using System.Collections.Generic;
using System.Windows;
using System.Windows.Input;
using System.Windows.Media;

namespace BBGWY.Controls.Extensions
{
    public static class VisualTreeExtension
    {
        public static T HitTest<T>(this FrameworkElement fe, Point? point) where T : FrameworkElement
        {
            if (point == null)
                point = Mouse.GetPosition(fe);
            var result = VisualTreeHelper.HitTest(fe, point.Value);
            if (result == null)
                return null;
            if (result.VisualHit != null)
            {
                var r = FindParentOfType<T>(result.VisualHit);
                return r;
            }
            return null;
        }

        /// <summary>
        /// 查找父控件
        /// </summary>
        /// <typeparam name="T">父控件类型</typeparam>
        /// <param name="obj">子控件实例</param>
        /// <returns></returns>
        public static T FindParentOfType<T>(this DependencyObject obj) where T : FrameworkElement
        {
            DependencyObject parent = VisualTreeHelper.GetParent(obj);
            while (parent != null)
            {
                if (parent is T)
                {
                    return (T)parent;
                }
                parent = VisualTreeHelper.GetParent(parent);
            }
            return null;
        }

        /// <summary>
        /// 查找子控件
        /// </summary>
        /// <typeparam name="T">需要查找的控件类型</typeparam>
        /// <param name="obj">父控件实例</param>
        /// <returns></returns>
        public static T FindFirstVisualChild<T>(this DependencyObject obj) where T : FrameworkElement
        {
            var queue = new Queue<DependencyObject>();
            queue.Enqueue(obj);
            while (queue.Count > 0)
            {
                DependencyObject current = queue.Dequeue();
                for (int i = VisualTreeHelper.GetChildrenCount(current) - 1; 0 <= i; i--)
                {
                    DependencyObject child = VisualTreeHelper.GetChild(current, i);
                    if (child != null && child is T)
                    {
                        return (T)child;
                    }
                    queue.Enqueue(child);
                }
            }
            return null;
        }
    }
}