<?php

// This function prints unique vowels (A, E, I, O, U)
// from a given string in the order they appear.
// A 'Y' is considered a consonant if it begins a string and this string is greater than 1 character.
// Otherwise, a 'Y' is considered a vowel.

function findVowels ($string) {

  //Handle 'Y' as a consonant
  if(strlen($string) > 1) {
    $string = preg_replace("/^y?/i", "", $string);
  }

  //Leave only vowels in the string
  $pattern = "/[^aeiouy]?/i";
  $string = preg_replace($pattern, '', $string);

  //Remove dublicate characters
  $string = implode(array_unique(str_split($string)));

  return $string;
}