class SiteConfigurationExcluder

class SiteConfigurationExcluder implements EventSubscriberInterface {
  public function __construct(protected string $sitePath, private readonly PathLocator $pathLocator, private readonly FileSystemInterface $fileSystem) {
  }
  
  /**
   * Excludes site configuration files from stage operations.
   *
   * @param \Drupal\package_manager\Event\CollectPathsToExcludeEvent $event
   *   The event object.
   */
  public function excludeSiteConfiguration(CollectPathsToExcludeEvent $event) : void {
    // These two files are never relevant to existing sites.
    $paths = [
      'sites/default/default.settings.php',
      'sites/default/default.services.yml',
    ];
    // Exclude site-specific settings files, which are always in the web root.
    // By default, Drupal core will always try to write-protect these files.
    // @see \Drupal\system\Hook\SystemRequirementsHooks
    $settings_files = [
      'settings.php',
      'settings.local.php',
      'services.yml',
    ];
    foreach ($settings_files as $settings_file) {
      $paths[] = $this->sitePath . '/' . $settings_file;
      $paths[] = 'sites/default/' . $settings_file;
    }
    // Site configuration files are always excluded relative to the web root.
    $event->addPathsRelativeToWebRoot($paths);
  }
  
  /**
   * Makes the staged `sites/default` directory owner-writable.
   *
   * This allows the core scaffold plugin to make changes in `sites/default`,
   * if needed. Otherwise, it would break if `sites/default` is not writable.
   * This can happen because rsync preserves directory permissions (and Drupal
   * tries to write-protect the site directory).
   *
   * We specifically exclude `default.settings.php` and `default.services.yml`
   * from Package Manager operations. This allows the scaffold plugin to change
   * those files in the stage directory.
   *
   * @param \Drupal\package_manager\Event\PostCreateEvent $event
   *   The event being handled.
   *
   * @see ::excludeSiteConfiguration()
   */
  public function makeDefaultSiteDirectoryWritable(PostCreateEvent $event) : void {
    $dir = $this->getDefaultSiteDirectoryPath($event->sandboxManager
      ->getSandboxDirectory());
    // If the directory doesn't even exist, there's nothing to do here.
    if (!is_dir($dir)) {
      return;
    }
    if (!$this->fileSystem
      ->chmod($dir, 0700)) {
      throw new FileException("Could not change permissions on '{$dir}'.");
    }
  }
  
  /**
   * Makes `sites/default` permissions the same in live and stage directories.
   *
   * @param \Drupal\package_manager\Event\PreApplyEvent $event
   *   The event being handled.
   *
   * @throws \Drupal\Core\File\Exception\FileException
   *   If the permissions of the live `sites/default` cannot be determined, or
   *   cannot be changed on the staged `sites/default`.
   */
  public function syncDefaultSiteDirectoryPermissions(PreApplyEvent $event) : void {
    $staged_dir = $this->getDefaultSiteDirectoryPath($event->sandboxManager
      ->getSandboxDirectory());
    // If the directory doesn't even exist, there's nothing to do here.
    if (!is_dir($staged_dir)) {
      return;
    }
    $live_dir = $this->getDefaultSiteDirectoryPath($this->pathLocator
      ->getProjectRoot());
    $permissions = fileperms($live_dir);
    if ($permissions === FALSE) {
      throw new FileException("Could not determine permissions for '{$live_dir}'.");
    }
    if (!$this->fileSystem
      ->chmod($staged_dir, $permissions)) {
      throw new FileException("Could not change permissions on '{$staged_dir}'.");
    }
  }
  
  /**
   * Returns the full path to `sites/default`, relative to a root directory.
   *
   * @param string $root_dir
   *   The root directory.
   *
   * @return string
   *   The full path to `sites/default` within the given root directory.
   */
  private function getDefaultSiteDirectoryPath(string $root_dir) : string {
    $dir = [
      $root_dir,
    ];
    $web_root = $this->pathLocator
      ->getWebRoot();
    if ($web_root) {
      $dir[] = $web_root;
    }
    return implode(DIRECTORY_SEPARATOR, [
      $dir,
      'sites',
      'default',
    ]);
  }
  
  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() : array {
    return [
      CollectPathsToExcludeEvent::class => 'excludeSiteConfiguration',
      PostCreateEvent::class => 'makeDefaultSiteDirectoryWritable',
      PreApplyEvent::class => 'syncDefaultSiteDirectoryPermissions',
    ];
  }

}