SocialPub/PrivaPub/Federation/Inbox/InboxProcessor.cs

using PrivaPub.Federation.Actors;
using PrivaPub.Infrastructure.Jobs;
using PrivaPub.Models.Jobs;
using PrivaPub.Models.User;

using System.Text.Json;
using System.Text.Json.Nodes;

using static PrivaPub.Federation.Objects.ActivityJson;

namespace PrivaPub.Federation.Inbox
{
	public interface IActivityHandler
	{
		string Type { get; }
		Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token);
	}

	public class InboxProcessor : IJobHandler
	{
		readonly IRemoteActorService _remoteActors;
		readonly IReadOnlyDictionary<string, IActivityHandler> _handlers;
		readonly ILogger<InboxProcessor> _logger;

		public InboxProcessor(IRemoteActorService remoteActors, IEnumerable<IActivityHandler> handlers, ILogger<InboxProcessor> logger)
		{
			_remoteActors = remoteActors;
			_handlers = handlers.ToDictionary(h => h.Type, StringComparer.Ordinal);
			_logger = logger;
		}

		public JobKind Kind => JobKind.ProcessInbox;
		public int Concurrency => 2;
		public int MaxAttempts => 8;
		public int PerHostLimit => 2;

		public async Task<JobOutcome> Handle(Job job, CancellationToken token)
		{
			var payload = JsonSerializer.Deserialize<InboxPayload>(job.Payload);
			var activity = payload == default ? default : JsonNode.Parse(payload.Activity);
			var type = Value(activity, "type");
			if (type == default || !_handlers.TryGetValue(type, out var handler))
				return JobOutcome.Done;

			var actor = await _remoteActors.GetActor(payload.ActorURI, refresh: false, token);
			if (actor == default)
				return JobOutcome.Retry("the actor could not be loaded");

			Arrival.Current = new Arrival(Id(activity), type, actor.ActorURI, payload.Inbox, payload.KeyId, payload.Algorithm,
				payload.SignedHeaders ?? Array.Empty<string>(), payload.ReceivedAt ?? job.CreatedAt, activity["@context"]?.ToJsonString());
			try
			{
				await handler.Handle(activity, actor, token);
			}
			finally
			{
				Arrival.Current = default;
			}
			_logger.LogInformation("Processed {Type} {Id} from {Actor}", type, Id(activity), actor.ActorURI);
			return JobOutcome.Done;
		}
	}
}