class ResourceFetcher

class ResourceFetcher implements ResourceFetcherInterface {
    use UseCacheBackendTrait;
    
    /**
     * The HTTP client.
     *
     * @var \GuzzleHttp\Client
     */
    protected $httpClient;
    
    /**
     * The oEmbed provider repository service.
     *
     * @var \Drupal\media\OEmbed\ProviderRepositoryInterface
     */
    protected $providers;
    
    /**
     * Constructs a ResourceFetcher object.
     *
     * @param \GuzzleHttp\ClientInterface $http_client
     *   The HTTP client.
     * @param \Drupal\media\OEmbed\ProviderRepositoryInterface $providers
     *   The oEmbed provider repository service.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
     *   (optional) The cache backend.
     */
    public function __construct(ClientInterface $http_client, ProviderRepositoryInterface $providers, CacheBackendInterface $cache_backend = NULL) {
        $this->httpClient = $http_client;
        $this->providers = $providers;
        $this->cacheBackend = $cache_backend;
        $this->useCaches = isset($cache_backend);
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchResource($url) {
        $cache_id = "media:oembed_resource:{$url}";
        $cached = $this->cacheGet($cache_id);
        if ($cached) {
            return $this->createResource($cached->data, $url);
        }
        try {
            $response = $this->httpClient
                ->get($url);
        } catch (RequestException $e) {
            throw new ResourceException('Could not retrieve the oEmbed resource.', $url, [], $e);
        }
        list($format) = $response->getHeader('Content-Type');
        $content = (string) $response->getBody();
        if (strstr($format, 'text/xml') || strstr($format, 'application/xml')) {
            $data = $this->parseResourceXml($content, $url);
        }
        elseif (strstr($format, 'text/javascript') || strstr($format, 'application/json')) {
            $data = Json::decode($content);
        }
        else {
            throw new ResourceException('The fetched resource did not have a valid Content-Type header.', $url);
        }
        $this->cacheSet($cache_id, $data);
        return $this->createResource($data, $url);
    }
    
    /**
     * Creates a Resource object from raw resource data.
     *
     * @param array $data
     *   The resource data returned by the provider.
     * @param string $url
     *   The URL of the resource.
     *
     * @return \Drupal\media\OEmbed\Resource
     *   A value object representing the resource.
     *
     * @throws \Drupal\media\OEmbed\ResourceException
     *   If the resource cannot be created.
     */
    protected function createResource(array $data, $url) {
        $data += [
            'title' => NULL,
            'author_name' => NULL,
            'author_url' => NULL,
            'provider_name' => NULL,
            'cache_age' => NULL,
            'thumbnail_url' => NULL,
            'thumbnail_width' => NULL,
            'thumbnail_height' => NULL,
            'width' => NULL,
            'height' => NULL,
            'url' => NULL,
            'html' => NULL,
            'version' => NULL,
        ];
        if ($data['version'] !== '1.0') {
            throw new ResourceException("Resource version must be '1.0'", $url, $data);
        }
        // Prepare the arguments to pass to the factory method.
        $provider = $data['provider_name'] ? $this->providers
            ->get($data['provider_name']) : NULL;
        // The Resource object will validate the data we create it with and throw an
        // exception if anything looks wrong. For better debugging, catch those
        // exceptions and wrap them in a more specific and useful exception.
        try {
            switch ($data['type']) {
                case Resource::TYPE_LINK:
                    return Resource::link($data['url'], $provider, $data['title'], $data['author_name'], $data['author_url'], $data['cache_age'], $data['thumbnail_url'], $data['thumbnail_width'], $data['thumbnail_height']);
                case Resource::TYPE_PHOTO:
                    return Resource::photo($data['url'], $data['width'], $data['height'], $provider, $data['title'], $data['author_name'], $data['author_url'], $data['cache_age'], $data['thumbnail_url'], $data['thumbnail_width'], $data['thumbnail_height']);
                case Resource::TYPE_RICH:
                    return Resource::rich($data['html'], $data['width'], $data['height'], $provider, $data['title'], $data['author_name'], $data['author_url'], $data['cache_age'], $data['thumbnail_url'], $data['thumbnail_width'], $data['thumbnail_height']);
                case Resource::TYPE_VIDEO:
                    return Resource::video($data['html'], $data['width'], $data['height'], $provider, $data['title'], $data['author_name'], $data['author_url'], $data['cache_age'], $data['thumbnail_url'], $data['thumbnail_width'], $data['thumbnail_height']);
                default:
                    throw new ResourceException('Unknown resource type: ' . $data['type'], $url, $data);
            }
        } catch (\InvalidArgumentException $e) {
            throw new ResourceException($e->getMessage(), $url, $data, $e);
        }
    }
    
    /**
     * Parses XML resource data.
     *
     * @param string $data
     *   The raw XML for the resource.
     * @param string $url
     *   The resource URL.
     *
     * @return array
     *   The parsed resource data.
     *
     * @throws \Drupal\media\OEmbed\ResourceException
     *   If the resource data could not be parsed.
     */
    protected function parseResourceXml($data, $url) {
        // Enable userspace error handling.
        $was_using_internal_errors = libxml_use_internal_errors(TRUE);
        libxml_clear_errors();
        $content = simplexml_load_string($data, 'SimpleXMLElement', LIBXML_NOCDATA);
        // Restore the previous error handling behavior.
        libxml_use_internal_errors($was_using_internal_errors);
        $error = libxml_get_last_error();
        if ($error) {
            libxml_clear_errors();
            throw new ResourceException($error->message, $url);
        }
        elseif ($content === FALSE) {
            throw new ResourceException('The fetched resource could not be parsed.', $url);
        }
        // Convert XML to JSON so that the parsed resource has a consistent array
        // structure, regardless of any XML attributes or quirks of the XML parser.
        $data = Json::encode($content);
        return Json::decode($data);
    }

}