Function descriptions

<?php

public function execute(): array
{
    $results = [];
    foreach ($this->storeManager->getWebsites(true) as $website) {
        if (!$this->configuration->isEnabled($website)) {
            continue;
        }
        $orders = $this->getNotScheduledForExportOrders->execute($website);
        if (empty($orders)) {
            continue;
        }
        $results[] = $this->initPipelinePerOrder($website, $orders);
        $this->bulkUpdateExportStatus->execute(
            $orders,
            [
                ExportStatusInterface::IS_SCHEDULED => 1,
                ExportStatusInterface::SCHEDULED_AT => (new \DateTime('now'))
                    ->setTimezone(new \DateTimeZone('UTC'))
                    ->format('Y-m-d H:i:s')
            ]
        );
    }
    if (!empty($results)) {
        $results = array_merge(...$results);
    }
    return $results;
}

<?php

/**
 * Retrieve a list of order entity IDs for orders, which are not scheduled for export yet
 *
 * @param WebsiteInterface $website
 * @return array
 */
public function execute(WebsiteInterface $website): array
{
    $orderTable = $this->resourceConnection->getTableName('sales_order');
    $paymentTable = $this->resourceConnection->getTableName('sales_order_payment');
    $storeTable = $this->resourceConnection->getTableName('store');
    $exportStatusTable = $this->resourceConnection->getTableName('pacemaker_order_export');
    $connection = $this->resourceConnection->getConnection();

    $select = $connection->select()
        ->from(['sales_order' => $orderTable], ['entity_id' => 'sales_order.entity_id'])
        ->joinLeft(['export' => $exportStatusTable], 'sales_order.entity_id = export.order_id', [])
        ->joinLeft(['store' => $storeTable], 'sales_order.store_id = store.store_id', [])
        ->joinLeft(['payment' => $paymentTable], 'payment.parent_id = sales_order.entity_id', []);

    $this->applyFilterConditionsForPaymentAndStatus($website, $select);
    $this->applyFilterForCreatedAtDatetime($website, $select);

    $select->order('sales_order.created_at DESC');
    return $connection->fetchCol($select);
}