codes.txt

app/Services/CouponCodePool.php

@@ -0,0 +1,77 @@
+<?php
+
+namespace App\Services;
+
+use App\Models\Coupon;
+
+class CouponCodePool
+{
+    /** @var list<string>|null */
+    private ?array $allCodesCache = null;
+
+    public function __construct(
+        private ?string $codesPath = null,
+    ) {}
+
+    /**
+     * @return list<string>
+     */
+    public function allCodes(): array
+    {
+        if ($this->allCodesCache !== null) {
+            return $this->allCodesCache;
+        }
+
+        $path = $this->codesPath ?? resource_path('codes/codes.txt');
+
+        if (! is_readable($path)) {
+            throw new \RuntimeException("Coupon codes file is not readable: {$path}");
+        }
+
+        $lines = file($path, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
+
+        if ($lines === false) {
+            throw new \RuntimeException("Unable to read coupon codes file: {$path}");
+        }
+
+        $codes = array_values(array_filter(array_map(trim(...), $lines)));
+
+        if ($codes === []) {
+            throw new \RuntimeException("Coupon codes file is empty: {$path}");
+        }
+
+        return $this->allCodesCache = $codes;
+    }
+
+    /**
+     * @return list<string>
+     */
+    public function usedCodes(): array
+    {
+        return Coupon::query()->pluck('code')->all();
+    }
+
+    /**
+     * @return list<string>
+     */
+    public function availableCodes(): array
+    {
+        return array_values(array_diff($this->allCodes(), $this->usedCodes()));
+    }
+
+    public function hasAvailable(): bool
+    {
+        return $this->availableCodes() !== [];
+    }
+
+    public function pickRandom(): ?string
+    {
+        $available = $this->availableCodes();
+
+        if ($available === []) {
+            return null;
+        }
+
+        return $available[array_rand($available)];
+    }
+}

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;
     }
 }