Replicate legacy path replacement, add new control

	public function filter_upload_dir( $dirs ) {

		$this->original_upload_dir = $dirs;

		$wp_content_len = strlen(WP_CONTENT_DIR);

		$orig_basedir = $dirs['basedir'];

		$orig_baseurl = $dirs['baseurl'];

		$new_basedir = 's3://' . $this->bucket;

		if ( defined( 'S3_UPLOADS_DISABLE_REPLACE_UPLOAD_URL' ) && S3_UPLOADS_DISABLE_REPLACE_UPLOAD_URL ) {

			$new_baseurl = $dirs['baseurl'];

			$new_baseurl = $orig_baseurl;

		} else if ( defined( 'S3_UPLOADS_USE_LOCAL' ) && S3_UPLOADS_USE_LOCAL ) {

			$new_baseurl = $dirs['baseurl'] . '/s3/' . $this->bucket;

			$new_baseurl = $orig_baseurl . '/s3/' . $this->bucket;

		} else {

			$new_baseurl = $this->get_s3_url();

		}

		if ( defined( 'S3_UPLOADS_BASEPATH' ) ) {

			/* If S3_UPLOADS_BASEPATH is set to a non-empty string, use it as a base

			 * path in the bucket.  It also acts as a toggle to disable legacy

			 * behaviour: set to null or false to avoid using the relative path under

			 * WP_CONTENT_DIR as a base path.

			 */

			if ( S3_UPLOADS_BASEPATH ) {

				$new_basedir .= '/' . S3_UPLOADS_BASEPATH;

				$new_baseurl .= '/' . S3_UPLOADS_BASEPATH;

			}

		} else if ( substr( $orig_basedir, 0, $wp_content_len ) === WP_CONTENT_DIR ) {

			/* For compatibility with legacy behaviour, if the basedir is in

			 * WP_CONTENT_DIR, append the relative path between the two to the new

			 * basedir.

			 */

			$new_basedir .= substr($orig_basedir, $wp_content_len);

			$orig_path = parse_url($orig_baseurl, PHP_URL_PATH);

			$new_baseurl .= substr($orig_path, $wp_content_len - strlen(ABSPATH) + 1);

		}

		return array(

			'subdir' => $dirs['subdir'],

			'path' => str_replace( $dirs['basedir'], $new_basedir, $dirs['path'] ),

			'url' => str_replace( $dirs['baseurl'], $new_baseurl, $dirs['url'] ),

			'path' => str_replace( $orig_basedir, $new_basedir, $dirs['path'] ),

			'url' => str_replace( $orig_baseurl, $new_baseurl, $dirs['url'] ),

			'basedir' => $new_basedir,

			'baseurl' => $new_baseurl,

			'error' => false,