class PagerFields

class PagerFields extends ViewsSlideshowWidgetBase {
    
    /**
     * {@inheritdoc}
     */
    public function defaultConfiguration() {
        return [
            'views_slideshow_pager_fields_fields' => [
                'default' => [],
            ],
            'views_slideshow_pager_fields_hover' => [
                'default' => 0,
            ],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
        // Settings for fields pager.
        $options = [];
        // Get each field and it's name.
        foreach ($this->getConfiguration()['view']->display_handler
            ->getHandlers('field') as $field_name => $field) {
            $options[$field_name] = $field->adminLabel();
        }
        // Need to wrap this so it indents correctly.
        $form['views_slideshow_pager_fields_wrapper'] = [
            '#markup' => '<div class="vs-dependent">',
        ];
        $default_values = $this->getConfiguration()['views_slideshow_pager_fields_fields'];
        if (isset($default_values['default'])) {
            $default_values = $default_values['default'];
        }
        // Add ability to choose which fields to show in the pager.
        $form['views_slideshow_pager_fields_fields'] = [
            '#type' => 'checkboxes',
            '#title' => $this->t('Pager fields'),
            '#options' => $options,
            '#default_value' => $default_values,
            '#description' => $this->t('Choose the fields that will appear in the pager.'),
            '#states' => [
                'visible' => [
                    ':input[name="' . $this->getConfiguration()['dependency'] . '[enable]"]' => [
                        'checked' => TRUE,
                    ],
                    ':input[name="' . $this->getConfiguration()['dependency'] . '[type]"]' => [
                        'value' => 'views_slideshow_pager_fields',
                    ],
                ],
            ],
        ];
        // Add field to see if they would like to activate slide and pause on pager
        // hover.
        $form['views_slideshow_pager_fields_hover'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Activate Slide and Pause on Pager Hover'),
            '#default_value' => $this->getConfiguration()['views_slideshow_pager_fields_hover'],
            '#description' => $this->t('Should the slide be activated and paused when hovering over a pager item.'),
            '#states' => [
                'visible' => [
                    ':input[name="' . $this->getConfiguration()['dependency'] . '[enable]"]' => [
                        'checked' => TRUE,
                    ],
                    ':input[name="' . $this->getConfiguration()['dependency'] . '[type]"]' => [
                        'value' => 'views_slideshow_pager_fields',
                    ],
                ],
            ],
        ];
        $form['views_slideshow_pager_fields_wrapper_close'] = [
            '#markup' => '</div>',
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function checkCompatiblity($view) {
        return $view->getStyle()
            ->usesFields();
    }

}