wip: first working version

src/Validator/Constraints/Booking.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace App\Validator\Constraints;
+
+use Symfony\Component\Validator\Constraint;
+
+#[\Attribute]
+class Booking extends Constraint
+{
+    public string $message = 'WTF?';
+
+    public function getTargets(): array|string
+    {
+        return static::CLASS_CONSTRAINT;
+    }
+}

src/Validator/Constraints/BookingValidator.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace App\Validator\Constraints;
+
+use App\BusProNet\ApiClient;
+use App\BusProNet\Model\BookingUpdate;
+use App\BusProNet\Model\Notification;
+use App\Form\Model\BookingData;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+
+class BookingValidator extends ConstraintValidator
+{
+    public function __construct(private readonly ApiClient $apiClient)
+    {
+    }
+
+    public function validate(mixed $value, Constraint $constraint): void
+    {
+        /** @var BookingData $booking */
+        $bookingData = $value;
+
+        $result = $this->apiClient->updateBooking($bookingData);
+
+        if ($result instanceof Notification) {
+            $this->context
+                ->buildViolation($result->message)
+                ->addViolation()
+            ;
+        }
+
+        if ($result instanceof BookingUpdate && false === $result->valid) {
+            $this->context
+                ->buildViolation($constraint->message)
+                ->addViolation()
+            ;
+        }
+    }
+}