<?php

  $str = "This is         a dummy text         . I need              




to                                      format
this.";

  $patterns = array("/\s+/", "/\s([?.!])/");
  $replacer = array(" ","$1");

  $str = preg_replace( $patterns, $replacer, $str );

  var_dump( $str );

string(44) "This is a dummy text. I need to format this."