<?php
$s = " Ł ę d \r\n Я ёb ";
$n = preg_replace('~(*ANYCRLF)^\h+|\h+$|(\h){2,}~um', '$1', $s); echo $n;
PD9waHAKCiRzID0gIiDFgSAgICDEmSAgZCAgICBcclxuICDQryAgICAgINGRYiAgICAgIjsKJG4gPSBwcmVnX3JlcGxhY2UoJ34oKkFOWUNSTEYpXlxoK3xcaCskfChcaCl7Mix9fnVtJywgJyQxJywgJHMpOwplY2hvICRuOwo=