asset_saver.module

<?php
namespace {

use Drupal\asset_saver;

/**
 * Implements @see hook_flush_caches()
 *
 * Well, kind of. This is supposed to return an array of cache tables to be
 * cleared but there aren't any relevant cache tables to be cleared so we just
 * do the clearing ourselves.
 *
 * @return array
 *   An empty array.
 * @author Donovan Mueller <zotobi@gmail.com>
 **/
function asset_saver_flush_caches()
{
  asset_saver\_clear_all_files();
  return array();
}

/**
 * Implements @see hook_admin_menu_cache_info()
 */
function asset_saver_admin_menu_cache_info()
{
  $caches['asset_saver'] = array(
     'title'    => t('Asset Saver saved files')
    ,'callback' => 'Drupal\\asset_saver\\_clear_all_files'
  );

  return $caches;
}

} // END namespace global


namespace Drupal\asset_saver {

const URI_PREFIX       = 'public://asset_saver'
    , MAX_AGE          = 86500 # 1 day
    , CLEAR_FILES_LOCK = 'asset_saver:flush_cache';


/**
 * Saves a remote asset to a file and returns the path.
 *
 * @param string $url
 *   The URL to the remote asset file.
 * @return The path to the local file or `FALSE` on failure.
 * @author Donovan Mueller <zotobi@gmail.com>
 **/
function url_to_file($url)
{
  if (strpos($url, '//') === 0) {
    $protocol = !empty($_SERVER['HTTPS']) ? 'https' : 'http';
    $url = "$protocol:$url";
  }

  $uri      = _url_to_file_uri($url);
  $filename = drupal_realpath($uri);

  lock_wait(CLEAR_FILES_LOCK);
    # Don't want to have the file disappear out from under the user or the
    # creation of a new file when the system is trying to remove all of them.

  # Does the file already exist?
  if ($filename and file_exists($filename)
  and (time() - filemtime($filename)) < MAX_AGE)
    return $uri;

  ## Save the file
  $lock_name = 'asset_saver:save_file:'.base64_encode($uri);
  if (!lock_acquire($lock_name))
    # Hopefully, the other request that is trying to save this file will be
    # finished by the time the client requests the file.
    return $uri;

  if (file_exists($filename)) {
    # Looks like a different request was able to create this file just as this
    # request tried to acquire the lock.
    lock_release($lock_name);
    return $uri;
  }

  $contents = file_get_contents($url);
  if ($contents === false) {
    lock_release($lock_name);
    watchdog('asset_saver', 'Failed downloading asset "%url"'
            ,array('%url' => $url), WATCHDOG_ERROR);
    return file_exists($filename) ? $uri : false;
      # The old file is better than no file.
  }

  # Uncompress if needed.
  $headers = get_headers($url, true);
  if (isset($headers['Content-Encoding'])
  and $headers['Content-Encoding'] === 'gzip')
    $contents = _gzdecode($contents);

  # Prepare the directory.
  $dir_is_ready = file_prepare_directory(
    drupal_dirname($uri), FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS
  );
  if (!$dir_is_ready) return false;

  # Write the file.
  $path = file_unmanaged_save_data($contents, $uri, FILE_EXISTS_REPLACE);

  lock_release($lock_name);
  return $path;
}


/**
 * Takes a remote URL and converts it to a local file URI.
 *
 * @param string $url
 *   The URL to the remote asset file.
 * @return The local file URI on success, `FALSE` otherwise.
 * @author Donovan Mueller <zotobi@gmail.com>
 **/
function _url_to_file_uri($url)
{
  # Break URL into manageable pieces.
  if (version_compare(PHP_VERSION, '5.4.7', '<') and strpos($url, '//') === 0)
    # Fix for PHP < 5.4.7 `parse_url()` not handling URLs with their scheme
    # ommitted.
    $url = "https:$url";
  $parts = parse_url($url);
  if ($parts === false or !isset($parts['host'])) return false;

  if (empty($parts['scheme']))
    $parts['scheme'] = !empty($_SERVER['HTTPS']) ? 'https' : 'http';

  $uri = "{$parts['scheme']}/{$parts['host']}"
       . (isset($parts['path']) ? $parts['path'] : '/index');
  if (isset($parts['query'])) {
    if ($uri[strlen($uri)-1] !== '/') $uri .= '/';
    $uri .= $parts['query'];
  }
  $uri = rtrim($uri, '/');
  if (!preg_match('#\.js$#', $uri))
    # Hint to the webserver to serve these with the correct mime type.
    $uri .= '.js';

  return URI_PREFIX . "/$uri";
}


/**
 * A workaround for PHP versions without `gzdecode()`.
 *
 * Taken from PartySoft's comment on this answer:
 * http://stackoverflow.com/a/3002691/134014
 *
 * @param string $data
 *   The GZIP compressed string.
 * @return The uncompressed string.
 */
function _gzdecode($data)
{
  if (function_exists('gzdecode'))
    return gzdecode($data);

  $file = tempnam('/tmp', 'asset_saver_');
  file_put_contents($file, $data);

  ob_start();
  readgzfile($file);
  $data = ob_get_clean();

  unlink($file);
  return $data;
}


/**
 * Clears all saved asset files.
 *
 * @return void
 * @author Donovan Mueller <zotobi@gmail.com>
 **/
function _clear_all_files()
{
  if (!lock_acquire(CLEAR_FILES_LOCK)) return;

  _rmdir(URI_PREFIX);

  lock_release(CLEAR_FILES_LOCK);
}


/**
 * An alternative to Drupal's `drupal_rmdir()` that can handle non-empty
 * directories.
 *
 * Adapted from http://stackoverflow.com/a/1334425/134014
 *
 * @param string $path
 *   A file path or Drupal URI.
 */
function _rmdir($path)
{
    $path = drupal_realpath($path);

    if (is_dir($path)) {
      $files = array_diff(scandir($path), array('.', '..'));
      foreach ($files as $file)
        _rmdir(realpath($path) . '/' . $file);

      return rmdir($path);
    }

    if (is_file($path))
      return unlink($path);

    return false;
}

} // END namespace Drupal\asset_saver