// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Collections.ObjectModel;
 
namespace System.Windows
{
    internal class ResourceDictionaryCollection : ObservableCollection<ResourceDictionary>
    {
        #region Constructor
 
        internal ResourceDictionaryCollection(ResourceDictionary owner)
        {
            Debug.Assert(owner != null, "ResourceDictionaryCollection's owner cannot be null");
 
            _owner = owner;
        }
 
        #endregion Constructor
        
        #region ProtectedMethods
 
        /// <summary>
        /// Called by base class Collection&lt;T&gt; when the list is being cleared;
        /// raises a CollectionChanged event to any listeners.
        /// </summary>
        protected override void ClearItems()
        {
            for (int i=0; i<Count; i++)
            {
                _owner.RemoveParentOwners(this[i]);
            }
            
            base.ClearItems();
        }
 
        /// <summary>
        /// Called by base class Collection&lt;T&gt; when an item is added to list;
        /// raises a CollectionChanged event to any listeners.
        /// </summary>
        protected override void InsertItem(int index, ResourceDictionary item)
        {
            ArgumentNullException.ThrowIfNull(item);
 
            base.InsertItem(index, item);
        }
 
        /// <summary>
        /// Called by base class Collection&lt;T&gt; when an item is set in list;
        /// raises a CollectionChanged event to any listeners.
        /// </summary>
        protected override void SetItem(int index, ResourceDictionary item)
        {
            ArgumentNullException.ThrowIfNull(item);
 
            base.SetItem(index, item);
        }
 
        #endregion ProtectedMethods
 
        #region Data
 
        private ResourceDictionary _owner;
        
        #endregion Data
    }
}