using System;
using System.Collections.Generic;
using System.Windows.Controls;

namespace WPFDark.Internals
{
    public static class ItemsControlExtensions
    {
        internal static IEnumerable<T> EnumerateChildren<T>(this ItemsControl self)
            where T : ItemsControl
        {
            if (self is null)
                throw new ArgumentNullException(nameof(self));

            for (var i = 0; i < self.Items.Count; i++)
            {
                if (!(self.ItemContainerGenerator.ContainerFromIndex(i) is T item))
                    continue;

                yield return item;

                foreach (var c in item.EnumerateChildren<T>())
                    yield return c;
            }
        }       
    }
}