feat: selectable drop-offs for inbound bus travel

src/BusProNet/DataProcessor/ServiceMappingCollector.php

@@ -143,6 +143,28 @@ class ServiceMappingCollector
         return $pickupMap;
     }
 
+    /**
+     * Collects drop-off location mappings.
+     *
+     * Collects the drop-off selection for the inbound/return direction.
+     *
+     * @return array<string, array<int>> Map of drop-off ID to participant IDs
+     */
+    public function collectDropOffMappings(BookingDto $bookingDto): array
+    {
+        $dropOffMap = [];
+
+        foreach ($bookingDto->participants as $index => $participant) {
+            $participantId = $index + 1;
+
+            if (null !== $participant->dropOff) {
+                $dropOffMap[$participant->dropOff->id][] = $participantId;
+            }
+        }
+
+        return $dropOffMap;
+    }
+
     /**
      * Collects insurance mappings.
      *