Implement a method to perform basic string compression using the counts of repeated/consecutive characters. Such as, the string "aaabbbccd" would become a3b3c2d1. If the compressed converted string does not become smaller than the original string, please return the original string.

compress_string.php

<?php
/**
Implement a method to perform basic string compression using the counts of repeated/consecutive characters. Such as, the string "aaabbbccd" would become a3b3c2d1. If the compressed converted string does not become smaller than the original string, please return the original string.
**/

function compress_string($word) {
  
    $word = strtolower($word);
    $compressed_word = "";
    $prev_letter = "";
    $count = 0;

    for ($i = 0; $i < strlen($word); $i++) {

        $curr_letter = substr($word, $i, 1);

        if ($curr_letter == $prev_letter) {
            $count++;
        } else {
            if ($count > 0) {
                $compressed_word .= ($prev_letter . $count);
            }
            $prev_letter = $curr_letter;
            $count = 1;
        }
    }
    $compressed_word .= ($prev_letter . $count);

    if (strlen($compressed_word) < strlen($word)) {
        return $compressed_word;
    } else {
        return $word;
    }
}

echo compress_string('aaabbbccd');