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);

		[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'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));
		}
	}
}