feat: finalize voucher handling and discount display in summary and overview

src/BusProNet/Model/BookingResponse.php

@@ -47,4 +47,59 @@ class BookingResponse
     {
         return 'erfolgt' === $this->status;
     }
+
+    /**
+     * Gets voucher discounts from price items (AKTION and KULANZGUTSCHEIN types).
+     *
+     * Promotional vouchers appear as negative price items with art="AKTION".
+     * Goodwill vouchers appear as negative price items with art="KULANZGUTSCHEIN".
+     *
+     * @return array<PriceItem> Price items representing voucher discounts
+     */
+    public function getVoucherDiscountsFromPrices(): array
+    {
+        return array_filter(
+            $this->priceItems,
+            fn (PriceItem $item) => \in_array($item->type, ['AKTION', 'KULANZGUTSCHEIN'], true)
+        );
+    }
+
+    /**
+     * Gets total discount from price-based vouchers (promotional and goodwill).
+     *
+     * Returns the absolute sum of negative price items with AKTION or KULANZGUTSCHEIN types.
+     */
+    public function getVoucherDiscountFromPrices(): float
+    {
+        $discount = 0.0;
+        foreach ($this->getVoucherDiscountsFromPrices() as $item) {
+            // Price items for vouchers are negative, so we take absolute value
+            $discount += abs($item->totalPrice);
+        }
+
+        return round($discount, 2);
+    }
+
+    /**
+     * Gets total discount from purchase vouchers in payment terms.
+     */
+    public function getPurchaseVoucherDiscount(): float
+    {
+        return $this->paymentTerms?->getPurchaseVoucherDiscount() ?? 0.0;
+    }
+
+    /**
+     * Gets total voucher discount from all sources.
+     *
+     * Combines discounts from:
+     * - Price items (art="AKTION" for promotional, art="KULANZGUTSCHEIN" for goodwill)
+     * - Payment terms (kaufgutschein elements for purchase vouchers)
+     */
+    public function getTotalVoucherDiscount(): float
+    {
+        return round(
+            $this->getVoucherDiscountFromPrices() + $this->getPurchaseVoucherDiscount(),
+            2
+        );
+    }
 }