Zend certified PHP/Magento developer

Magento 2: Upload custom generated file to pub/media

I have generated a custom html file and instead of downloading I want to upload it to the pub/media programmatically.

<?php
use MagentoFrameworkAppResponseInterface;
use MagentoFrameworkAppFilesystemDirectoryList;
use MagentoMediaStorageModelFileUploaderFactory;
class PrintAction extends MagentoBackendAppAction
{
const ADMIN_RESOURCE = 'Magento_Sales::sales_order';
/**
* @var MagentoFrameworkAppResponseHttpFileFactory
*/
protected $fileFactory;
/**
* @var MagentoFrameworkControllerResultRedirectFactory
*/
protected $resultRedirectFactory;
/**
* @var MagentoSalesApiOrderRepositoryInterface
*/
protected $orderRepository;
/**
* @var MagentoFrameworkStdlibDateTimeDateTime
*/
protected $date;
/**
* @var MagemechanicWorkorderModelPdfOrderFactory
*/
protected $orderPdfFactory;
/**
* @param MagentoBackendAppActionContext                $context
* @param MagentoFrameworkAppResponseHttpFileFactory   $fileFactory
* @param MagentoSalesApiOrderRepositoryInterface        $orderRepository
* @param MagentoFrameworkStdlibDateTimeDateTime        $date
*/
public function __construct(
MagentoBackendAppActionContext $context,
MagentoFrameworkAppResponseHttpFileFactory $fileFactory,
MagentoSalesApiOrderRepositoryInterface $orderRepository,
MagemechanicWorkorderModelPdfOrderFactory $orderPdfFactory,
MagentoFrameworkStdlibDateTimeDateTime $date,
UploaderFactory $uploaderFactory,
MagentoFrameworkFilesystem $filesystem 
) {
parent::__construct($context);
$this->fileFactory = $fileFactory;
$this->resultRedirectFactory = $context->getResultRedirectFactory();
$this->orderRepository = $orderRepository;
$this->orderPdfFactory = $orderPdfFactory;
$this->date = $date;
$this->_url = $context->getUrl();
$this->uploaderFactory = $uploaderFactory;
$this->filesystem = $filesystem;
}
/**
* @return MagentoBackendModelViewResultRedirect|ResponseInterface|MagentoFrameworkControllerResultRedirect|MagentoFrameworkControllerResultInterface
* @throws Exception
*/
public function execute()
{
$orderId = $this->getRequest()->getParam('order_id');
if ($orderId) {
$order = $this->orderRepository->get($orderId);
if ($order->getEntityId()) {
$pdf = $this->orderPdfFactory->create()->getPdf([$order]);
$date = $this->date->date('Y-m-d_H-i-s');
$createdAt = $order->getCreatedAt();
$objectManager = MagentoFrameworkAppObjectManager::getInstance();
$addressCollection = $objectManager->create('MagentoSalesModelResourceModelOrderAddressCollectionFactory');
$orderBillingId = $order->getBillingAddressId();
$orderShippingId = $order->getShippingAddressId();
$payment = $order->getPayment();
$method = $payment->getMethodInstance();
$methodTitle = $method->getTitle();
$shippingMethod = $order->getShippingMethod();
foreach ($order->getAllItems() as $item) {
$productName = $item->getName();
$qty = $item->getQty();
$sku = $item->getSku();
}                
$html = '';
$html .= '<section class="admin__page-section order-view-account-information">
<div class="admin__page-section-title">
<span class="title">Order &amp; Account Information</span>
</div>
<div class="admin__page-section-content">
<div class="admin__page-section-item order-information">
<div class="admin__page-section-item-content">
<table class="admin__table-secondary order-information-table">
<tbody>
<tr>
<th>Order Date</th>
<td>'. $createdAt . '</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
</section>
<div class="admin__page-section-item order-billing-address">
<div class="admin__page-section-item-title">
<span class="title">Billing Address</span>
</div>
<address class="admin__page-section-item-content">'.
$order->getBillingAddress()->getFirstname(). '</br>'.
$order->getBillingAddress()->getLastName(). '</br>'.
implode(" ", $order->getBillingAddress()->getStreet()) . '</br>'.
$order->getBillingAddress()->getCity(). ' '.
$order->getBillingAddress()->getRegion(). ' '.
$order->getBillingAddress()->getCountryId(). '</br>'.
$order->getBillingAddress()->getTelephone(). '</br>'
.'
</address>
</div></br>
<div class="admin__page-section-item order-billing-address">
<div class="admin__page-section-item-title">
<span class="title">Shipping Address</span>
</div>
<address class="admin__page-section-item-content">'.
$order->getShippingAddress()->getFirstname(). '</br>'.
$order->getShippingAddress()->getLastName(). '</br>'.
implode(" ", $order->getShippingAddress()->getStreet()). '</br>'.
$order->getShippingAddress()->getCity(). ' '.
$order->getShippingAddress()->getRegion(). ' '. 
$order->getShippingAddress()->getCountryId().'</br>'. 
$order->getShippingAddress()->getTelephone() . '</br>'
.'
</address>
</div></br>';
$html .= '<div class="admin__page-section-item order-payment-method">
<div class="admin__page-section-item-title">
<span class="title">Payment Information</span>
</div>
<div class="admin__page-section-item-content">
<div class="order-payment-method-title">'. $methodTitle .'</div>
</div>
</div>
</div>';
$html .= '<div class="admin__page-section-item order-shipping-method">
<div class="admin__page-section-item-title">
<span class="title">Shipping & Handling Information</span>
</div>
<div class="admin__page-section-item-content">
'. $shippingMethod .'
</div> </br>';
$html .= '<section class="admin__page-section">
<div class="admin__page-section-title">
<span class="title">Items Ordered</span>
</div>
<div class="admin__table-wrapper">
<table class="data-table admin__table-primary edit-order-table">
<thead>
<tr class="headings">
<th class="col-product"><span>Product</span></th>
<th class="col-ordered-qty"><span>Qty</span></th>
</tr>
</thead>
<tbody class="even">
<tr>
<td class="col-product">
<div class="product-title">
'. $productName .' </br>
'. $sku .'
</div>
</td>
<td class="col-ordered-qty">
<table class="qty-table">
<tbody>
<tr>
<td>'.$qty.'</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</div>
</section>';
// echo $html;
$fileContent = ['type' => 'string', 'value' => $html, 'rm' => true];
return $this->fileFactory->create(
__('order') . '_' . $date . '.html',
$fileContent,
DirectoryList::VAR_DIR,
'application/pdf'
);
}
}
// return $this->resultRedirectFactory->create()->setPath('sales/*/view');
}
}

Any help would be appreciated.