use PhpOffice\PhpSpreadsheet\IOFactory;

function bg_load_xlsx_rows($url) {
    $response = wp_remote_get($url);
    if ( is_wp_error($response) ) return [];

    $file_content = wp_remote_retrieve_body($response);
    if (empty($file_content)) return [];

    // save to temp
    $tmp = wp_tempnam($url);
    file_put_contents($tmp, $file_content);

    // load with PhpSpreadsheet
    $spreadsheet = IOFactory::load($tmp);
    unlink($tmp);

    $sheet = $spreadsheet->getActiveSheet();
    $rows = $sheet->toArray(null, true, true, true);

    // parse headers
    $header = [];
    $data = [];
    foreach ($rows as $index => $row) {
        if ($index === 1) {
            foreach ($row as $col => $val) {
                $normalized = strtolower(preg_replace('/[^a-z0-9]+/', '', trim($val)));
                $header[$col] = $normalized;
            }
            continue;
        }
        $assoc = [];
        foreach ($row as $col => $val) {
            $key = $header[$col] ?? $col;
            $assoc[$key] = trim((string)$val);
        }
        if (!empty($assoc['submission'])) {
            $data[] = $assoc;
        }
    }
    return $data;
}