Replace space with hyphen for image filename on upload - wordpress

Question

I'm using the code bellow (I found it here on stack overflow from this post) to auto rename image filename and fill alt and title field based on post title.
The good thing is it's working, it's doing its job but problem is with filename : it's using post title with spaces, comas, etc. as filename, which is really not good. It's perfect for filling the title and alt fields but not for a filename.
So, just for the filename, I would like to add something to replace spaces by hyphen (and if possible remove potentials comas or other punctuation)
I thought that the part add_filter( 'sanitize_file_name', 'file_renamer', 10, 1 ); would to the job, but it's not.
But as I'm really not sure what I'm doing, and as I have poor PHP knowledge, I would be very grateful if you could teach me how to make it work :
function file_renamer( $filename ) {
$info = pathinfo( $filename );
$ext = empty( $info['extension'] ) ? '' : '.' . $info['extension'];
$name = basename( $filename, $ext );
if( $post_id = array_key_exists("post_id", $_POST) ? $_POST["post_id"] : null) {
if($post = get_post($post_id)) {
return $post->post_title . $ext;
}
}
$my_image_title = $post;
$file['name'] = $my_image_title . - uniqid() . $ext; // uniqid method
// $file['name'] = md5($name) . $ext; // md5 method
// $file['name'] = base64_encode($name) . $ext; // base64 method
return $filename;
}
add_filter( 'sanitize_file_name', 'file_renamer', 10, 1 );
/* Automatically set the image Title, Alt-Text, Caption & Description upon upload */
add_action( 'add_attachment', 'my_set_image_meta_upon_image_upload' );
function my_set_image_meta_upon_image_upload( $post_ID ) {
// Check if uploaded file is an image, else do nothing
if ( wp_attachment_is_image( $post_ID ) ) {
// Get the parent post ID, if there is one
if( isset($_REQUEST['post_id']) ) {
$post_id = $_REQUEST['post_id'];
} else {
$post_id = false;
}
if ($post_id != false) {
$my_image_title = get_the_title($post_id);
} else {
$my_image_title = get_post( $post_ID )->post_title;
}
// Sanitize the title: remove hyphens, underscores & extra spaces:
$my_image_title = preg_replace( '%\s*[-_\s]+\s*%', ' ', $my_image_title );
// Create an array with the image meta (Title, Caption, Description) to be updated
// Note: comment out the Excerpt/Caption or Content/Description lines if not needed
$my_image_meta = array(
'ID' => $post_ID, // Specify the image (ID) to be updated
'post_title' => $my_image_title, // Set image Title to sanitized title
'post_content' => $my_image_title, // Set image Description (Content) to sanitized title
);
// Set the image Alt-Text
update_post_meta( $post_ID, '_wp_attachment_image_alt', $my_image_title );
// Set the image meta (e.g. Title, Excerpt, Content)
wp_update_post( $my_image_meta );
}
}
Thanks for your help !

Answer 1

So solution was replacing post_title by post_name in file_renamer function.
Exactly this part : change return $post->post_title . $ext; and replace it with return $post->post_name . $ext;
And it's working. On upload, this function is renaming the file name with hyphens and filling title, alt text and description fields based on Post Title (without hyphens).