using System;
using System.ServiceModel;

namespace Roblox.ServiceModel;

public class PersistentChannel<TChannel> : IDisposable where TChannel : IClientChannel
{
	private ChannelFactory<TChannel> factory;

	private TChannel channel;

	private TimeSpan? operationTimeout;

	public PersistentChannel(ChannelFactory<TChannel> factory)
		: this(factory, (TimeSpan?)null)
	{
	}

	public PersistentChannel(ChannelFactory<TChannel> factory, TimeSpan? operationTimeout)
	{
		this.factory = factory;
		this.operationTimeout = operationTimeout;
		AppDomain.CurrentDomain.DomainUnload += CurrentDomain_DomainUnload;
	}

	public TChannel Get()
	{
		if (channel != null && channel.State == CommunicationState.Opened)
		{
			return channel;
		}
		lock (factory)
		{
			if (channel == null || channel.State != CommunicationState.Opened)
			{
				CloseChannel();
				channel = factory.CreateChannel();
				if (operationTimeout.HasValue)
				{
					channel.OperationTimeout = operationTimeout.Value;
				}
				try
				{
					channel.Open();
				}
				catch (Exception)
				{
					CloseChannel();
					channel = factory.CreateChannel();
					if (operationTimeout.HasValue)
					{
						channel.OperationTimeout = operationTimeout.Value;
					}
					channel.Open();
				}
			}
		}
		return channel;
	}

	private void CurrentDomain_DomainUnload(object sender, EventArgs e)
	{
		CloseChannel();
	}

	private void CloseChannel()
	{
		if (channel == null)
		{
			return;
		}
		try
		{
			if (channel.State != CommunicationState.Faulted)
			{
				channel.Close();
			}
			else
			{
				channel.Abort();
			}
		}
		catch (CommunicationException)
		{
			channel.Abort();
		}
		catch (TimeoutException)
		{
			channel.Abort();
		}
		catch (Exception)
		{
			channel.Abort();
			throw;
		}
		finally
		{
			channel = default(TChannel);
		}
	}

	public void Dispose()
	{
		AppDomain.CurrentDomain.DomainUnload -= CurrentDomain_DomainUnload;
		CloseChannel();
	}
}