Automod: Spam detection

modules/automod/automod.ts

@@ -18,6 +18,7 @@ import { ESTABLISHED_THRESHOLD, getLevelForXp } from "../xp/misc.js";
 import { xpDatabase } from "../xp/util.js";
 import tryCensor, { badWordRegexps, badWordsAllowed } from "./misc.js";
 import { ignoredDeletions } from "../logging/messages.js";
+import { handleMessage } from "./spam.js";
 
 const { threads } = (await config.channels.servers?.threads.fetchActive()) ?? {};
 const whitelistedInvites = await Promise.all(
@@ -61,10 +62,16 @@ const BLACKLISTED_DOMAINS = [
 
 export default async function automodMessage(message: Message): Promise<boolean> {
 	const baseChannel = getBaseChannel(message.channel);
-
 	let needsDelete = false;
 	const deletionMessages: string[] = [];
 
+	const spam = handleMessage(message.author, message.content);
+	if (spam) {
+		await warn(message.author, "Spamming", 1, message.content);
+		needsDelete = true;
+		deletionMessages.push("Please don’t spam!");
+	}
+
 	const animatedEmojis =
 		baseChannel?.id !== config.channels.bots?.id && message.content.match(GlobalAnimatedEmoji);
 	const badAnimatedEmojis =

modules/automod/spam.ts

@@ -0,0 +1,53 @@
+import type { User } from "discord.js";
+import { xpDatabase } from "../xp/util.js";
+import { getLevelForXp } from "../xp/misc.js";
+
+const timeWindow = 20;
+
+type Message = {
+	message: string;
+	timestamp: number;
+};
+const userMessages: Record<string, Message[]> = {};
+function logMessage(userId: string, message: string): void {
+	const timestamp: number = Math.floor(Date.now() / 1000);
+	if (!userMessages[userId]) {
+		userMessages[userId] = [];
+	}
+
+	userMessages[userId]?.push({ message, timestamp });
+
+	userMessages[userId] =
+		userMessages[userId]?.filter((m) => timestamp - m.timestamp <= timeWindow) ?? [];
+}
+
+export function isSpam(user: User, message: string): boolean {
+	const xp = xpDatabase.data.find((entry) => entry.user === user.id)?.xp ?? 0;
+	const level = getLevelForXp(xp);
+	const levelFactor = Math.min(10 * Math.log10(1 + level), 15);
+
+	const x = Math.max(2, Math.round((5 + levelFactor) * (1 - message.length / 2000)));
+
+	const timestamp: number = Math.floor(Date.now() / 1000);
+	console.log(message.length, x, message.length / 400);
+	if ((userMessages[user.id]?.length || 0) < x) {
+		return false;
+	}
+
+	const recentMessages = userMessages[user.id]?.slice(-x);
+
+	return (
+		recentMessages?.every(
+			(m) => m.message === message && timestamp - m.timestamp <= timeWindow,
+		) || false
+	);
+}
+
+export function handleMessage(user: User, message: string): boolean {
+	if (isSpam(user, message)) {
+		return true;
+	} else {
+		logMessage(user.id, message);
+		return false;
+	}
+}