Issue #3417468: Add message about missing styles for Style Form

Closes #3417468

src/Form/ParagraphsGridstackManageStyles.php

@@ -5,6 +5,7 @@ namespace Drupal\paragraphs_gridstack\Form;
 use Drupal\Core\Entity\EntityForm;
 use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Url;
 use Drupal\paragraphs_gridstack\GridstackBreakpointsManagerInterface;
 use Drupal\paragraphs_gridstack\GridstackStylesManager;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -113,12 +114,39 @@ class ParagraphsGridstackManageStyles extends EntityForm {
       $options_list[$option['class']] = $option['name'];
     }
 
-    $form['options'] = [
-      '#type' => 'select',
-      '#title' => $this->t('Choose style options'),
-      '#options' => $options_list,
-      '#description' => $this->t('What options you choose?'),
-    ];
+    if (empty($options_list)) {
+      $form['missing_styles_message'] = [
+        '#type' => 'container',
+        '#weight' => -100,
+        '#attributes' => [
+          'class' => ['gridstack-missing-styles-message'],
+        ],
+      ];
+      $form['missing_styles_message']['message_text'] = [
+        '#type' => 'html_tag',
+        '#tag' => 'span',
+        '#value' => t('Missing style options, please set it for the:'),
+        '#attributes' => [
+          'class' => ['gridstack-missing-styles-message-link'],
+        ],
+      ];
+      $form['missing_styles_message']['message_link'] = [
+        '#title' => 'Gridstack Optionset',
+        '#type' => 'link',
+        '#url' => Url::fromRoute('entity.paragraphs_gridstack.edit_form', ['paragraphs_gridstack' => $this->getEntity()->id()]),
+        '#attributes' => [
+          'class' => ['gridstack-missing-styles-message-link'],
+        ],
+      ];
+    }
+    else {
+      $form['options'] = [
+        '#type' => 'select',
+        '#title' => $this->t('Choose style options'),
+        '#options' => $options_list,
+        '#description' => $this->t('What options you choose?'),
+      ];
+    }
 
     // Return the form.
     return $form;