SocialPub/PrivaPub/Federation/Controllers/PeasantsController.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.RateLimiting;

using MongoDB.Entities;

using PrivaPub.Models.Federation;
using PrivaPub.StaticServices;

using System.Text.Json.Nodes;

using PostEntity = PrivaPub.Models.Post.Post;
using PrivaPub.Federation.Actors;
using PrivaPub.Federation.Rendering;
using PrivaPub.Federation.Inbox;
using PrivaPub.Infrastructure;

namespace PrivaPub.Federation.Controllers
{
	[ApiController, Route("peasants")]
	public class PeasantsController : ControllerBase
	{
		const string ActivityContentType = "application/activity+json; charset=utf-8";
		const int OutboxSize = 20;

		readonly ILocalActorService _localActors;
		readonly IInboxReceiver _inbox;
		readonly DbEntities _dbEntities;
		readonly ILogger<PeasantsController> _logger;

		public PeasantsController(ILocalActorService localActors, IInboxReceiver inbox, DbEntities dbEntities,
			ILogger<PeasantsController> logger)
		{
			_localActors = localActors;
			_inbox = inbox;
			_dbEntities = dbEntities;
			_logger = logger;
		}

		[HttpGet, Route("{actor}")]
		public async Task<IActionResult> GetActor(string actor, CancellationToken token)
		{
			var local = await _localActors.FindByUserName(actor, token);
			return local is not { IsFederated: true } ? NotFound() : Activity(ActivityPubRenderer.Actor(local));
		}

		[HttpGet, Route("{actor}/anus")]
		public async Task<IActionResult> Outbox(string actor, CancellationToken token)
		{
			var local = await _localActors.FindByUserName(actor, token);
			if (local is not { IsFederated: true })
				return NotFound();

			var total = local.Kind == LocalActorKind.Group
				? await DB.Default.CountAsync<PostEntity>(p => p.GroupId == local.Id && !p.IsLocalOnly, token)
				: await DB.Default.CountAsync<PostEntity>(p => p.GroupUserId == local.Id && !p.IsFederatedCopy && !p.IsLocalOnly, token);

			var latest = await (local.Kind == LocalActorKind.Group
					? _dbEntities.Posts.Match(p => p.GroupId == local.Id && !p.IsLocalOnly)
					: _dbEntities.Posts.Match(p => p.GroupUserId == local.Id && !p.IsFederatedCopy && !p.IsLocalOnly))
				.Sort(p => p.CreationDate, Order.Descending)
				.Limit(OutboxSize)
				.ExecuteAsync(token);

			var items = new List<JsonNode>();
			foreach (var post in latest)
			{
				if (local.Kind == LocalActorKind.Group)
				{
					items.Add(ActivityPubRenderer.Announce(local, post.ObjectURI, $"announce-{post.ID}"));
					continue;
				}
				var group = string.IsNullOrEmpty(post.GroupId) ? default : await _localActors.FindById(LocalActorKind.Group, post.GroupId, token);
				var note = ActivityPubRenderer.Note(post, local, group, default);
				items.Add(ActivityPubRenderer.Create(local, note, $"create-{post.ID}"));
			}

			return Activity(ActivityPubRenderer.OrderedCollection(local.Outbox, (int)total, items));
		}

		[HttpGet, Route("{actor}/followers")]
		public async Task<IActionResult> Followers(string actor, CancellationToken token)
		{
			var local = await _localActors.FindByUserName(actor, token);
			if (local is not { IsFederated: true })
				return NotFound();
			var count = await DB.Default.CountAsync<Follower>(
				f => f.LocalActorId == local.Id && f.LocalActorKind == local.Kind && f.IsAccepted, token);
			return Activity(ActivityPubRenderer.OrderedCollection(local.Followers, (int)count, default));
		}

		[HttpGet, Route("{actor}/following")]
		public async Task<IActionResult> Following(string actor, CancellationToken token)
		{
			var local = await _localActors.FindByUserName(actor, token);
			return local is not { IsFederated: true } ? NotFound() : Activity(ActivityPubRenderer.OrderedCollection(local.Following, 0, Enumerable.Empty<JsonNode>()));
		}

		[HttpGet, Route("{actor}/posts/{postId}")]
		public async Task<IActionResult> Post(string actor, string postId, CancellationToken token)
		{
			var local = await _localActors.FindByUserName(actor, token);
			if (local == default || local.Kind != LocalActorKind.Person)
				return NotFound();

			var post = await _dbEntities.Posts
				.Match(p => p.ID == postId && p.GroupUserId == local.Id && !p.IsFederatedCopy && !p.IsLocalOnly)
				.ExecuteFirstAsync(token);
			if (post == default)
				return NotFound();

			var group = string.IsNullOrEmpty(post.GroupId) ? default : await _localActors.FindById(LocalActorKind.Group, post.GroupId, token);
			var replyTo = await ReplyTarget(post.AnsweringToPostId, token);
			var note = ActivityPubRenderer.Note(post, local, group, replyTo);
			note["@context"] = ActivityPubRenderer.ActivityStreams;
			return Activity(note);
		}

		[HttpPost, Route("{actor}/mouth"), EnableRateLimiting(RateLimiting.Inbox)]
		public async Task<IActionResult> Inbox(string actor, CancellationToken token)
		{
			var local = await _localActors.FindByUserName(actor, token);
			if (local is not { IsFederated: true })
				return NotFound();
			return Answer(await _inbox.Receive(Request, local, token));
		}

		[HttpPost, Route("{actor}/human-centipede"), EnableRateLimiting(RateLimiting.Inbox)]
		public async Task<IActionResult> ActorSharedInbox(string actor, CancellationToken token) =>
			Answer(await _inbox.Receive(Request, default, token));

		[HttpPost, Route("/human-centipede"), EnableRateLimiting(RateLimiting.Inbox)]
		public async Task<IActionResult> SharedInbox(CancellationToken token) =>
			Answer(await _inbox.Receive(Request, default, token));

		async Task<string> ReplyTarget(string answeringToPostId, CancellationToken token)
		{
			if (string.IsNullOrEmpty(answeringToPostId))
				return default;
			if (answeringToPostId.StartsWith("https://", StringComparison.OrdinalIgnoreCase))
				return answeringToPostId;
			return (await _dbEntities.Posts.MatchID(answeringToPostId).ExecuteFirstAsync(token))?.ObjectURI;
		}

		IActionResult Answer(InboxResult result)
		{
			if (result.Error != default)
				_logger.LogInformation("Inbox refused with {Status}: {Error}", result.StatusCode, result.Error);
			return result.Error == default ? StatusCode(result.StatusCode) : StatusCode(result.StatusCode, result.Error);
		}

		ContentResult Activity(JsonObject document) => new()
		{
			Content = document.ToJsonString(),
			ContentType = ActivityContentType,
			StatusCode = StatusCodes.Status200OK
		};
	}
}