SocialPub/PrivaPub/Federation/Inbox/Handlers/JoinHandler.cs

using PrivaPub.Federation.Actors;
using PrivaPub.Federation.Outbox;
using PrivaPub.Federation.Rendering;
using PrivaPub.Models.Federation;
using PrivaPub.Models.User;
using PrivaPub.StaticServices;

using System.Text.Json.Nodes;

using static PrivaPub.Federation.Objects.ActivityJson;

namespace PrivaPub.Federation.Inbox.Handlers
{
	public class JoinHandler : IActivityHandler
	{
		readonly DbEntities _dbEntities;
		readonly ILocalActorService _localActors;
		readonly IDeliveryService _delivery;

		public JoinHandler(DbEntities dbEntities, ILocalActorService localActors, IDeliveryService delivery)
		{
			_dbEntities = dbEntities;
			_localActors = localActors;
			_delivery = delivery;
		}

		public string Type => "Join";

		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token)
		{
			var objectUri = Id(activity["object"]);
			if (objectUri == default || !objectUri.StartsWith(_localActors.BaseAddress + "/", StringComparison.OrdinalIgnoreCase))
			{
				Arrival.Drop("unknown-object");
				return;
			}
			var post = await _dbEntities.Posts.Match(p => p.ObjectURI == objectUri && !p.IsFederatedCopy && !p.DeletedAt.HasValue).ExecuteFirstAsync(token);
			var owner = post == default ? default : await _localActors.FindById(LocalActorKind.Person, post.GroupUserId, token);
			if (owner == default || string.IsNullOrEmpty(actor.InboxURL))
			{
				Arrival.Drop("unknown-object");
				return;
			}
			Arrival.About(post.ObjectType ?? "Note", post.Visibility, post.CreationDate);
			Arrival.Reject("ignored");
			await _delivery.Enqueue(owner, new[] { actor.InboxURL }, new JsonObject
			{
				["@context"] = ActivityPubRenderer.ActivityStreams,
				["id"] = owner.ActivityUri($"ignore-{Guid.NewGuid():N}"),
				["type"] = "Ignore",
				["actor"] = owner.Uri,
				["object"] = activity.DeepClone()
			}, token);
		}
	}
}