using System;
using System.Collections;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;

namespace Wpf.Ui.Extend.UserControls
{
    /// <summary>
    /// 多选控件绑定选中项
    /// </summary>
    /// <example>
    /// <c><DataGrid</c>
    /// <c>local:MultiSelectorHelper.BindableSelectedItems="{Binding SelectItems, Mode=OneWayToSource}"</c>
    /// <c>local:MultiSelectorHelper.MonitorSelectionChanged="True" /></c>
    /// </example>
    public class MultiSelectorHelper : DependencyObject
    {
        public static readonly DependencyProperty BindableSelectedItemsProperty = DependencyProperty.Register(
            "BindableSelectedItems",
            typeof(IList),
            typeof(MultiSelectorHelper),
            new PropertyMetadata(default(IList))
        );

        public static IList GetBindableSelectedItems(DependencyObject obj)
        {
            return (IList)obj.GetValue(BindableSelectedItemsProperty);
        }

        public static void SetBindableSelectedItems(DependencyObject obj, IList value)
        {
            obj.SetValue(BindableSelectedItemsProperty, value);
        }

        public static readonly DependencyProperty MonitorSelectionChangedProperty = DependencyProperty.RegisterAttached(
            "SetMonitorSelectionChanged",
            typeof(bool),
            typeof(MultiSelectorHelper),
            new PropertyMetadata(false, MonitorSelectionChangedPropertyChangedCallBack)
        );

        private static void MonitorSelectionChangedPropertyChangedCallBack(
            DependencyObject d,
            DependencyPropertyChangedEventArgs e
        )
        {
            if (d is not MultiSelector selector)
            {
                throw new NotImplementedException();
            }

            if ((bool)e.NewValue)
            {
                selector.SelectionChanged += Selector_SelectionChanged;
            }
            else
            {
                selector.SelectionChanged -= Selector_SelectionChanged;
            }
        }

        private static void Selector_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (sender is MultiSelector selector)
            {
                SetBindableSelectedItems(selector, selector.SelectedItems);
                selector.GetBindingExpression(BindableSelectedItemsProperty).UpdateSource();
            }
        }

        public static void SetMonitorSelectionChanged(DependencyObject element, bool value)
        {
            element.SetValue(MonitorSelectionChangedProperty, value);
        }

        public static bool GetMonitorSelectionChanged(DependencyObject element)
        {
            return (bool)element.GetValue(MonitorSelectionChangedProperty);
        }
    }
}