Automatically remove bot's messages when commands are deleted

Author: typeofweb

package-lock.json

@@ -28,6 +28,7 @@
     "dotenv": "8.2.0",
     "erlpack": "github:discordapp/erlpack",
     "isolated-vm": "3.3.3",
+    "node-cache": "5.1.2",
     "node-fetch": "2.6.0",
     "polish-plurals": "1.1.0",
     "request": "2.88.2",

package.json

@@ -6,6 +6,10 @@ import { handleCommand } from './commands';
 import { getConfig } from './config';
 import { InvalidUsageError } from './types';
 
+import Cache from 'node-cache';
+const ONE_HOUR_S = 3600;
+const cache = new Cache({ stdTTL: ONE_HOUR_S });
+
 const client = new Discord.Client();
 const drss = new DiscordRSS.Client({
   database: {
@@ -48,6 +52,10 @@ client.on('debug', (debug) => {
   }
 });
 
+function isCommand(msg: Discord.Message) {
+  return msg.content.startsWith(getConfig('PREFIX'));
+}
+
 client.on('message', async (msg) => {
   if (msg.author.bot) {
     return;
@@ -57,9 +65,15 @@ client.on('message', async (msg) => {
     return msg.channel.send(`┬─┬ノ( ◕◡◕ ノ)`);
   }
 
-  if (msg.content.startsWith(getConfig('PREFIX'))) {
+  if (isCommand(msg)) {
     try {
+      const collector = msg.channel.createMessageCollector(
+        (m: Discord.Message) => m.author.id === client.user.id
+      );
       await handleCommand(msg);
+      const ids = collector.collected.map((m) => m.id);
+      cache.set(msg.id, ids);
+      collector.stop();
     } catch (err) {
       if (err instanceof InvalidUsageError) {
         void msg.reply(err.message);
@@ -75,6 +89,30 @@ client.on('message', async (msg) => {
   return;
 });
 
+async function revertCommand(msg: Discord.Message) {
+  if (!cache.has(msg.id)) {
+    return undefined;
+  }
+  const messagesToDelete = cache.get<string[]>(msg.id)!;
+  return msg.channel.bulkDelete(messagesToDelete);
+}
+
+client.on('messageDelete', async (msg) => {
+  if (msg.author.bot) {
+    return;
+  }
+
+  if (isCommand(msg)) {
+    try {
+      await revertCommand(msg);
+    } catch (err) {
+      errors.push(err);
+    }
+  }
+
+  return;
+});
+
 async function init() {
   await client.login(getConfig('DISCORD_BOT_TOKEN'));
   drss._defineBot(client);

src/app.ts

@@ -24,7 +24,7 @@ import wiki from './wiki';
 
 const COMMAND_PATTERN = new RegExp(getConfig('PREFIX') + '([a-z]+)(?: (.*))?');
 
-const allCommands = {
+const allCommands = [
   co,
   execute,
   link,
@@ -44,7 +44,7 @@ const allCommands = {
   youtube,
   typeofweb,
   wiki,
-};
+];
 
 const cooldowns = new Discord.Collection<string, Discord.Collection<string, number>>();
 const PERMISSION_TO_OVERRIDE_COOLDOWN: PermissionString = 'ADMINISTRATOR';
@@ -86,16 +86,11 @@ async function verifyCooldown(msg: Discord.Message, command: Command) {
 }
 
 function printHelp(msg: Discord.Message, member: Discord.GuildMember) {
-  const commands = Object.entries(allCommands)
-    .sort(([a], [b]) => {
-      if (a > b) {
-        return 1;
-      } else if (a < b) {
-        return -1;
-      }
-      return 1;
+  const commands = allCommands
+    .sort((a, b) => {
+      return a.name.localeCompare(b.name);
     })
-    .filter(([, command]) => {
+    .filter((command) => {
       if (command.permissions && !member.hasPermission(command.permissions)) {
         return false;
       }
@@ -104,8 +99,8 @@ function printHelp(msg: Discord.Message, member: Discord.GuildMember) {
 
   const data = [
     `**Oto lista wszystkich komend:**`,
-    ...commands.map(([name, command]) => {
-      return `**\`${getConfig('PREFIX')}${name}\`** — ${command.description}`;
+    ...commands.map((command) => {
+      return `**\`${getConfig('PREFIX')}${command.name}\`** — ${command.description}`;
     }),
   ];
 
@@ -136,20 +131,19 @@ export async function handleCommand(msg: Discord.Message) {
     return printHelp(msg, member);
   }
 
-  if (!maybeCommand || !(maybeCommand in allCommands)) {
+  const command = allCommands.find((c) => maybeCommand === c.name);
+
+  if (!command || !maybeCommand) {
     return undefined;
   }
 
-  const commandName = maybeCommand as keyof typeof allCommands;
-
-  const command = allCommands[commandName];
   const member = await msg.guild.fetchMember(msg.author);
 
   if (command.permissions && !member.hasPermission(command.permissions)) {
     return undefined; // silence is golden
   }
 
-  void msg.channel.startTyping();
+  msg.channel.startTyping();
 
   if (command.guildOnly && msg.channel.type !== 'text') {
     throw new InvalidUsageError(`to polecenie można wywołać tylko na kanałach.`);