using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.Windows;
using System.Windows.Media;
using System.Windows.Shapes;

namespace XP.ImageProcessing.RoiControl
{
    /// <summary>
    /// 多边形Points附加行为，支持ObservableCollection绑定
    /// </summary>
    public static class PolygonPointsBehavior
    {
        private static readonly Dictionary<Polygon, ObservableCollection<Point>> _attachedCollections
            = new Dictionary<Polygon, ObservableCollection<Point>>();

        public static ObservableCollection<Point> GetPointsSource(DependencyObject obj)
        {
            return (ObservableCollection<Point>)obj.GetValue(PointsSourceProperty);
        }

        public static void SetPointsSource(DependencyObject obj, ObservableCollection<Point> value)
        {
            obj.SetValue(PointsSourceProperty, value);
        }

        public static readonly DependencyProperty PointsSourceProperty =
            DependencyProperty.RegisterAttached(
                "PointsSource",
                typeof(ObservableCollection<Point>),
                typeof(PolygonPointsBehavior),
                new PropertyMetadata(null, OnPointsSourceChanged));

        private static void OnPointsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (!(d is Polygon polygon))
                return;

            // 清理旧的订阅
            if (e.OldValue is ObservableCollection<Point> oldCollection)
            {
                oldCollection.CollectionChanged -= GetCollectionChangedHandler(polygon);
                _attachedCollections.Remove(polygon);
            }

            // 设置新的订阅
            if (e.NewValue is ObservableCollection<Point> newCollection)
            {
                // 初始化Points
                UpdatePolygonPoints(polygon, newCollection);

                // 监听集合变化
                NotifyCollectionChangedEventHandler handler = (s, args) => UpdatePolygonPoints(polygon, newCollection);
                newCollection.CollectionChanged += handler;

                // 保存引用以便后续清理
                _attachedCollections[polygon] = newCollection;

                // 监听Polygon卸载事件以清理资�?
                polygon.Unloaded += (s, args) =>
                {
                    if (_attachedCollections.TryGetValue(polygon, out var collection))
                    {
                        collection.CollectionChanged -= handler;
                        _attachedCollections.Remove(polygon);
                    }
                };
            }
        }

        private static NotifyCollectionChangedEventHandler GetCollectionChangedHandler(Polygon polygon)
        {
            return (s, args) =>
            {
                if (s is ObservableCollection<Point> collection)
                {
                    UpdatePolygonPoints(polygon, collection);
                }
            };
        }

        private static void UpdatePolygonPoints(Polygon polygon, ObservableCollection<Point> points)
        {
            // 使用Dispatcher确保在UI线程更新
            polygon.Dispatcher.BeginInvoke(new Action(() =>
            {
                // 创建新的PointCollection以触发UI更新
                polygon.Points = new PointCollection(points);
            }), System.Windows.Threading.DispatcherPriority.Render);
        }
    }
}