Connected.Framework/Connected.Notifications/Events/EventService.cs

using System.Reflection;
using Connected.Interop;
using Connected.Middleware;
using Connected.Net.Server;
using Connected.Notifications.Events.Server;
using Connected.ServiceModel;
using Connected.ServiceModel.Transactions;

namespace Connected.Notifications.Events;

internal class EventService : IEventService, IDisposable
{
	public event ServiceEventHandler<EventServiceArgs>? Event;

	public EventService(IEndpointServer endpoints, EventDispatcher dispatcher, EventServer server, EventServerConnection backplaneClient, IContextProvider provider)
	{
		Dispatcher = dispatcher;
		Server = server;
		BackplaneClient = backplaneClient;
		Provider = provider;
		Endpoints = endpoints;

		endpoints.Changed += OnServerChanged;
		endpoints.Initialized += OnServerInitialized;

		BackplaneClient.Received += OnReceived;
	}

	private IEndpointServer Endpoints { get; }

	private EventDispatcher Dispatcher { get; set; }
	private EventServer Server { get; }
	private EventServerConnection BackplaneClient { get; }
	private IContextProvider Provider { get; }
	private bool IsDisposed { get; set; }

	private async void OnServerInitialized(object? sender, EventArgs e)
	{
		await Initialize();
	}

	public async Task Initialize()
	{
		await BackplaneClient.Disconnect();

		try
		{
			if (!await Endpoints.IsServer())
			{
				await BackplaneClient.Initialize(Endpoints.ServerUrl);
				await BackplaneClient.Connect();
			}
		}
		catch
		{
			// Server probably not initalized yet
		}
	}

	private async void OnServerChanged(object? sender, ServerChangedArgs e)
	{
		await Initialize();
	}

	private async void OnReceived(object? sender, EventNotificationArgs e)
	{
		//TODO: we are going to need some additional info here, like assembly
		var serviceType = Type.GetType(e.Service);

		if (serviceType is null)
			return;

		//Enqueue(serviceType, e.Event, EventOrigin.Remote, e.Arguments);

		await Task.CompletedTask;
	}

	internal async Task Trigger(EventServiceArgs args)
	{
		Event?.Invoke(args.Sender, args);

		await Server.Send(new EventNotificationArgs
		{
			Arguments = await Serializer.Serialize(args.Arguments),
			Event = args.Event,
			Service = args.Service.GetType().Name
		});

		using var context = Provider.Create();

		var middlewareService = context.GetService<IMiddlewareService>();
		var targetMiddleware = typeof(IEventListener<>);
		var gt = targetMiddleware.MakeGenericType(args.Arguments.GetType());
		var middleware = await middlewareService.Query(gt, new CallerContext(args.Service, args.Event));

		foreach (var m in middleware)
		{
			if (m.GetType().GetMethod(nameof(IEventListener<IDto>.Invoke), BindingFlags.Public | BindingFlags.Instance, new Type[] { typeof(IOperationState), args.Arguments.GetType() }) is not MethodInfo method)
				continue;

			await method.InvokeAsync(m, args.Sender, args.Arguments);
		}

		if (context.GetService<ITransactionContext>() is ITransactionContext transactionContext)
			await transactionContext.Commit();
	}

	public async Task Enqueue<TService, TArgs>(IOperationState sender, TService service, string @event, TArgs args)
	{
		await Enqueue(sender, service, @event, EventOrigin.InProcess, args);
	}

	public async Task Enqueue<TService, TArgs>(IOperationState sender, TService service, string @event, EventOrigin origin, TArgs args)
	{
		Dispatcher.Enqueue(new EventServiceArgs
		{
			Sender = sender,
			Service = service.GetType(),
			Event = @event,
			Origin = origin,
			Arguments = args
		});

		await Task.CompletedTask;
	}

	protected virtual void Dispose(bool disposing)
	{
		if (!IsDisposed)
		{
			if (disposing)
			{
				if (Dispatcher is not null)
				{
					Dispatcher.Cancel();
					Dispatcher = null;
				}
			}

			IsDisposed = true;
		}
	}

	public void Dispose()
	{
		Dispose(true);
		GC.SuppressFinalize(this);
	}
}