Substring search in text with fuzzy tail (PHP): fuzzyChain

fuzzyChain_test.php

<?php
function fuzzyChain($search,$where,$skipFirst=0) {
/********************************
FuzzyChain
©Copyright,2017 @xmoonlight
https://github.com/xmoonlight
********************************/
  $spaces="\s";
  $sWords=preg_split("/[".$spaces."]+/iu",$search);
  $wWords=preg_split("/[".$spaces."]+/iu",$where);
  $OnlyRu = "БбвГгДдЁёЖжЗзИиЙйЛлмнПптУФфЦцЧчШшЩщЪъЫыЬьЭэЮюЯя";
  $OnlyEn = "DdFfGghIiJjLlNQqRrSstUVvWwYZz";
  $Rus = array("А","а","В","Е","е","К","к","М","Н","О","о","Р","р","С","с","Т","у","Х","х","З","О","1","т","и","а","@","п","ь");
  $Eng = array("A","a","B","E","e","K","k","M","H","O","o","P","p","C","c","T","y","X","x","3","0","i","m","u","@","a","n","b");
  $RRus=array();
  $REng=array();
  foreach ($Rus as $k=>$i) $RRus[$k]="/".$i."/u";
  foreach ($Eng as $k=>$i) $REng[$k]="/".$i."/u";
  $wordPos=0;
  $chain=0;

  foreach($wWords as $wpos=>$w) {
      $w=mb_strtolower($w, 'UTF-8');
      $s=mb_strtolower($sWords[$chain], 'UTF-8');
      if(!preg_match("/[".$OnlyEn."]/u",$w)) {
             $w=preg_replace($REng,$Rus,$w);
             $s=preg_replace($REng,$Rus,$s);
      } else {
             $w=preg_replace($RRus,$Eng,$w);
             $s=preg_replace($RRus,$Eng,$s);
      }
      $found=0;
      $d=0;
      $pos=0;
      $len=min(mb_strlen($w),mb_strlen($s));
      for ($i = 0; $i < $len-$skipFirst; $i++) { 
          if (mb_substr($s,$skipFirst+$d,1)===mb_substr($w,$skipFirst+$i,1)) {
               if($d==0) $pos=$i;
               $d++;
           } else $d=0;

          if (mb_substr($s,$skipFirst,$len-$pos)===mb_substr($w,$skipFirst+$pos,$len-$pos) || $d>=$len/2) {
             $found=1;break;
          }
      }
      if ($found===1) {
          $chain++;
          if ($chain===1) $wordPos=$wpos;
          if ($chain===count($sWords)) break;
      } else $chain=0;
  }
  if ($chain===count($sWords)) return array($wordPos+1,$wWords[$wordPos]);
  else return false;
}
///MAIN///
$search='протектор зимней шины';
$where='Одним из основных элементов реnpoтeктушкатоpатора зимних шин являются ламели.';
if ($result=fuzzyChain($search,$where)) echo 'Найдено с '.$result[0].'-го слова: ['.$result[1].']';
else echo 'Ничего не найдено';
?>