using MongoDB.Entities;

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

using System.Text.Json.Nodes;

using PostEntity = PrivaPub.Models.Post.Post;

namespace PrivaPub.Federation.Inbox
{
	// ActivityPub's inbox forwarding of replies (owner decision 2026-10-05): a public or unlisted reply to one of our
	// personas' own posts reaches the persona's followers as its author sent it, and so do its edits and its deletion, as
	// Mastodon forwards the replies to its accounts' posts. The author's server sends a reply to its own followers and to
	// the persona, never to the persona's followers, who would otherwise see half of the thread. It goes as it came (an
	// LD signature in it stays good), signed by the persona; never to the replier's own server, never once more when it
	// reached us forwarded, and never for a followers-only reply or a DM, which were not for the persona's followers.
	public static class ReplyRelay
	{
		public static async Task Pass(PostEntity reply, DbEntities db, ILocalActorService localActors, IDeliveryService delivery, CancellationToken token)
		{
			var raw = Arrival.Current?.Raw;
			if (raw == default || delivery == default || localActors == default || reply is not { IsFederatedCopy: true }
				|| reply.Visibility is not (PostVisibility.Public or PostVisibility.Unlisted) || string.IsNullOrEmpty(reply.AnsweringToPostId))
				return;
			var parent = await db.Posts.MatchID(reply.AnsweringToPostId).ExecuteFirstAsync(token);
			if (parent is not { IsFederatedCopy: false, IsLocalOnly: false } || !string.IsNullOrEmpty(parent.GroupId)
				|| parent.Visibility is not (PostVisibility.Public or PostVisibility.Unlisted or PostVisibility.FollowersOnly))
				return;
			var owner = await localActors.FindById(LocalActorKind.Person, parent.GroupUserId, token);
			if (owner is not { IsFederated: true } || JsonNode.Parse(raw) is not JsonObject activity)
				return;
			var replier = Interactions.HostOf(reply.ActorURI);
			var inboxes = (await delivery.FollowerInboxes(owner, token)).Where(i => Interactions.HostOf(i) != replier).ToList();
			if (inboxes.Count > 0)
				await delivery.Enqueue(owner, inboxes, activity, token);
		}
	}
}