Add message editing command

Signed-off-by: Ske <voltasalt@gmail.com>

PluralKit.Bot/Commands/CommandTree.cs

@@ -79,6 +79,7 @@ namespace PluralKit.Bot
         public static Command Help = new Command("help", "help", "Shows help information about PluralKit");
         public static Command Explain = new Command("explain", "explain", "Explains the basics of systems and proxying");
         public static Command Message = new Command("message", "message <id|link> [delete|author]", "Looks up a proxied message");
+        public static Command MessageEdit = new Command("edit", "edit [link] <text>", "Edit a previously proxied message");
         public static Command LogChannel = new Command("log channel", "log channel <channel>", "Designates a channel to post proxied messages to");
         public static Command LogChannelClear = new Command("log channel", "log channel -clear", "Clears the currently set log channel");
         public static Command LogEnable = new Command("log enable", "log enable all|<channel> [channel 2] [channel 3...]", "Enables message logging in certain channels");
@@ -160,6 +161,8 @@ namespace PluralKit.Bot
                 return ctx.Execute<Help>(Explain, m => m.Explain(ctx));
             if (ctx.Match("message", "msg"))
                 return ctx.Execute<Misc>(Message, m => m.GetMessage(ctx));
+            if (ctx.Match("edit", "e"))
+                return ctx.Execute<MessageEdit>(MessageEdit, m => m.EditMessage(ctx));
             if (ctx.Match("log"))
                 if (ctx.Match("channel"))
                     return ctx.Execute<ServerConfig>(LogChannel, m => m.SetLogChannel(ctx));

PluralKit.Bot/Commands/MessageEdit.cs

@@ -0,0 +1,91 @@
+#nullable enable
+using System.Threading.Tasks;
+
+using Myriad.Rest;
+using Myriad.Rest.Exceptions;
+using Myriad.Types;
+
+using NodaTime;
+
+using PluralKit.Core;
+
+namespace PluralKit.Bot
+{
+    public class MessageEdit
+    {
+        private static readonly Duration EditTimeout = Duration.FromMinutes(10);
+        
+        private readonly IDatabase _db;
+        private readonly ModelRepository _repo;
+        private readonly IClock _clock;
+        private readonly DiscordApiClient _rest;
+        private readonly WebhookExecutorService _webhookExecutor;
+
+        public MessageEdit(IDatabase db, ModelRepository repo, IClock clock, DiscordApiClient rest, WebhookExecutorService webhookExecutor)
+        {
+            _db = db;
+            _repo = repo;
+            _clock = clock;
+            _rest = rest;
+            _webhookExecutor = webhookExecutor;
+        }
+
+        public async Task EditMessage(Context ctx)
+        {
+            var msg = await GetMessageToEdit(ctx);
+            if (!ctx.HasNext())
+                throw new PKSyntaxError("You need to include the message to edit in.");
+
+            if (ctx.Author.Id != msg.Sender)
+                throw new PKError("Can't edit a message sent from a different account.");
+            
+            var newContent = ctx.RemainderOrNull();
+
+            try
+            {
+                await _webhookExecutor.EditWebhookMessage(msg.Channel, msg.Mid, newContent);
+                
+                if (ctx.BotPermissions.HasFlag(PermissionSet.ManageMessages))
+                    await _rest.DeleteMessage(ctx.Channel.Id, ctx.Message.Id);
+            }
+            catch (NotFoundException)
+            {
+                throw new PKError("Could not edit message.");
+            }
+        }
+        
+        private async Task<PKMessage> GetMessageToEdit(Context ctx)
+        {
+            var referencedMessage = ctx.MatchMessage(false);
+            if (referencedMessage != null)
+            {
+                await using var conn = await _db.Obtain();
+                var msg = await _repo.GetMessage(conn, referencedMessage.Value);
+                if (msg == null)
+                    throw new PKError("This is not a message proxied by PluralKit.");
+                
+                return msg.Message;
+            }
+
+            var recent = await FindRecentMessage(ctx);
+            if (recent == null)
+                throw new PKError("Could not find a recent message to edit.");
+            
+            return recent;
+        }
+
+        private async Task<PKMessage?> FindRecentMessage(Context ctx)
+        {
+            await using var conn = await _db.Obtain();
+            var lastMessage = await _repo.GetLastMessage(conn, ctx.Guild.Id, ctx.Channel.Id, ctx.Author.Id);
+            if (lastMessage == null)
+                return null;
+            
+            var timestamp = DiscordUtils.SnowflakeToInstant(lastMessage.Mid);
+            if (_clock.GetCurrentInstant() - timestamp > EditTimeout)
+                return null;
+
+            return lastMessage;
+        }
+    }
+}

PluralKit.Bot/Commands/Misc.cs

@@ -215,17 +215,16 @@ namespace PluralKit.Bot {
         
         public async Task GetMessage(Context ctx)
         {
-            var word = ctx.PopArgument() ?? throw new PKSyntaxError("You must pass a message ID or link.");
-
-            ulong messageId;
-            if (ulong.TryParse(word, out var id))
-                messageId = id;
-            else if (Regex.Match(word, "https://(?:\\w+.)?discord(?:app)?.com/channels/\\d+/\\d+/(\\d+)") is Match match && match.Success)
-                messageId = ulong.Parse(match.Groups[1].Value);
-            else throw new PKSyntaxError($"Could not parse {word.AsCode()} as a message ID or link.");
-
-            var message = await _db.Execute(c => _repo.GetMessage(c, messageId));
-            if (message == null) throw Errors.MessageNotFound(messageId);
+            var messageId = ctx.MatchMessage(true);
+            if (messageId == null)
+            {
+                if (!ctx.HasNext())
+                    throw new PKSyntaxError("You must pass a message ID or link.");
+                throw new PKSyntaxError($"Could not parse {ctx.PeekArgument().AsCode()} as a message ID or link.");
+            }
+            
+            var message = await _db.Execute(c => _repo.GetMessage(c, messageId.Value));
+            if (message == null) throw Errors.MessageNotFound(messageId.Value);
 
             if (ctx.Match("delete") || ctx.MatchFlag("delete"))
             {