using MongoDB.Entities;

using PrivaPub.Federation.Actors;
using PrivaPub.Models.User;

using System.Text.Json.Nodes;

using static PrivaPub.Federation.Objects.ActivityJson;

namespace PrivaPub.Federation.Inbox.Handlers
{
	// An account moving to another (Mastodon's Move{object: itself, target: the new account}), believed as Mastodon
	// believes it: the moving account sends it about itself, and the new account, read again from its own server, names
	// it among its alsoKnownAs. The old account then shows where it went (`moved`). The personas following it keep
	// following it: following the new one is theirs to do.
	public class MoveHandler : IActivityHandler
	{
		readonly IRemoteActorService _remoteActors;

		public MoveHandler(IRemoteActorService remoteActors)
		{
			_remoteActors = remoteActors;
		}

		public string Type => "Move";

		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token)
		{
			var target = Id(activity["target"]);
			if (Id(activity["object"]) != actor.ActorURI || string.IsNullOrEmpty(target) || target == actor.ActorURI)
			{
				Arrival.Drop("not-self");
				return;
			}
			var moved = await _remoteActors.GetActor(target, refresh: true, token);
			if (moved == default)
			{
				Arrival.Drop("target-unavailable");
				return;
			}
			if (!moved.AlsoKnownAs.Contains(actor.ActorURI))
			{
				Arrival.Drop("not-aliased");
				return;
			}
			await DB.Default.Update<ForeignAvatar>().MatchID(actor.ID).Modify(a => a.MovedToURL, target).ExecuteAsync(token);
			Arrival.Accept("moved");
		}
	}
}