Prestashop 1.7 file saving - php

Question

How to upload a file and save it in Prestashop 1.7?
In ProductComments module I have a modal with a <form>:
post-comment-modal.tpl
<form id="post-product-comment-form" action="{$post_comment_url nofilter}" method="POST" enctype="multipart/form-data">
<div>
<div class="form-floating">
<input name="comment_title" type="text" class="form-control" placeholder="Title"/>
<label for="comment_title">Title</label>
</div>
<div class="form-floating">
<input name="customer_name" type="text" class="form-control" placeholder="Name"/>
<label for="customer_name">Name</label>
</div>
<div class="form-floating">
<textarea name="comment_content" class="form-control" placeholder="Review"></textarea>
<label for="comment_content">Review</label>
</div>
<input type="file" id="photo_input" name="photo_input" multiple> // I've added this field
<button type="submit">Send</button>
</div>
</form>
I've added there a <input type="file">.
This form is posted into ProductCommentsPostCommentModuleFrontController which extends ModuleFrontController
PostComment.php
class ProductCommentsPostCommentModuleFrontController extends ModuleFrontController
{
public function display()
{
$id_product = (int) Tools::getValue('id_product');
$comment_title = Tools::getValue('comment_title'); // Proper value
$comment_content = Tools::getValue('comment_content'); // Proper value
$customer_name = Tools::getValue('customer_name'); // Proper value
$criterions = (array) Tools::getValue('criterion');
$photo = Tools::getValue('photo_input'); // false
$file = $_FILES['photo_input']['name']; // null
// Validation
/** #var EntityManagerInterface $entityManager */
$entityManager = $this->container->get('doctrine.orm.entity_manager');
//Create product comment
$productComment = new ProductComment();
// Validation
$productComment
->setProductId($id_product)
->setTitle($comment_title)
->setContent($comment_content)
->setCustomerName($customer_name)
->setCustomerId($this->context->cookie->id_customer)
->setGuestId($this->context->cookie->id_guest)
->setDateAdd(new \DateTime('now', new \DateTimeZone('UTC')))
;
$entityManager->persist($productComment);
$this->addCommentGrades($productComment, $criterions);
$entityManager->flush();
$this->ajaxRender(
json_encode(
[
'success' => true,
'product_comment' => $productComment->toArray(),
]
)
);
}
Is there a way to extend this controller, and add a variable which holds a file upoaded by user by POST method?