using MongoDB.Entities;

using PrivaPub.Federation.Actors;
using PrivaPub.Federation.Objects;
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
{
	// Lemmy 1.0 tells a report's sender that it was dealt with: Resolve{Flag}, the Flag being one we sent
	// (`/grunts/flag-<report id>`). It is believed from the server holding what was reported, or the community it was
	// reported to, and kept on the report beside our own moderators' resolution, which it never replaces.
	public class ResolveHandler : IActivityHandler
	{
		const string FlagMarker = "/grunts/flag-";

		readonly DbEntities _dbEntities;
		readonly ILocalActorService _localActors;

		public ResolveHandler(DbEntities dbEntities, ILocalActorService localActors)
		{
			_dbEntities = dbEntities;
			_localActors = localActors;
		}

		public string Type => "Resolve";

		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token)
		{
			var flag = activity["object"];
			var flagId = Id(flag);
			var marker = flagId?.IndexOf(FlagMarker, StringComparison.Ordinal) ?? -1;
			if (flag is JsonObject && Value(flag, "type") != "Flag" || marker < 0
				|| !flagId.StartsWith(_localActors.BaseAddress + "/", StringComparison.OrdinalIgnoreCase))
			{
				Arrival.Drop("not-ours");
				return;
			}
			var reportId = flagId[(marker + FlagMarker.Length)..].Split('-')[0];
			var report = await DB.Default.Find<Report>().MatchID(reportId).ExecuteFirstAsync(token);
			if (report == default)
			{
				Arrival.Drop("unknown-object");
				return;
			}
			var concerned = new List<string>(report.ObjectURIs) { report.TargetActorURI };
			foreach (var post in report.PostIds.Count == 0 ? new List<Models.Post.Post>() : await _dbEntities.Posts.Match(p => report.PostIds.Contains(p.ID)).ExecuteAsync(token))
				concerned.Add(await Communities.Of(post, _dbEntities, token));
			if (!concerned.Any(uri => Origin.Same(uri, actor.ActorURI)))
			{
				Arrival.Drop("misattributed");
				return;
			}
			await DB.Default.Update<Report>().MatchID(report.ID)
				.Modify(r => r.RemoteResolvedAt, DateTime.UtcNow)
				.Modify(r => r.RemoteResolvedBy, actor.ActorURI)
				.ExecuteAsync(token);
			Arrival.Accept("resolved");
		}
	}
}