update to provisioner code

app/Services/Accounts/PurchasedAccountProvisioner.php

@@ -3,33 +3,74 @@
 namespace App\Services\Accounts;
 
 use App\Models\User;
+use Illuminate\Database\UniqueConstraintViolationException;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Password;
 use Illuminate\Support\Str;
+use RuntimeException;
 
 final class PurchasedAccountProvisioner
 {
-    public function ensure(?string $email, ?string $name = null, bool $sendSetupLink = true): ?User
-    {
+    public function ensure(
+        ?string $email,
+        ?string $name = null,
+        bool $sendSetupLink = true
+    ): ?User {
         $email = strtolower(trim((string) $email));
+
         if ($email === '' || ! filter_var($email, FILTER_VALIDATE_EMAIL)) {
             return null;
         }
 
-        $user = User::query()->whereRaw('lower(email) = ?', [$email])->first();
+        /*
+         * Fast path for the normal case.
+         *
+         * Paddle can deliver several related webhook events concurrently, so
+         * this lookup alone cannot guarantee that another request will not
+         * create the user between this SELECT and our INSERT.
+         */
+        $user = $this->findByEmail($email);
+
         if ($user) {
             return $user;
         }
 
-        $user = User::create([
-            'name' => $this->displayName($name, $email),
-            'email' => $email,
-            'email_verified_at' => now(),
-            'password' => Str::random(64),
-            'is_admin' => false,
-        ]);
+        $created = false;
 
-        if ($sendSetupLink) {
+        try {
+            $user = User::create([
+                'name' => $this->displayName($name, $email),
+                'email' => $email,
+                'email_verified_at' => now(),
+                'password' => Str::random(64),
+                'is_admin' => false,
+            ]);
+
+            $created = true;
+        } catch (UniqueConstraintViolationException $exception) {
+            /*
+             * Another webhook may have created this account after our SELECT
+             * but before our INSERT. In that case the unique email constraint
+             * correctly rejects our INSERT; simply reuse the account that won
+             * the race.
+             */
+            $user = $this->findByEmail($email);
+
+            if (! $user) {
+                /*
+                 * The unique violation was not caused by the email account
+                 * appearing concurrently, so preserve the original failure.
+                 */
+                throw $exception;
+            }
+        }
+
+        /*
+         * Only the request that actually created the account should send the
+         * account setup/reset link. Concurrent Paddle events must not result
+         * in several setup emails being sent to the customer.
+         */
+        if ($created && $sendSetupLink) {
             DB::afterCommit(static function () use ($email): void {
                 Password::sendResetLink(['email' => $email]);
             });
@@ -38,9 +79,17 @@ final class PurchasedAccountProvisioner
         return $user;
     }
 
+    private function findByEmail(string $email): ?User
+    {
+        return User::query()
+            ->whereRaw('LOWER(email) = ?', [$email])
+            ->first();
+    }
+
     private function displayName(?string $name, string $email): string
     {
         $name = trim((string) $name);
+
         if ($name !== '') {
             return mb_substr($name, 0, 120);
         }
@@ -48,6 +97,12 @@ final class PurchasedAccountProvisioner
         $localPart = strstr($email, '@', true) ?: 'SonarDesk Customer';
         $localPart = trim(str_replace(['.', '_', '-'], ' ', $localPart));
 
-        return mb_substr($localPart !== '' ? ucwords($localPart) : 'SonarDesk Customer', 0, 120);
+        return mb_substr(
+            $localPart !== ''
+                ? ucwords($localPart)
+                : 'SonarDesk Customer',
+            0,
+            120
+        );
     }
 }