using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Media;

using Wpf.Ui.Extend.Extensions;

namespace Wpf.Ui.Extend.Controls;

/// <summary>
/// 多选树形视图控件。
/// </summary>
public sealed class MultiTreeView : TreeView
{

    //    public static readonly DependencyPropertyKey SelectedItemsPropertyKey =
    //        DependencyProperty.RegisterReadOnly(
    //nameof(SelectedItems),
    //            typeof(IList),
    //            typeof(MultiTreeViewItem),
    //            new FrameworkPropertyMetadata(null)
    //        );

    //    public static readonly DependencyProperty SelectedItemsProperty = SelectedItemsPropertyKey.DependencyProperty;

    //    public IList SelectedItems
    //    {
    //        get { return (IList)GetValue(SelectedItemsProperty); }
    //        private set { SetValue(SelectedItemsPropertyKey, value); }
    //    }
    public IList SelectedItems
    {
        get { return (IList)GetValue(SelectedItemsProperty); }
        set { SetValue(SelectedItemsProperty, value); }
    }

    public static readonly DependencyProperty SelectedItemsProperty =
        DependencyProperty.Register(nameof(SelectedItems), typeof(IList), typeof(MultiTreeView), new PropertyMetadata(null, new PropertyChangedCallback(OnSelectedItemsChanged)));

    private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var list = e.NewValue as IList;
        //foreach (var item in list)
        //{

        //}
    }

    #region Event Handlers

    /// <summary>
    /// 在鼠标按下事件发生时调用。
    /// </summary>
    //protected override void OnPreviewMouseDown(MouseButtonEventArgs e)
    //{
    //    base.OnPreviewMouseDown(e);

    //    //// 如果点击树分支expander
    //    //if (e.OriginalSource is Grid or Border or TextBlock)
    //    //    return;
    //    var obj = e.OriginalSource as DependencyObject;

    //    var checkBox = obj.FindParent<CheckBox>();
       
    //    if (checkBox != null)
    //    {
    //        //当前点击的MultiTreeViewItem
    //        var currentItem = GetTreeViewItemClicked((FrameworkElement)e.OriginalSource);

    //        if (currentItem != null)
    //        {
    //            SelectedItems = GetTreeViewItems(this, true).Where(d => d.IsChecked == true).ToList();
    //        }
    //    }
    //}

    #endregion Event Handlers
    #region Utility Methods

    #region 重写

    ///// <summary>
    ///// 准备项的容器
    ///// </summary>
    ///// <param name="element">控件元素</param>
    ///// <param name="item">绑定的对象</param>
    //protected override void PrepareContainerForItemOverride(DependencyObject element, object item)
    //{
    //    if (item is not MultiTreeViewItem)
    //    {
    //        if (element is MultiTreeViewItem multiTreeViewItem && !string.IsNullOrEmpty(this.DisplayMemberPath))
    //        {
    //            var binding = new Binding(this.DisplayMemberPath);
    //            multiTreeViewItem.SetBinding(MultiTreeViewItem.HeaderProperty, binding);
    //        }
    //    }
    //    base.PrepareContainerForItemOverride(element, item);
    //}

    /// <summary>
    /// 获取项的容器。
    /// </summary>
    protected override DependencyObject GetContainerForItemOverride()
    {
        return new MultiTreeViewItem();
    }

    /// <summary>
    /// 确定项是否是其自己的容器。
    /// </summary>
    protected override bool IsItemItsOwnContainerOverride(object item)
    {
        return item is MultiTreeViewItem;
    }

    #endregion

    /// <summary>
    /// 获取当前被点击的MultiTreeViewItem。
    /// </summary>
    private static MultiTreeViewItem GetTreeViewItemClicked(DependencyObject sender)
    {
        while (sender is not null and not MultiTreeViewItem)
            sender = VisualTreeHelper.GetParent(sender);
        return sender as MultiTreeViewItem;
    }

    /// <summary>
    /// 获取树形视图的所有展开的项。
    /// </summary>
    private  List<MultiTreeViewItem> GetTreeViewItems(ItemsControl parentItem, bool includeCollapsedItems, List<MultiTreeViewItem> itemList = null)
    {
        itemList ??= [];

        for (var index = 0; index < parentItem.Items.Count; index++)
        {
            if (parentItem.ItemContainerGenerator.ContainerFromIndex(index) is not MultiTreeViewItem tvItem)
            {
                continue;
            }
            itemList.Add(tvItem);
            if (includeCollapsedItems || tvItem.IsExpanded)
            {
                GetTreeViewItems(tvItem, includeCollapsedItems, itemList);
            }
        }
        return itemList;
    }

    internal void NotifyMultiTreeViewItemClicked(MultiTreeViewItem multiTreeViewItem)
    {
        var selectedItems = GetTreeViewItems(this, true).Where(d => d.IsChecked == true);
        if (ItemsSource==null)
        {
            SelectedItems = selectedItems.ToList();
        }
        else
        {
            //选择绑定的对象
            SelectedItems = selectedItems.Select(d => d.DataContext).ToList();
        }
    }

    ///// <summary>
    ///// 获取两个树形视图项之间的所有项。
    ///// </summary>
    //private List<MultiTreeViewItem> GetTreeViewItemRange(MultiTreeViewItem start, MultiTreeViewItem end)
    //{
    //    var items = GetTreeViewItems(this, false);
    //    var startIndex = items.IndexOf(start);
    //    var endIndex = items.IndexOf(end);
    //    var rangeStart = startIndex > endIndex || startIndex == -1 ? endIndex : startIndex;
    //    var rangeCount = startIndex > endIndex ? startIndex - endIndex + 1 : endIndex - startIndex + 1;

    //    if (startIndex == -1 && endIndex == -1)
    //        rangeCount = 0;

    //    else if (startIndex == -1 || endIndex == -1)
    //        rangeCount = 1;

    //    return rangeCount > 0 ? items.GetRange(rangeStart, rangeCount) : new List<MultiTreeViewItem>();
    //}

    #endregion Utility Methods

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

    /// <summary>
    /// 初始化 MultiTreeView 类的新实例。
    /// </summary>
    //public MultiTreeView()
    //{
    //SelectedItemChanged += (sender, e) =>
    //{
    //    if (e.NewValue is MultiTreeViewItem item)
    //        SelectedItemChangedInternal(item);
    //};
    //}
}