codes.txt

app/Services/CouponService.php

@@ -2,12 +2,16 @@
 
 namespace App\Services;
 
+use App\Exceptions\CouponPoolExhaustedException;
 use App\Models\Coupon;
 use Illuminate\Database\UniqueConstraintViolationException;
-use Illuminate\Support\Str;
 
 class CouponService
 {
+    public function __construct(
+        private CouponCodePool $couponCodePool,
+    ) {}
+
     public function findOrCreateForPhone(string $phone): Coupon
     {
         $existing = Coupon::query()->where('phone', $phone)->first();
@@ -22,24 +26,22 @@ class CouponService
     private function createWithUniqueCode(string $phone): Coupon
     {
         for ($attempt = 0; $attempt < 10; $attempt++) {
+            $code = $this->couponCodePool->pickRandom();
+
+            if ($code === null) {
+                throw new CouponPoolExhaustedException;
+            }
+
             try {
                 return Coupon::query()->create([
                     'phone' => $phone,
-                    'code' => $this->generateCouponCode(),
+                    'code' => $code,
                 ]);
             } catch (UniqueConstraintViolationException) {
                 continue;
             }
         }
 
-        throw new \RuntimeException('Unable to generate a unique coupon code.');
-    }
-
-    private function generateCouponCode(): string
-    {
-        $x = random_int(1, 9);
-        $yyyy = Str::upper(Str::random(4));
-
-        return "{$x}_{$yyyy}";
+        throw new CouponPoolExhaustedException;
     }
 }