input;

                double x = renderer.ZoomRect.Left - delta_x;
                double y = renderer.ZoomRect.Top - delta_y;

                if (x < 0)
                {
                    x = 0;
                }

                if (y < 0)
                {
                    y = 0;
                }

                if (x + renderer.ZoomRect.Width > SurfaceWidth)
                {
                    x = x - (x + renderer.ZoomRect.Width - SurfaceWidth);
                }

                if (y + renderer.ZoomRect.Height > SurfaceHeight)
                {
                    y = y - (y + renderer.ZoomRect.Height - SurfaceHeight);
                }

                Rect target_rect = new Rect(x, y, renderer.ZoomRect.Width, renderer.ZoomRect.Height);

                renderer.SetZoomRect(target_rect.ToGraphRect());
            }

            _last_mouse_position = _current_mouse_position;
        }

        /// <summary>
        /// Called when the mouse released from the zoom/pan selection canvas.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="MouseButtonEventArgs"/> instance containing the event data.</param>
        protected virtual void OnSelectionCanvasMouseUp(object sender, MouseButtonEventArgs e)
        {
            _selection_canvas.ReleaseMouseCapture();

            if (_is_selection_mouse_down_pan)
            {
                _is_selection_mouse_down_pan = false;
                _pan_rect = Input.ZoomRect.ToWpfRect();
            }
            else if (_is_selection_mouse_down_zoom)
            {
                _is_selection_mouse_down_zoom = false;

                Rect target_rect = new Rect(Canvas.GetLeft(_selection_rectangle), Canvas.GetTop(_selection_rectangle), _selection_rectangle.Width, _selection_rectangle.Height);
                _pan_rect = target_rect;
                Input.SetZoomRect(target_rect.ToGraphRect());
                _selection_rectangle.Visibility = Visibility.Hidden;
                _is_scaled = true;
            }
        }

        /// <summary>
        /// Called when the mouse pressed on the zoom/pan selection canvas.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="MouseButtonEventArgs"/> instance containing the event data.</param>
        protected virtual void OnSelectionCanvasMouseDown(object sender, MouseButtonEventArgs e)
        {
            Mouse.Capture(_selection_canvas);

            _selection_start_point = e.GetPosition(_selection_canvas);
            _current_mouse_position = _selection_start_point;
            _last_mouse_position = _current_mouse_position;

            if (e.ClickCount == 2)
            {
                Input.ResetZoomRect();
                _is_scaled = false;
            }
            else if (Keyboard.IsKeyDown(Key.LeftCtrl))
            {
                _selection_rectangle.Width = 0;
                _selection_rectangle.Height = 0;
                _is_selection_mouse_down_zoom = true;
                _is_selection_mouse_down_pan = false;
                _selection_rectangle.Visibility = Visibility.Visible;
            }
            else
            {
                _is_selection_mouse_down_pan = true;
            }
        }

        /// <summary>
        /// Called when the control size changes
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="SizeChangedEventArgs"/> instance containing the event data.</param>
        protected virtual void OnSizeChanged(object sender, SizeChangedEventArgs e)
        {
            OnSurfaceSizeChanged(_grid.ActualWidth, _grid.ActualHeight);
        }

        /// <summary>
        /// Called when surface size has changed.
        /// </summary>
        /// <param name="width">The width.</param>
        /// <param name="height">The height.</param>
        protected virtual void OnSurfaceSizeChanged(double width, double height)
        {
            SurfaceWidth = width;
            SurfaceHeight = height;

            SurfaceSizeChanged?.Invoke(this, new SurfaceSizeChangedEventArgs() { Width = width, Height = height });

            if (Input != null)
            {
                Input.ResetZoomRect();
            }
        }

        /// <summary>
        /// Raises the <see cref="InputChanged"/> event.
        /// </summary>
        /// <param name="input">The input.</param>
        protected virtual void OnInputChanged(IGraphPainter<WpfDataSeries, BitmapSource> input)
        {
            InputChanged?.Invoke(this, new InputChangedEventArgs<IGraphPainter<WpfDataSeries, BitmapSource>>(input));
        }

        /// <summary>
        /// Called when the painter has deliverd a new image to display.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="PaintingCompletedEventArgs{BitmapSource}"/> instance containing the event data.</param>
        protected virtual void OnPaintingCompleted(object sender, PaintingCompletedEventArgs<BitmapSource> e)
        {
            Image = e.Image;
        }

        #endregion

        #region Apply Template

        /// <summary>
        /// When overridden in a derived class, is invoked whenever application code or internal processes call <see cref="M:System.Windows.FrameworkElement.ApplyTemplate" />.
        /// </summary>
        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();

            _selection_rectangle = GetTemplateChild("PART_SelectionRectangle") as Rectangle;
            _selection_canvas = GetTemplateChild("PART_SelectionCanvas") as Canvas;
            _grid = GetTemplateChild("PART_Grid") as Grid;

            _selection_canvas.MouseDown += OnSelectionCanvasMouseDown;
            _selection_canvas.MouseUp += OnSelectionCanvasMouseUp;
            _selection_canvas.MouseMove += OnSelectionCanvasMouseMove;
        }

        #endregion

        #region Public Methods

        /// <summary>
        /// Invokes a method on the surface thread.
        /// </summary>
        /// <param name="action">The action.</param>
        public void InvokeOnSurface(Action action)
        {
            Dispatcher.BeginInvoke(action);
        }

        /// <summary>
        /// Connects this surface to the specified <see cref="IGraphPainter{TImage}"/>.
        /// </summary>
        /// <param name="painter">The painter.</param>
        /// <param name="fromInput">Specifies whether this call was made from an input <see cref="IGraphPainter{TImage}"/>.</param>
        public void ConnectInput(IGraphPainter<WpfDataSeries,BitmapSource> painter, bool fromInput = false)
        {
            painter.ThrowIfNull("Cannot connect a null painter.");

            DisconnectInput();

            Input = painter;

            Input.PaintingCompleted += OnPaintingCompleted;

            if (!fromInput)
            {
                Input.ConnectOutput(this, true);
            }

            if (_grid != null)
            {
                OnSurfaceSizeChanged(_grid.ActualWidth, _grid.ActualHeight);
            }
        }

        /// <summary>
        /// Disconnects the current connected input <see cref="IGraphPainter"/>.
        /// </summary>
        /// <param name="fromInput">Specifies whether this call was made from an input <see cref="IGraphPainter"/>.</param>
        public void DisconnectInput(bool fromInput = false)
        {
            if (Input != null)
            {
                if (!fromInput)
                {
                    Input.DisconnectOutput(true);
                }

                Input.PaintingCompleted -= OnPaintingCompleted;

                Input = null;
            }
        }

        /// <summary>
        /// Connects this surface to the specified <see cref="IGraphPainter"/>.
        /// </summary>
        /// <param name="painter">The painter.</param>
        /// <param name="fromInput">Specifies whether this call was made from an input <see cref="IGraphPainter"/>.</param>
        void IGraphInputComponent<IGraphPainter>.ConnectInput(IGraphPainter painter, bool fromInput)
        {
            ConnectInput(painter as IGraphPainter<WpfDataSeries, BitmapSource>, fromInput);
        }

        #endregion
    }
}