<?php
error_reporting(-1);
 
mb_internal_encoding('utf-8');
 
$lookalikes = [
'a' => 'а', 'b' => 'в', 'c' => 'с', 'e' => 'е', 'h' => 'н',
'k' => 'к', 'm' => 'м', 'o' => 'о', 'p' => 'р', 't' => 'т',
'x' => 'х', 'y' => 'у'
];
 
function isDurak($word) {
global $lookalikes;
$word = mb_strtolower(str_replace(' ', '', $word));
$word = strtr($word, $GLOBALS['lookalikes']);
return $word === 'дурак';
}
 
$text = 'Ты ДуРАк и вообще д у р а к, а еще ты durak!';
$words = preg_split('/(\s+)/u', $text, -1, PREG_SPLIT_NO_EMPTY);
 
$result = [];
foreach ($words as $word) {
$result[] = isDurak($word) ? 'хороший человек' : $word;
}
 
echo implode(' ', $result) . "\n";

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