using PrivaPub.Federation.Objects;
using PrivaPub.Infrastructure.Jobs;
using PrivaPub.Models.Jobs;
using PrivaPub.Models.User;

using System.Text.Json;
using System.Text.Json.Nodes;

using static PrivaPub.Federation.Objects.ActivityJson;

namespace PrivaPub.Federation.Inbox
{
	// FEP-171b conversation containers (Hubzilla, Streams, Forte): a thread's owner adds each activity in it to the
	// thread's context, a collection of its own, and tells the thread's audience with Add{activity}. The activity it adds
	// is another's, so it is taken as forwarded by the owner: a Create, Update or Delete of the actor's own object,
	// believed on its FEP-8b32 proof or as its origin has it (Forwarded). Hubzilla also passes the activity on by itself;
	// the two are one job.
	public static class ConversationContainers
	{
		public static async Task<bool> Unwrap(JsonNode add, ForeignAvatar owner, IJobQueue queue, CancellationToken token)
		{
			if (add["object"] is not JsonObject inner || Value(inner, "type") is not ("Create" or "Update" or "Delete") || Id(inner) is not { } innerId)
				return false;
			var target = add["target"];
			var context = Id(target);
			if (context == default || !Origin.Same(context, owner.ActorURI)
				|| target is JsonObject collection && Id(collection["attributedTo"]) is { } attributedTo && attributedTo != owner.ActorURI)
				return false;
			var actorUri = Id(inner["actor"]);
			if (actorUri == default || !Forwarded.Takeable(Value(inner, "type"), inner, actorUri))
			{
				Arrival.Drop("container-unusable");
				return true;
			}
			var payload = JsonSerializer.Serialize(new InboxPayload(actorUri, inner.ToJsonString(), "shared", ReceivedAt: DateTime.UtcNow, ForwardedBy: owner.ActorURI));
			var host = new Uri(actorUri).Host.ToLowerInvariant();
			var dedupe = "inbox|forwarded|" + innerId;
			var queued = await queue.Enqueue(JobKind.ProcessInbox, payload, host, dedupe, token);
			// one id for two activities (Forte's Update of a post has its Create's id): what each carries tells them apart
			if (!queued && InboxReceiver.CarriesOther(await queue.Payload(dedupe, token), inner))
				queued = await queue.Enqueue(JobKind.ProcessInbox, payload, host, $"{dedupe}|{InboxReceiver.Digest(inner)}", token);
			if (queued)
				Arrival.Accept("unwrapped");
			else
				Arrival.Drop("duplicate");
			return true;
		}
	}
}