SocialPub/PrivaPub/Federation/Inbox/Arrival.cs

using PrivaPub.Federation.Actors;
using PrivaPub.Infrastructure.Statistics;
using PrivaPub.Models.Federation;
using PrivaPub.Models.Post;

namespace PrivaPub.Federation.Inbox
{
	// Raw: the activity as it came, when its own author sent it (ReplyRelay passes it on as it is); ForwardedBy: the server
	// that passed it on instead (a relay, a thread's server)
	public sealed record Arrival(string ActivityId, string ActivityType, string ActorURI, string Inbox, string KeyId, string Algorithm,
		IReadOnlyList<string> SignedHeaders, DateTime ReceivedAt, string Context = default, string Raw = default, string ForwardedBy = default)
	{
		static readonly AsyncLocal<Arrival> current = new();

		public static Arrival Current
		{
			get => current.Value;
			set => current.Value = value;
		}

		public ArrivalVerdict Verdict { get; } = new();

		public static void Drop(string reason) => Current?.Verdict.Drop(reason);

		public static void Reject(string reason) => Current?.Verdict.Reject(reason);

		public static void Accept(string reason) => Current?.Verdict.Accept(reason);

		public static void About(string objectType = default, PostVisibility? visibility = default, DateTime? created = default, LocalActor local = default) =>
			Current?.Verdict.About(objectType, visibility, created, local);
	}

	public sealed class ArrivalVerdict
	{
		public string Outcome { get; private set; }
		public string Reason { get; private set; }
		public string ObjectType { get; private set; }
		public string Audience { get; private set; }
		public string LocalKind { get; private set; }
		public long? AgeSeconds { get; private set; }

		public void Drop(string reason) => Decide(Interactions.Dropped, reason);

		public void Reject(string reason) => Decide(Interactions.Rejected, reason);

		public void Accept(string reason) => Decide(Interactions.Accepted, reason);

		void Decide(string outcome, string reason)
		{
			if (Outcome != default)
				return;
			Outcome = outcome;
			Reason = reason;
		}

		public void About(string objectType, PostVisibility? visibility, DateTime? created, LocalActor local)
		{
			ObjectType = objectType ?? ObjectType;
			if (visibility is { } known)
				Audience = AudienceOf(known);
			if (created is { } at)
				AgeSeconds = Math.Max(0, (long)(DateTime.UtcNow - at).TotalSeconds);
			if (local != default)
				LocalKind = local.Kind switch
				{
					LocalActorKind.Person => "person",
					LocalActorKind.Group when !local.IsCircle => "group",
					LocalActorKind.Application => "application",
					_ => default
				};
		}

		public static string AudienceOf(PostVisibility visibility) => visibility switch
		{
			PostVisibility.Public => Interactions.Public,
			PostVisibility.Unlisted => Interactions.Unlisted,
			_ => Interactions.Private
		};
	}
}