fix: resync room selections with travel data before step 2

src/Controller/Booking/Create/Step2Controller.php

@@ -13,6 +13,7 @@ use App\Form\BookingCreateStep2Type;
 use App\Form\Model\BookingDto;
 use App\Form\Model\ParticipantDto;
 use App\Form\Model\RoomSelectionDto;
+use App\Model\RoomSelectionAdjustment;
 use App\Service\BookingConfigurator;
 use App\Service\BookingCreateContextFactory;
 use App\Service\BookingSessionManager;
@@ -66,6 +67,12 @@ class Step2Controller extends AbstractBookingCreateController
         // Enrich with fresh availability data
         $this->travelDataService->enrichWithFreshAvailabilities($bookingCreateDto->travel);
 
+        // Resync the room selections with the refreshed travel before any participant count is derived
+        // from them, and send the customer back to step 1 when a room they picked is gone.
+        if (null !== $redirect = $this->guardAgainstUnavailableRoomSelection($request, $bookingCreateDto)) {
+            return $redirect;
+        }
+
         // Ensure correct number of participants first, then prepopulate the applicant if needed.
         if (null !== $redirect = $this->guardAgainstEmptyParticipantList($bookingCreateDto)) {
             return $redirect;
@@ -120,6 +127,79 @@ class Step2Controller extends AbstractBookingCreateController
         return $this->render('booking/create/step_2.html.twig', $templateData);
     }
 
+    /**
+     * Sends the customer back to step 1 when the refreshed travel data no longer covers their rooms.
+     *
+     * Deriving the participant count from a room that has disappeared would silently fall back to a
+     * capacity of one and render too few participants, and a quantity the contingent no longer covers
+     * reaches the BusPro submit unchecked, because no later step re-reads room availability. The
+     * selections are resynced and saved before every exit, so step 1 and the neighbouring guard both
+     * see a collection that matches the rooms the template renders: leaving a stale entry behind would
+     * fail step 1's own validation on a field it never shows.
+     */
+    private function guardAgainstUnavailableRoomSelection(Request $request, BookingDto $bookingCreateDto): ?RedirectResponse
+    {
+        $adjustments = $this->bookingService->reconcileRoomSelections($bookingCreateDto);
+
+        $this->bookingSessionService->saveBookingDto($request, $bookingCreateDto, BookingDto::MODE_CREATE);
+
+        if ([] === $bookingCreateDto->travel->getAvailableRooms()) {
+            $this->handleApiError(
+                $this->logger,
+                'Travel has no bookable rooms left while a booking is in progress.',
+                $this->createRoomContext($bookingCreateDto, $adjustments),
+                'Für diese Reise sind leider keine Zimmer mehr verfügbar.'
+            );
+
+            return $this->redirectToRoute('app_booking_create_error');
+        }
+
+        if ([] === $adjustments) {
+            return null;
+        }
+
+        $hasDroppedRoom = false;
+        foreach ($adjustments as $adjustment) {
+            $hasDroppedRoom = $hasDroppedRoom || $adjustment->isDropped();
+        }
+
+        $this->handleApiError(
+            $this->logger,
+            'Room selection exceeds what the current travel data still offers.',
+            $this->createRoomContext($bookingCreateDto, $adjustments),
+            true === $hasDroppedRoom
+                ? 'Dein gewähltes Zimmer ist leider nicht mehr verfügbar. Bitte wähle dein Zimmer erneut.'
+                : 'Für dein gewähltes Zimmer sind nicht mehr genügend Plätze verfügbar. Wir haben deine Auswahl angepasst, bitte überprüfe sie.'
+        );
+
+        return $this->redirectToRoute('app_booking_create_step_1');
+    }
+
+    /**
+     * @param list<RoomSelectionAdjustment> $adjustments
+     *
+     * @return array<string, mixed>
+     */
+    private function createRoomContext(BookingDto $bookingCreateDto, array $adjustments): array
+    {
+        $rooms = [];
+        foreach ($adjustments as $adjustment) {
+            $rooms[] = [
+                'roomId' => $adjustment->roomId,
+                'label' => $adjustment->label,
+                'requestedQuantity' => $adjustment->requestedQuantity,
+                'bookableQuantity' => $adjustment->bookableQuantity,
+            ];
+        }
+
+        return [
+            'travelId' => $bookingCreateDto->travel->id,
+            'travelCode' => $bookingCreateDto->travel->code,
+            'hotelId' => $bookingCreateDto->hotelId,
+            'rooms' => $rooms,
+        ];
+    }
+
     /**
      * Rejects a room selection that resolves to no participants at all.
      *
@@ -190,7 +270,14 @@ class Step2Controller extends AbstractBookingCreateController
         $rooms = $travelData->getAvailableRooms();
 
         foreach ($roomSelections as $roomSelection) {
-            $room = $rooms[$roomSelection->id];
+            $room = $rooms[$roomSelection->id] ?? null;
+
+            if (null === $room) {
+                // Unreachable from index(), which reconciles the selections first. Kept so a future
+                // caller cannot silently fall back to a capacity of one and book too few people.
+                continue;
+            }
+
             $participantsCount += ($room->minPax ?? 1) * $roomSelection->quantity;
         }