class SettingsForm

class SettingsForm extends ConfigFormBase {
    
    /**
     * The CSS asset collection optimizer service.
     *
     * @var \Drupal\Core\Asset\AssetCollectionOptimizerInterface
     */
    protected $cssCollectionOptimizer;
    
    /**
     * The JavaScript asset collection optimizer service.
     *
     * @var \Drupal\Core\Asset\AssetCollectionOptimizerInterface
     */
    protected $jsCollectionOptimizer;
    
    /**
     * {@inheritdoc}
     *
     * @param Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   Defines the configuration object factory.
     * @param \Drupal\Core\Asset\AssetCollectionOptimizerInterface $css_collection_optimizer
     *   The CSS asset collection optimizer service.
     * @param \Drupal\Core\Asset\AssetCollectionOptimizerInterface $js_collection_optimizer
     *   The JavaScript asset collection optimizer service.
     */
    public function __construct(ConfigFactoryInterface $config_factory, AssetCollectionOptimizerInterface $css_collection_optimizer, AssetCollectionOptimizerInterface $js_collection_optimizer) {
        parent::__construct($config_factory);
        $this->cssCollectionOptimizer = $css_collection_optimizer;
        $this->jsCollectionOptimizer = $js_collection_optimizer;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('config.factory'), $container->get('asset.css.collection_optimizer'), $container->get('asset.js.collection_optimizer'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'advagg_cdn_settings';
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getEditableConfigNames() {
        return [
            'advagg_cdn.settings',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $config = $this->config('advagg_cdn.settings');
        $form = [];
        $form['cdn'] = [
            '#type' => 'radios',
            '#title' => $this->t('CDN to use'),
            '#default_value' => $config->get('cdn'),
            '#options' => [
                'google' => 'Google',
                'microsoft' => 'Microsoft',
            ],
        ];
        $form['minified'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Use Minified Resources'),
            '#default_value' => $config->get('minified'),
            '#description' => $this->t('When available use minified versions of any resources being served by the CDN.'),
        ];
        if ($this->config('advagg.settings')
            ->get('cache_level') < 0) {
            $form['minified']['#description'] .= $this->t('This setting will not have any effect because AdvAgg is currently in <a href="@devel">development mode</a>. Once the cache settings have been set to normal or aggressive, JS minification will take place.', [
                '@devel' => Url::fromRoute('advagg.settings', [
                    'fragment' => 'edit-advagg-cache-level',
                ])->toString(),
            ]);
        }
        $form['jquery'] = [
            '#type' => 'details',
            '#title' => 'jQuery',
        ];
        $form['jquery']['jquery_active'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Serve jQuery by CDN'),
            '#default_value' => $config->get('jquery'),
        ];
        $form['jquery']['jquery_version'] = [
            '#type' => 'textfield',
            '#title' => $this->t('jQuery version'),
            '#default_value' => $config->get('jquery_version'),
            '#description' => $this->t('Version of jQuery to load.'),
            '#states' => [
                'disabled' => [
                    ':input[name="jquery_active"]' => [
                        'value' => "0",
                    ],
                ],
            ],
        ];
        $form['jquery_ui'] = [
            '#type' => 'details',
            '#title' => 'jQuery UI',
        ];
        $form['jquery_ui']['jquery_ui_css'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Serve jQuery UI CSS by CDN'),
            '#default_value' => $config->get('jquery_ui_css'),
            '#description' => $this->t('Warning: this may change your site appearance as Drupal 8 by default uses the base jQuery theme and the base theme is not available by CDN.'),
        ];
        $jquery_themes = [
            'black-tie',
            'blitzer',
            'cupertino',
            'dark-hive',
            'dot-luv',
            'eggplant',
            'excite-bike',
            'flick',
            'hot-sneaks',
            'humanity',
            'le-frog',
            'mint-choc',
            'overcast',
            'pepper-grinder',
            'redmond',
            'smoothness',
            'south-street',
            'start',
            'sunny',
            'swanky-purse',
            'trontastic',
            'ui-darkness',
            'ui-lightness',
            'vader',
        ];
        $form['jquery_ui']['jquery_ui_theme'] = [
            '#type' => 'select',
            '#title' => $this->t('jQuery UI theme'),
            '#default_value' => $config->get('jquery_ui_theme'),
            '#description' => $this->t('Choose which jQuery theme to use. Smoothness is the most basic and similar to Drupal standard version.'),
            '#options' => array_combine($jquery_themes, $jquery_themes),
        ];
        $form['jquery_ui']['jquery_ui_js'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Serve jQuery UI JavaScript by CDN'),
            '#default_value' => $config->get('jquery_ui_js'),
        ];
        $form['jquery_ui']['jquery_ui_version'] = [
            '#type' => 'textfield',
            '#title' => $this->t('jQuery UI version'),
            '#default_value' => $config->get('jquery_ui_version'),
            '#description' => $this->t('Version of jQuery UI to load.'),
        ];
        return parent::buildForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $this->config('advagg_cdn.settings')
            ->set('cdn', $form_state->getValue('cdn'))
            ->set('jquery', $form_state->getValue('jquery_active'))
            ->set('jquery_version', $form_state->getValue('jquery_version'))
            ->set('jquery_ui_css', $form_state->getValue('jquery_ui_css'))
            ->set('jquery_ui_js', $form_state->getValue('jquery_ui_js'))
            ->set('jquery_ui_theme', $form_state->getValue('jquery_ui_theme'))
            ->set('jquery_ui_version', $form_state->getValue('jquery_ui_version'))
            ->set('minified', $form_state->getValue('minified'))
            ->save();
        parent::submitForm($form, $form_state);
        // Clear relevant caches.
        $this->cssCollectionOptimizer
            ->deleteAll();
        $this->jsCollectionOptimizer
            ->deleteAll();
        Cache::invalidateTags([
            'library_info',
        ]);
    }

}