sanitize profane usernames

src/core/validations/username.ts

@@ -1,8 +1,41 @@
+import {
+  RegExpMatcher,
+  englishDataset,
+  englishRecommendedTransformers,
+} from "obscenity";
+import { simpleHash } from "../Util";
+
+const matcher = new RegExpMatcher({
+  ...englishDataset.build(),
+  ...englishRecommendedTransformers,
+});
+
 export const MIN_USERNAME_LENGTH = 3;
 export const MAX_USERNAME_LENGTH = 20;
 
 const validPattern = /^[a-zA-Z0-9_ ]+$/;
 
+const shadowNames = [
+  "NicePeopleOnly",
+  "BeKindPlz",
+  "LearningManners",
+  "StayClassy",
+  "BeNicer",
+  "NeedHugs",
+  "MakeFriends",
+];
+
+export function fixProfaneUsername(username: string): string {
+  if (isProfaneUsername(username)) {
+    return shadowNames[simpleHash(username) % shadowNames.length];
+  }
+  return username;
+}
+
+export function isProfaneUsername(username: string): boolean {
+  return matcher.hasMatch(username);
+}
+
 export function validateUsername(username: string): {
   isValid: boolean;
   error?: string;