feat: unique email addresses of participants unless child, cleanup

addresses #869axbn21

src/Form/Model/BookingDto.php

@@ -195,4 +195,44 @@ class BookingDto
                 ->addViolation();
         }
     }
+
+    #[Assert\Callback(groups: ['booking_create_step_2', 'booking_edit'])]
+    public function validateEmailUniqueness(ExecutionContextInterface $context): void
+    {
+        // Build map of email addresses to participant indices (adults only)
+        $emailMap = [];
+
+        foreach ($this->participants as $index => $participant) {
+            // Skip children (they can share email addresses)
+            if (true === $participant->isChild()) {
+                continue;
+            }
+
+            // Skip null or empty emails (handled by other validators)
+            if (null === $participant->email || '' === trim($participant->email)) {
+                continue;
+            }
+
+            // Normalize email for case-insensitive comparison
+            $normalizedEmail = strtolower(trim($participant->email));
+
+            // Add participant index to the email map
+            if (false === isset($emailMap[$normalizedEmail])) {
+                $emailMap[$normalizedEmail] = [];
+            }
+            $emailMap[$normalizedEmail][] = $index;
+        }
+
+        // Add validation errors for duplicate emails
+        foreach ($emailMap as $email => $indices) {
+            // Only add violations if email is used by multiple adult participants
+            if (1 < count($indices)) {
+                foreach ($indices as $index) {
+                    $context->buildViolation('Diese E-Mail Adresse wird bereits von einem anderen erwachsenen Teilnehmer verwendet')
+                        ->atPath(sprintf('participants[%d].email', $index))
+                        ->addViolation();
+                }
+            }
+        }
+    }
 }

src/Form/Model/ParticipantDto.php

@@ -224,4 +224,26 @@ class ParticipantDto
             'message' => $message,
         ];
     }
+
+    /**
+     * Determines if the participant is a child based on age at current date.
+     *
+     * A child is defined as someone under the specified age threshold (default: 16 years).
+     * This classification is used for email uniqueness validation (children can share emails with adults).
+     *
+     * @param int $ageThreshold The age threshold for child classification (default: 16)
+     *
+     * @return bool True if participant is under the age threshold, false otherwise or if age unknown
+     */
+    public function isChild(int $ageThreshold = 16): bool
+    {
+        $age = $this->getAge();
+
+        // Treat unknown age as adult for safety (requires email uniqueness)
+        if (null === $age) {
+            return false;
+        }
+
+        return $ageThreshold > $age;
+    }
 }