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

using MongoDB.Entities;

using PrivaPub.Federation.Actors;
using PrivaPub.Domain.Statuses;
using PrivaPub.Federation.Objects;
using PrivaPub.Federation.Outbox;
using PrivaPub.Models.Post;
using PrivaPub.Models.User;
using PrivaPub.StaticServices;

using System.Text.Json.Nodes;

using static PrivaPub.Federation.Objects.ActivityJson;

using PostEntity = PrivaPub.Models.Post.Post;

namespace PrivaPub.Federation.Inbox.Handlers
{
	public class UpdateHandler : IActivityHandler
	{

		readonly DbEntities _dbEntities;
		readonly ILocalActorService _localActors;
		readonly IRemoteActorService _remoteActors;
		readonly IGroupDistributor _groups;
		readonly IObjectRecords _records;
		readonly IQuoteService _quotes;

		public UpdateHandler(DbEntities dbEntities, ILocalActorService localActors, IRemoteActorService remoteActors, IGroupDistributor groups,
			IObjectRecords records, IQuoteService quotes)
		{
			_quotes = quotes;
			_records = records;
			_groups = groups;
			_dbEntities = dbEntities;
			_localActors = localActors;
			_remoteActors = remoteActors;
		}

		public string Type => "Update";

		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token)
		{
			var inner = activity["object"];
			if (Id(inner) == actor.ActorURI)
			{
				await _remoteActors.GetActor(actor.ActorURI, refresh: true, token);
				Arrival.Accept("actor-refresh");
				Arrival.About(actor.AvatarType.ToString());
				return;
			}
			if (inner is not JsonObject || !Origin.Same(Id(inner), actor.ActorURI))
			{
				Arrival.Drop("cross-origin");
				return;
			}
			var note = NoteParser.Parse(inner);
			// edited by another account of the author's own server (Mobilizon's organiser edits the group's event): applied
			// as that server has it now
			if (note != default && note.AttributedTo != actor.ActorURI && Origin.Same(note.AttributedTo, actor.ActorURI))
			{
				using var fetched = await _remoteActors.FetchObject(note.Id, token);
				var current = fetched == default ? default : NoteParser.Parse(JsonNode.Parse(fetched.Root.GetRawText()));
				if (current == default || current.Id != note.Id || current.AttributedTo != note.AttributedTo)
				{
					Arrival.Drop("fetch-failed");
					return;
				}
				note = current;
				actor = await _remoteActors.GetActor(note.AttributedTo, refresh: false, token);
				if (actor == default)
				{
					Arrival.Drop("author-unavailable");
					return;
				}
			}
			if (note == default || note.AttributedTo != actor.ActorURI)
			{
				Arrival.Drop(note == default ? "unparseable" : "misattributed");
				return;
			}

			var post = await _dbEntities.Posts.Match(p => p.ObjectURI == note.Id && p.ActorURI == actor.ActorURI).ExecuteFirstAsync(token);
			if (post == default || post.DeletedAt.HasValue)
			{
				Arrival.Drop("unknown-object");
				return;
			}
			Arrival.About(note.Type, post.Visibility, post.CreationDate);

			var edited = await RemoteEdits.Apply(post, note, Id(activity), _localActors, _records, _quotes, token);
			Arrival.Accept(edited ? "edit" : "refresh");
			if (edited && !string.IsNullOrEmpty(post.GroupId) && await _localActors.FindById(Models.Federation.LocalActorKind.Group, post.GroupId, token) is { IsCircle: false } community)
				await _groups.Announce(community, activity.AsObject(), post.ObjectURI, isNewPost: false, token);
		}
	}
}