pewc_offload_media.php

<?php
/**
 * Move uploaded images to media library and thence to third-party storage like Amazon S3 etc
 */

add_filter( 'pewc_offload_media', '__return_true' );

function demo_upload_image( $uploaded_files ) {
	
	$moved_files = array();
	$delete_files = array();
	
	if( $uploaded_files ) {
		foreach( $uploaded_files as $index=>$upload ) {
			
			$moved_files[$index] = $upload;
			
			// Create the full URL
			$url = get_site_url() .  $upload['url'];

			// Ensure we don't generate all the different media sizes for this upload
			add_filter( 'intermediate_image_sizes_advanced', '__return_empty_array' );

			// Move the upload to the media library
			$id = media_handle_sideload( $moved_files[$index], 0 );
			$moved_files[$index]['file'] = get_attached_file( $id );
			$moved_files[$index]['url'] = wp_get_attachment_url( $id );

			// If error storing permanently, unlink
			if ( is_wp_error( $id ) ) {
				// Something went wrong
				@unlink( $upload['file'] );
				return $uploaded_files;
			} else {
				// Clear the upload file and any temporary files from the original directory
				$delete_files[] = $upload['file'];
				$delete_files[] = $moved_files[$index]['file'];
			}
			
		}
	}
	
	if( $delete_files ) {
		foreach( $delete_files as $delete_file ) {
			@unlink( $delete_file );
		}
	}

	return $moved_files;
}

function demo_move_uploads_to_media_library( $uploaded_files, $post_obj ) {
	
	if( apply_filters( 'pewc_offload_media', false ) ) {
		$uploaded_files = demo_upload_image( $uploaded_files );
	}
	return $uploaded_files;
	
}
add_filter( 'pewc_after_ajax_upload', 'demo_move_uploads_to_media_library', 10, 2 );