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

using MongoDB.Entities;

using PrivaPub.Federation.Actors;
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
	{
		const int MaxRevisions = 20;

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

		public UpdateHandler(DbEntities dbEntities, ILocalActorService localActors, IRemoteActorService remoteActors, IGroupDistributor groups,
			IObjectRecords records)
		{
			_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);
				return;
			}
			if (inner is not JsonObject || !Origin.Same(Id(inner), actor.ActorURI))
				return;
			var note = NoteParser.Parse(inner);
			if (note == default || note.AttributedTo != actor.ActorURI)
				return;

			var post = await _dbEntities.Posts.Match(p => p.ObjectURI == note.Id && p.ActorURI == actor.ActorURI).ExecuteFirstAsync(token);
			if (post == default || post.DeletedAt.HasValue)
				return;

			post.Poll = note.Poll ?? post.Poll;
			post.Video = note.Video ?? post.Video;
			post.Audio = note.Audio ?? post.Audio;
			post.Event = note.Event ?? post.Event;
			if (!IsEdit(note, post))
			{
				await DB.Default.SaveAsync(post, token);
				await _records.Revise(note, Id(activity), token);
				return;
			}

			post.Revisions.Add(new PostRevision
			{
				Title = post.Title,
				SpoilerText = post.SpoilerText,
				ContentHtml = post.ContentHtml,
				HasContentWarning = post.HasContentWarning,
				EditedAt = post.EditedAt ?? post.CreationDate
			});
			if (post.Revisions.Count > MaxRevisions)
				post.Revisions.RemoveRange(0, post.Revisions.Count - MaxRevisions);

			var mentions = new List<PostMention>();
			foreach (var mention in note.Mentions)
			{
				var local = await _localActors.FindByUri(mention.ActorURI, token);
				mentions.Add(new PostMention { ActorURI = mention.ActorURI, Handle = mention.Handle, IsLocal = local != default, AccountId = local?.Id });
			}

			post.Title = note.Title;
			post.SpoilerText = note.SpoilerText;
			post.Excerpt = note.Excerpt;
			post.Source = note.Source;
			post.Emojis = note.Emojis.ToList();
			post.CoverURL = note.CoverURL;
			post.Link = note.Link;
			post.HasContentWarning = note.Sensitive;
			post.Text = note.ContentHtml;
			post.ContentHtml = note.ContentHtml;
			post.Language = note.Language;
			post.Tags = note.Tags.ToList();
			post.Mentions = mentions;
			post.Media = note.Attachments.ToList();
			post.EditedAt = note.Updated ?? DateTime.UtcNow;
			post.UpdateDate = DateTime.UtcNow;
			await DB.Default.SaveAsync(post, token);
			await _records.Revise(note, Id(activity), token);
			if (!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);
		}

		static bool IsEdit(NoteDocument note, PostEntity post) =>
			note.Updated is { } updated && updated > (post.EditedAt ?? post.CreationDate);
	}
}