class InstallStorage

class InstallStorage extends FileStorage {
    
    /**
     * Extension sub-directory containing default configuration for installation.
     */
    const CONFIG_INSTALL_DIRECTORY = 'config/install';
    
    /**
     * Extension sub-directory containing optional configuration for installation.
     */
    const CONFIG_OPTIONAL_DIRECTORY = 'config/optional';
    
    /**
     * Extension sub-directory containing configuration schema.
     */
    const CONFIG_SCHEMA_DIRECTORY = 'config/schema';
    
    /**
     * Folder map indexed by configuration name.
     *
     * @var array
     */
    protected $folders;
    
    /**
     * The directory to scan in each extension to scan for files.
     *
     * @var string
     */
    protected $directory;
    
    /**
     * Constructs an InstallStorage object.
     *
     * @param string $directory
     *   The directory to scan in each extension to scan for files. Defaults to
     *   'config/install'.
     * @param string $collection
     *   (optional) The collection to store configuration in. Defaults to the
     *   default collection.
     */
    public function __construct($directory = self::CONFIG_INSTALL_DIRECTORY, $collection = StorageInterface::DEFAULT_COLLECTION) {
        parent::__construct($directory, $collection);
    }
    
    /**
     * Overrides Drupal\Core\Config\FileStorage::getFilePath().
     *
     * Returns the path to the configuration file.
     *
     * Determines the owner and path to the default configuration file of a
     * requested config object name located in the installation profile, a module,
     * or a theme (in this order).
     *
     * @return string
     *   The path to the configuration file.
     *
     * @todo Improve this when figuring out how we want to handle configuration in
     *   installation profiles. For instance, a config object actually has to be
     *   searched in the profile first (whereas the profile is never the owner);
     *   only afterwards check for a corresponding module or theme.
     */
    public function getFilePath($name) {
        $folders = $this->getAllFolders();
        if (isset($folders[$name])) {
            return $folders[$name] . '/' . $name . '.' . $this->getFileExtension();
        }
        // If any code in the early installer requests a configuration object that
        // does not exist anywhere as default config, then that must be mistake.
        throw new StorageException("Missing configuration file: {$name}");
    }
    
    /**
     * {@inheritdoc}
     */
    public function exists($name) {
        return array_key_exists($name, $this->getAllFolders());
    }
    
    /**
     * Overrides Drupal\Core\Config\FileStorage::write().
     *
     * @throws \Drupal\Core\Config\StorageException
     */
    public function write($name, array $data) {
        throw new StorageException('Write operation is not allowed.');
    }
    
    /**
     * Overrides Drupal\Core\Config\FileStorage::delete().
     *
     * @throws \Drupal\Core\Config\StorageException
     */
    public function delete($name) {
        throw new StorageException('Delete operation is not allowed.');
    }
    
    /**
     * Overrides Drupal\Core\Config\FileStorage::rename().
     *
     * @throws \Drupal\Core\Config\StorageException
     */
    public function rename($name, $new_name) {
        throw new StorageException('Rename operation is not allowed.');
    }
    
    /**
     * {@inheritdoc}
     */
    public function listAll($prefix = '') {
        $names = array_keys($this->getAllFolders());
        if (!$prefix) {
            return $names;
        }
        else {
            $return = [];
            foreach ($names as $index => $name) {
                if (strpos($name, $prefix) === 0) {
                    $return[$index] = $names[$index];
                }
            }
            return $return;
        }
    }
    
    /**
     * Returns a map of all config object names and their folders.
     *
     * @return array
     *   An array mapping config object names with directories.
     */
    protected function getAllFolders() {
        if (!isset($this->folders)) {
            $this->folders = [];
            $this->folders += $this->getCoreNames();
            // Perform an ExtensionDiscovery scan as we cannot use
            // \Drupal\Core\Extension\ExtensionList::getPath() yet because the system
            // module may not yet be enabled during install.
            // @todo Remove as part of https://www.drupal.org/node/2186491
            $listing = new ExtensionDiscovery(\Drupal::root());
            if ($profile = \Drupal::installProfile()) {
                $profile_list = $listing->scan('profile');
                if (isset($profile_list[$profile])) {
                    // Prime the \Drupal\Core\Extension\ExtensionList::getPathname static
                    // cache with the profile info file location so we can use
                    // \Drupal\Core\Extension\ExtensionList::getPath() on the active
                    // profile during the module scan.
                    // @todo Remove as part of https://www.drupal.org/node/2186491
                    
                    /** @var \Drupal\Core\Extension\ProfileExtensionList $profile_extension_list */
                    $profile_extension_list = \Drupal::service('extension.list.profile');
                    $profile_extension_list->setPathname($profile, $profile_list[$profile]->getPathname());
                    $this->folders += $this->getComponentNames([
                        $profile_list[$profile],
                    ]);
                }
            }
            // @todo Remove as part of https://www.drupal.org/node/2186491
            $this->folders += $this->getComponentNames($listing->scan('module'));
            $this->folders += $this->getComponentNames($listing->scan('theme'));
        }
        return $this->folders;
    }
    
    /**
     * Get all configuration names and folders for a list of modules or themes.
     *
     * @param \Drupal\Core\Extension\Extension[] $list
     *   An associative array of Extension objects, keyed by extension name.
     *
     * @return array
     *   Folders indexed by configuration name.
     */
    public function getComponentNames(array $list) {
        $extension = '.' . $this->getFileExtension();
        $pattern = '/' . preg_quote($extension, '/') . '$/';
        $folders = [];
        foreach ($list as $extension_object) {
            // We don't have to use ExtensionDiscovery here because our list of
            // extensions was already obtained through an ExtensionDiscovery scan.
            $directory = $this->getComponentFolder($extension_object);
            if (is_dir($directory)) {
                // glob() directly calls into libc glob(), which is not aware of PHP
                // stream wrappers. Same for \GlobIterator (which additionally requires
                // an absolute realpath() on Windows).
                // @see https://github.com/mikey179/vfsStream/issues/2
                $files = scandir($directory);
                foreach ($files as $file) {
                    if ($file[0] !== '.' && preg_match($pattern, $file)) {
                        $folders[basename($file, $extension)] = $directory;
                    }
                }
            }
        }
        return $folders;
    }
    
    /**
     * Get all configuration names and folders for Drupal core.
     *
     * @return array
     *   Folders indexed by configuration name.
     */
    public function getCoreNames() {
        $extension = '.' . $this->getFileExtension();
        $pattern = '/' . preg_quote($extension, '/') . '$/';
        $folders = [];
        $directory = $this->getCoreFolder();
        if (is_dir($directory)) {
            // glob() directly calls into libc glob(), which is not aware of PHP
            // stream wrappers. Same for \GlobIterator (which additionally requires an
            // absolute realpath() on Windows).
            // @see https://github.com/mikey179/vfsStream/issues/2
            $files = scandir($directory);
            foreach ($files as $file) {
                if ($file[0] !== '.' && preg_match($pattern, $file)) {
                    $folders[basename($file, $extension)] = $directory;
                }
            }
        }
        return $folders;
    }
    
    /**
     * Get folder inside each component that contains the files.
     *
     * @param \Drupal\Core\Extension\Extension $extension
     *   The Extension object for the component.
     *
     * @return string
     *   The configuration folder name for this component.
     */
    protected function getComponentFolder(Extension $extension) {
        return $extension->getPath() . '/' . $this->getCollectionDirectory();
    }
    
    /**
     * Get folder inside Drupal core that contains the files.
     *
     * @return string
     *   The configuration folder name for core.
     */
    protected function getCoreFolder() {
        return 'core/' . $this->getCollectionDirectory();
    }
    
    /**
     * Overrides Drupal\Core\Config\FileStorage::deleteAll().
     *
     * @throws \Drupal\Core\Config\StorageException
     */
    public function deleteAll($prefix = '') {
        throw new StorageException('Delete operation is not allowed.');
    }
    
    /**
     * Resets the static cache.
     */
    public function reset() {
        $this->folders = NULL;
    }

}