Combine lookup username array generation logic

app/Libraries/User/UsernamesForDbLookup.php

@@ -0,0 +1,30 @@
+<?php
+
+// Copyright (c) ppy Pty Ltd <[email protected]>. Licensed under the GNU Affero General Public License v3.0.
+// See the LICENCE file in the repository root for full licence text.
+
+declare(strict_types=1);
+
+namespace App\Libraries\User;
+
+class UsernamesForDbLookup
+{
+    public static function make($username, bool $trimPrefix = true): array
+    {
+        $searchUsername = presence(get_string($username));
+
+        if ($searchUsername === null) {
+            return [];
+        }
+
+        if ($trimPrefix && $searchUsername[0] === '@') {
+            $searchUsername = substr($searchUsername, 1);
+        }
+
+        return [
+            $searchUsername,
+            strtr($searchUsername, ' ', '_'),
+            strtr($searchUsername, '_', ' '),
+        ];
+    }
+}

app/Models/User.php

@@ -16,6 +16,7 @@
 use App\Libraries\Transactions\AfterCommit;
 use App\Libraries\User\DatadogLoginAttempt;
 use App\Libraries\User\ProfileBeatmapset;
+use App\Libraries\User\UsernamesForDbLookup;
 use App\Libraries\UsernameValidation;
 use App\Models\Forum\TopicWatch;
 use App\Models\OAuth\Client;
@@ -417,7 +418,7 @@ public static function findByUsernameForInactive($username): ?self
     {
         return static::whereIn(
             'username',
-            [str_replace(' ', '_', $username), str_replace('_', ' ', $username)]
+            UsernamesForDbLookup::make($username, trimPrefix: false),
         )->first();
     }
 
@@ -494,15 +495,7 @@ public static function lookup($usernameOrId, $type = null, $findAll = false): ?s
 
         switch ($type) {
             case 'username':
-                $searchUsername = (string) $usernameOrId;
-                if ($searchUsername[0] === '@') {
-                    $searchUsername = substr($searchUsername, 1);
-                }
-                $searchUsernames = [
-                    $searchUsername,
-                    strtr($searchUsername, ' ', '_'),
-                    strtr($searchUsername, '_', ' '),
-                ];
+                $searchUsernames = UsernamesForDbLookup::make($usernameOrId);
 
                 $user = static::where(fn ($query) => $query
                     ->whereIn('username', $searchUsernames)
@@ -550,17 +543,8 @@ public static function lookupWithHistory($usernameOrId, $type = null, $findAll =
             return null;
         }
 
-        $searchUsername = $usernameOrId[0] === '@'
-            ? substr($usernameOrId, 1)
-            : $usernameOrId;
-        $searchUsernames = [
-            $searchUsername,
-            strtr($searchUsername, ' ', '_'),
-            strtr($searchUsername, '_', ' '),
-        ];
-
         $change = UsernameChangeHistory::visible()
-            ->whereIn('username_last', $searchUsernames)
+            ->whereIn('username_last', UsernamesForDbLookup::make($usernameOrId))
             ->orderBy('change_id', 'desc')
             ->first();