using System.Windows.Input;
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Media;
using System;
using System.Windows.Shapes;

namespace WPFProject.Utils
{
    public class Resize
    {
        private static readonly double MinWidth = 60;
        private static readonly double MinHeight = 60;

        public static double GetReMaxWidth(DependencyObject obj)
        {
            return (double)obj.GetValue(ReMaxWithProperty);
        }
        public static void SetReMaxWidth(DependencyObject obj, double value)
        {
            obj.SetValue(ReMaxWithProperty, value);
        }
        public static readonly DependencyProperty ReMaxWithProperty =
            DependencyProperty.RegisterAttached("ReMaxWith", typeof(double), typeof(Resize), new PropertyMetadata(0.0));


        // 拖拽模板
        public static ControlTemplate GetResizeTemplate(DependencyObject obj)
        {
            return (ControlTemplate)obj.GetValue(ResizeTemplateProperty);
        }

        public static void SetResizeTemplate(DependencyObject obj, ControlTemplate value)
        {
            obj.SetValue(ResizeTemplateProperty, value);
        }

        public static readonly DependencyProperty ResizeTemplateProperty =
            DependencyProperty.RegisterAttached("ResizeTemplate", typeof(ControlTemplate), typeof(Resize), new PropertyMetadata(null, (d, e) =>
            {
                FrameworkElement element = d as FrameworkElement;
                if (element == null) return;
                var resize = GetResizeable(element);
                if (resize == null) return;
                resize.Detach();
                resize.Attach();
            }));

        // 是否可以拖拽改变大小
        public static bool GetIsResizeable(DependencyObject obj)
        {
            return (bool)obj.GetValue(IsResizeableProperty);
        }
        public static void SetIsResizeable(DependencyObject obj, bool value)
        {
            obj.SetValue(IsResizeableProperty, value);
        }
        public static readonly DependencyProperty IsResizeableProperty =
            DependencyProperty.RegisterAttached("IsResizeable", typeof(bool), typeof(Resize), new PropertyMetadata(false, (d, e) =>
            {
                FrameworkElement element = d as FrameworkElement;
                if (element == null) return;
                // 先取消之前的拖拽装饰
                Resizeable resize = GetResizeable(element);
                if (resize != null) resize.Detach();
                // 实现逻辑
                // 判断属性设置的是不是true
                if (!(bool)e.NewValue)
                {
                    SetResizeable(element, null);
                    return;
                }

                if (!element.IsLoaded)
                {
                    RoutedEventHandler Loaded_Resize = null;
                    Loaded_Resize = (sender, e1) =>
                    {
                        Resizeable resize = new Resizeable(element);
                        resize.Attach();
                        SetResizeable(element, resize);
                        element.Loaded -= Loaded_Resize;
                    };
                    element.Loaded += Loaded_Resize;
                }
                else
                {
                    resize = new Resizeable(element);
                    resize.Attach();
                    SetResizeable(element, resize);
                }
            }));

        public static Resizeable GetResizeable(DependencyObject obj)
        {
            return (Resizeable)obj.GetValue(ResizeableProperty);
        }

        public static void SetResizeable(DependencyObject obj, Resizeable value)
        {
            obj.SetValue(ResizeableProperty, value);
        }

        // Using a DependencyProperty as the backing store for Resizeable.  This enables animation, styling, binding, etc...
        static readonly DependencyProperty ResizeableProperty =
           DependencyProperty.RegisterAttached("Resizeable", typeof(Resizeable), typeof(Resize), new PropertyMetadata(null));

        public class Resizeable
        {
            ResizeType _resizeType;
            enum ResizeType
            {
                None,
                Grid,
                Canvas,
                Window,
                Others,
            }
            FrameworkElement _resizeTarget;

            FrameworkElement _thumbsParent = null;
            public Resizeable(FrameworkElement resizeTarget)
            {
                _resizeTarget = resizeTarget;
            }

            public void Attach()
            {
                FrameworkElement thumbsRoot = null;
                ControlTemplate template = GetResizeTemplate(_resizeTarget);
                // 看不懂了，大概是拖拽模板
                if (template != null)
                {
                    Control control = new Control();
                    control.Template = template;
                    control.ApplyTemplate();
                    thumbsRoot = control;
                    _thumbsParent = VisualTreeHelper.GetChild(thumbsRoot, 0) as FrameworkElement;
                }


                if (thumbsRoot != null)
                {
                    UIElement target = _resizeTarget is Window _windowTarget ? _windowTarget.Content as UIElement : _resizeTarget;
                    if (target != null)
                    {
                        AdornerLayer layer = AdornerLayer.GetAdornerLayer(target);
                        if (layer == null) throw new Exception("获取控件装饰层失败，控件可能没有装饰层！");
                        layer.Add(new ResizeAdorner(target, thumbsRoot));
                    }
                }

                // 使用缺省样式
                if (thumbsRoot == null)
                {
                    Thumb leftThumb = null, topThumb = null, rightThumb = null, bottomThumb = null, 
                        lefTopThumb = null, rightTopThumb = null, rightBottomThumb = null, leftbottomThumb = null;
                    int thumnSize = 5;
                    // 初始化thumb
                    leftThumb = new Thumb();
                    leftThumb.Template = new ControlTemplate(typeof(Thumb))
                    {
                        VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))
                    };
                    leftThumb.HorizontalAlignment = HorizontalAlignment.Left;
                    leftThumb.VerticalAlignment = VerticalAlignment.Stretch;
                    leftThumb.Cursor = Cursors.SizeWE;
                    leftThumb.Width = thumnSize;
                    leftThumb.Height = double.NaN;
                    leftThumb.Margin = new Thickness(0, thumnSize, 0, thumnSize);

                    topThumb = new Thumb();
                    topThumb.Template = new ControlTemplate(typeof(Thumb))
                    {
                        VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))
                    };
                    topThumb.HorizontalAlignment = HorizontalAlignment.Stretch;
                    topThumb.VerticalAlignment = VerticalAlignment.Top;
                    topThumb.Cursor = Cursors.SizeNS;
                    topThumb.Width = double.NaN;
                    topThumb.Height = thumnSize;
                    topThumb.Margin = new Thickness(thumnSize, 0, thumnSize, 0);

                    rightThumb = new Thumb();
                    rightThumb.Template = new ControlTemplate(typeof(Thumb))
                    {
                        VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))
                    };
                    rightThumb.HorizontalAlignment = HorizontalAlignment.Right;
                    rightThumb.VerticalAlignment = VerticalAlignment.Stretch;
                    rightThumb.Cursor = Cursors.SizeWE;
                    rightThumb.Width = thumnSize;
                    rightThumb.Height = double.NaN;
                    rightThumb.Margin = new Thickness(0, thumnSize, 0, thumnSize);

                    bottomThumb = new Thumb();
                    bottomThumb.Template = new ControlTemplate(typeof(Thumb))
                    {
                        VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))
                    };
                    bottomThumb.HorizontalAlignment = HorizontalAlignment.Stretch;
                    bottomThumb.VerticalAlignment = VerticalAlignment.Bottom;
                    bottomThumb.Cursor = Cursors.SizeNS;
                    bottomThumb.Width = double.NaN;
                    bottomThumb.Height = thumnSize;
                    bottomThumb.Margin = new Thickness(thumnSize, 0, thumnSize, 0);

                    lefTopThumb = new Thumb();
                    lefTopThumb.Template = new ControlTemplate(typeof(Thumb))
                    {
                        VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))
                    };
                    lefTopThumb.HorizontalAlignment = HorizontalAlignment.Left;
                    lefTopThumb.VerticalAlignment = VerticalAlignment.Top;
                    lefTopThumb.Cursor = Cursors.SizeNWSE;
                    lefTopThumb.Width = thumnSize;
                    lefTopThumb.Height = thumnSize;

                    rightTopThumb = new Thumb();
                    rightTopThumb.Template = new ControlTemplate(typeof(Thumb))
                    {
                        VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))
                    };
                    rightTopThumb.HorizontalAlignment = HorizontalAlignment.Right;
                    rightTopThumb.VerticalAlignment = VerticalAlignment.Top;
                    rightTopThumb.Cursor = Cursors.SizeNESW;
                    rightTopThumb.Width = thumnSize;
                    rightTopThumb.Height = thumnSize;

                    rightBottomThumb = new Thumb();
                    rightBottomThumb.Template = new ControlTemplate(typeof(Thumb))
                    {
                        VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))
                    };
                    rightBottomThumb.HorizontalAlignment = HorizontalAlignment.Right;
                    rightBottomThumb.VerticalAlignment = VerticalAlignment.Bottom;
                    rightBottomThumb.Cursor = Cursors.SizeNWSE;
                    rightBottomThumb.Width = thumnSize;
                    rightBottomThumb.Height = thumnSize;

                    leftbottomThumb = new Thumb();
                    leftbottomThumb.Template = new ControlTemplate(typeof(Thumb))
                    {
                        VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))
                    };
                    leftbottomThumb.HorizontalAlignment = HorizontalAlignment.Left;
                    leftbottomThumb.VerticalAlignment = VerticalAlignment.Bottom;
                    leftbottomThumb.Cursor = Cursors.SizeNESW;
                    leftbottomThumb.Width = thumnSize;
                    leftbottomThumb.Height = thumnSize;

                    Grid grid = new Grid();
                    grid.Children.Add(leftThumb);
                    grid.Children.Add(topThumb);
                    grid.Children.Add(rightThumb);
                    grid.Children.Add(bottomThumb);
                    grid.Children.Add(lefTopThumb);
                    grid.Children.Add(rightTopThumb);
                    grid.Children.Add(rightBottomThumb);
                    grid.Children.Add(leftbottomThumb);
                    UIElement element;
                    if (_resizeTarget is Window _resizeTargetWindow)
                    {
                        element = _resizeTargetWindow.Content as UIElement;
                    }
                    else
                    {
                        element = _resizeTarget;
                    }
                    if (element != null)
                    {
                        var layer = AdornerLayer.GetAdornerLayer(element);
                        if (layer == null)
                            throw new Exception("获取控件装饰层失败，控件可能没有装饰层！");
                        layer.Add(new ResizeAdorner(element, grid));
                    }
                    thumbsRoot = grid;
                    _thumbsParent = thumbsRoot;
                }

                //注册事件
                for (int i = 0; i < VisualTreeHelper.GetChildrenCount(_thumbsParent); i++)
                {
                    Thumb thumb = VisualTreeHelper.GetChild(_thumbsParent, i) as Thumb;
                    if (thumb != null)
                    {
                        thumb.DragStarted += Thumb_DragStarted;
                        thumb.DragDelta += Thumb_DragDelta;
                    }
                }
            }
            public void Detach()
            {
                for (int i = 0; i < VisualTreeHelper.GetChildrenCount(_thumbsParent); i++)
                {
                    Thumb thumb = VisualTreeHelper.GetChild(_thumbsParent, i) as Thumb;
                    if (thumb != null)
                    {
                        thumb.DragStarted -= Thumb_DragStarted;
                        thumb.DragDelta -= Thumb_DragDelta;
                    }
                }
                _thumbsParent = null;
            }

            private void Thumb_DragStarted(object sender, DragStartedEventArgs e)
            {
                _resizeType = GetResizeType();
                if (_resizeType == ResizeType.Canvas)
                {
                    Canvas parent = GetCanvas(_resizeTarget);
                    CanvasHelper.SetTopZIndex(_resizeTarget, parent, _resizeTarget.GetType());
                }
            }
            private void Thumb_DragDelta(object sender, DragDeltaEventArgs e)
            {
                switch (_resizeType)
                {
                    case ResizeType.None:
                        break;
                    case ResizeType.Grid:
                        {
                            FrameworkElement element = _resizeTarget;
                            FrameworkElement thumb = sender as FrameworkElement;
                            double left, top, right, bottom, width, height;
                            if (thumb.HorizontalAlignment == HorizontalAlignment.Left)
                            {
                                right = element.Margin.Right;
                                left = element.Margin.Left + e.HorizontalChange;
                                width = (double.IsNaN(element.Width) ? element.ActualWidth : element.Width) - e.HorizontalChange;
                            }
                            else
                            {
                                left = element.Margin.Left;
                                right = element.Margin.Right - e.HorizontalChange;
                                width = (double.IsNaN(element.Width) ? element.ActualWidth : element.Width) + e.HorizontalChange;
                            }

                            if (thumb.VerticalAlignment == VerticalAlignment.Top)
                            {
                                bottom = element.Margin.Bottom;
                                top = element.Margin.Top + e.VerticalChange;
                                height = (double.IsNaN(element.Height) ? element.ActualHeight : element.Height) - e.VerticalChange;
                            }
                            else
                            {
                                top = element.Margin.Top;
                                bottom = element.Margin.Bottom - e.VerticalChange;
                                height = (double.IsNaN(element.Height) ? element.ActualHeight : element.Height) + e.VerticalChange;
                            }
                            if (thumb.HorizontalAlignment != HorizontalAlignment.Center && thumb.HorizontalAlignment != HorizontalAlignment.Stretch)
                            {
                                if (width >= 0)
                                {
                                    element.Margin = new Thickness(left, element.Margin.Top, right, element.Margin.Bottom);
                                    element.Width = width;
                                }
                            }
                            if (thumb.VerticalAlignment != VerticalAlignment.Center && thumb.VerticalAlignment != VerticalAlignment.Stretch)
                            {
                                if (height >= 0)
                                {
                                    element.Margin = new Thickness(element.Margin.Left, top, element.Margin.Right, bottom);
                                    element.Height = height;
                                }
                            }
                        }
                        break;
                    case ResizeType.Canvas:
                        {   
                            FrameworkElement target = _resizeTarget;
                            Canvas parent = GetCanvas(target);
                            FrameworkElement thumb = sender as FrameworkElement;
                            if (parent == null)
                            {
                                // 一般不会出现这种情况，保险判断一下
                                return;
                            }

                            double left, top, width, height;
                            if (thumb.HorizontalAlignment == HorizontalAlignment.Left)
                            {
                                left = double.IsNaN(Canvas.GetLeft(target)) ? 0 : Canvas.GetLeft(target) + e.HorizontalChange;
                                width = (double.IsNaN(target.ActualWidth) ? 0 : target.ActualWidth) - e.HorizontalChange;
                            }
                            else
                            {
                                left = Canvas.GetLeft(target);
                                width = (double.IsNaN(target.ActualWidth) ? 0 : target.ActualWidth) + e.HorizontalChange;
                            }
                            if (thumb.VerticalAlignment == VerticalAlignment.Top)
                            {
                                top = double.IsNaN(Canvas.GetTop(target)) ? 0 : Canvas.GetTop(target) + e.VerticalChange;
                                height = (double.IsNaN(target.ActualHeight) ? 0 : target.ActualHeight) - e.VerticalChange;
                            }
                            else
                            {
                                top = Canvas.GetTop(target);
                                height = (double.IsNaN(target.ActualHeight) ? 0 : target.ActualHeight) + e.VerticalChange;
                            }
                            if (thumb.HorizontalAlignment != HorizontalAlignment.Center && thumb.HorizontalAlignment != HorizontalAlignment.Stretch)
                            {
                                if (e.HorizontalChange > 0 || (width >= MinWidth && left >= 0))
                                {
                                    Canvas.SetLeft(target, left);
                                    target.Width = width;
                                }
                            }
                            if (thumb.VerticalAlignment != VerticalAlignment.Center && thumb.VerticalAlignment != VerticalAlignment.Stretch)
                            {
                                if (e.VerticalChange > 0 || (height >= MinHeight && top >= 0))
                                {
                                    Canvas.SetTop(target, top);
                                    target.Height = height;
                                }
                            }
                        }
                        break;
                    case ResizeType.Window:
                        {
                            var c = _resizeTarget as Window;
                            var thumb = sender as FrameworkElement;
                            double left, top, width, height;
                            if (thumb.HorizontalAlignment == HorizontalAlignment.Left)
                            {
                                left = c.Left + e.HorizontalChange;
                                width = c.Width - e.HorizontalChange;
                            }
                            else
                            {
                                left = c.Left;
                                width = c.Width + e.HorizontalChange;
                            }

                            if (thumb.VerticalAlignment == VerticalAlignment.Top)
                            {

                                top = c.Top + e.VerticalChange;
                                height = c.Height - e.VerticalChange;
                            }
                            else
                            {
                                top = c.Top;
                                height = c.Height + e.VerticalChange;
                            }

                            if (thumb.HorizontalAlignment != HorizontalAlignment.Center && thumb.HorizontalAlignment != HorizontalAlignment.Stretch)
                            {
                                if (width > 63)
                                {
                                    c.Width = width;
                                    c.Left = left;
                                }
                            }
                            if (thumb.VerticalAlignment != VerticalAlignment.Center && thumb.VerticalAlignment != VerticalAlignment.Stretch)
                            {
                                if (height > 63)
                                {
                                    c.Top = top;
                                    c.Height = height;
                                }
                            }
                        }
                        break;
                    case ResizeType.Others:

                        break;
                }
            }
            ResizeType GetResizeType()
            {
                ResizeType rt;
                DependencyObject parent = VisualTreeHelper.GetParent(_resizeTarget);
                if (parent is Grid)
                {
                    rt = ResizeType.Grid;
                }
                else if (parent is Canvas)
                {
                    rt = ResizeType.Canvas;
                }
                else if (_resizeTarget is Window)
                {
                    rt = ResizeType.Window;
                }
                else
                {
                    rt = ResizeType.Grid;
                }
                return rt;
            }

            // 方形工厂      
            FrameworkElementFactory GetFactory(Brush back)
            {
                FrameworkElementFactory fac = new FrameworkElementFactory(typeof(Rectangle));
                fac.SetValue(Rectangle.FillProperty, back);
                return fac;
            }

            // 装饰器
            class ResizeAdorner : Adorner
            {
                // 布局容器，如果不使用布局容器，则需要给上述8个控件布局，实现和Grid布局定位是一样的，会比较繁琐且意义不大。
                UIElement _child;
                public ResizeAdorner(UIElement adornedElement, UIElement child) : base(adornedElement)
                {
                    _child = child;
                    AddVisualChild(child);
                }

                protected override Visual GetVisualChild(int index)
                {
                    return _child;
                }
                protected override int VisualChildrenCount { get; } = 1;
                protected override Size ArrangeOverride(Size finalSize)
                {
                    // 直接给grid布局，grid内部的thumb会自动布局。
                    _child.Arrange(new Rect(new Point(0, 0), finalSize));
                    return finalSize;
                }
            }
        }

        static Canvas GetCanvas(DependencyObject element)
        {
            DependencyObject e = element;
            while (e is not null and not Canvas)
            {
                e = VisualTreeHelper.GetParent(e);
            }
            return e == null ? null : e as Canvas;
        }
    }
}