Issue #3397732: Configuration option to set which version of Bootstrap is being used

src/Form/BaseConfigurationForm.php

+<?php
+
+namespace Drupal\bootstrap_horizontal_tabs\Form;
+
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Entity\EntityTypeManager;
+use Drupal\Core\Form\ConfigFormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Configure settings for the utnews module.
+ */
+class BaseConfigurationForm extends ConfigFormBase {
+
+  /**
+   * The Config Factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * The EntityTypeManager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManager
+   */
+  protected $entityTypeManager;
+
+  /**
+   * Class constructor.
+   *
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The configuration object factory.
+   * @param \Drupal\Core\Entity\EntityTypeManager $entity_type_manager
+   *   The entity type manager.
+   */
+  public function __construct(ConfigFactoryInterface $config_factory, EntityTypeManager $entity_type_manager) {
+    parent::__construct($config_factory);
+    $this->entityTypeManager = $entity_type_manager;
+    $this->configFactory = $config_factory;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('config.factory'),
+      $container->get('entity_type.manager')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'bootstrap_horizontal_tabs_general_config';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEditableConfigNames() {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $map = ['3'=>'0','4'=>'1','5'=>'2'];
+    $version = $this->config('bootstrap_horizontal_tabs.settings')->get('version');
+    $form['intro']['#markup'] = $this->t('<p>Please select your Bootstrap verion.</p>');
+    $form['version'] = [
+      '#title' => '',
+      '#type' => 'radios',
+      '#options' => [
+        $this->t('Bootstrap 3'),
+        $this->t('Bootstrap 4'),
+        $this->t('Bootstrap 5'),
+    ],
+      '#default_value' => $map[$version],
+    ];
+    return parent::buildForm($form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $map = ['0'=>'3', '1'=>'4', '2'=>'5'];
+    $config = $this->configFactory->getEditable('bootstrap_horizontal_tabs.settings');
+    $config->set('version', $map[$form_state->getValue('version')])->save();
+    drupal_flush_all_caches();
+    parent::submitForm($form, $form_state);
+  }
+}