class UrlGenerator

class UrlGenerator implements UrlGeneratorInterface {
    
    /**
     * The route provider.
     *
     * @var \Drupal\Core\Routing\RouteProviderInterface
     */
    protected $provider;
    
    /**
     * @var RequestContext
     */
    protected $context;
    
    /**
     * A request stack object.
     *
     * @var \Symfony\Component\HttpFoundation\RequestStack
     */
    protected $requestStack;
    
    /**
     * The path processor to convert the system path to one suitable for urls.
     *
     * @var \Drupal\Core\PathProcessor\OutboundPathProcessorInterface
     */
    protected $pathProcessor;
    
    /**
     * The route processor.
     *
     * @var \Drupal\Core\RouteProcessor\OutboundRouteProcessorInterface
     */
    protected $routeProcessor;
    
    /**
     * Overrides characters that will not be percent-encoded in the path segment.
     *
     * The first two elements are the first two parameters of str_replace(), so
     * if you override this variable you can also use arrays for the encoded
     * and decoded characters.
     *
     * @see \Symfony\Component\Routing\Generator\UrlGenerator
     */
    protected $decodedChars = [
        // the slash can be used to designate a hierarchical structure and we want allow using it with this meaning
        // some webservers don't allow the slash in encoded form in the path for security reasons anyway
        // see http://stackoverflow.com/questions/4069002/http-400-if-2f-part-of-get-url-in-jboss
        // Map from these encoded characters.
'%2F',
        // Map to these decoded characters.
'/',
    ];
    
    /**
     * Constructs a new generator object.
     *
     * @param \Drupal\Core\Routing\RouteProviderInterface $provider
     *   The route provider to be searched for routes.
     * @param \Drupal\Core\PathProcessor\OutboundPathProcessorInterface $path_processor
     *   The path processor to convert the system path to one suitable for urls.
     * @param \Drupal\Core\RouteProcessor\OutboundRouteProcessorInterface $route_processor
     *   The route processor.
     * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
     *   A request stack object.
     * @param string[] $filter_protocols
     *   (optional) An array of protocols allowed for URL generation.
     */
    public function __construct(RouteProviderInterface $provider, OutboundPathProcessorInterface $path_processor, OutboundRouteProcessorInterface $route_processor, RequestStack $request_stack, array $filter_protocols = [
        'http',
        'https',
    ]) {
        $this->provider = $provider;
        $this->context = new RequestContext();
        $this->pathProcessor = $path_processor;
        $this->routeProcessor = $route_processor;
        UrlHelper::setAllowedProtocols($filter_protocols);
        $this->requestStack = $request_stack;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setContext(SymfonyRequestContext $context) {
        $this->context = $context;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContext() {
        return $this->context;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setStrictRequirements($enabled) {
        // Ignore changes to this.
    }
    
    /**
     * {@inheritdoc}
     */
    public function isStrictRequirements() {
        return TRUE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPathFromRoute($name, $parameters = []) {
        $route = $this->getRoute($name);
        $name = $this->getRouteDebugMessage($name);
        $this->processRoute($name, $route, $parameters);
        $path = $this->getInternalPathFromRoute($name, $route, $parameters);
        // Router-based paths may have a querystring on them but Drupal paths may
        // not have one, so remove any ? and anything after it. For generate() this
        // is handled in processPath().
        $path = preg_replace('/\\?.*/', '', $path);
        return trim($path, '/');
    }
    
    /**
     * Substitute the route parameters into the route path.
     *
     * Note: This code was copied from
     * \Symfony\Component\Routing\Generator\UrlGenerator::doGenerate() and
     * shortened by removing code that is not relevant to Drupal or that is
     * handled separately in ::generateFromRoute(). The Symfony version should be
     * examined for changes in new Symfony releases.
     *
     * @param array $variables
     *   The variables from the compiled route, corresponding to slugs in the
     *   route path.
     * @param array $defaults
     *   The defaults from the route.
     * @param array $tokens
     *   The tokens from the compiled route.
     * @param array $parameters
     *   The route parameters passed to the generator. Parameters that do not
     *   match any variables will be added to the result as query parameters.
     * @param array $query_params
     *   Query parameters passed to the generator as $options['query']. This may
     *   be modified if there are extra parameters not used as route variables.
     * @param string $name
     *   The route name or other identifying string from ::getRouteDebugMessage().
     *
     * @return string
     *   The URL path, without any base path, without the query string, not URL
     *   encoded.
     *
     * @throws \Symfony\Component\Routing\Exception\MissingMandatoryParametersException
     *   When some parameters are missing that are mandatory for the route.
     * @throws \Symfony\Component\Routing\Exception\InvalidParameterException
     *   When a parameter value for a placeholder is not correct because it does
     *   not match the requirement.
     */
    protected function doGenerate(array $variables, array $defaults, array $tokens, array $parameters, array &$query_params, $name) {
        $variables = array_flip($variables);
        $mergedParams = array_replace($defaults, $this->context
            ->getParameters(), $parameters);
        // all params must be given
        if ($diff = array_diff_key($variables, $mergedParams)) {
            throw new MissingMandatoryParametersException(sprintf('Some mandatory parameters are missing ("%s") to generate a URL for route "%s".', implode('", "', array_keys($diff)), $name));
        }
        $url = '';
        // Tokens start from the end of the path and work to the beginning. The
        // first one or several variable tokens may be optional, but once we find a
        // supplied token or a static text portion of the path, all remaining
        // variables up to the start of the path must be supplied to there is no gap.
        $optional = TRUE;
        // Structure of $tokens from the compiled route:
        // If the path is /admin/config/user-interface/shortcut/manage/{shortcut_set}/add-link-inline
        // [ [ 0 => 'text', 1 => '/add-link-inline' ], [ 0 => 'variable', 1 => '/', 2 => '[^/]++', 3 => 'shortcut_set' ], [ 0 => 'text', 1 => '/admin/config/user-interface/shortcut/manage' ] ]
        //
        // For a simple fixed path, there is just one token.
        // If the path is /admin/config
        // [ [ 0 => 'text', 1 => '/admin/config' ] ]
        foreach ($tokens as $token) {
            if ('variable' === $token[0]) {
                if (!$optional || !array_key_exists($token[3], $defaults) || isset($mergedParams[$token[3]]) && (string) $mergedParams[$token[3]] !== (string) $defaults[$token[3]]) {
                    // check requirement
                    if (!preg_match('#^' . $token[2] . '$#', $mergedParams[$token[3]])) {
                        $message = sprintf('Parameter "%s" for route "%s" must match "%s" ("%s" given) to generate a corresponding URL.', $token[3], $name, $token[2], $mergedParams[$token[3]]);
                        throw new InvalidParameterException($message);
                    }
                    $url = $token[1] . $mergedParams[$token[3]] . $url;
                    $optional = FALSE;
                }
            }
            else {
                // Static text
                $url = $token[1] . $url;
                $optional = FALSE;
            }
        }
        if ('' === $url) {
            $url = '/';
        }
        // Add extra parameters to the query parameters.
        $query_params += array_diff_key($parameters, $variables, $defaults);
        return $url;
    }
    
    /**
     * Gets the path of a route.
     *
     * @param $name
     *   The route name or other debug message.
     * @param \Symfony\Component\Routing\Route $route
     *   The route object.
     * @param array $parameters
     *   An array of parameters as passed to
     *   \Symfony\Component\Routing\Generator\UrlGeneratorInterface::generate().
     * @param array $query_params
     *   An array of query string parameter, which will get any extra values from
     *   $parameters merged in.
     *
     * @return string
     *   The URL path corresponding to the route, without the base path, not URL
     *   encoded.
     */
    protected function getInternalPathFromRoute($name, SymfonyRoute $route, $parameters = [], &$query_params = []) {
        // The Route has a cache of its own and is not recompiled as long as it does
        // not get modified.
        $compiledRoute = $route->compile();
        return $this->doGenerate($compiledRoute->getVariables(), $route->getDefaults(), $compiledRoute->getTokens(), $parameters, $query_params, $name);
    }
    
    /**
     * {@inheritdoc}
     */
    public function generate($name, $parameters = [], $referenceType = self::ABSOLUTE_PATH) : string {
        $options['absolute'] = is_bool($referenceType) ? $referenceType : $referenceType === self::ABSOLUTE_URL;
        return $this->generateFromRoute($name, $parameters, $options);
    }
    
    /**
     * {@inheritdoc}
     */
    public function generateFromRoute($name, $parameters = [], $options = [], $collect_bubbleable_metadata = FALSE) {
        $options += [
            'prefix' => '',
        ];
        if (!isset($options['query']) || !is_array($options['query'])) {
            $options['query'] = [];
        }
        $route = $this->getRoute($name);
        $generated_url = $collect_bubbleable_metadata ? new GeneratedUrl() : NULL;
        // Generate a relative URL having no path, just query string and fragment.
        if ($route->getOption('_no_path')) {
            $query = $options['query'] ? '?' . UrlHelper::buildQuery($options['query']) : '';
            $fragment = '';
            if (isset($options['fragment'])) {
                if (($fragment = trim($options['fragment'])) != '') {
                    $fragment = '#' . $fragment;
                }
            }
            $url = $query . $fragment;
            return $collect_bubbleable_metadata ? $generated_url->setGeneratedUrl($url) : $url;
        }
        $options += $route->getOption('default_url_options') ?: [];
        $options += [
            'prefix' => '',
            'path_processing' => TRUE,
        ];
        $name = $this->getRouteDebugMessage($name);
        $this->processRoute($name, $route, $parameters, $generated_url);
        $path = $this->getInternalPathFromRoute($name, $route, $parameters, $options['query']);
        // Outbound path processors might need the route object for the path, e.g.
        // to get the path pattern.
        $options['route'] = $route;
        if ($options['path_processing']) {
            $path = $this->processPath($path, $options, $generated_url);
        }
        // Ensure the resulting path has at most one leading slash, to prevent it
        // becoming an external URL without a protocol like //example.com.
        if (strpos($path, '//') === 0) {
            $path = '/' . ltrim($path, '/');
        }
        // The contexts base URL is already encoded
        // (see Symfony\Component\HttpFoundation\Request).
        $path = str_replace($this->decodedChars[0], $this->decodedChars[1], rawurlencode($path));
        // Drupal paths rarely include dots, so skip this processing if possible.
        if (strpos($path, '/.') !== FALSE) {
            // the path segments "." and ".." are interpreted as relative reference when
            // resolving a URI; see http://tools.ietf.org/html/rfc3986#section-3.3
            // so we need to encode them as they are not used for this purpose here
            // otherwise we would generate a URI that, when followed by a user agent
            // (e.g. browser), does not match this route
            $path = strtr($path, [
                '/../' => '/%2E%2E/',
                '/./' => '/%2E/',
            ]);
            if ('/..' === substr($path, -3)) {
                $path = substr($path, 0, -2) . '%2E%2E';
            }
            elseif ('/.' === substr($path, -2)) {
                $path = substr($path, 0, -1) . '%2E';
            }
        }
        if (!empty($options['prefix'])) {
            $path = ltrim($path, '/');
            $prefix = empty($path) ? rtrim($options['prefix'], '/') : $options['prefix'];
            $path = '/' . str_replace('%2F', '/', rawurlencode($prefix)) . $path;
        }
        $query = $options['query'] ? '?' . UrlHelper::buildQuery($options['query']) : '';
        $fragment = '';
        if (isset($options['fragment'])) {
            if (($fragment = trim($options['fragment'])) != '') {
                $fragment = '#' . $fragment;
            }
        }
        // The base_url might be rewritten from the language rewrite in domain mode.
        if (isset($options['base_url'])) {
            $base_url = $options['base_url'];
            if (isset($options['https'])) {
                if ($options['https'] === TRUE) {
                    $base_url = str_replace('http://', 'https://', $base_url);
                }
                elseif ($options['https'] === FALSE) {
                    $base_url = str_replace('https://', 'http://', $base_url);
                }
            }
            $url = $base_url . $path . $query . $fragment;
            return $collect_bubbleable_metadata ? $generated_url->setGeneratedUrl($url) : $url;
        }
        $base_url = $this->context
            ->getBaseUrl();
        $absolute = !empty($options['absolute']);
        if (!$absolute || !($host = $this->context
            ->getHost())) {
            $url = $base_url . $path . $query . $fragment;
            return $collect_bubbleable_metadata ? $generated_url->setGeneratedUrl($url) : $url;
        }
        // Prepare an absolute URL by getting the correct scheme, host and port from
        // the request context.
        if (isset($options['https'])) {
            $scheme = $options['https'] ? 'https' : 'http';
        }
        else {
            $scheme = $this->context
                ->getScheme();
        }
        $scheme_req = $route->getSchemes();
        if ($scheme_req && ($req = $scheme_req[0]) && $scheme !== $req) {
            $scheme = $req;
        }
        $port = '';
        if ('http' === $scheme && 80 != $this->context
            ->getHttpPort()) {
            $port = ':' . $this->context
                ->getHttpPort();
        }
        elseif ('https' === $scheme && 443 != $this->context
            ->getHttpsPort()) {
            $port = ':' . $this->context
                ->getHttpsPort();
        }
        if ($collect_bubbleable_metadata) {
            $generated_url->addCacheContexts([
                'url.site',
            ]);
        }
        $url = $scheme . '://' . $host . $port . $base_url . $path . $query . $fragment;
        return $collect_bubbleable_metadata ? $generated_url->setGeneratedUrl($url) : $url;
    }
    
    /**
     * Passes the path to a processor manager to allow alterations.
     */
    protected function processPath($path, &$options = [], BubbleableMetadata $bubbleable_metadata = NULL) {
        $actual_path = $path === '/' ? $path : rtrim($path, '/');
        return $this->pathProcessor
            ->processOutbound($actual_path, $options, $this->requestStack
            ->getCurrentRequest(), $bubbleable_metadata);
    }
    
    /**
     * Passes the route to the processor manager for altering before compilation.
     *
     * @param string $name
     *   The route name.
     * @param \Symfony\Component\Routing\Route $route
     *   The route object to process.
     * @param array $parameters
     *   An array of parameters to be passed to the route compiler.
     * @param \Drupal\Core\Render\BubbleableMetadata $bubbleable_metadata
     *   (optional) Object to collect route processors' bubbleable metadata.
     */
    protected function processRoute($name, SymfonyRoute $route, array &$parameters, BubbleableMetadata $bubbleable_metadata = NULL) {
        $this->routeProcessor
            ->processOutbound($name, $route, $parameters, $bubbleable_metadata);
    }
    
    /**
     * Find the route using the provided route name.
     *
     * @param string|\Symfony\Component\Routing\Route $name
     *   The route name or a route object.
     *
     * @return \Symfony\Component\Routing\Route
     *   The found route.
     *
     * @throws \Symfony\Component\Routing\Exception\RouteNotFoundException
     *   Thrown if there is no route with that name in this repository.
     *
     * @see \Drupal\Core\Routing\RouteProviderInterface
     */
    protected function getRoute($name) {
        if ($name instanceof SymfonyRoute) {
            $route = $name;
        }
        else {
            $route = clone $this->provider
                ->getRouteByName($name);
        }
        return $route;
    }
    
    /**
     * {@inheritdoc}
     */
    public function supports($name) {
        // Support a route object and any string as route name.
        return is_string($name) || $name instanceof SymfonyRoute;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getRouteDebugMessage($name, array $parameters = []) {
        if (is_scalar($name)) {
            return $name;
        }
        if ($name instanceof SymfonyRoute) {
            return 'Route with pattern ' . $name->getPath();
        }
        return serialize($name);
    }

}