feat: prevent selection of baby rooms without regular rooms

src/Validator/Constraints/RoomSelection.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Validator\Constraints;
+
+use Symfony\Component\Validator\Constraint;
+
+#[\Attribute]
+class RoomSelection extends Constraint
+{
+    public const BABY_ROOM_CODE = 'Baby';
+
+    public string $noRoomSelectedMessage = 'Bitte mindestens ein Zimmer/Bett auswählen';
+    public string $onlyBabyRoomsMessage = 'Baby-Zimmer können nur in Kombination mit regulären Zimmern gebucht werden.';
+
+    public function getTargets(): array|string
+    {
+        return static::CLASS_CONSTRAINT;
+    }
+}

src/Validator/Constraints/RoomSelectionValidator.php

@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Validator\Constraints;
+
+use App\Form\Model\BookingDto;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+
+class RoomSelectionValidator extends ConstraintValidator
+{
+    public function validate(mixed $value, Constraint $constraint): void
+    {
+        if (!$constraint instanceof RoomSelection) {
+            throw new UnexpectedTypeException($constraint, RoomSelection::class);
+        }
+
+        if (!$value instanceof BookingDto) {
+            throw new UnexpectedTypeException($value, BookingDto::class);
+        }
+
+        $selectedRooms = $value->getSelectedRooms();
+
+        // Check that at least one room is selected
+        if (0 === count($selectedRooms)) {
+            $this->context->buildViolation($constraint->noRoomSelectedMessage)
+                ->addViolation();
+
+            return;
+        }
+
+        // Check that not only Baby rooms are selected
+        $this->assertNotOnlyBabyRooms($value, $constraint);
+    }
+
+    private function assertNotOnlyBabyRooms(BookingDto $bookingDto, RoomSelection $constraint): void
+    {
+        $availableRooms = $bookingDto->travel->getAvailableRooms();
+        $selectedRooms = $bookingDto->getSelectedRooms();
+
+        $hasRegularRoom = false;
+        $hasBabyRoom = false;
+
+        foreach ($selectedRooms as $roomSelection) {
+            $room = $availableRooms[$roomSelection->roomId] ?? null;
+
+            if (null === $room) {
+                continue;
+            }
+
+            if (RoomSelection::BABY_ROOM_CODE === $room->code) {
+                $hasBabyRoom = true;
+            } else {
+                $hasRegularRoom = true;
+            }
+        }
+
+        if ($hasBabyRoom && !$hasRegularRoom) {
+            $this->context->buildViolation($constraint->onlyBabyRoomsMessage)
+                ->addViolation();
+        }
+    }
+}