Custom Wordpress Function for RSS output and file size calculation

code-example-2

<?php
/*
*
* Custom function to add a field to the top of all RSS feeds. Captures the most recent post from a custom post type, finds the attached 
* PDF file (news archive) and the calculates the size and outputs the variables into the RSS XML.
*
*
*/

add_action('rss2_head','current_archive');
add_action('rss_head','current_archive');
add_action('commentsrss2_head','current_archive');

function current_archive() {
	$pdfArchive = new WP_query( array (
	    'post_type' => 'wn_back_issues',
	    'showposts' => 1 
	) );
	if ( $pdfArchive->have_posts() ):
		while ( $pdfArchive->have_posts() ): $pdfArchive->the_post();
			$thumb_id = get_post_thumbnail_id();
			$thumb_url_array = wp_get_attachment_image_src($thumb_id);
			$thumb_url = $thumb_url_array[0];
			$media = get_attached_media('application/pdf');
			foreach($media as $pdfLinks) {
				$pdfFileLink = array( wp_get_attachment_url( $pdfLinks->ID ) );	
				$pdfServerLink = array( get_attached_file( $pdfLinks->ID ) );
			}
			$pdfFileSize = number_format( filesize( $pdfServerLink[0] ) / 1048576 , 2 );
			
		?>	
			<archivepdf>
				<currentpdf><?php echo $pdfFileLink[0];  ?></currentpdf>
				<pdfCover><?php echo $thumb_url; ?></pdfCover>
				<pdfSize><?php echo $pdfFileSize; ?>MB</pdfSize>
			</archivepdf>
		<?php 		
		
		endwhile;
	endif;
	wp_reset_postdata();

}