<?php
  
  namespace Sabre\VObject;
  
  /**
   * Useful utilities for working with various strings.
   *

   * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
   * @author Evert Pot (http://evertpot.com/)

   * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
   */
  class StringUtil {
  
      /**
       * Returns true or false depending on if a string is valid UTF-8
       *
       * @param string $str
       * @return bool
       */
      static function isUTF8($str) {
  
          // First check.. mb_check_encoding
          if (!mb_check_encoding($str, 'UTF-8')) {
              return false;
          }
  
          // Control characters
          if (preg_match('%(?:[\x00-\x08\x0B-\x0C\x0E\x0F])%', $str)) {
              return false;
          }
  
          return true;
  
      }
  
      /**
       * This method tries its best to convert the input string to UTF-8.
       *
       * Currently only ISO-5991-1 input and UTF-8 input is supported, but this
       * may be expanded upon if we receive other examples.
       *
       * @param string $str
       * @return string
       */
      static function convertToUTF8($str) {
  
          $encoding = mb_detect_encoding($str , array('UTF-8','ISO-8859-1'), true);
  
          if ($encoding === 'ISO-8859-1') {
              $newStr = utf8_encode($str);
          } else {
              $newStr = $str;
          }
  
          // Removing any control characters
          return (preg_replace('%(?:[\x00-\x08\x0B-\x0C\x0E\x0F])%', '', $newStr));
  
      }
  
  }