class OpmlFeedAdd

class OpmlFeedAdd extends FormBase {
    
    /**
     * The feed storage.
     *
     * @var \Drupal\aggregator\FeedStorageInterface
     */
    protected $feedStorage;
    
    /**
     * The HTTP client to fetch the feed data with.
     *
     * @var \GuzzleHttp\ClientInterface
     */
    protected $httpClient;
    
    /**
     * Constructs a database object.
     *
     * @param \Drupal\aggregator\FeedStorageInterface $feed_storage
     *   The feed storage.
     * @param \GuzzleHttp\ClientInterface $http_client
     *   The Guzzle HTTP client.
     */
    public function __construct(FeedStorageInterface $feed_storage, ClientInterface $http_client) {
        $this->feedStorage = $feed_storage;
        $this->httpClient = $http_client;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('entity_type.manager')
            ->getStorage('aggregator_feed'), $container->get('http_client'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'aggregator_opml_add';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $intervals = [
            900,
            1800,
            3600,
            7200,
            10800,
            21600,
            32400,
            43200,
            64800,
            86400,
            172800,
            259200,
            604800,
            1209600,
            2419200,
        ];
        $period = array_map([
            \Drupal::service('date.formatter'),
            'formatInterval',
        ], array_combine($intervals, $intervals));
        $form['upload'] = [
            '#type' => 'file',
            '#title' => $this->t('OPML File'),
            '#description' => $this->t('Upload an OPML file containing a list of feeds to be imported.'),
        ];
        $form['remote'] = [
            '#type' => 'url',
            '#title' => $this->t('OPML Remote URL'),
            '#maxlength' => 1024,
            '#description' => $this->t('Enter the URL of an OPML file. This file will be downloaded and processed only once on submission of the form.'),
        ];
        $form['refresh'] = [
            '#type' => 'select',
            '#title' => $this->t('Update interval'),
            '#default_value' => 3600,
            '#options' => $period,
            '#description' => $this->t('The length of time between feed updates. Requires a correctly configured <a href=":cron">cron maintenance task</a>.', [
                ':cron' => Url::fromRoute('system.status')->toString(),
            ]),
        ];
        $form['actions'] = [
            '#type' => 'actions',
        ];
        $form['actions']['submit'] = [
            '#type' => 'submit',
            '#value' => $this->t('Import'),
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        // If both fields are empty or filled, cancel.
        $all_files = $this->getRequest()->files
            ->get('files', []);
        if ($form_state->isValueEmpty('remote') == empty($all_files['upload'])) {
            $form_state->setErrorByName('remote', $this->t('<em>Either</em> upload a file or enter a URL.'));
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $validators = [
            'file_validate_extensions' => [
                'opml xml',
            ],
        ];
        if ($file = file_save_upload('upload', $validators, FALSE, 0)) {
            $data = file_get_contents($file->getFileUri());
        }
        else {
            // @todo Move this to a fetcher implementation.
            try {
                $response = $this->httpClient
                    ->get($form_state->getValue('remote'));
                $data = (string) $response->getBody();
            } catch (RequestException $e) {
                $this->logger('aggregator')
                    ->warning('Failed to download OPML file due to "%error".', [
                    '%error' => $e->getMessage(),
                ]);
                $this->messenger()
                    ->addStatus($this->t('Failed to download OPML file due to "%error".', [
                    '%error' => $e->getMessage(),
                ]));
                return;
            }
        }
        $feeds = $this->parseOpml($data);
        if (empty($feeds)) {
            $this->messenger()
                ->addStatus($this->t('No new feed has been added.'));
            return;
        }
        // @todo Move this functionality to a processor.
        foreach ($feeds as $feed) {
            // Ensure URL is valid.
            if (!UrlHelper::isValid($feed['url'], TRUE)) {
                $this->messenger()
                    ->addWarning($this->t('The URL %url is invalid.', [
                    '%url' => $feed['url'],
                ]));
                continue;
            }
            // Check for duplicate titles or URLs.
            $query = $this->feedStorage
                ->getQuery();
            $condition = $query->orConditionGroup()
                ->condition('title', $feed['title'])
                ->condition('url', $feed['url']);
            $ids = $query->condition($condition)
                ->execute();
            $result = $this->feedStorage
                ->loadMultiple($ids);
            foreach ($result as $old) {
                if (strcasecmp($old->label(), $feed['title']) == 0) {
                    $this->messenger()
                        ->addWarning($this->t('A feed named %title already exists.', [
                        '%title' => $old->label(),
                    ]));
                    continue 2;
                }
                if (strcasecmp($old->getUrl(), $feed['url']) == 0) {
                    $this->messenger()
                        ->addWarning($this->t('A feed with the URL %url already exists.', [
                        '%url' => $old->getUrl(),
                    ]));
                    continue 2;
                }
            }
            $new_feed = $this->feedStorage
                ->create([
                'title' => $feed['title'],
                'url' => $feed['url'],
                'refresh' => $form_state->getValue('refresh'),
            ]);
            $new_feed->save();
        }
        $form_state->setRedirect('aggregator.admin_overview');
    }
    
    /**
     * Parses an OPML file.
     *
     * Feeds are recognized as <outline> elements with the attributes "text" and
     * "xmlurl" set.
     *
     * @param string $opml
     *   The complete contents of an OPML document.
     *
     * @return array
     *   An array of feeds, each an associative array with a "title" and a "url"
     *   element, or NULL if the OPML document failed to be parsed. An empty array
     *   will be returned if the document is valid but contains no feeds, as some
     *   OPML documents do.
     *
     * @todo Move this to a parser in https://www.drupal.org/node/1963540.
     */
    protected function parseOpml($opml) {
        $feeds = [];
        $xml_parser = xml_parser_create();
        xml_parser_set_option($xml_parser, XML_OPTION_TARGET_ENCODING, 'utf-8');
        if (xml_parse_into_struct($xml_parser, $opml, $values)) {
            foreach ($values as $entry) {
                if ($entry['tag'] == 'OUTLINE' && isset($entry['attributes'])) {
                    $item = $entry['attributes'];
                    if (!empty($item['XMLURL']) && !empty($item['TEXT'])) {
                        $feeds[] = [
                            'title' => $item['TEXT'],
                            'url' => $item['XMLURL'],
                        ];
                    }
                }
            }
        }
        xml_parser_free($xml_parser);
        return $feeds;
    }

}