02_Uppercase_Words_examTask

<?php
$text = trim($_GET['text']);

$arrayOfWords = [];
$arrayOfWords = preg_split('/[^a-zA-Z]/', $text, -1, PREG_SPLIT_NO_EMPTY);

$index = 0;
$indexOfCurrentWord = 0;

for($i = 0; $i < count($arrayOfWords); $i++) {
    $tempIndex = stripos($text, $arrayOfWords[$i], $index);
    $currentWord = $arrayOfWords[$i];

    if(preg_match('/^[A-Z0-9\s]*$/', $currentWord)) {
        $currentMatch = strrev($currentWord);
        if($currentMatch === $currentWord) {
            $arrCurrentMatch = str_split($currentMatch);
            $currentMatch = '';
            foreach ($arrCurrentMatch as $ch) {
                $currentMatch .= $ch . $ch;
            }
        }
        $lenOfCurrentWord = strlen($currentMatch);
        $index = $tempIndex + strlen($currentWord);

        if(strlen($currentMatch) !== strlen($currentWord)) {
            $arrText = str_split($text);
            for($j = 0; $j < strlen($currentWord); $j++) {
                array_splice($arrText, $index, 0,  " ");
            }
            $arrText = join('',$arrText);
            $text = $arrText;
        }
        $text = substr_replace($text, $currentMatch, $tempIndex, $lenOfCurrentWord);
    }
    $index = $tempIndex + strlen($currentWord);
}
echo "<p>".htmlspecialchars($text)."</p>";