class PathLocator

class PathLocator {
    public function __construct(string $appRoot, ConfigFactoryInterface $configFactory, FileSystemInterface $fileSystem) {
    }
    
    /**
     * Returns the absolute path of the project root.
     *
     * This is where the project-level composer.json should normally be found, and
     * may or may not be the same path as the Drupal code base.
     *
     * @return string
     *   The absolute path of the project root.
     */
    public function getProjectRoot() : string {
        // Assume that the vendor directory is immediately below the project root.
        return realpath($this->getVendorDirectory() . DIRECTORY_SEPARATOR . '..');
    }
    
    /**
     * Returns the absolute path of the vendor directory.
     *
     * @return string
     *   The absolute path of the vendor directory.
     */
    public function getVendorDirectory() : string {
        // There may be multiple class loaders at work.
        // ClassLoader::getRegisteredLoaders() keeps track of them all, indexed by
        // the path of the vendor directory they load classes from.
        $loaders = ClassLoader::getRegisteredLoaders();
        // If there's only one class loader, we don't need to search for the right
        // one.
        if (count($loaders) === 1) {
            return key($loaders);
        }
        // To determine which class loader is the one for Drupal's vendor directory,
        // look for the loader whose vendor path starts the same way as the path to
        // this file.
        foreach (array_keys($loaders) as $path) {
            if (str_starts_with(__FILE__, dirname($path))) {
                return $path;
            }
        }
        // If we couldn't find a match, assume that the first registered class
        // loader is the one we want.
        return key($loaders);
    }
    
    /**
     * Returns the path of the Drupal installation, relative to the project root.
     *
     * @return string
     *   The path of the Drupal installation, relative to the project root and
     *   without leading or trailing slashes. Will return an empty string if the
     *   project root and Drupal root are the same.
     */
    public function getWebRoot() : string {
        $web_root = str_replace(trim($this->getProjectRoot(), DIRECTORY_SEPARATOR), '', trim($this->appRoot, DIRECTORY_SEPARATOR));
        return trim($web_root, DIRECTORY_SEPARATOR);
    }
    
    /**
     * Returns the directory where stage directories will be created.
     *
     * The stage root may be affected by site settings, so stages may wish to
     * cache the value returned by this method, to ensure that they use the same
     * stage root directory throughout their life cycle.
     *
     * @return string
     *   The absolute path of the directory where stage directories should be
     *   created.
     */
    public function getStagingRoot() : string {
        $site_id = $this->configFactory
            ->get('system.site')
            ->get('uuid');
        return $this->fileSystem
            ->getTempDirectory() . DIRECTORY_SEPARATOR . '.package_manager' . $site_id;
    }

}