<?php
  
  /*
   * This file is part of the Symfony package.
   *
   * (c) Fabien Potencier <fabien@symfony.com>
   *
   * For the full copyright and license information, please view the LICENSE
   * file that was distributed with this source code.
   */
  
  namespace Symfony\Component\Translation\Extractor;
  
  use Symfony\Component\Translation\Exception\InvalidArgumentException;
  
  /**
   * Base class used by classes that extract translation messages from files.
   *
   * @author Marcos D. Sánchez <marcosdsanchez@gmail.com>
   */
  abstract class AbstractFileExtractor
  {
      /**
       * @param string|iterable $resource Files, a file or a directory
       *
       * @return iterable
       */
      protected function extractFiles($resource)
      {
          if (is_iterable($resource)) {
              $files = [];
              foreach ($resource as $file) {
                  if ($this->canBeExtracted($file)) {
                      $files[] = $this->toSplFileInfo($file);
                  }
              }
          } elseif (is_file($resource)) {
              $files = $this->canBeExtracted($resource) ? [$this->toSplFileInfo($resource)] : [];
          } else {
              $files = $this->extractFromDirectory($resource);
          }
  
          return $files;
      }
  
      private function toSplFileInfo(string $file): \SplFileInfo
      {
          return new \SplFileInfo($file);
      }
  
      /**
       * @return bool
       *
       * @throws InvalidArgumentException
       */
      protected function isFile(string $file)
      {
          if (!is_file($file)) {
              throw new InvalidArgumentException(sprintf('The "%s" file does not exist.', $file));
          }
  
          return true;
      }
  
      /**
       * @return bool
       */
      abstract protected function canBeExtracted(string $file);
  
      /**
       * @param string|array $resource Files, a file or a directory
       *
       * @return iterable
       */
      abstract protected function extractFromDirectory($resource);
  }