Piwik\Plugins\MultiSites\Dashboard::nestedSearch PHP Method

    private function nestedSearch(DataTable $sitesByGroup, $pattern)
    {
        foreach ($sitesByGroup->getRows() as $index => $site) {
            $label = strtolower($site->getColumn('label'));
            $labelMatches = false !== strpos($label, $pattern);
            if ($site->getMetadata('isGroup')) {
                $subtable = $site->getSubtable();
                $this->nestedSearch($subtable, $pattern);
                if (!$labelMatches && !$subtable->getRowsCount()) {
                    // we keep the group if at least one site within the group matches the pattern
                    $sitesByGroup->deleteRow($index);
                }
            } elseif (!$labelMatches) {
                $group = $site->getMetadata('group');
                if (!$group || false === strpos(strtolower($group), $pattern)) {
                    $sitesByGroup->deleteRow($index);
                }
            }
        }
    }