feat: improved promotional and purchase vouchers

src/BusProNet/Model/PurchaseVoucher.php

@@ -16,6 +16,9 @@ namespace App\BusProNet\Model;
  */
 final readonly class PurchaseVoucher
 {
+    public const TYPE_PURCHASE = 'Kauf';
+    public const TYPE_GOODWILL = 'Kulanz';
+
     public function __construct(
         public string $voucherNumber,
         public string $redemptionCode,
@@ -24,4 +27,25 @@ final readonly class PurchaseVoucher
         public string $type,
     ) {
     }
+
+    /**
+     * Checks if this voucher is a purchase voucher.
+     *
+     * Purchase vouchers (Kauf) are aggregated into <gutscheine>.
+     */
+    public function isPurchase(): bool
+    {
+        return self::TYPE_PURCHASE === $this->type;
+    }
+
+    /**
+     * Checks if this voucher is a goodwill voucher.
+     *
+     * Goodwill vouchers (Kulanz) must be treated as promo vouchers and added
+     * per participant as <aktionscode>, not aggregated into <gutscheine>.
+     */
+    public function isGoodwill(): bool
+    {
+        return self::TYPE_GOODWILL === $this->type;
+    }
 }