feat: Support for deleting bot messages

Author: Gerrit0

src/modules/etc.ts

@@ -4,7 +4,8 @@ import {
 	Module,
 	listener,
 } from 'cookiecord';
-import { Message } from 'discord.js';
+import { Message, MessageReaction, GuildMember } from 'discord.js';
+import { clearMessageOwnership, ownsBotMessage } from '../util/send';
 
 export class EtcModule extends Module {
 	constructor(client: CookiecordClient) {
@@ -39,4 +40,15 @@ export class EtcModule extends Module {
 		await msg.react('❌');
 		await msg.react('🤷');
 	}
+
+	@listener({ event: 'messageReactionAdd' })
+	async onReact(reaction: MessageReaction, member: GuildMember) {
+		if (
+			reaction.emoji.name === '❌' &&
+			ownsBotMessage(reaction.message, member)
+		) {
+			clearMessageOwnership(reaction.message);
+			await reaction.message.delete();
+		}
+	}
 }

src/modules/twoslash.ts

@@ -2,6 +2,7 @@ import { command, Module, listener } from 'cookiecord';
 import { Message, TextChannel } from 'discord.js';
 import { twoslasher } from '@typescript/twoslash';
 import { findCodeFromChannel } from '../util/findCodeblockFromChannel';
+import { sendWithMessageOwnership } from '../util/send';
 
 const CODEBLOCK = '```';
 
@@ -15,18 +16,19 @@ export class TwoslashModule extends Module {
 		const match = /^[_$a-zA-Z][_$0-9a-zA-Z]*/.exec(content);
 
 		if (!match) {
-			msg.channel.send(
+			return sendWithMessageOwnership(
+				msg,
 				'You need to give me a valid symbol name to look for!',
 			);
-			return;
 		}
 
 		const symbol = match[0];
 
 		const code = await findCodeFromChannel(msg.channel as TextChannel);
 
 		if (!code)
-			return msg.channel.send(
+			return sendWithMessageOwnership(
+				msg,
 				`:warning: could not find any TypeScript codeblocks in the past 10 messages`,
 			);
 
@@ -38,11 +40,13 @@ export class TwoslashModule extends Module {
 			i => i.targetString === symbol.trim(),
 		);
 		if (!value)
-			return msg.channel.send(
+			return sendWithMessageOwnership(
+				msg,
 				`:warning: no symbol named \`${symbol}\` in the most recent codeblock`,
 			);
 
-		return msg.channel.send(
+		await sendWithMessageOwnership(
+			msg,
 			`${CODEBLOCK}typescript\n${value.text}${CODEBLOCK}`,
 		);
 	}
@@ -55,7 +59,8 @@ export class TwoslashModule extends Module {
 		const code = await findCodeFromChannel(msg.channel as TextChannel);
 
 		if (!code)
-			return msg.channel.send(
+			return sendWithMessageOwnership(
+				msg,
 				`:warning: could not find any TypeScript codeblocks in the past 10 messages`,
 			);
 
@@ -131,6 +136,9 @@ export class TwoslashModule extends Module {
 		});
 
 		const output = resultLines.join('\n');
-		return msg.channel.send(`${CODEBLOCK}ts\n${output}${CODEBLOCK}\n`);
+		return sendWithMessageOwnership(
+			msg,
+			`${CODEBLOCK}ts\n${output}${CODEBLOCK}\n`,
+		);
 	}
 }

src/util/send.ts

@@ -0,0 +1,27 @@
+import { Message, MessageEmbed, GuildMember } from 'discord.js';
+
+const MAX_TRACKED_MESSAGES = 1000;
+
+const messageIdToMemberId = new Map<string, string>();
+
+export async function sendWithMessageOwnership(
+	message: Message,
+	toSend: string | MessageEmbed,
+) {
+	const sent = await message.channel.send(toSend);
+	messageIdToMemberId.set(sent.id, message.author.id);
+
+	// Without this memory grows unboundedly... very slowly, but better to avoid the issue.
+	if (messageIdToMemberId.size > MAX_TRACKED_MESSAGES) {
+		// Keys returns an iterable in insertion order, so we remove the oldest message from the map.
+		messageIdToMemberId.delete(messageIdToMemberId.keys().next().value);
+	}
+}
+
+export function ownsBotMessage(message: Message, member: GuildMember) {
+	return messageIdToMemberId.get(message.id) === member.id;
+}
+
+export function clearMessageOwnership(message: Message) {
+	messageIdToMemberId.delete(message.id);
+}