Feat: Avoid adding of existing availabilities

src/Repository/AvailabilityRepository.php

@@ -78,4 +78,20 @@ class AvailabilityRepository extends ServiceEntityRepository
             ->getResult()
         ;
     }
+
+    public function assertUnique(array $fields): array
+    {
+        $qb = $this->createQueryBuilder('availability');
+
+        return $qb
+            ->where($qb->expr()->andX(
+                $qb->expr()->eq('availability.dateFrom', ':dateFrom'),
+                $qb->expr()->eq('availability.dateTo', ':dateTo'),
+                $qb->expr()->isNull('availability.owner')
+            ))
+            ->setParameters($fields)
+            ->getQuery()
+            ->getResult()
+        ;
+    }
 }