CLI script to convert integer to roman number

int_2_roman.php

<?php

function getPeriod(int $int, int $n): int {
  $m = '1';
  $m .= str_repeat(0, $n);
  
  return $int * ((int) $m);
}

function getRomanNumber(int $input): string{
  $codes = [
    1 => 'I',
    4 => 'IV',
    5 => 'V',
    9 => 'IX',
    10 => 'X',
    40 => 'XL',
    50 => 'L',
    90 => 'XC',
    100 => 'C',
    400 => 'CD',
    500 => 'D',
    900 => 'CM',
    1000 => 'M',
  ];
  
  $result = '';
  
  if (1 > $input){
    return $result;
  }
  
  foreach (array_reverse($codes, true) as $key => $romanNumber){
      $d = $input/$key;
      
      if ($d == 1){
          $result .= $romanNumber;
          break;
      }
      
      if ($d > 1 && $input%$key !== 0){
          $result .= $romanNumber;
          $result .= getRomanNumber($input%$key);
          break;
      }
      
      if ($d > 1 && $input%$key === 0){
          $result .= str_repeat($romanNumber,$input/$key);
          break;
      }
  }
  
  return $result;
}

function solution(int $number): string {
  if (!is_int($number) || 0 >= $number) return false;
  
  $numStr = (string) $number;
  $len = strlen($numStr);
  $result = '';
  
  for ($i = 0; $i < $len; $i++){
    $s = (int) $numStr[$i];
    $result .= getRomanNumber(getPeriod($s, ($len - $i - 1)));
  }
  
  return $result;
}

$handle = fopen ('php://stdin','r');

while (1) {
  echo "Input integer to convert:\n";
  $arg = fgets($handle);

  if ($arg === 'exit'){
    echo "Bye bye\n";
    die; 
  }

  $num = (int) $arg;

  if (!is_numeric($num)){
    echo "Input should be numeric!\n";
    continue;
  }

  echo solution($num) . "\n";
}