<?php
$orig = '/catalog/shassi/product/view/28/152.html';
$replaced = preg_replace('/catalog\/.+\/product/', 'catalog/product', $orig);
echo $replaced;
PD9waHAKCiRvcmlnID0gJy9jYXRhbG9nL3NoYXNzaS9wcm9kdWN0L3ZpZXcvMjgvMTUyLmh0bWwnOwoKJHJlcGxhY2VkID0gcHJlZ19yZXBsYWNlKCcvY2F0YWxvZ1wvLitcL3Byb2R1Y3QvJywgJ2NhdGFsb2cvcHJvZHVjdCcsICRvcmlnKTsKCmVjaG8gJHJlcGxhY2VkOwo=