feat: store system UUIDs of banned users per guild

Catalogger.Backend/Api/MetaController.cs

@@ -65,6 +65,10 @@ public class MetaController(
         );
     }
 
+    [HttpGet("coffee")]
+    public IActionResult BrewCoffee() =>
+        Problem("Sorry, I'm a teapot!", statusCode: StatusCodes.Status418ImATeapot);
+
     private record MetaResponse(
         int Guilds,
         string InviteUrl,

Catalogger.Backend/Bot/Responders/Guilds/GuildBanAddResponder.cs

@@ -76,7 +76,12 @@ public class GuildBanAddResponder(
                     evt.GuildID
                 );
 
-                await guildRepository.BanSystemAsync(evt.GuildID, pkSystem.Id, pkSystem.Uuid);
+                await guildRepository.BanSystemAsync(
+                    evt.GuildID,
+                    evt.User.ID,
+                    pkSystem.Id,
+                    pkSystem.Uuid
+                );
             }
 
             embed.AddField(

Catalogger.Backend/Bot/Responders/Guilds/GuildBanRemoveResponder.cs

@@ -67,8 +67,19 @@ public class GuildBanRemoveResponder(
         var pkSystem = await pluralkitApi.GetPluralKitSystemAsync(evt.User.ID.Value, ct);
         if (pkSystem != null)
         {
-            await guildRepository.UnbanSystemAsync(evt.GuildID, pkSystem.Id, pkSystem.Uuid);
+            await guildRepository.UnbanSystemAsync(
+                evt.GuildID,
+                evt.User.ID,
+                pkSystem.Id,
+                pkSystem.Uuid
+            );
 
+            var systemUsers = await guildRepository.GetSystemAccountsAsync(
+                evt.GuildID,
+                pkSystem.Uuid
+            );
+            if (systemUsers.Length == 0)
+            {
                 embed.AddField(
                     "PluralKit system",
                     $"""
@@ -82,6 +93,27 @@ public class GuildBanRemoveResponder(
                     """
                 );
             }
+            else
+            {
+                var users = new List<string>();
+                foreach (var id in systemUsers)
+                    users.Add("- " + await userCache.TryFormatUserAsync(id));
+
+                embed.AddField(
+                    "PluralKit system",
+                    $"""
+                    **ID:** {pkSystem.Id}
+                    **UUID:** `{pkSystem.Uuid}`
+                    **Name:** {pkSystem.Name ?? "*(none)*"}
+                    **Tag:** {pkSystem.Tag ?? "*(none)*"}
+
+                    This system has been unbanned.
+                    Note that the following accounts are known to be linked to this system and banned from this server:
+                    {string.Join("\n", users)}
+                    """
+                );
+            }
+        }
 
         webhookExecutor.QueueLog(
             guildConfig,

Catalogger.Backend/Bot/Responders/Guilds/GuildCreateResponder.cs

@@ -107,14 +107,14 @@ public class GuildCreateResponder(
         }
 
         // Clear the cache for this guild
-        guildCache.Remove(evt.ID, out _);
+        var wasCached = guildCache.Remove(evt.ID, out var guild);
         emojiCache.Remove(evt.ID);
         channelCache.RemoveGuild(evt.ID);
         roleCache.RemoveGuild(evt.ID);
         await memberCache.RemoveAllMembersAsync(evt.ID);
         await inviteCache.RemoveAsync(evt.ID);
 
-        if (!guildCache.TryGet(evt.ID, out var guild))
+        if (!wasCached || guild == null)
         {
             _logger.Information("Left uncached guild {GuildId}", evt.ID);
             return Result.Success;

Catalogger.Backend/CataloggerMetrics.cs

@@ -39,6 +39,11 @@ public static class CataloggerMetrics
         "Number of channels in the cache"
     );
 
+    public static readonly Gauge RolesCached = Metrics.CreateGauge(
+        "catalogger_cache_roles",
+        "Number of roles in the cache"
+    );
+
     public static readonly Gauge UsersCached = Metrics.CreateGauge(
         "catalogger_cache_users",
         "Number of users in the cache"

Catalogger.Backend/Database/Migrations/002_store_pk_systems.down.sql

@@ -0,0 +1 @@
+drop table pluralkit_systems;

Catalogger.Backend/Database/Migrations/002_store_pk_systems.up.sql

@@ -0,0 +1,9 @@
+create table pluralkit_systems (
+    system_id uuid not null,
+    user_id bigint not null,
+    guild_id bigint not null,
+    
+    primary key (system_id, user_id, guild_id)
+);
+
+create index ix_pluralkit_systems_user_guild on pluralkit_systems (user_id, guild_id);

Catalogger.Backend/Database/Repositories/GuildRepository.cs

@@ -15,6 +15,8 @@
 
 using Catalogger.Backend.Database.Models;
 using Dapper;
+using Npgsql.Replication;
+using Remora.Discord.API;
 using Remora.Rest.Core;
 
 namespace Catalogger.Backend.Database.Repositories;
@@ -58,13 +60,30 @@ public class GuildRepository(ILogger logger, DatabaseConnection conn)
             new { Id = id, Channels = new Guild.ChannelConfig() }
         );
 
-    public async Task BanSystemAsync(Snowflake guildId, string hid, Guid uuid) =>
+    public async Task BanSystemAsync(Snowflake guildId, Snowflake userId, string hid, Guid uuid)
+    {
         await conn.ExecuteAsync(
             "update guilds set banned_systems = array_cat(banned_systems, @SystemIds) where id = @GuildId",
             new { GuildId = guildId.Value, SystemIds = (string[])[hid, uuid.ToString()] }
         );
 
-    public async Task UnbanSystemAsync(Snowflake guildId, string hid, Guid uuid) =>
+        await conn.ExecuteAsync(
+            """
+            insert into pluralkit_systems (system_id, user_id, guild_id)
+            values (@SystemId, @UserId, @GuildId)
+            on conflict (system_id, user_id, guild_id) do nothing
+            """,
+            new
+            {
+                SystemId = uuid,
+                UserId = userId.Value,
+                GuildId = guildId.Value,
+            }
+        );
+    }
+
+    public async Task UnbanSystemAsync(Snowflake guildId, Snowflake userId, string hid, Guid uuid)
+    {
         await conn.ExecuteAsync(
             "update guilds set banned_systems = array_remove(array_remove(banned_systems, @Hid), @Uuid) where id = @Id",
             new
@@ -75,6 +94,32 @@ public class GuildRepository(ILogger logger, DatabaseConnection conn)
             }
         );
 
+        await conn.ExecuteAsync(
+            """
+            delete from pluralkit_systems where system_id = @SystemId
+            and user_id = @UserId
+            and guild_id = @GuildId
+            """,
+            new
+            {
+                SystemId = uuid,
+                UserId = userId.Value,
+                GuildId = guildId.Value,
+            }
+        );
+    }
+
+    public async Task<Snowflake[]> GetSystemAccountsAsync(Snowflake guildId, Guid systemId)
+    {
+        var bannedAccounts = await conn.QueryAsync<BannedSystem>(
+            "select * from pluralkit_systems where system_id = @SystemId and guild_id = @GuildId",
+            new { SystemId = systemId, GuildId = guildId.Value }
+        );
+        return bannedAccounts.Select(s => DiscordSnowflake.New(s.UserId)).ToArray();
+    }
+
+    private record BannedSystem(Guid SystemId, ulong UserId, ulong GuildId);
+
     public async Task AddKeyRoleAsync(Snowflake guildId, Snowflake roleId) =>
         await conn.ExecuteAsync(
             "update guilds set key_roles = array_append(key_roles, @RoleId) where id = @GuildId",

Catalogger.Backend/Services/MetricsCollectionService.cs

@@ -26,6 +26,7 @@ public class MetricsCollectionService(
     ILogger logger,
     GuildCache guildCache,
     ChannelCache channelCache,
+    RoleCache roleCache,
     UserCache userCache,
     EmojiCache emojiCache,
     IServiceProvider services
@@ -44,6 +45,7 @@ public class MetricsCollectionService(
 
         CataloggerMetrics.GuildsCached.Set(guildCache.Size);
         CataloggerMetrics.ChannelsCached.Set(channelCache.Size);
+        CataloggerMetrics.RolesCached.Set(roleCache.Size);
         CataloggerMetrics.UsersCached.Set(userCache.Size);
         CataloggerMetrics.EmojiCached.Set(emojiCache.Size);
         CataloggerMetrics.MessagesStored.Set(messageCount);