class EntityAutocompleteMatcher

class EntityAutocompleteMatcher implements EntityAutocompleteMatcherInterface {
    
    /**
     * The entity reference selection handler plugin manager.
     *
     * @var \Drupal\Core\Entity\EntityReferenceSelection\SelectionPluginManagerInterface
     */
    protected $selectionManager;
    
    /**
     * Constructs an EntityAutocompleteMatcher object.
     *
     * @param \Drupal\Core\Entity\EntityReferenceSelection\SelectionPluginManagerInterface $selection_manager
     *   The entity reference selection handler plugin manager.
     */
    public function __construct(SelectionPluginManagerInterface $selection_manager) {
        $this->selectionManager = $selection_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getMatches($target_type, $selection_handler, $selection_settings, $string = '') {
        $matches = [];
        $options = $selection_settings + [
            'target_type' => $target_type,
            'handler' => $selection_handler,
        ];
        $handler = $this->selectionManager
            ->getInstance($options);
        if (isset($string)) {
            // Get an array of matching entities.
            $match_operator = !empty($selection_settings['match_operator']) ? $selection_settings['match_operator'] : 'CONTAINS';
            $match_limit = isset($selection_settings['match_limit']) ? (int) $selection_settings['match_limit'] : 10;
            $entity_labels = $handler->getReferenceableEntities($string, $match_operator, $match_limit);
            // Loop through the entities and convert them into autocomplete output.
            foreach ($entity_labels as $values) {
                foreach ($values as $entity_id => $label) {
                    $key = "{$label} ({$entity_id})";
                    // Strip things like starting/trailing white spaces, line breaks and
                    // tags.
                    $key = preg_replace('/\\s\\s+/', ' ', str_replace("\n", '', trim(Html::decodeEntities(strip_tags($key)))));
                    // Names containing commas or quotes must be wrapped in quotes.
                    $key = Tags::encode($key);
                    $matches[] = [
                        'value' => $key,
                        'label' => $label,
                    ];
                }
            }
        }
        return $matches;
    }

}