--- /dev/null
+<?php
+
+namespace Drupal\user\Plugin\Block;
+
+use Drupal\Core\Access\AccessResult;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Routing\RedirectDestinationTrait;
+use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\Core\Routing\UrlGeneratorTrait;
+use Drupal\Core\Url;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\Block\BlockBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides a 'User login' block.
+ *
+ * @Block(
+ * id = "user_login_block",
+ * admin_label = @Translation("User login"),
+ * category = @Translation("Forms")
+ * )
+ */
+class UserLoginBlock extends BlockBase implements ContainerFactoryPluginInterface {
+
+ use UrlGeneratorTrait;
+ use RedirectDestinationTrait;
+
+ /**
+ * The route match.
+ *
+ * @var \Drupal\Core\Routing\RouteMatchInterface
+ */
+ protected $routeMatch;
+
+ /**
+ * Constructs a new UserLoginBlock instance.
+ *
+ * @param array $configuration
+ * The plugin configuration, i.e. an array with configuration values keyed
+ * by configuration option name. The special key 'context' may be used to
+ * initialize the defined contexts by setting it to an array of context
+ * values keyed by context names.
+ * @param string $plugin_id
+ * The plugin_id for the plugin instance.
+ * @param mixed $plugin_definition
+ * The plugin implementation definition.
+ * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
+ * The route match.
+ */
+ public function __construct(array $configuration, $plugin_id, $plugin_definition, RouteMatchInterface $route_match) {
+ parent::__construct($configuration, $plugin_id, $plugin_definition);
+
+ $this->routeMatch = $route_match;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+ return new static(
+ $configuration,
+ $plugin_id,
+ $plugin_definition,
+ $container->get('current_route_match')
+ );
+ }
+
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function blockAccess(AccountInterface $account) {
+ $route_name = $this->routeMatch->getRouteName();
+ if ($account->isAnonymous() && !in_array($route_name, ['user.login', 'user.logout'])) {
+ return AccessResult::allowed()
+ ->addCacheContexts(['route.name', 'user.roles:anonymous']);
+ }
+ return AccessResult::forbidden();
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function build() {
+ $form = \Drupal::formBuilder()->getForm('Drupal\user\Form\UserLoginForm');
+ unset($form['name']['#attributes']['autofocus']);
+ // When unsetting field descriptions, also unset aria-describedby attributes
+ // to avoid introducing an accessibility bug.
+ // @todo Do this automatically in https://www.drupal.org/node/2547063.
+ unset($form['name']['#description']);
+ unset($form['name']['#attributes']['aria-describedby']);
+ unset($form['pass']['#description']);
+ unset($form['pass']['#attributes']['aria-describedby']);
+ $form['name']['#size'] = 15;
+ $form['pass']['#size'] = 15;
+ $form['#action'] = $this->url('<current>', [], ['query' => $this->getDestinationArray(), 'external' => FALSE]);
+ // Build action links.
+ $items = [];
+ if (\Drupal::config('user.settings')->get('register') != USER_REGISTER_ADMINISTRATORS_ONLY) {
+ $items['create_account'] = [
+ '#type' => 'link',
+ '#title' => $this->t('Create new account'),
+ '#url' => Url::fromRoute('user.register', [], [
+ 'attributes' => [
+ 'title' => $this->t('Create a new user account.'),
+ 'class' => ['create-account-link'],
+ ],
+ ]),
+ ];
+ }
+ $items['request_password'] = [
+ '#type' => 'link',
+ '#title' => $this->t('Reset your password'),
+ '#url' => Url::fromRoute('user.pass', [], [
+ 'attributes' => [
+ 'title' => $this->t('Send password reset instructions via email.'),
+ 'class' => ['request-password-link'],
+ ],
+ ]),
+ ];
+ return [
+ 'user_login_form' => $form,
+ 'user_links' => [
+ '#theme' => 'item_list',
+ '#items' => $items,
+ ],
+ ];
+ }
+
+}