php regex获取一本书的名称和作者

I have some book names that are like this

lastname, firstname - bookname.extension
firstname lastname - bookname.extension

I wanted to use a php regex to change this formats into

bookname - firstname lastname.extension

I hope there is an easy way to make a regex to extract an array having the firstname, lastname, author and extension.

Say my solution

<?php 
$book = "Alfred, Zusak - Time of the death.pdf";

$book = preg_replace("#^([a-zA-Z0-9-_. ]+)\,([a-zA-Z0-9-_. ]+)\-([a-zA-Z0-9-_. ]+)\.([a-zA-Z0-9-_.]+)$#isU", "$3 - $2 $1.$4", $book);
echo $book;
?>