class ProviderRepository

class ProviderRepository implements ProviderRepositoryInterface {
    
    /**
     * How long the provider data should be cached, in seconds.
     *
     * @var int
     */
    protected $maxAge;
    
    /**
     * The HTTP client.
     *
     * @var \GuzzleHttp\Client
     */
    protected $httpClient;
    
    /**
     * URL of a JSON document which contains a database of oEmbed providers.
     *
     * @var string
     */
    protected $providersUrl;
    
    /**
     * The time service.
     *
     * @var \Drupal\Component\Datetime\TimeInterface
     */
    protected $time;
    
    /**
     * The key-value store.
     *
     * @var \Drupal\Core\KeyValueStore\KeyValueStoreInterface
     */
    protected $keyValue;
    
    /**
     * The logger channel.
     *
     * @var \Drupal\Core\Logger\LoggerChannelInterface
     */
    protected $logger;
    
    /**
     * Constructs a ProviderRepository instance.
     *
     * @param \GuzzleHttp\ClientInterface $http_client
     *   The HTTP client.
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The config factory service.
     * @param \Drupal\Component\Datetime\TimeInterface $time
     *   The time service.
     * @param \Drupal\Core\KeyValueStore\KeyValueFactoryInterface $key_value_factory
     *   The key-value store factory.
     * @param \Drupal\Core\Logger\LoggerChannelFactoryInterface $logger_factory
     *   The logger channel factory.
     * @param int $max_age
     *   (optional) How long the cache data should be kept. Defaults to a week.
     */
    public function __construct(ClientInterface $http_client, ConfigFactoryInterface $config_factory, TimeInterface $time, KeyValueFactoryInterface $key_value_factory, LoggerChannelFactoryInterface $logger_factory, int $max_age = 604800) {
        $this->httpClient = $http_client;
        $this->providersUrl = $config_factory->get('media.settings')
            ->get('oembed_providers_url');
        $this->time = $time;
        $this->maxAge = $max_age;
        $this->keyValue = $key_value_factory->get('media');
        $this->logger = $logger_factory->get('media');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getAll() {
        $current_time = $this->time
            ->getCurrentTime();
        $stored = $this->keyValue
            ->get('oembed_providers');
        // If we have stored data that hasn't yet expired, return that. We need to
        // store the data in a key-value store because, if the remote provider
        // database is unavailable, we'd rather return stale data than throw an
        // exception. This means we cannot use a normal cache backend or expirable
        // key-value store, since those could delete the stale data at any time.
        if ($stored && $stored['expires'] > $current_time) {
            return $stored['data'];
        }
        try {
            $response = $this->httpClient
                ->request('GET', $this->providersUrl);
        } catch (ClientExceptionInterface $e) {
            if (isset($stored['data'])) {
                // Use the stale data to fall back gracefully, but warn site
                // administrators that we used stale data.
                $this->logger
                    ->warning('Remote oEmbed providers could not be retrieved due to error: @error. Using previously stored data. This may contain out of date information.', [
                    '@error' => $e->getMessage(),
                ]);
                return $stored['data'];
            }
            // We have no previous data and the request failed.
            throw new ProviderException("Could not retrieve the oEmbed provider database from {$this->providersUrl}", NULL, $e);
        }
        $providers = Json::decode((string) $response->getBody());
        if (!is_array($providers) || empty($providers)) {
            if (isset($stored['data'])) {
                // Use the stale data to fall back gracefully, but as above, warn site
                // administrators that we used stale data.
                $this->logger
                    ->warning('Remote oEmbed providers database returned invalid or empty list. Using previously stored data. This may contain out of date information.');
                return $stored['data'];
            }
            // We have no previous data and the current data is corrupt.
            throw new ProviderException('Remote oEmbed providers database returned invalid or empty list.');
        }
        $keyed_providers = [];
        foreach ($providers as $provider) {
            try {
                $name = (string) $provider['provider_name'];
                $keyed_providers[$name] = new Provider($provider['provider_name'], $provider['provider_url'], $provider['endpoints']);
            } catch (ProviderException $e) {
                // Skip invalid providers, but log the exception message to help with
                // debugging.
                $this->logger
                    ->warning($e->getMessage());
            }
        }
        $this->keyValue
            ->set('oembed_providers', [
            'data' => $keyed_providers,
            'expires' => $current_time + $this->maxAge,
        ]);
        return $keyed_providers;
    }
    
    /**
     * {@inheritdoc}
     */
    public function get($provider_name) {
        $providers = $this->getAll();
        if (!isset($providers[$provider_name])) {
            throw new \InvalidArgumentException("Unknown provider '{$provider_name}'");
        }
        return $providers[$provider_name];
    }

}