using GongSolutions.Wpf.DragDrop;
using GongSolutions.Wpf.DragDrop.Utilities;
using HMI.Base;
using HMI.UI;
using Plugin.TestBuilder.Entity;
using Plugin.TestBuilder.Model;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;

namespace Plugin.TestBuilder
{
    public class TestHandler : DefaultDropHandler
    {
        /// <summary>
        /// Test the specified drop information for the right data.
        /// </summary>
        /// <param name="dropInfo">The drop information.</param>
        private bool CanDrop(IDropInfo dropInfo)
        {
            if (dropInfo?.DragInfo == null)
            {
                return false;
            }

            if (!dropInfo.IsSameDragDropContextAsSource)
            {
                return false;
            }

            // do not drop on itself
            var isTreeViewItem = dropInfo.InsertPosition.HasFlag(RelativeInsertPosition.TargetItemCenter)
                                 && dropInfo.VisualTargetItem is TreeViewItem;
            if (isTreeViewItem && dropInfo.VisualTargetItem == dropInfo.DragInfo.VisualSourceItem)
            {
                return false;
            }

            if (dropInfo.TargetCollection is null)
            {
                return false;
            }

            if (ReferenceEquals(dropInfo.DragInfo.SourceCollection, dropInfo.TargetCollection))
            {
                var dragData = dropInfo.DragInfo?.Data as TreeItemData;
                var dropData = dropInfo.Data as TreeItemData;
                if (dragData == null || dropData == null)
                {
                    return false;
                }
                if (dropData.ParentItem != dragData.ParentItem)
                {
                    return false;
                }

                var targetList = dropInfo.TargetCollection.TryGetList();
                return targetList != null;
            }

            if (TestCompatibleTypes(dropInfo.TargetCollection, dropInfo.Data))
            {
                var isChildOf = IsChildOf(dropInfo.VisualTargetItem, dropInfo.DragInfo.VisualSourceItem);
                return !isChildOf;
            }

            return false;
        }

        public bool CanConvert(IDropInfo dropInfo)
        {
            bool InterfaceFilter(Type t, object o) => (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(IEnumerable<>));
            Type[] enumerableInterfaces = dropInfo.TargetCollection.GetType().FindInterfaces(InterfaceFilter, null);
            var enumerableTypes = from i in enumerableInterfaces
                                  select i.GetGenericArguments().Single();

            if (enumerableTypes.Any())
            {
                Type dataType = TypeUtilities.GetCommonBaseClass(ExtractData(dropInfo.Data));
                return dataType == typeof(FuncModel) && enumerableTypes.Any(t => t == typeof(Step));
            }

            return false;
        }

        public Step ConvertFunc2Step(FuncModel func)
        {
            return new Step
            {
                Name = func.Name
            };
        }

        public override void DragOver(IDropInfo dropInfo)
        {
            if (CanAcceptData(dropInfo))
            {
                base.DragOver(dropInfo);
            }
            else if (CanConvert(dropInfo))
            {
                // 固定Copy
                dropInfo.Effects = DragDropEffects.Copy;
                var isTreeViewItem = dropInfo.InsertPosition.HasFlag(RelativeInsertPosition.TargetItemCenter) && dropInfo.VisualTargetItem is TreeViewItem;
                dropInfo.DropTargetAdorner = isTreeViewItem ? DropTargetAdorners.Highlight : DropTargetAdorners.Insert;
            }
        }

        public override void Drop(IDropInfo dropInfo)
        {
            if (CanDrop(dropInfo))
            {
                base.Drop(dropInfo);
            }
            else if (CanConvert(dropInfo))
            {
                int insertIndex = GetInsertIndex(dropInfo);
                var destinationList = dropInfo.TargetCollection.TryGetList();
                var data = ExtractData(dropInfo.Data).OfType<object>().ToList();

                if (destinationList != null)
                {
                    var objects2Insert = new List<object>();

                    foreach (var o in data)
                    {
                        var obj2Insert = ConvertFunc2Step(o as FuncModel);

                        objects2Insert.Add(obj2Insert);

                        destinationList.Insert(insertIndex++, obj2Insert);
                        // 下方对象如果实现了 IDragItemSource 接口，会在这里调用 ItemDropped 方法，算是后置处理
                        if (obj2Insert is IDragItemSource dragItemSource)
                        {
                            dragItemSource.ItemDropped(dropInfo);
                        }
                    }

                    SelectDroppedItems(dropInfo, objects2Insert);
                }
            }

        }

    }

    /// <summary>
    /// WorkControl.xaml 的交互逻辑
    /// </summary>
    public partial class TestBuilder : PluginControl
    {
        public TestBuilder()
        {
            DataContext = this;
            InitializeComponent();
            Loaded += UserControl_Loaded;
        }
        public IDropTarget dropHandler { get; set; } = new TestHandler();

        private ObservableCollection<SeqData> datasource = new ObservableCollection<SeqData>() {
            new SeqData{ Name="test",Children = new ObservableCollection<SeqData>{ 
                new SeqData{ Name="CCC"}
            } }
        };

        public ObservableCollection<SeqData> Datasource
        {
            get => datasource;
            set { Set(ref datasource, value); }
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            Button btn = sender as Button;
            switch (btn.Name)
            {
                case "addBtn":
                    Datasource.Add(new SeqData());
                    break;
                case "sda":
                    DataGridRow s = (DataGridRow)btn.DataContext;
                    SeqData data = s.Item as SeqData;
                    data.Children.Add(new SeqData { Name = "CCC" });

                    s.DetailsVisibility =
                        s.DetailsVisibility == Visibility.Visible ? Visibility.Collapsed : Visibility.Visible;
                    break;
                default:
                    break;
            }
        }

        private void UserControl_Loaded(object sender, RoutedEventArgs e)
        {
            SizeChanged += WorkControl_SizeChanged;
            Loaded -= UserControl_Loaded;
        }

        /// <summary>
        /// 重设大小
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void WorkControl_SizeChanged(object sender, SizeChangedEventArgs e)
        {

        }

        /// <summary>
        /// 树数据展示过滤
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CollectionViewSource_Filter(object sender, FilterEventArgs e)
        {
            if (e.Item is TreeItemData data)
            {
                e.Accepted = data.IsVisible;
            }
        }

        /// <summary>
        /// 树展开/关闭事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void treeDataGrid_ExpandedChange(object sender, bool e)
        {
            CollectionViewSource cvs = this.Resources["TreeGridFilter"] as CollectionViewSource;
            cvs?.View.Refresh();
        }
    }
}