class RestExampleClientEdit

class RestExampleClientEdit extends FormBase {
    
    /**
     * RestExampleClientCalls service.
     *
     * @var \Drupal\rest_example\RestExampleClientCalls
     */
    private $client;
    
    /**
     * {@inheritdoc}
     */
    public function __construct(RestExampleClientCalls $restExampleClientCalls) {
        $this->client = $restExampleClientCalls;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('rest_example_client_calls'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'rest_example_client_edit';
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        if (!is_null($form_state->get('node_id')) && !is_numeric($form_state->get('node_id'))) {
            $form_state->setErrorByName('submit', $this->t('The ID passed in the URL is not an integer'));
        }
    }
    
    /**
     * {@inheritdoc}
     *
     * @throws \GuzzleHttp\Exception\GuzzleException
     */
    public function buildForm(array $form, FormStateInterface $form_state, $id = NULL) {
        $config_factory = \Drupal::configFactory();
        if (empty($config_factory->get('rest_example.settings')
            ->get('server_url'))) {
            $this->messenger()
                ->addError($this->t('The remote endpoint service address have not been set. Please go and provide the credentials and the endpoint address on the <a href="@url">config page</a>.', [
                '@url' => base_path() . 'examples/rest-client-settings',
            ]));
            return [
                'error' => [
                    '#markup' => 'Unable to establish to the remote site.',
                ],
            ];
        }
        if (!is_null($id) && !is_numeric($id)) {
            return new Response('The ID passed in the URL is not an integer', 500);
        }
        $title = '';
        $form_state->set('node_id', NULL);
        $form_state->set('node_type', 'rest_example_test');
        // If this an existing node, we pull the data from the remote and set the
        // variables that we use as default values later on.
        if (is_numeric($id)) {
            $node = $this->client
                ->index($id);
            if (isset($node[0])) {
                $title = $node[0]['title'];
                $form_state->set('node_id', $id);
            }
        }
        $form['title'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Node title'),
            '#default_value' => $title,
        ];
        $form['submit'] = [
            '#type' => 'submit',
            '#value' => $this->t('Save'),
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     *
     * @throws \GuzzleHttp\Exception\GuzzleException
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $node_id = $form_state->get('node_id');
        $node_type = $form_state->get('node_type');
        $form_values = $form_state->getValues();
        $node = [
            'nid' => $node_id,
            'title' => $form_values['title'],
            'type' => $node_type,
        ];
        if (is_null($node_id)) {
            $this->client
                ->create($node);
        }
        else {
            $this->client
                ->update($node);
        }
        $this->messenger()
            ->addStatus($this->t('Node was successfully created'));
        $form_state->setRedirect('rest_example.client_actions_index');
    }

}