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

using MongoDB.Entities;

using PrivaPub.Domain.Statuses;
using PrivaPub.Federation.Actors;
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 AcceptHandler : IActivityHandler
	{
		readonly DbEntities _dbEntities;
		readonly ILocalActorService _localActors;
		readonly IQuoteService _quotes;

		public AcceptHandler(DbEntities dbEntities, ILocalActorService localActors, IQuoteService quotes)
		{
			_dbEntities = dbEntities;
			_localActors = localActors;
			_quotes = quotes;
		}

		public virtual string Type => "Accept";

		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token)
		{
			if (await _quotes.Answered(activity, actor, accepted: Type == "Accept", token))
			{
				Arrival.Accept("quote-answer");
				return;
			}
			var following = await FindFollowing(activity["object"], actor, _dbEntities, _localActors, token);
			if (following == default)
			{
				Arrival.Drop("unknown-object");
				return;
			}
			Arrival.About("Follow");
			Arrival.Accept("follow-answer");
			await Apply(following, token);
		}

		protected virtual Task Apply(Following following, CancellationToken token) =>
			DB.Default.Update<Following>().MatchID(following.ID).Modify(f => f.State, FollowState.Accepted).ExecuteAsync(token);

		public static async Task<Following> FindFollowing(JsonNode follow, ForeignAvatar target, DbEntities dbEntities, ILocalActorService localActors,
			CancellationToken token)
		{
			if (follow is JsonObject && Value(follow, "type") is { } type && type != "Follow")
				return default;
			var followId = Id(follow);
			var byId = followId == default
				? default
				: await dbEntities.Followings.Match(f => f.FollowActivityURI == followId && f.TargetActorURI == target.ActorURI).ExecuteFirstAsync(token);
			if (byId != default || follow is not JsonObject)
				return byId;

			var follower = await localActors.FindByUri(Id(follow["actor"]), token);
			return follower == default
				? default
				: await dbEntities.Followings.Match(f => f.AvatarId == follower.Id && f.TargetActorURI == target.ActorURI).ExecuteFirstAsync(token);
		}
	}

	public class RejectHandler : AcceptHandler
	{
		public RejectHandler(DbEntities dbEntities, ILocalActorService localActors, IQuoteService quotes) : base(dbEntities, localActors, quotes)
		{
		}

		public override string Type => "Reject";

		protected override Task Apply(Following following, CancellationToken token) => DB.Default.DeleteAsync<Following>(following.ID);
	}
}