SocialPub/PrivaPub/Federation/Controllers/WellKnownController.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;

using MongoDB.Entities;

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

using System.Text.Json.Nodes;

using PostEntity = PrivaPub.Models.Post.Post;
using PrivaPub.Domain.Privacy;
using PrivaPub.Federation.Actors;
using PrivaPub.Infrastructure;

namespace PrivaPub.Federation.Controllers
{
	[ApiController]
	public class WellKnownController : ControllerBase
	{
		readonly ILocalActorService _localActors;
		readonly DbEntities _dbEntities;
		readonly IOptionsMonitor<RegistrationOptions> _registrations;
		readonly Domain.Instance.IInstanceSettings _settings;

		public WellKnownController(ILocalActorService localActors, DbEntities dbEntities, IOptionsMonitor<RegistrationOptions> registrations,
			Domain.Instance.IInstanceSettings settings)
		{
			_registrations = registrations;
			_settings = settings;
			_localActors = localActors;
			_dbEntities = dbEntities;
		}

		[HttpGet, Route("/.well-known/webfinger")]
		public async Task<IActionResult> WebFinger([FromQuery] string resource, CancellationToken token)
		{
			if (string.IsNullOrEmpty(resource))
				return BadRequest();
			// the server itself (FEP-d556): its instance actor
			if (resource.TrimEnd('/') == _localActors.BaseAddress)
			{
				var instance = await _localActors.GetInstanceActor(token);
				return Content(new JsonObject
				{
					["subject"] = resource,
					["links"] = new JsonArray(new JsonObject
					{
						["rel"] = "https://www.w3.org/ns/activitystreams#Service", ["type"] = "application/activity+json", ["href"] = instance.Uri
					})
				}.ToJsonString(), "application/jrd+json; charset=utf-8");
			}

			LocalActor actor;
			// Mastodon, GoToSocial and Pleroma also take a bare user@domain or @user@domain, so we do too.
			var acct = resource.StartsWith("acct:", StringComparison.OrdinalIgnoreCase) ? resource[5..]
				: !resource.Contains("://", StringComparison.Ordinal) && resource.Contains('@') ? resource
				: default;
			if (acct != default)
			{
				var parts = acct.TrimStart('@').Split('@');
				var domain = new Uri(_localActors.BaseAddress).Authority;
				if (parts.Length != 2 || !parts[1].Equals(domain, StringComparison.OrdinalIgnoreCase))
					return NotFound();
				actor = await _localActors.FindByUserName(parts[0], token);
				if (actor == default && await _localActors.Gone(parts[0], token) != default)
					return StatusCode(StatusCodes.Status410Gone);
			}
			else
				actor = await _localActors.FindByUri(resource, token);

			if (actor is not { IsFederated: true })
				return NotFound();

			var document = new JsonObject
			{
				["subject"] = $"acct:{actor.Handle}",
				["aliases"] = actor.IsServerActor ? new JsonArray(actor.Uri) : new JsonArray(actor.HtmlUrl, actor.Uri),
				["links"] = actor.IsServerActor
					? new JsonArray(new JsonObject { ["rel"] = "self", ["type"] = "application/activity+json", ["href"] = actor.Uri })
					: new JsonArray(
						new JsonObject { ["rel"] = "http://webfinger.net/rel/profile-page", ["type"] = "text/html", ["href"] = actor.HtmlUrl },
						new JsonObject { ["rel"] = "self", ["type"] = "application/activity+json", ["href"] = actor.Uri })
			};
			return Content(document.ToJsonString(), "application/jrd+json; charset=utf-8");
		}

		[HttpGet, Route("/.well-known/nodeinfo")]
		public async Task<IActionResult> NodeInfoLinks(CancellationToken token)
		{
			var document = new JsonObject
			{
				["links"] = new JsonArray(
					new JsonObject
					{
						["rel"] = "http://nodeinfo.diaspora.software/ns/schema/2.1",
						["href"] = $"{_localActors.BaseAddress}/nodeinfo/2.1"
					},
					new JsonObject
					{
						["rel"] = "http://nodeinfo.diaspora.software/ns/schema/2.0",
						["href"] = $"{_localActors.BaseAddress}/nodeinfo/2.0"
					},
					// the application actor (FEP-2677)
					new JsonObject
					{
						["rel"] = "https://www.w3.org/ns/activitystreams#Application",
						["href"] = (await _localActors.GetInstanceActor(token)).Uri
					})
			};
			return Content(document.ToJsonString(), "application/json; charset=utf-8");
		}

		[HttpGet, Route("/nodeinfo/{version:regex(^2\\.[[01]]$)}")]
		public async Task<IActionResult> NodeInfo(string version, CancellationToken token)
		{
			var users = await Counted.Users(token);
			var posts = await Counted.LocalPosts(token);
			var software = new JsonObject { ["name"] = "privapub", ["version"] = BuildInfo.Ref };
			if (version == "2.1")
			{
				software["repository"] = "https://git.thepra.dev/thepra/SocialPub";
				software["homepage"] = "https://git.thepra.dev/thepra/SocialPub";
			}
			var document = new JsonObject
			{
				["version"] = version,
				["software"] = software,
				["protocols"] = new JsonArray("activitypub"),
				["services"] = new JsonObject { ["inbound"] = new JsonArray(), ["outbound"] = new JsonArray() },
				["openRegistrations"] = _registrations.CurrentValue.IsOpen,
				["usage"] = new JsonObject
				{
					["users"] = new JsonObject
					{
						["total"] = users,
						["activeMonth"] = await Counted.ActiveUsers(30, token),
						["activeHalfyear"] = await Counted.ActiveUsers(180, token)
					},
					["localPosts"] = posts
				},
				["metadata"] = new JsonObject
				{
					// the server's name and short description, as its administrator set them (IInstanceSettings)
					["nodeName"] = _settings.Current.Title,
					["nodeDescription"] = _settings.Current.ShortDescription ?? string.Empty,
					["federation"] = new JsonObject { ["document"] = "https://git.thepra.dev/thepra/SocialPub/src/branch/master/FEDERATION.md" }
				}
			};
			return Content(document.ToJsonString(),
				$"application/json; profile=\"http://nodeinfo.diaspora.software/ns/schema/{version}#\"; charset=utf-8");
		}
	}
}