SocialPub/PrivaPub.Tests/Federation/InboxGapTests.cs

using MongoDB.Entities;

using PrivaPub.ClientModels.Social;
using PrivaPub.Domain.Statuses;
using PrivaPub.Federation.Actors;
using PrivaPub.Federation.Objects;
using PrivaPub.Models.Federation;
using PrivaPub.Models.Post;
using PrivaPub.Models.Social;
using PrivaPub.Models.User;
using PrivaPub.Tests.Support;

using System.Security.Cryptography;
using System.Text.Json.Nodes;

using static PrivaPub.Tests.Support.FederatedSeeds;

namespace PrivaPub.Tests.Federation
{
	[Trait("Category", "Integration")]
	public sealed class InboxGapTests : IAsyncLifetime
	{
		Harness _harness;

		public async ValueTask InitializeAsync()
		{
			Assert.SkipUnless(MongoFixture.Enabled, MongoFixture.Skip);
			_harness = await Harness.Start();
		}

		public async ValueTask DisposeAsync()
		{
			if (_harness != default)
				await _harness.DisposeAsync();
		}

		static JsonObject Follow(RemoteActor follower, string target) =>
			new() { ["id"] = NewId(follower, "follows"), ["type"] = "Follow", ["actor"] = follower.Id, ["object"] = target };

		Task<ForeignAvatar> Stored(RemoteActor actor) =>
			DB.Default.Find<ForeignAvatar>().Match(f => f.ActorURI == actor.Id).ExecuteSingleAsync(TestContext.Current.CancellationToken);

		PrivaPub.Models.Statistics.InteractionEvent Processed(string activity) => _harness.Ledger.Of("in").Last(e => e.Activity == activity);

		// a follow request nobody answers is sent again after 15 minutes, an hour, 6 hours... (Lemmy 1.0 lost the Accept of a
		// follow it took before it started sending to us, and the community's posts were refused as not followed)
		[Fact]
		public async Task A_follow_request_nobody_answers_is_sent_again_with_a_growing_pause_until_it_is()
		{
			var token = TestContext.Current.CancellationToken;
			var (root, alice) = await _harness.Persona("alice");
			var quiet = new RemoteActor(_harness.Peer, "quiet");
			await _harness.Follows.Follow(root, new FollowForm { AvatarId = alice.Id, Target = quiet.Id }, token);
			var following = await DB.Default.Find<Following>().Match(f => f.AvatarId == alice.Id && f.TargetActorURI == quiet.Id).ExecuteSingleAsync(token);
			async Task<int> Follows() => (await _harness.Outgoing(quiet.Id + "/inbox")).Count(a => a["type"]!.GetValue<string>() == "Follow");
			var made = following.CreatedAt;
			Assert.Equal(1, await Follows());

			// (the store is shared with other tests' requests: what this one got is counted on its own inbox)
			async Task<int> After(TimeSpan wait)
			{
				var before = await Follows();
				await _harness.Follows.ResendPending(made + wait, token);
				return await Follows() - before;
			}
			Assert.Equal(0, await After(TimeSpan.FromMinutes(10)));
			Assert.Equal(1, await After(TimeSpan.FromMinutes(16)));
			Assert.Equal(0, await After(TimeSpan.FromMinutes(30)));
			Assert.Equal(1, await After(TimeSpan.FromMinutes(77)));
			Assert.Equal(3, await Follows());
			// each one again under its own id (Lemmy never answers an id it has seen), and an answer naming it counts
			var sentIds = (await _harness.Outgoing(quiet.Id + "/inbox")).Select(a => a["id"]!.GetValue<string>()).ToList();
			Assert.Equal(new[] { following.FollowActivityURI, following.FollowActivityURI + "-again-1", following.FollowActivityURI + "-again-2" }, sentIds);

			// a request older than the count is sent again too; an answered one never
			await DB.Default.Update<Following>().MatchID(following.ID).Modify(b => b.Unset(f => f.Resent)).Modify(b => b.Unset(f => f.ResentAt)).ExecuteAsync(token);
			Assert.Equal(1, await After(TimeSpan.FromDays(1)));
			await _harness.Deliver(quiet, "/human-centipede", new JsonObject
			{
				["id"] = NewId(quiet, "accepts"), ["type"] = "Accept", ["actor"] = quiet.Id, ["object"] = following.FollowActivityURI + "-again-2"
			});
			Assert.Equal(FollowState.Accepted, (await DB.Default.Find<Following>().OneAsync(following.ID, token)).State);
			Assert.Equal(0, await After(TimeSpan.FromDays(30)));
		}

		// Pixelfed names our post by its page (/@name/<id>, the post's url) in its Like, Announce and their Undo: the post is
		// found the same as by its id
		// Friendica's activity ids are uniqid(), a prefix and the microsecond: two of its processes answering two follows at
		// once gave both Accepts one id, and the second was dropped as a copy of the first, leaving that follow pending
		[Fact]
		public async Task Two_activities_a_server_gave_one_id_are_both_taken_and_a_true_copy_once()
		{
			var token = TestContext.Current.CancellationToken;
			var (root, alice) = await _harness.Persona("alice");
			var dario = new RemoteActor(_harness.Peer, "dario");
			var jun = new RemoteActor(_harness.Peer, "jun");
			await _harness.Follows.Follow(root, new FollowForm { AvatarId = alice.Id, Target = dario.Id }, token);
			await _harness.Follows.Follow(root, new FollowForm { AvatarId = alice.Id, Target = jun.Id }, token);
			Task<Following> Of(RemoteActor target) =>
				DB.Default.Find<Following>().Match(f => f.AvatarId == alice.Id && f.TargetActorURI == target.Id).ExecuteSingleAsync(token);
			async Task<JsonObject> Accept(RemoteActor by, string id) => new()
			{
				["id"] = id,
				["type"] = "Accept",
				["actor"] = by.Id,
				["object"] = new JsonObject { ["id"] = (await Of(by)).FollowActivityURI, ["type"] = "Follow", ["actor"] = alice.Uri, ["object"] = by.Id }
			};
			var shared = NewId(dario, "activity");

			var first = await _harness.Deliver(dario, "/human-centipede", await Accept(dario, shared));
			var second = await _harness.Deliver(jun, "/human-centipede", await Accept(jun, shared));
			var copy = await _harness.Deliver(jun, "/human-centipede", await Accept(jun, shared));

			Assert.Equal(("queued", "queued", "duplicate"), (first.Reason, second.Reason, copy.Reason));
			Assert.Equal(FollowState.Accepted, (await Of(dario)).State);
			Assert.Equal(FollowState.Accepted, (await Of(jun)).State);
		}

		// Mobilizon: the organiser creates, edits and deletes an event attributed to the group, which announces it. They used
		// to be refused as misattributed (400), so the edit was lost and the deletion left the event in place
		[Fact]
		public async Task An_event_its_organiser_edits_and_deletes_for_a_group_on_the_same_server_follows_that_server()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var group = new RemoteActor(_harness.Peer, "group", type: "Group");
			var organiser = new RemoteActor(_harness.Peer, "organiser");
			await Follows(alice.Id, group);
			var path = $"/events/{Guid.NewGuid():N}";
			JsonObject Event(string name) => new()
			{
				["id"] = _harness.Peer.A + path, ["type"] = "Event", ["name"] = name, ["content"] = "<p>bring bread</p>",
				["attributedTo"] = group.Id, ["actor"] = organiser.Id, ["startTime"] = "2026-10-08T18:00:00Z",
				["to"] = new JsonArray(PrivaPub.Federation.Objects.Addressing.Public), ["cc"] = new JsonArray(group.Id + "/followers")
			};
			_harness.Peer.Serve(path, Event("A picnic").ToJsonString());
			Task<Post> Stored() => DB.Default.Find<Post>().Match(p => p.ObjectURI == _harness.Peer.A + path).ExecuteFirstAsync(token);

			var created = await _harness.Deliver(organiser, "/human-centipede", Create(organiser, Event("A picnic")));
			Assert.Equal(202, created.StatusCode);
			Assert.Equal(group.Id, (await Stored()).ActorURI);

			var moved = Event("A picnic, moved indoors");
			moved["updated"] = DateTime.UtcNow.AddMinutes(1).ToString("O");
			_harness.Peer.Serve(path, moved.ToJsonString());
			await _harness.Deliver(organiser, "/human-centipede", Activity(organiser, "Update", Event("what the activity claims")));
			Assert.Equal("A picnic, moved indoors", (await Stored()).Title);

			await _harness.Deliver(organiser, "/human-centipede", Activity(organiser, "Delete", JsonValue.Create(_harness.Peer.A + path)!));
			Assert.NotNull(await Stored());
			_harness.Peer.Answer(path, 410);
			await _harness.Deliver(organiser, "/human-centipede", Activity(organiser, "Delete", JsonValue.Create(_harness.Peer.A + path)!));
			Assert.Null(await Stored());

			// attributed to someone of another server, it is still refused
			var elsewhere = new RemoteActor(_harness.Peer, "elsewhere", _harness.Peer.B);
			var claimed = Event("Someone else's");
			claimed["id"] = _harness.Peer.A + $"/events/{Guid.NewGuid():N}";
			claimed["attributedTo"] = elsewhere.Id;
			Assert.Equal(400, (await _harness.Deliver(organiser, "/human-centipede", Create(organiser, claimed))).StatusCode);
		}

		// Funkwhale names its Accept after the Follow it answers (`<our Follow's id>/accept`), on our origin, not its own
		[Fact]
		public async Task An_answer_named_after_our_follow_is_taken_and_one_naming_someone_elses_is_not()
		{
			var token = TestContext.Current.CancellationToken;
			var (root, alice) = await _harness.Persona("alice");
			var channel = new RemoteActor(_harness.Peer, "channel");
			await _harness.Follows.Follow(root, new FollowForm { AvatarId = alice.Id, Target = channel.Id }, token);
			var following = await DB.Default.Find<Following>().Match(f => f.AvatarId == alice.Id && f.TargetActorURI == channel.Id).ExecuteSingleAsync(token);

			var elsewhere = await _harness.Deliver(channel, "/human-centipede", new JsonObject
			{
				["id"] = "https://privapub.test/peasants/somebody/accept", ["type"] = "Accept", ["actor"] = channel.Id, ["object"] = following.FollowActivityURI
			});
			Assert.Equal(400, elsewhere.StatusCode);

			var named = await _harness.Deliver(channel, "/human-centipede", new JsonObject
			{
				["id"] = following.FollowActivityURI + "/accept", ["type"] = "Accept", ["actor"] = channel.Id,
				["object"] = new JsonObject { ["id"] = following.FollowActivityURI, ["type"] = "Follow", ["actor"] = alice.Uri, ["object"] = channel.Id }
			});
			Assert.Equal(202, named.StatusCode);
			Assert.Equal(FollowState.Accepted, (await DB.Default.Find<Following>().OneAsync(following.ID, token)).State);
		}

		// Funkwhale's channel deletes its uploads in one Delete, their ids in a list as the object's id (and the Delete has
		// no id of its own)
		[Fact]
		public async Task A_delete_naming_several_objects_removes_each()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var channel = new RemoteActor(_harness.Peer, "channel");
			await Follows(alice.Id, channel);
			var first = PublicNote(channel, "<p>a first track</p>");
			var second = PublicNote(channel, "<p>a second track</p>");
			await _harness.Deliver(channel, "/human-centipede", Create(channel, first));
			await _harness.Deliver(channel, "/human-centipede", Create(channel, second));
			Task<bool> Held(JsonObject note) => DB.Default.Find<Post>().Match(p => p.ObjectURI == IdOf(note)).ExecuteAnyAsync(token);
			Assert.True(await Held(first) && await Held(second));

			var result = await _harness.Receiver.Receive(channel.Post(Harness.Host, "/human-centipede", new JsonObject
			{
				["type"] = "Delete", ["actor"] = channel.Id,
				["object"] = new JsonObject { ["id"] = new JsonArray(IdOf(first), IdOf(second)), ["type"] = "Audio" }
			}), default, token);
			Assert.Equal(202, result.StatusCode);
			var listed = IdOf(first);
			var job = await DB.Default.Find<PrivaPub.Models.Jobs.Job>().Match(j => j.Kind == PrivaPub.Models.Jobs.JobKind.ProcessInbox
				&& j.State == PrivaPub.Models.Jobs.JobState.Pending && j.Payload.Contains(listed)).Sort(j => j.CreatedAt, MongoDB.Entities.Order.Descending)
				.ExecuteFirstAsync(token);
			await _harness.Processor.Handle(job, token);

			Assert.False(await Held(first));
			Assert.False(await Held(second));
		}

		[Fact]
		public async Task A_like_naming_a_post_by_its_page_counts_and_its_undo_too()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var fan = new RemoteActor(_harness.Peer, "fan");
			var post = (await _harness.Statuses.Publish(alice, new StatusDraft { Text = "a picture" }, token)).Post;
			var page = alice.PostHtmlUrl(post.ID);
			Assert.NotEqual(post.ObjectURI, page);
			var like = new JsonObject { ["id"] = NewId(fan, "likes"), ["type"] = "Like", ["actor"] = fan.Id, ["object"] = page };

			await _harness.Deliver(fan, "/human-centipede", like);
			Assert.Equal("accepted", Processed("Like").Outcome);
			Assert.Equal(1, (await DB.Default.Find<Post>().OneAsync(post.ID, token)).FavouritesCount);
			await _harness.Deliver(fan, "/human-centipede", Activity(fan, "Undo", like));
			Assert.Equal(0, (await DB.Default.Find<Post>().OneAsync(post.ID, token)).FavouritesCount);

			// a page that is no post of ours stays as it is
			var elsewhere = new JsonObject { ["id"] = NewId(fan, "likes"), ["type"] = "Like", ["actor"] = fan.Id, ["object"] = alice.PostHtmlUrl("000000000000000000000000") };
			await _harness.Deliver(fan, "/human-centipede", elsewhere);
			Assert.Equal(("dropped", "unknown-object"), (Processed("Like").Outcome, Processed("Like").Reason));
		}

		[Fact]
		public async Task An_actor_update_refreshes_the_account_from_its_origin_even_when_its_updated_is_older()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var bob = new RemoteActor(_harness.Peer, "bob");
			await _harness.Deliver(bob, "/human-centipede", Follow(bob, alice.Uri));
			var before = await Stored(bob);
			using var rotated = RSA.Create(2048);
			var document = bob.Document();
			document["name"] = "Bob Renamed";
			document["summary"] = "<p>a new bio<script>alert(1)</script></p>";
			document["publicKey"]!["publicKeyPem"] = rotated.ExportSubjectPublicKeyInfoPem();
			_harness.Peer.Serve(new Uri(bob.Id).AbsolutePath, document.ToJsonString());
			var embedded = (JsonObject)document.DeepClone();
			embedded["name"] = "What the activity claims";
			embedded["updated"] = "2001-01-01T00:00:00Z";

			var result = await _harness.Deliver(bob, "/human-centipede", Activity(bob, "Update", embedded));

			var after = await Stored(bob);
			Assert.Equal(202, result.StatusCode);
			Assert.Null(before.Name);
			Assert.Equal(before.ID, after.ID);
			Assert.Equal("Bob Renamed", after.Name);
			Assert.Equal("<p>a new bio</p>", after.Biography);
			Assert.Equal(bob.KeyId, after.PublicKeyId);
			Assert.NotEqual(before.PublicKey, after.PublicKey);
			Assert.Equal(rotated.ExportSubjectPublicKeyInfoPem(), after.PublicKey);
			Assert.Equal(("accepted", "actor-refresh"), (Processed("Update").Outcome, Processed("Update").Reason));
		}

		[Fact]
		public async Task A_key_moved_to_a_new_id_replaces_the_old_one()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var bob = new RemoteActor(_harness.Peer, "bob");
			await _harness.Deliver(bob, "/human-centipede", Follow(bob, alice.Uri));
			using var rotated = RSA.Create(2048);
			var document = bob.Document();
			document["publicKey"] = new JsonObject { ["id"] = bob.Id + "#key-2", ["owner"] = bob.Id, ["publicKeyPem"] = rotated.ExportSubjectPublicKeyInfoPem() };
			_harness.Peer.Serve(new Uri(bob.Id).AbsolutePath, document.ToJsonString());

			await _harness.Deliver(bob, "/human-centipede", Activity(bob, "Update", JsonValue.Create(bob.Id)!));

			var after = await Stored(bob);
			Assert.Equal(bob.Id + "#key-2", after.PublicKeyId);
			Assert.Equal(rotated.ExportSubjectPublicKeyInfoPem(), after.PublicKey);
		}

		[Fact]
		public async Task Undoing_a_follow_removes_the_follower_by_the_activity_id_or_by_its_object()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var bob = new RemoteActor(_harness.Peer, "bob");
			var carol = new RemoteActor(_harness.Peer, "carol");
			var bobFollows = Follow(bob, alice.Uri);
			await _harness.Deliver(bob, "/human-centipede", bobFollows);
			await _harness.Deliver(carol, "/human-centipede", Follow(carol, alice.Uri));
			Assert.Equal(2, await DB.Default.CountAsync<Follower>(f => f.LocalActorId == alice.Id, token));

			await _harness.Deliver(bob, "/human-centipede", Activity(bob, "Undo", JsonValue.Create(IdOf(bobFollows))!));
			Assert.False(await DB.Default.Find<Follower>().Match(f => f.LocalActorId == alice.Id && f.ActorURI == bob.Id).ExecuteAnyAsync(token));
			Assert.Equal(("accepted", "undone"), (Processed("Undo").Outcome, Processed("Undo").Reason));

			var forgotten = Follow(carol, alice.Uri);
			forgotten["id"] = NewId(carol, "follows");
			await _harness.Deliver(carol, "/human-centipede", Activity(carol, "Undo", forgotten));
			Assert.False(await DB.Default.Find<Follower>().Match(f => f.LocalActorId == alice.Id).ExecuteAnyAsync(token));

			await _harness.Deliver(carol, "/human-centipede", Activity(carol, "Undo", forgotten));
			Assert.Equal(("dropped", "unknown-object"), (Processed("Undo").Outcome, Processed("Undo").Reason));
		}

		[Fact]
		public async Task A_rejected_quote_request_marks_the_quote_rejected_and_only_the_quoted_author_can_reject_it()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var ann = new RemoteActor(_harness.Peer, "ann");
			var mallory = new RemoteActor(_harness.Peer, "mallory");
			var note = PublicNote(ann, "<p>ask me first</p>", alice.Uri);
			note["tag"] = new JsonArray(new JsonObject { ["type"] = "Mention", ["href"] = alice.Uri, ["name"] = "@alice" });
			note["interactionPolicy"] = new JsonObject { ["canQuote"] = new JsonObject { ["manualApproval"] = new JsonArray(Addressing.Public) } };
			await _harness.Deliver(ann, "/human-centipede", Create(ann, note));
			var original = await DB.Default.Find<Post>().Match(p => p.ObjectURI == IdOf(note)).ExecuteSingleAsync(token);
			var outcome = await _harness.Statuses.Publish(alice, new StatusDraft { Text = "may I?", QuotedStatusId = original.ID }, token);
			Assert.Equal(QuoteState.Pending, outcome.Post.QuoteState);
			var request = Assert.Single(await _harness.Outgoing(ann.Id + "/inbox"), a => a["type"]!.GetValue<string>() == "QuoteRequest");

			await _harness.Deliver(mallory, "/human-centipede", Activity(mallory, "Reject", JsonValue.Create(IdOf(request))!));
			Assert.Equal(QuoteState.Pending, (await DB.Default.Find<Post>().OneAsync(outcome.Post.ID, token)).QuoteState);

			await _harness.Deliver(ann, "/human-centipede", Activity(ann, "Reject", request));

			var quoting = await DB.Default.Find<Post>().OneAsync(outcome.Post.ID, token);
			Assert.Equal(QuoteState.Rejected, quoting.QuoteState);
			Assert.Null(quoting.QuoteAuthorizationURI);
			Assert.Equal(0, (await DB.Default.Find<Post>().OneAsync(original.ID, token)).QuotesCount);
			Assert.Equal(("accepted", "quote-answer"), (Processed("Reject").Outcome, Processed("Reject").Reason));
		}

		[Fact]
		public async Task A_vote_a_followed_community_relays_counts_and_its_undo_takes_it_back()
		{
			var token = TestContext.Current.CancellationToken;
			var (root, alice) = await _harness.Persona("alice");
			var community = new RemoteActor(_harness.Peer, "cats", type: "Group");
			var stranger = new RemoteActor(_harness.Peer, "dogs", type: "Group");
			var poster = new RemoteActor(_harness.Peer, "poster");
			var voter = new RemoteActor(_harness.Peer, "voter");
			await _harness.Follows.Follow(root, new FollowForm { AvatarId = alice.Id, Target = community.Id }, token);
			await DB.Default.Update<Following>().Match(f => f.AvatarId == alice.Id).Modify(f => f.State, FollowState.Accepted).ExecuteAsync(token);
			var page = PublicNote(poster, "<p>a post</p>", community.Id);
			page["type"] = "Page";
			page["name"] = "a title";
			page["audience"] = community.Id;
			_harness.Peer.Serve(new Uri(IdOf(page)).AbsolutePath, page.ToJsonString());
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", Create(poster, page)));
			var post = await DB.Default.Find<Post>().Match(p => p.ObjectURI == IdOf(page)).ExecuteSingleAsync(token);
			var like = new JsonObject { ["id"] = NewId(voter, "likes"), ["type"] = "Like", ["actor"] = voter.Id, ["object"] = post.ObjectURI, ["audience"] = community.Id };

			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", like));
			var liked = Processed("Announce");
			Assert.Equal(1, (await DB.Default.Find<Post>().OneAsync(post.ID, token)).FavouritesCount);
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", Activity(voter, "Undo", like)));
			var unliked = Processed("Announce");
			await _harness.Deliver(stranger, "/human-centipede", Activity(stranger, "Announce", like));
			var unfollowed = Processed("Announce");

			//Lemmy relays its members' votes inside the community's Announce (G-0003): a voter on the community's own server
			//is vouched for by it, and the vote is handled as if the voter had sent it; a community nobody follows is ignored
			Assert.Equal("accepted", liked.Outcome);
			Assert.Equal("accepted", unliked.Outcome);
			Assert.Equal(("dropped", "not-followed"), (unfollowed.Outcome, unfollowed.Reason));
			var after = await DB.Default.Find<Post>().OneAsync(post.ID, token);
			Assert.Equal(0, after.FavouritesCount);
			Assert.False(await DB.Default.Find<Favourite>().Match(f => f.PostId == post.ID).ExecuteAnyAsync(token));
		}

		// Lemmy sends a vote to the community alone: a vote on our reply in a thread of a community nobody here follows still
		// reaches us through it, and only through that community (found by the town's village)
		[Fact]
		public async Task A_vote_on_our_reply_in_an_unfollowed_communitys_thread_counts_through_that_community_only()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var community = new RemoteActor(_harness.Peer, "cats", type: "Group");
			var other = new RemoteActor(_harness.Peer, "dogs", type: "Group");
			var poster = new RemoteActor(_harness.Peer, "poster");
			var voter = new RemoteActor(_harness.Peer, "voter");
			var page = PublicNote(poster, "<p>a thread</p>", community.Id);
			page["type"] = "Page";
			page["name"] = "a thread";
			page["audience"] = community.Id;
			_harness.Peer.Serve(new Uri(IdOf(page)).AbsolutePath, page.ToJsonString());
			var root = await _harness.RemotePosts.StoreContext(IdOf(page), 0, token);
			Assert.Equal(community.Id, root.AudienceURI);
			var reply = (await _harness.Statuses.Publish(alice, new StatusDraft { Text = "my answer", InReplyTo = root.ID }, token)).Post;
			var like = new JsonObject { ["id"] = NewId(voter, "likes"), ["type"] = "Like", ["actor"] = voter.Id, ["object"] = reply.ObjectURI };

			await _harness.Deliver(other, "/human-centipede", Activity(other, "Announce", like));
			Assert.Equal(("dropped", "not-followed"), (Processed("Announce").Outcome, Processed("Announce").Reason));
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", like));
			Assert.Equal("accepted", Processed("Announce").Outcome);
			Assert.Equal(1, (await DB.Default.Find<Post>().OneAsync(reply.ID, token)).FavouritesCount);
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", Activity(voter, "Undo", like)));
			Assert.Equal(0, (await DB.Default.Find<Post>().OneAsync(reply.ID, token)).FavouritesCount);
		}

		// PieFed moves a post to another community, and the community it leaves relays the Move: the post's thread goes with it
		[Fact]
		public async Task A_post_moved_to_another_community_takes_its_thread_along()
		{
			var token = TestContext.Current.CancellationToken;
			var (root, alice) = await _harness.Persona("alice");
			var community = new RemoteActor(_harness.Peer, "cats", type: "Group");
			var other = new RemoteActor(_harness.Peer, "dogs", type: "Group");
			var poster = new RemoteActor(_harness.Peer, "poster");
			await _harness.Follows.Follow(root, new FollowForm { AvatarId = alice.Id, Target = community.Id }, token);
			await DB.Default.Update<Following>().Match(f => f.AvatarId == alice.Id).Modify(f => f.State, FollowState.Accepted).ExecuteAsync(token);
			async Task<Post> Announced(JsonObject note)
			{
				note["audience"] = community.Id;
				_harness.Peer.Serve(new Uri(IdOf(note)).AbsolutePath, note.ToJsonString());
				await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", Create(poster, note)));
				return await DB.Default.Find<Post>().Match(p => p.ObjectURI == IdOf(note)).ExecuteSingleAsync(token);
			}
			var page = PublicNote(poster, "<p>misplaced</p>", community.Id);
			page["type"] = "Page";
			page["name"] = "misplaced";
			var post = await Announced(page);
			var comment = PublicNote(poster, "<p>a comment</p>", community.Id);
			comment["inReplyTo"] = IdOf(page);
			var answer = await Announced(comment);
			var move = new JsonObject
			{
				["id"] = NewId(poster, "moves"), ["type"] = "Move", ["actor"] = poster.Id, ["object"] = post.ObjectURI, ["origin"] = community.Id, ["target"] = other.Id
			};

			// only the community it leaves speaks for it
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", new JsonObject
			{
				["id"] = NewId(poster, "moves"), ["type"] = "Move", ["actor"] = poster.Id, ["object"] = post.ObjectURI, ["origin"] = other.Id, ["target"] = community.Id
			}));
			Assert.Equal(("dropped", "unsupported"), (Processed("Announce").Outcome, Processed("Announce").Reason));
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", move));
			Assert.Equal(("accepted", "moved"), (Processed("Announce").Outcome, Processed("Announce").Reason));
			Assert.Equal(other.Id, (await DB.Default.Find<Post>().OneAsync(post.ID, token)).AudienceURI);
			Assert.Equal(other.Id, (await DB.Default.Find<Post>().OneAsync(answer.ID, token)).AudienceURI);
		}

		// Lemmy's moderators lock a community's post and ban members, and the community relays both inside its Announce
		// (G-0006): a locked post takes no reply, a banned persona posts nothing there, until the Undo
		[Fact]
		public async Task A_community_locks_a_post_and_bans_a_persona_until_it_undoes_either()
		{
			var token = TestContext.Current.CancellationToken;
			var (root, alice) = await _harness.Persona("alice");
			var community = new RemoteActor(_harness.Peer, "cats", type: "Group");
			var poster = new RemoteActor(_harness.Peer, "poster");
			var moderator = new RemoteActor(_harness.Peer, "moderator");
			await _harness.Follows.Follow(root, new FollowForm { AvatarId = alice.Id, Target = community.Id }, token);
			await DB.Default.Update<Following>().Match(f => f.AvatarId == alice.Id).Modify(f => f.State, FollowState.Accepted).ExecuteAsync(token);
			JsonObject Page(string text, bool commentsEnabled = true)
			{
				var page = PublicNote(poster, $"<p>{text}</p>", community.Id);
				page["type"] = "Page";
				page["name"] = text;
				page["audience"] = community.Id;
				page["commentsEnabled"] = commentsEnabled;
				_harness.Peer.Serve(new Uri(IdOf(page)).AbsolutePath, page.ToJsonString());
				return page;
			}
			async Task<Post> Announced(JsonObject page)
			{
				await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", Create(poster, page)));
				return await DB.Default.Find<Post>().Match(p => p.ObjectURI == IdOf(page)).ExecuteSingleAsync(token);
			}
			Task<StatusOutcome> Reply(Post post) => _harness.Statuses.Publish(alice, new StatusDraft { Text = "a reply", InReplyTo = post.ID }, token);
			var post = await Announced(Page("a thread"));
			var lockIt = new JsonObject { ["id"] = NewId(moderator, "locks"), ["type"] = "Lock", ["actor"] = moderator.Id, ["object"] = post.ObjectURI };

			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", lockIt));
			Assert.Equal(("accepted", "locked"), (Processed("Announce").Outcome, Processed("Announce").Reason));
			var refused = await Reply(post);
			Assert.Equal((422, "Validation failed: This thread is locked"), (refused.Status, refused.Error));
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", Activity(moderator, "Undo", lockIt)));
			Assert.Null((await DB.Default.Find<Post>().OneAsync(post.ID, token)).LockedAt);
			Assert.True((await Reply(post)).Ok);
			// a post its community serves locked arrives locked
			Assert.NotNull((await Announced(Page("born locked", commentsEnabled: false))).LockedAt);

			var ban = new JsonObject { ["id"] = NewId(moderator, "bans"), ["type"] = "Block", ["actor"] = moderator.Id, ["object"] = alice.Uri, ["target"] = community.Id };
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", ban));
			Assert.Equal(("accepted", "banned"), (Processed("Announce").Outcome, Processed("Announce").Reason));
			var banned = await Reply(post);
			Assert.Equal((422, "Validation failed: This community banned you"), (banned.Status, banned.Error));
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", Activity(moderator, "Undo", ban)));
			Assert.Equal(("accepted", "unbanned"), (Processed("Announce").Outcome, Processed("Announce").Reason));
			Assert.True((await Reply(post)).Ok);

			// Lemmy also sends the ban straight to the persona's server, as its moderator's Block: still the community's ban,
			// never the moderator's own block of the persona
			var direct = new JsonObject { ["id"] = NewId(moderator, "bans"), ["type"] = "Block", ["actor"] = moderator.Id, ["object"] = alice.Uri, ["target"] = community.Id };
			await _harness.Deliver(moderator, "/human-centipede", direct);
			Assert.Equal(("accepted", "banned"), (Processed("Block").Outcome, Processed("Block").Reason));
			Assert.False(await DB.Default.Find<BlockedBy>().Match(b => b.AvatarId == alice.Id && b.ActorURI == moderator.Id).ExecuteAnyAsync(token));
			Assert.Equal(422, (await Reply(post)).Status);
			await _harness.Deliver(moderator, "/human-centipede", Activity(moderator, "Undo", direct));
			Assert.True((await Reply(post)).Ok);

			var elsewhere = new JsonObject { ["id"] = NewId(moderator, "bans"), ["type"] = "Block", ["actor"] = moderator.Id, ["object"] = poster.Id, ["target"] = community.Id };
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", elsewhere));
			Assert.Equal(("dropped", "not-ours"), (Processed("Announce").Outcome, Processed("Announce").Reason));
		}

		// a voter on another server than the community is believed for the community's own posts, as Lemmy trusts it; for
		// anything else only once its vote is fetched from its own origin
		[Fact]
		public async Task A_relayed_vote_from_another_server_counts_on_the_communitys_posts_and_elsewhere_only_once_fetched()
		{
			var token = TestContext.Current.CancellationToken;
			var (root, alice) = await _harness.Persona("alice");
			var community = new RemoteActor(_harness.Peer, "cats", type: "Group");
			var poster = new RemoteActor(_harness.Peer, "poster");
			var voter = new RemoteActor(_harness.Peer, "voter", origin: _harness.Peer.B);
			var forger = new RemoteActor(_harness.Peer, "forger", origin: _harness.Peer.B);
			await _harness.Follows.Follow(root, new FollowForm { AvatarId = alice.Id, Target = community.Id }, token);
			await DB.Default.Update<Following>().Match(f => f.AvatarId == alice.Id).Modify(f => f.State, FollowState.Accepted).ExecuteAsync(token);
			var page = PublicNote(poster, "<p>a post</p>", community.Id);
			page["type"] = "Page";
			page["name"] = "a title";
			_harness.Peer.Serve(new Uri(IdOf(page)).AbsolutePath, page.ToJsonString());
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", Create(poster, page)));
			var post = await DB.Default.Find<Post>().Match(p => p.ObjectURI == IdOf(page)).ExecuteSingleAsync(token);
			var other = await OwnPost(alice, token);
			var like = new JsonObject { ["id"] = NewId(voter, "likes"), ["type"] = "Like", ["actor"] = voter.Id, ["object"] = post.ObjectURI };
			var forged = new JsonObject { ["id"] = NewId(forger, "likes"), ["type"] = "Like", ["actor"] = forger.Id, ["object"] = other.ObjectURI };

			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", like));
			await _harness.Deliver(community, "/human-centipede", Activity(community, "Announce", forged));

			Assert.Equal(1, (await DB.Default.Find<Post>().OneAsync(post.ID, token)).FavouritesCount);
			Assert.True(await DB.Default.Find<Favourite>().Match(f => f.PostId == post.ID && f.ActorURI == voter.Id).ExecuteAnyAsync(token));
			Assert.Equal(("dropped", "fetch-failed"), (Processed("Announce").Outcome, Processed("Announce").Reason));
			Assert.Equal(0, (await DB.Default.Find<Post>().OneAsync(other.ID, token)).FavouritesCount);
		}

		// a public post of a persona's own, outside any community
		static async Task<Post> OwnPost(PrivaPub.Federation.Actors.LocalActor author, CancellationToken token)
		{
			var post = new Post { GroupUserId = author.Id, AuthorAccountId = author.Id, Text = "not the community's" };
			post.ID = (string)post.GenerateNewID();
			post.ObjectURI = author.PostUri(post.ID);
			await DB.Default.SaveAsync(post, token);
			return post;
		}

		[Fact]
		public async Task A_locked_persona_holds_a_follow_until_it_decides_and_answers_with_the_original_follow()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, open) = await _harness.Persona("alice");
			await DB.Default.Update<Avatar>().MatchID(open.Id).Modify(a => a.Settings.IsLocked, true).ExecuteAsync(token);
			var alice = await _harness.Local.FindById(LocalActorKind.Person, open.Id, token);
			var bob = new RemoteActor(_harness.Peer, "bob");
			var carol = new RemoteActor(_harness.Peer, "carol");
			var bobFollows = Follow(bob, alice.Uri);
			var carolFollows = Follow(carol, alice.Uri);
			Assert.True(alice.ManuallyApprovesFollowers);

			await _harness.Deliver(bob, "/human-centipede", bobFollows);
			await _harness.Deliver(carol, "/human-centipede", carolFollows);

			var pending = await DB.Default.Find<Follower>().Match(f => f.LocalActorId == alice.Id).ExecuteAsync(token);
			Assert.Equal(2, pending.Count);
			Assert.All(pending, f => Assert.False(f.IsAccepted));
			Assert.Equal(("accepted", "pending"), (Processed("Follow").Outcome, Processed("Follow").Reason));
			var requests = await DB.Default.Find<Notification>().Match(n => n.AvatarId == alice.Id).ExecuteAsync(token);
			Assert.Equal(2, requests.Count);
			Assert.All(requests, n => Assert.Equal(NotificationType.FollowRequest, n.Type));
			Assert.Empty(await _harness.Outgoing(bob.Id + "/inbox"));
			Assert.Empty(await _harness.Delivery.FollowerInboxes(alice, token));

			var bobAccount = await Stored(bob);
			var carolAccount = await Stored(carol);
			Assert.True(await _harness.Follows.Decide(alice, bobAccount.ID, accept: true, token));
			Assert.True(await _harness.Follows.Decide(alice, carolAccount.ID, accept: false, token));
			Assert.False(await _harness.Follows.Decide(alice, carolAccount.ID, accept: true, token));

			var accept = Assert.Single(await _harness.Outgoing(bob.Id + "/inbox"));
			Assert.Equal("Accept", accept["type"]!.GetValue<string>());
			Assert.Equal(alice.Uri, accept["actor"]!.GetValue<string>());
			Assert.Equal(IdOf(bobFollows), IdOf(accept["object"]!));
			Assert.Equal(bob.Id, accept["object"]!["actor"]!.GetValue<string>());
			var reject = Assert.Single(await _harness.Outgoing(carol.Id + "/inbox"));
			Assert.Equal("Reject", reject["type"]!.GetValue<string>());
			Assert.Equal(IdOf(carolFollows), IdOf(reject["object"]!));
			Assert.True((await DB.Default.Find<Follower>().Match(f => f.LocalActorId == alice.Id && f.ActorURI == bob.Id).ExecuteSingleAsync(token)).IsAccepted);
			Assert.False(await DB.Default.Find<Follower>().Match(f => f.LocalActorId == alice.Id && f.ActorURI == carol.Id).ExecuteAnyAsync(token));
			Assert.Contains(await DB.Default.Find<Notification>().Match(n => n.AvatarId == alice.Id && n.Type == NotificationType.Follow).ExecuteAsync(token),
				n => n.FromAccountId == bobAccount.ID);
			Assert.Equal(new[] { bob.Id + "/inbox" }, await _harness.Delivery.FollowerInboxes(alice, token));
		}
	}
}