class Extension

class Extension {
    
    /**
     * The type of the extension (e.g., 'module').
     *
     * @var string
     */
    protected $type;
    
    /**
     * The relative pathname of the extension (e.g., 'core/modules/node/node.info.yml').
     *
     * @var string
     */
    protected $pathname;
    
    /**
     * The filename of the main extension file (e.g., 'node.module').
     *
     * @var string|null
     */
    protected $filename;
    
    /**
     * An SplFileInfo instance for the extension's info file.
     *
     * Note that SplFileInfo is a PHP resource and resources cannot be serialized.
     *
     * @var \SplFileInfo
     */
    protected $splFileInfo;
    
    /**
     * The app root.
     *
     * @var string
     */
    protected $root;
    
    /**
     * Constructs a new Extension object.
     *
     * @param string $root
     *   The app root.
     * @param string $type
     *   The type of the extension; e.g., 'module'.
     * @param string $pathname
     *   The relative path and filename of the extension's info file; e.g.,
     *   'core/modules/node/node.info.yml'.
     * @param string $filename
     *   (optional) The filename of the main extension file; e.g., 'node.module'.
     */
    public function __construct($root, $type, $pathname, $filename = NULL) {
        // @see \Drupal\Core\Theme\ThemeInitialization::getActiveThemeByName()
        assert($pathname === 'core/core.info.yml' || $pathname[0] !== '/' && file_exists($root . '/' . $pathname), sprintf('The file specified by the given app root, relative path and file name (%s) do not exist.', $root . '/' . $pathname));
        $this->root = $root;
        $this->type = $type;
        $this->pathname = $pathname;
        $this->filename = $filename;
    }
    
    /**
     * Returns the type of the extension.
     *
     * @return string
     */
    public function getType() {
        return $this->type;
    }
    
    /**
     * Returns the internal name of the extension.
     *
     * @return string
     */
    public function getName() {
        return basename($this->pathname, '.info.yml');
    }
    
    /**
     * Returns the relative path of the extension.
     *
     * @return string
     */
    public function getPath() {
        return dirname($this->pathname);
    }
    
    /**
     * Returns the relative path and filename of the extension's info file.
     *
     * @return string
     */
    public function getPathname() {
        return $this->pathname;
    }
    
    /**
     * Returns the filename of the extension's info file.
     *
     * @return string
     */
    public function getFilename() {
        return basename($this->pathname);
    }
    
    /**
     * Returns the relative path of the main extension file, if any.
     *
     * @return string|null
     */
    public function getExtensionPathname() {
        if ($this->filename) {
            return $this->getPath() . '/' . $this->filename;
        }
    }
    
    /**
     * Returns the name of the main extension file, if any.
     *
     * @return string|null
     */
    public function getExtensionFilename() {
        return $this->filename;
    }
    
    /**
     * Loads the main extension file, if any.
     *
     * @return bool
     *   TRUE if this extension has a main extension file, FALSE otherwise.
     */
    public function load() {
        if ($this->filename) {
            include_once $this->root . '/' . $this->getPath() . '/' . $this->filename;
            return TRUE;
        }
        return FALSE;
    }
    
    /**
     * Re-routes method calls to SplFileInfo.
     *
     * Offers all SplFileInfo methods to consumers; e.g., $extension->getMTime().
     */
    public function __call($method, array $args) {
        if (!isset($this->splFileInfo)) {
            $this->splFileInfo = new \SplFileInfo($this->root . '/' . $this->pathname);
        }
        return call_user_func_array([
            $this->splFileInfo,
            $method,
        ], $args);
    }
    
    /**
     * Magic method implementation to serialize the extension object.
     *
     * @return array
     *   The names of all variables that should be serialized.
     */
    public function __sleep() {
        // @todo \Drupal\Core\Extension\ThemeExtensionList is adding custom
        //   properties to the Extension object.
        $properties = get_object_vars($this);
        // Don't serialize the app root, since this could change if the install is
        // moved. Don't serialize splFileInfo because it can not be.
        unset($properties['splFileInfo'], $properties['root']);
        return array_keys($properties);
    }
    
    /**
     * Magic method implementation to unserialize the extension object.
     */
    public function __wakeup() {
        // Get the app root from the container.
        $this->root = \Drupal::hasService('app.root') ? \Drupal::root() : DRUPAL_ROOT;
    }

}