// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
 
using System.Collections.Generic;
using System.ServiceModel.Channels;
 
namespace System.ServiceModel.Dispatcher
{
    internal class SynchronizedChannelCollection<TChannel> : SynchronizedCollection<TChannel>
        where TChannel : IChannel
    {
        private EventHandler _onChannelClosed;
        private EventHandler _onChannelFaulted;
 
        internal SynchronizedChannelCollection(object syncRoot)
            : base(syncRoot)
        {
            _onChannelClosed = new EventHandler(OnChannelClosed);
            _onChannelFaulted = new EventHandler(OnChannelFaulted);
        }
 
        private void AddingChannel(TChannel channel)
        {
            channel.Faulted += _onChannelFaulted;
            channel.Closed += _onChannelClosed;
        }
 
        private void RemovingChannel(TChannel channel)
        {
            channel.Faulted -= _onChannelFaulted;
            channel.Closed -= _onChannelClosed;
        }
 
        private void OnChannelClosed(object sender, EventArgs args)
        {
            TChannel channel = (TChannel)sender;
            Remove(channel);
        }
 
        private void OnChannelFaulted(object sender, EventArgs args)
        {
            TChannel channel = (TChannel)sender;
            Remove(channel);
        }
 
        protected override void ClearItems()
        {
            List<TChannel> items = Items;
 
            for (int i = 0; i < items.Count; i++)
            {
                RemovingChannel(items[i]);
            }
 
            base.ClearItems();
        }
 
        protected override void InsertItem(int index, TChannel item)
        {
            AddingChannel(item);
            base.InsertItem(index, item);
        }
 
        protected override void RemoveItem(int index)
        {
            TChannel oldItem = Items[index];
 
            base.RemoveItem(index);
            RemovingChannel(oldItem);
        }
 
        protected override void SetItem(int index, TChannel item)
        {
            TChannel oldItem = Items[index];
 
            AddingChannel(item);
            base.SetItem(index, item);
            RemovingChannel(oldItem);
        }
    }
}