<?php

/**
 * @file
 * Contains \Drupal\image\PathProcessor\PathProcessorImageStyles.
 */

namespace Drupal\image\PathProcessor;

use Drupal\Core\PathProcessor\InboundPathProcessorInterface;
use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
use Symfony\Component\HttpFoundation\Request;

/**
 * Defines a path processor to rewrite image styles URLs.
 *
 * As the route system does not allow arbitrary amount of parameters convert
 * the file path to a query parameter on the request.
 *
 * This processor handles two different cases:
 * - public image styles: In order to allow the webserver to serve these files
 *   directly, the route is registered under the same path as the image style so
 *   it took over the first generation. Therefore the path processor converts
 *   the file path to a query parameter.
 * - private image styles: In contrast to public image styles, private
 *   derivatives are already using system/files/styles. Similar to public image
 *   styles, it also converts the file path to a query parameter.
 */
class PathProcessorImageStyles implements InboundPathProcessorInterface {

  /**
   * The stream wrapper manager service.
   *
   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
   */
  protected $streamWrapperManager;

  /**
   * Constructs a new PathProcessorImageStyles object.
   *
   * @param \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrapper_manager
   *   The stream wrapper manager service.
   */
  public function __construct(StreamWrapperManagerInterface $stream_wrapper_manager) {
    $this->streamWrapperManager = $stream_wrapper_manager;
  }

  /**
   * {@inheritdoc}
   */
  public function processInbound($path, Request $request) {
    $directory_path = $this->streamWrapperManager->getViaScheme('public')->getDirectoryPath();
    if (strpos($path, '/' . $directory_path . '/styles/') === 0) {
      $path_prefix = '/' . $directory_path . '/styles/';
    }
    elseif (strpos($path, '/system/files/styles/') === 0) {
      $path_prefix = '/system/files/styles/';
    }
    else {
      return $path;
    }

    // Strip out path prefix.
    $rest = preg_replace('|^' . preg_quote($path_prefix, '|') . '|', '', $path);

    // Get the image style, scheme and path.
    if (substr_count($rest, '/') >= 2) {
      list($image_style, $scheme, $file) = explode('/', $rest, 3);

      // Set the file as query parameter.
      $request->query->set('file', $file);

      return $path_prefix . $image_style . '/' . $scheme;
    }
    else {
      return $path;
    }
  }

}