SocialPub/PrivaPub/Federation/Inbox/Handlers/LockHandler.cs

using MongoDB.Entities;

using PrivaPub.Federation.Objects;
using PrivaPub.Models.User;
using PrivaPub.StaticServices;

using System.Text.Json.Nodes;

using static PrivaPub.Federation.Objects.ActivityJson;

using PostEntity = PrivaPub.Models.Post.Post;

namespace PrivaPub.Federation.Inbox.Handlers
{
	// A moderator's lock of a thread sent as it is, not inside its community's announce (Mbin sends it to the magazine's
	// subscribers itself): taken only from the post's own server, which speaks for it. Replies are refused until the
	// Undo{Lock}, as for a lock a community announces.
	public class LockHandler : IActivityHandler
	{
		readonly DbEntities _dbEntities;

		public LockHandler(DbEntities dbEntities)
		{
			_dbEntities = dbEntities;
		}

		public string Type => "Lock";

		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token)
		{
			if (await Set(_dbEntities, Id(activity["object"]), actor, locked: true, token))
				Arrival.Accept("locked");
			else
				Arrival.Drop("unknown-object");
		}

		// whether the post is ours to lock or unlock for that actor, and was
		public static async Task<bool> Set(DbEntities dbEntities, string objectUri, ForeignAvatar actor, bool locked, CancellationToken token)
		{
			if (objectUri == default || !Origin.Same(objectUri, actor.ActorURI))
				return false;
			var post = await dbEntities.Posts.Match(p => p.ObjectURI == objectUri && p.IsFederatedCopy).ExecuteFirstAsync(token);
			if (post == default)
				return false;
			Arrival.About(visibility: post.Visibility, created: post.CreationDate);
			await DB.Default.Update<PostEntity>().MatchID(post.ID).Modify(p => p.LockedAt, locked ? DateTime.UtcNow : null).ExecuteAsync(token);
			return true;
		}
	}
}