class StreamWrapperManager

class StreamWrapperManager implements ContainerAwareInterface, StreamWrapperManagerInterface {
    use ContainerAwareTrait;
    
    /**
     * Contains stream wrapper info.
     *
     * An associative array where keys are scheme names and values are themselves
     * associative arrays with the keys class, type and (optionally) service_id,
     * and string values.
     *
     * @var array
     */
    protected $info = [];
    
    /**
     * Contains collected stream wrappers.
     *
     * Keyed by filter, each value is itself an associative array keyed by scheme.
     * Each of those values is an array representing a stream wrapper, with the
     * following keys and values:
     *   - class: stream wrapper class name
     *   - type: a bitmask corresponding to the type constants in
     *     StreamWrapperInterface
     *   - service_id: name of service
     *
     * The array on key StreamWrapperInterface::ALL contains representations of
     * all schemes and corresponding wrappers.
     *
     * @var array
     */
    protected $wrappers = [];
    
    /**
     * {@inheritdoc}
     */
    public function getWrappers($filter = StreamWrapperInterface::ALL) {
        if (isset($this->wrappers[$filter])) {
            return $this->wrappers[$filter];
        }
        elseif (isset($this->wrappers[StreamWrapperInterface::ALL])) {
            $this->wrappers[$filter] = [];
            foreach ($this->wrappers[StreamWrapperInterface::ALL] as $scheme => $info) {
                // Bit-wise filter.
                if (($info['type'] & $filter) == $filter) {
                    $this->wrappers[$filter][$scheme] = $info;
                }
            }
            return $this->wrappers[$filter];
        }
        else {
            return [];
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getNames($filter = StreamWrapperInterface::ALL) {
        $names = [];
        foreach (array_keys($this->getWrappers($filter)) as $scheme) {
            $names[$scheme] = $this->getViaScheme($scheme)
                ->getName();
        }
        return $names;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDescriptions($filter = StreamWrapperInterface::ALL) {
        $descriptions = [];
        foreach (array_keys($this->getWrappers($filter)) as $scheme) {
            $descriptions[$scheme] = $this->getViaScheme($scheme)
                ->getDescription();
        }
        return $descriptions;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getViaScheme($scheme) {
        return $this->getWrapper($scheme, $scheme . '://');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getViaUri($uri) {
        $scheme = static::getScheme($uri);
        return $this->getWrapper($scheme, $uri);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getClass($scheme) {
        if (isset($this->info[$scheme])) {
            return $this->info[$scheme]['class'];
        }
        return FALSE;
    }
    
    /**
     * Returns a stream wrapper instance.
     *
     * @param string $scheme
     *   The scheme of the desired stream wrapper.
     * @param string $uri
     *   The URI of the stream.
     *
     * @return \Drupal\Core\StreamWrapper\StreamWrapperInterface|bool
     *   A stream wrapper object, or false if the scheme is not available.
     */
    protected function getWrapper($scheme, $uri) {
        if (isset($this->info[$scheme]['service_id'])) {
            $instance = $this->container
                ->get($this->info[$scheme]['service_id']);
            $instance->setUri($uri);
            return $instance;
        }
        return FALSE;
    }
    
    /**
     * Adds a stream wrapper.
     *
     * Internal use only.
     *
     * @param string $service_id
     *   The service id.
     * @param string $class
     *   The stream wrapper class.
     * @param string $scheme
     *   The scheme for which the wrapper should be registered.
     */
    public function addStreamWrapper($service_id, $class, $scheme) {
        $this->info[$scheme] = [
            'class' => $class,
            'type' => $class::getType(),
            'service_id' => $service_id,
        ];
    }
    
    /**
     * Registers the tagged stream wrappers.
     *
     * Internal use only.
     */
    public function register() {
        foreach ($this->info as $scheme => $info) {
            $this->registerWrapper($scheme, $info['class'], $info['type']);
        }
    }
    
    /**
     * Unregisters the tagged stream wrappers.
     *
     * Internal use only.
     */
    public function unregister() {
        // Normally, there are definitely wrappers set for the ALL filter. However,
        // in some cases involving many container rebuilds (e.g. WebTestBase),
        // $this->wrappers may be empty although wrappers are still registered
        // globally. Thus an isset() check is needed before iterating.
        if (isset($this->wrappers[StreamWrapperInterface::ALL])) {
            foreach (array_keys($this->wrappers[StreamWrapperInterface::ALL]) as $scheme) {
                stream_wrapper_unregister($scheme);
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function registerWrapper($scheme, $class, $type) {
        if (in_array($scheme, stream_get_wrappers(), TRUE)) {
            stream_wrapper_unregister($scheme);
        }
        if (($type & StreamWrapperInterface::LOCAL) == StreamWrapperInterface::LOCAL) {
            stream_wrapper_register($scheme, $class);
        }
        else {
            stream_wrapper_register($scheme, $class, STREAM_IS_URL);
        }
        // Pre-populate the static cache with the filters most typically used.
        $info = [
            'type' => $type,
            'class' => $class,
        ];
        $this->wrappers[StreamWrapperInterface::ALL][$scheme] = $info;
        if (($type & StreamWrapperInterface::WRITE_VISIBLE) == StreamWrapperInterface::WRITE_VISIBLE) {
            $this->wrappers[StreamWrapperInterface::WRITE_VISIBLE][$scheme] = $info;
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getTarget($uri) {
        // Remove the scheme from the URI and remove erroneous leading or trailing,
        // forward-slashes and backslashes.
        $target = trim(preg_replace('/^[\\w\\-]+:\\/\\/|^data:/', '', $uri), '\\/');
        // If nothing was replaced, the URI doesn't have a valid scheme.
        return $target !== $uri ? $target : FALSE;
    }
    
    /**
     * Normalizes a URI by making it syntactically correct.
     *
     * A stream is referenced as "scheme://target".
     *
     * The following actions are taken:
     * - Remove trailing slashes from target
     * - Trim erroneous leading slashes from target. e.g. ":///" becomes "://".
     *
     * @param string $uri
     *   String reference containing the URI to normalize.
     *
     * @return string
     *   The normalized URI.
     */
    public function normalizeUri($uri) {
        $scheme = $this->getScheme($uri);
        if ($this->isValidScheme($scheme)) {
            $target = $this->getTarget($uri);
            if ($target !== FALSE) {
                $uri = $scheme . '://' . $target;
            }
        }
        return $uri;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getScheme($uri) {
        if (preg_match('/^([\\w\\-]+):\\/\\/|^(data):/', $uri, $matches)) {
            // The scheme will always be the last element in the matches array.
            return array_pop($matches);
        }
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isValidScheme($scheme) {
        if (!$scheme) {
            return FALSE;
        }
        return class_exists($this->getClass($scheme));
    }
    
    /**
     * {@inheritdoc}
     */
    public function isValidUri($uri) {
        // Assert that the URI has an allowed scheme. Bare paths are not allowed.
        return $this->isValidScheme($this->getScheme($uri));
    }

}