feat: add guildCreate event and server guard utilities (#16)

* feat: add guildCreate event and server guard utilities

* fix: update ephemeral reply flag to use MessageFlags.Ephemeral for better compatibility with Discord.js

Author: wiktoriavh

src/events/guild-create.ts

@@ -0,0 +1,13 @@
+import { Events } from 'discord.js';
+import { createEvent } from '../util/events.js';
+import { leaveIfNotAllowedServer } from '../util/server-guard.js';
+
+export const guildCreateEvent = createEvent(
+  {
+    name: Events.GuildCreate,
+  },
+  async (guild) => {
+    // Leave the server if it's not the allowed one
+    await leaveIfNotAllowedServer(guild);
+  }
+);

src/events/index.ts

@@ -1,3 +1,4 @@
+import { guildCreateEvent } from './guild-create.js';
 import { hasVarEvent } from './has-var.js';
 import { interactionCreateEvent } from './interaction-create.js';
 import { justAskEvent } from './just-ask.js';
@@ -6,6 +7,7 @@ import type { DiscordEvent } from './types.js';
 
 export const events = [
   readyEvent,
+  guildCreateEvent,
   justAskEvent,
   hasVarEvent,
   interactionCreateEvent,

src/events/interaction-create.ts

@@ -1,13 +1,26 @@
-import { Events } from 'discord.js';
+import { Events, MessageFlags } from 'discord.js';
 import { commands } from '../commands/index.js';
 import { createEvent } from '../util/events.js';
+import { isAllowedServer } from '../util/server-guard.js';
 
 export const interactionCreateEvent = createEvent(
   {
     name: Events.InteractionCreate,
   },
   async (interaction) => {
     if (interaction.isChatInputCommand() || interaction.isMessageContextMenuCommand()) {
+      // Block commands from unauthorized servers
+      if (!interaction.guildId || !isAllowedServer(interaction.guildId)) {
+        console.log(`⚠️ Command blocked from unauthorized server: ${interaction.guildId}`);
+        if (interaction.isRepliable()) {
+          await interaction.reply({
+            content: '❌ This bot is not authorized to operate in this server.',
+            flags: MessageFlags.Ephemeral,
+          });
+        }
+        return;
+      }
+
       console.log(`Interaction received: ${interaction.commandName}`);
       const command = commands.get(interaction.commandName);
 

src/events/ready.ts

@@ -3,6 +3,7 @@ import { config } from '../env.js';
 import { fetchAndCachePublicChannelsMessages } from '../util/cache.js';
 import { createEvent } from '../util/events.js';
 import { syncGuidesToChannel } from '../util/post-guides.js';
+import { leaveIfNotAllowedServer } from '../util/server-guard.js';
 
 export const readyEvent = createEvent(
   {
@@ -11,6 +12,13 @@ export const readyEvent = createEvent(
   },
   async (client) => {
     console.log(`Ready! Logged in as ${client.user.tag}`);
+
+    // Check all guilds and leave any unauthorized ones
+    console.log(`🔍 Checking ${client.guilds.cache.size} guild(s)...`);
+    for (const guild of client.guilds.cache.values()) {
+      await leaveIfNotAllowedServer(guild);
+    }
+
     if (config.fetchAndSyncMessages) {
       const guild = client.guilds.cache.get(config.serverId);
       if (guild) {

src/util/server-guard.ts

@@ -0,0 +1,24 @@
+import type { Guild } from 'discord.js';
+import { config } from '../env.js';
+
+/**
+ * Checks if a guild is the allowed server
+ */
+export function isAllowedServer(guildId: string): boolean {
+  return guildId === config.serverId;
+}
+
+/**
+ * Leaves a guild if it's not the allowed server
+ * @returns true if the bot left the guild, false if it stayed
+ */
+export async function leaveIfNotAllowedServer(guild: Guild): Promise<boolean> {
+  if (!isAllowedServer(guild.id)) {
+    console.log(`⚠️ Bot added to unauthorized server: ${guild.name} (${guild.id})`);
+    console.log(`🚪 Leaving server...`);
+    await guild.leave();
+    console.log(`✅ Left unauthorized server: ${guild.name}`);
+    return true;
+  }
+  return false;
+}