class GitExcluder

final class GitExcluder implements EventSubscriberInterface {
    public function __construct(PathLocator $pathLocator, ComposerInspector $composerInspector) {
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() : array {
        return [
            CollectPathsToExcludeEvent::class => 'excludeGitDirectories',
        ];
    }
    
    /**
     * Excludes .git directories from stage operations.
     *
     * Any .git directories that are a part of an installed package -- for
     * example, a module that Composer installed from source -- are included.
     *
     * @param \Drupal\package_manager\Event\CollectPathsToExcludeEvent $event
     *   The event object.
     *
     * @throws \Exception
     *   See \Drupal\package_manager\ComposerInspector::validate().
     */
    public function excludeGitDirectories(CollectPathsToExcludeEvent $event) : void {
        $project_root = $this->pathLocator
            ->getProjectRoot();
        // To determine which .git directories to exclude, the installed packages
        // must be known, and that requires Composer commands to be able to run.
        // This intentionally does not catch exceptions: failed Composer validation
        // in the project root implies that this excluder cannot function correctly.
        // Note: the call to ComposerInspector::getInstalledPackagesList() would
        // also have triggered this, but explicitness is preferred here.
        // @see \Drupal\package_manager\StatusCheckTrait::runStatusCheck()
        $this->composerInspector
            ->validate($project_root);
        $paths_to_exclude = [];
        $installed_paths = [];
        // Collect the paths of every installed package.
        $installed_packages = $this->composerInspector
            ->getInstalledPackagesList($project_root);
        foreach ($installed_packages as $package) {
            if (!empty($package->path)) {
                $installed_paths[] = $package->path;
            }
        }
        $paths = $event->scanForDirectoriesByName('.git');
        foreach ($paths as $git_directory) {
            // Don't exclude any `.git` directory that is directly under an installed
            // package's path, since it means Composer probably installed that package
            // from source and therefore needs the `.git` directory in order to update
            // the package.
            if (!in_array(dirname($git_directory), $installed_paths, TRUE)) {
                $paths_to_exclude[] = $git_directory;
            }
        }
        $event->addPathsRelativeToProjectRoot($paths_to_exclude);
    }

}