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

using MongoDB.Entities;

using PrivaPub.Federation.Actors;
using PrivaPub.Models.Federation;
using PrivaPub.Models.Social;
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 FlagHandler : IActivityHandler
	{
		readonly DbEntities _dbEntities;
		readonly ILocalActorService _localActors;

		public FlagHandler(DbEntities dbEntities, ILocalActorService localActors)
		{
			_dbEntities = dbEntities;
			_localActors = localActors;
		}

		public string Type => "Flag";

		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token)
		{
			var objects = activity["object"] switch
			{
				JsonArray array => array.Select(Id).Where(i => i != default).ToList(),
				JsonNode single when Id(single) is { } id => new List<string> { id },
				_ => new List<string>()
			};

			LocalActor target = default;
			var postUris = new List<string>();
			foreach (var uri in objects.Take(50))
			{
				var local = await _localActors.FindByUri(uri, token);
				if (local is { Kind: LocalActorKind.Person } && uri.TrimEnd('/') == local.Uri)
					target ??= local;
				else
					postUris.Add(uri);
			}
			var posts = postUris.Count == 0
				? new List<Models.Post.Post>()
				: await _dbEntities.Posts.Match(p => postUris.Contains(p.ObjectURI) && !p.IsFederatedCopy).ExecuteAsync(token);
			if (target == default && posts.Count > 0)
				target = await _localActors.FindById(LocalActorKind.Person, posts[0].GroupUserId, token);
			if (target == default)
			{
				Arrival.Drop("unknown-object");
				return;
			}
			Arrival.Accept("reported");

			await DB.Default.SaveAsync(new Report
			{
				ReporterActorURI = actor.ActorURI,
				TargetAccountId = target.Id,
				TargetActorURI = target.Uri,
				PostIds = posts.Where(p => p.GroupUserId == target.Id).Select(p => p.ID).ToList(),
				ObjectURIs = posts.Where(p => p.GroupUserId == target.Id).Select(p => p.ObjectURI).ToList(),
				Comment = Value(activity, "content")
			}, token);
		}
	}
}