noptin_clean_url( string $url = '' )

function noptin_clean_url( $url = '' ) {

	// If no url is passed, use the current url.
	if ( empty( $url ) ) {
		$url = $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
	}

	// Remove query variables
	$clean_url = strtok( $url, '?' );

	// Remove the scheme and www parts.
	$clean_url = preg_replace('#^(http(s)?://)?(www\.)?(.+\.)#i', '$4', $clean_url );

	// Take care of edge cases
	$clean_url = preg_replace('#^http(s)?://#i', '', $clean_url );

	// remove forwad slash at the end of the url
	$clean_url = strtolower( untrailingslashit( $clean_url ) );

	return apply_filters( 'noptin_clean_url', $clean_url, $url ); 
}