- Add storing bot response messages in postgres

- Add scheduled task to clean up said store

PluralKit.Bot/Bot.cs

@@ -9,6 +9,8 @@ using App.Metrics;
 
 using Autofac;
 
+using Dapper;
+
 using DSharpPlus;
 using DSharpPlus.Entities;
 using DSharpPlus.EventArgs;
@@ -34,18 +36,21 @@ namespace PluralKit.Bot
         private readonly PeriodicStatCollector _collector;
         private readonly IMetrics _metrics;
         private readonly ErrorMessageService _errorMessageService;
+        private readonly IDatabase _db;
 
         private bool _hasReceivedReady = false;
         private Timer _periodicTask; // Never read, just kept here for GC reasons
 
-        public Bot(DiscordShardedClient client, ILifetimeScope services, ILogger logger, PeriodicStatCollector collector, IMetrics metrics, ErrorMessageService errorMessageService)
+        public Bot(DiscordShardedClient client, ILifetimeScope services, ILogger logger, PeriodicStatCollector collector, IMetrics metrics, 
+            ErrorMessageService errorMessageService, IDatabase db)
         {
             _client = client;
+            _logger = logger.ForContext<Bot>();
             _services = services;
             _collector = collector;
             _metrics = metrics;
             _errorMessageService = errorMessageService;
-            _logger = logger.ForContext<Bot>();
+            _db = db;
         }
 
         public void Init()
@@ -177,6 +182,9 @@ namespace PluralKit.Bot
 
             await UpdateBotStatus();
 
+            // Clean up message cache in postgres
+            await _db.Execute(conn => conn.QueryAsync("select from cleanup_command_message()"));
+
             // Collect some stats, submit them to the metrics backend
             await _collector.CollectStats();
             await Task.WhenAll(((IMetricsRoot) _metrics).ReportRunner.RunAllAsync());

PluralKit.Bot/CommandSystem/Context.cs

@@ -64,7 +64,7 @@ namespace PluralKit.Bot
         internal IDatabase Database => _db;
         internal ModelRepository Repository => _repo;
 
-        public Task<DiscordMessage> Reply(string text = null, DiscordEmbed embed = null, IEnumerable<IMention> mentions = null)
+        public async Task<DiscordMessage> Reply(string text = null, DiscordEmbed embed = null, IEnumerable<IMention> mentions = null)
         {
             if (!this.BotHasAllPermissions(Permissions.SendMessages))
                 // Will be "swallowed" during the error handler anyway, this message is never shown.
@@ -72,7 +72,12 @@ namespace PluralKit.Bot
 
             if (embed != null && !this.BotHasAllPermissions(Permissions.EmbedLinks))
                 throw new PKError("PluralKit does not have permission to send embeds in this channel. Please ensure I have the **Embed Links** permission enabled.");
-            return Channel.SendMessageFixedAsync(text, embed: embed, mentions: mentions);
+            var msg = await Channel.SendMessageFixedAsync(text, embed: embed, mentions: mentions);
+            if (embed != null) 
+                // Sensitive information that might want to be deleted by :x: reaction is typically in an embed format (member cards, for example)
+                // This may need to be changed at some point but works well enough for now
+                await _db.Execute(conn => _repo.SaveCommandMessage(conn, msg.Id, Author.Id));
+            return msg;
         }
         
         public async Task Execute<T>(Command commandDef, Func<T, Task> handler)

PluralKit.Bot/Commands/CommandTree.cs

@@ -189,9 +189,9 @@ namespace PluralKit.Bot
             if (ctx.Match("random", "r"))
                 return ctx.Execute<Member>(MemberRandom, m => m.MemberRandom(ctx));
 
-            ctx.Reply(
+            // remove compiler warning
+            return ctx.Reply(
                 $"{Emojis.Error} Unknown command {ctx.PeekArgument().AsCode()}. For a list of possible commands, see <https://pluralkit.me/commands>.");
-            return Task.CompletedTask;
         }
 
         private async Task HandleSystemCommand(Context ctx)

PluralKit.Core/Database/Database.cs

@@ -19,7 +19,7 @@ namespace PluralKit.Core
     internal class Database: IDatabase
     {
         private const string RootPath = "PluralKit.Core.Database"; // "resource path" root for SQL files
-        private const int TargetSchemaVersion = 10;
+        private const int TargetSchemaVersion = 11;
         
         private readonly CoreConfig _config;
         private readonly ILogger _logger;

PluralKit.Core/Database/Migrations/11.sql

@@ -0,0 +1,17 @@
+-- SCHEMA VERSION 11: (insert date) --
+-- Create command message table --
+
+create table command_message
+(
+	message_id bigint primary key,
+	invoker_id bigint not null,
+	timestamp timestamp not null default now()
+);
+
+create function cleanup_command_message() returns void as $$
+begin
+    delete from command_message where timestamp < now() - interval '1 minute';
+end;
+$$ language plpgsql;
+
+update info set schema_version = 11;

PluralKit.Core/Database/Repository/ModelRepository.CommandMessage.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+using System.Data;
+using System.Threading.Tasks;
+
+using Dapper;
+
+namespace PluralKit.Core
+{
+    public partial class ModelRepository
+	{
+		public Task SaveCommandMessage(IPKConnection conn, ulong message_id, ulong author_id) =>
+			conn.QueryAsync("insert into command_message (message_id, invoker_id) values (@Message, @Author)",
+				new {Message = message_id, Author = author_id });
+	}
+}