Discriminator in username

ts/types/Username.ts

@@ -1,23 +1,13 @@
-// Copyright 2021 Signal Messenger, LLC
+// Copyright 2022 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
-export const MAX_USERNAME = 26;
-export const MIN_USERNAME = 4;
+export type UsernameReservationType = Readonly<{
+  username: string;
+  previousUsername: string | undefined;
+  reservationToken: string;
+}>;
 
-export function isValidUsername(searchTerm: string): boolean {
-  return /^[a-z_][0-9a-z_]{3,25}$/.test(searchTerm);
-}
-
-export function getUsernameFromSearch(searchTerm: string): string | undefined {
-  if (/^[+0-9]+$/.test(searchTerm)) {
-    return undefined;
-  }
-
-  const match = /^@?(.*?)@?$/.exec(searchTerm);
-
-  if (match && match[1]) {
-    return match[1];
-  }
-
-  return undefined;
+export enum ReserveUsernameError {
+  Unprocessable = 'Unprocessable',
+  Conflict = 'Conflict',
 }