/**
  * Perform full text search and find IDs of matching products.
  *
  * @param string
  * @return int[]
  */
 private function searchProductsFullText($query)
 {
     $searchCriteria = $this->fullTextSearchCriteriaFactory->create();
     /** To get list of available request names see Magento/CatalogSearch/etc/search_request.xml */
     $searchCriteria->setRequestName('quick_search_container');
     $filter = $this->filterBuilder->setField('search_term')->setValue($query)->setConditionType('like')->create();
     $filterGroup = $this->searchFilterGroupBuilder->addFilter($filter)->create();
     $currentPage = 1;
     $searchCriteria->setFilterGroups([$filterGroup])->setCurrentPage($currentPage)->setPageSize(self::PRODUCTS_NUMBER_IN_SUGGEST);
     $searchResults = $this->fullTextSearchApi->search($searchCriteria);
     $productIds = [];
     /**
      * Full text search returns document IDs (in this case product IDs),
      * so to get products information we need to load them using filtration by these IDs
      */
     foreach ($searchResults->getItems() as $searchDocument) {
         $productIds[] = $searchDocument->getId();
     }
     return $productIds;
 }
 /**
  * Create a filter group based on the filter array provided and add to the filter groups
  *
  * @param \Magento\Framework\Api\Filter $filter
  * @return $this
  */
 public function addFilter(\Magento\Framework\Api\Filter $filter)
 {
     $this->filterGroupBuilder->addFilter($filter);
     return $this;
 }