class FileTransferAuthorizeForm

class FileTransferAuthorizeForm extends FormBase {
    
    /**
     * The app root.
     *
     * @var string
     */
    protected $root;
    
    /**
     * Constructs a new FileTransferAuthorizeForm object.
     *
     * @param string $root
     *   The app root.
     */
    public function __construct($root) {
        $this->root = $root;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('app.root'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'authorize_filetransfer_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        // Get all the available ways to transfer files.
        $available_backends = $this->getRequest()
            ->getSession()
            ->get('authorize_filetransfer_info', []);
        if (empty($available_backends)) {
            $this->messenger()
                ->addError($this->t('Unable to continue, no available methods of file transfer'));
            return [];
        }
        if (!$this->getRequest()
            ->isSecure()) {
            $form['information']['https_warning'] = [
                '#prefix' => '<div class="messages messages--error">',
                '#markup' => $this->t('WARNING: You are not using an encrypted connection, so your password will be sent in plain text. <a href=":https-link">Learn more</a>.', [
                    ':https-link' => 'https://www.drupal.org/https-information',
                ]),
                '#suffix' => '</div>',
            ];
        }
        // Decide on a default backend.
        $authorize_filetransfer_default = $form_state->getValue([
            'connection_settings',
            'authorize_filetransfer_default',
        ]);
        if (!$authorize_filetransfer_default) {
            $authorize_filetransfer_default = key($available_backends);
        }
        $form['information']['main_header'] = [
            '#prefix' => '<h3>',
            '#markup' => $this->t('To continue, provide your server connection details'),
            '#suffix' => '</h3>',
        ];
        $form['connection_settings']['#tree'] = TRUE;
        $form['connection_settings']['authorize_filetransfer_default'] = [
            '#type' => 'select',
            '#title' => $this->t('Connection method'),
            '#default_value' => $authorize_filetransfer_default,
            '#weight' => -10,
        ];
        
        /*
         * Here we create two submit buttons. For a JS enabled client, they will
         * only ever see submit_process. However, if a client doesn't have JS
         * enabled, they will see submit_connection on the first form (when picking
         * what filetransfer type to use, and submit_process on the second one (which
         * leads to the actual operation).
         */
        $form['submit_connection'] = [
            '#prefix' => "<br style='clear:both'/>",
            '#name' => 'enter_connection_settings',
            '#type' => 'submit',
            '#value' => $this->t('Enter connection settings'),
            '#weight' => 100,
        ];
        $form['submit_process'] = [
            '#name' => 'process_updates',
            '#type' => 'submit',
            '#value' => $this->t('Continue'),
            '#weight' => 100,
        ];
        // Build a container for each connection type.
        foreach ($available_backends as $name => $backend) {
            $form['connection_settings']['authorize_filetransfer_default']['#options'][$name] = $backend['title'];
            $form['connection_settings'][$name] = [
                '#type' => 'container',
                '#attributes' => [
                    'class' => [
                        "filetransfer-{$name}",
                        'filetransfer',
                    ],
                ],
                '#states' => [
                    'visible' => [
                        'select[name="connection_settings[authorize_filetransfer_default]"]' => [
                            'value' => $name,
                        ],
                    ],
                ],
            ];
            // We can't use #prefix on the container itself since then the header won't
            // be hidden and shown when the containers are being manipulated via JS.
            $form['connection_settings'][$name]['header'] = [
                '#markup' => '<h4>' . $this->t('@backend connection settings', [
                    '@backend' => $backend['title'],
                ]) . '</h4>',
            ];
            $form['connection_settings'][$name] += $this->addConnectionSettings($name);
            // Start non-JS code.
            if ($form_state->getValue([
                'connection_settings',
                'authorize_filetransfer_default',
            ]) == $name) {
                // Change the submit button to the submit_process one.
                $form['submit_process']['#attributes'] = [];
                unset($form['submit_connection']);
                // Activate the proper filetransfer settings form.
                $form['connection_settings'][$name]['#attributes']['style'] = 'display:block';
                // Disable the select box.
                $form['connection_settings']['authorize_filetransfer_default']['#disabled'] = TRUE;
                // Create a button for changing the type of connection.
                $form['connection_settings']['change_connection_type'] = [
                    '#name' => 'change_connection_type',
                    '#type' => 'submit',
                    '#value' => $this->t('Change connection type'),
                    '#weight' => -5,
                    '#attributes' => [
                        'class' => [
                            'filetransfer-change-connection-type',
                        ],
                    ],
                ];
            }
            // End non-JS code.
        }
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        // Only validate the form if we have collected all of the user input and are
        // ready to proceed with updating or installing.
        if ($form_state->getTriggeringElement()['#name'] != 'process_updates') {
            return;
        }
        if ($form_connection_settings = $form_state->getValue('connection_settings')) {
            $backend = $form_connection_settings['authorize_filetransfer_default'];
            $filetransfer = $this->getFiletransfer($backend, $form_connection_settings[$backend]);
            try {
                if (!$filetransfer) {
                    throw new \Exception("The connection protocol '{$backend}' does not exist.");
                }
                $filetransfer->connect();
            } catch (\Exception $e) {
                // The format of this error message is similar to that used on the
                // database connection form in the installer.
                $form_state->setErrorByName('connection_settings', $this->t('Failed to connect to the server. The server reports the following message: <p class="error">@message</p> For more help installing or updating code on your server, see the <a href=":handbook_url">handbook</a>.', [
                    '@message' => $e->getMessage(),
                    ':handbook_url' => 'https://www.drupal.org/docs/8/extending-drupal-8/overview',
                ]));
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $form_connection_settings = $form_state->getValue('connection_settings');
        switch ($form_state->getTriggeringElement()['#name']) {
            case 'process_updates':
                // Save the connection settings to the DB.
                $filetransfer_backend = $form_connection_settings['authorize_filetransfer_default'];
                // If the database is available then try to save our settings. We have
                // to make sure it is available since this code could potentially (will
                // likely) be called during the installation process, before the
                // database is set up.
                try {
                    $filetransfer = $this->getFiletransfer($filetransfer_backend, $form_connection_settings[$filetransfer_backend]);
                    // Now run the operation.
                    $response = $this->runOperation($filetransfer);
                    if ($response instanceof Response) {
                        $form_state->setResponse($response);
                    }
                } catch (\Exception $e) {
                    // If there is no database available, we don't care and just skip
                    // this part entirely.
                }
                break;
            case 'enter_connection_settings':
                $form_state->setRebuild();
                break;
            case 'change_connection_type':
                $form_state->setRebuild();
                $form_state->unsetValue([
                    'connection_settings',
                    'authorize_filetransfer_default',
                ]);
                break;
        }
    }
    
    /**
     * Gets a FileTransfer class for a specific transfer method and settings.
     *
     * @param $backend
     *   The FileTransfer backend to get the class for.
     * @param $settings
     *   Array of settings for the FileTransfer.
     *
     * @return \Drupal\Core\FileTransfer\FileTransfer|bool
     *   An instantiated FileTransfer object for the requested method and settings,
     *   or FALSE if there was an error finding or instantiating it.
     */
    protected function getFiletransfer($backend, $settings = []) {
        $filetransfer = FALSE;
        $info = $this->getRequest()
            ->getSession()
            ->get('authorize_filetransfer_info', []);
        if (!empty($info[$backend])) {
            if (class_exists($info[$backend]['class'])) {
                $filetransfer = $info[$backend]['class']::factory($this->root, $settings);
            }
        }
        return $filetransfer;
    }
    
    /**
     * Generates the Form API array for a given connection backend's settings.
     *
     * @param string $backend
     *   The name of the backend (e.g. 'ftp', 'ssh', etc).
     *
     * @return array
     *   Form API array of connection settings for the given backend.
     *
     * @see hook_filetransfer_backends()
     */
    protected function addConnectionSettings($backend) {
        $defaults = [];
        $form = [];
        // Create an instance of the file transfer class to get its settings form.
        $filetransfer = $this->getFiletransfer($backend);
        if ($filetransfer) {
            $form = $filetransfer->getSettingsForm();
        }
        // Fill in the defaults based on the saved settings, if any.
        $this->setConnectionSettingsDefaults($form, NULL, $defaults);
        return $form;
    }
    
    /**
     * Sets the default settings on a file transfer connection form recursively.
     *
     * The default settings for the file transfer connection forms are saved in
     * the database. The settings are stored as a nested array in the case of a
     * settings form that has details or otherwise uses a nested structure.
     * Therefore, to properly add defaults, we need to walk through all the
     * children form elements and process those defaults recursively.
     *
     * @param $element
     *   Reference to the Form API form element we're operating on.
     * @param $key
     *   The key for our current form element, if any.
     * @param array $defaults
     *   The default settings for the file transfer backend we're operating on.
     */
    protected function setConnectionSettingsDefaults(&$element, $key, array $defaults) {
        // If we're operating on a form element which isn't a details, and we have
        // a default setting saved, stash it in #default_value.
        if (!empty($key) && isset($defaults[$key]) && isset($element['#type']) && $element['#type'] != 'details') {
            $element['#default_value'] = $defaults[$key];
        }
        // Now, we walk through all the child elements, and recursively invoke
        // ourselves on each one. Since the $defaults settings array can be nested
        // (because of #tree, any values inside details will be nested), if
        // there's a subarray of settings for the form key we're currently
        // processing, pass in that subarray to the recursive call. Otherwise, just
        // pass on the whole $defaults array.
        foreach (Element::children($element) as $child_key) {
            $this->setConnectionSettingsDefaults($element[$child_key], $child_key, isset($defaults[$key]) && is_array($defaults[$key]) ? $defaults[$key] : $defaults);
        }
    }
    
    /**
     * Runs the operation specified in 'authorize_operation' session property.
     *
     * @param $filetransfer
     *   The FileTransfer object to use for running the operation.
     *
     * @return \Symfony\Component\HttpFoundation\Response|null
     *   The result of running the operation. If this is an instance of
     *   \Symfony\Component\HttpFoundation\Response the calling code should use
     *   that response for the current page request.
     */
    protected function runOperation($filetransfer) {
        $operation = $this->getRequest()
            ->getSession()
            ->remove('authorize_operation');
        require_once $operation['file'];
        return call_user_func_array($operation['callback'], array_merge([
            $filetransfer,
        ], $operation['arguments']));
    }

}