class SessionTestController

class SessionTestController extends ControllerBase {

  /**
   * Prints the stored session value to the screen.
   *
   * @return string
   *   A notification message.
   */
  public function get() {
    return empty($_SESSION['session_test_value']) ? [] : [
      '#markup' => $this
        ->t('The current value of the stored session variable is: %val', [
        '%val' => $_SESSION['session_test_value'],
      ]),
    ];
  }

  /**
   * Prints the stored session value to the screen.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The incoming request.
   *
   * @return string
   *   A notification message.
   */
  public function getFromSessionObject(Request $request) {
    $value = $request
      ->getSession()
      ->get("session_test_key");
    return empty($value) ? [] : [
      '#markup' => $this
        ->t('The current value of the stored session variable is: %val', [
        '%val' => $value,
      ]),
    ];
  }

  /**
   * Print the current session ID.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The incoming request.
   *
   * @return string
   *   A notification message with session ID.
   */
  public function getId(Request $request) {

    // Set a value in $_SESSION, so that SessionManager::save() will start
    // a session.
    $_SESSION['test'] = 'test';
    $request
      ->getSession()
      ->save();
    return [
      '#markup' => 'session_id:' . session_id() . "\n",
    ];
  }

  /**
   * Print the current session ID as read from the cookie.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   *
   * @return string
   *   A notification message with session ID.
   */
  public function getIdFromCookie(Request $request) {
    return [
      '#markup' => 'session_id:' . $request->cookies
        ->get(session_name()) . "\n",
      '#cache' => [
        'contexts' => [
          'cookies:' . session_name(),
        ],
      ],
    ];
  }

  /**
   * Stores a value in $_SESSION['session_test_value'].
   *
   * @param string $test_value
   *   A session value.
   *
   * @return string
   *   A notification message.
   */
  public function set($test_value) {
    $_SESSION['session_test_value'] = $test_value;
    return [
      '#markup' => $this
        ->t('The current value of the stored session variable has been set to %val', [
        '%val' => $test_value,
      ]),
    ];
  }

  /**
   * Turns off session saving and then tries to save a value anyway.
   *
   * @param string $test_value
   *   A session value.
   *
   * @return string
   *   A notification message.
   */
  public function noSet($test_value) {
    \Drupal::service('session_handler.write_safe')
      ->setSessionWritable(FALSE);
    $this
      ->set($test_value);
    return [
      '#markup' => $this
        ->t('session saving was disabled, and then %val was set', [
        '%val' => $test_value,
      ]),
    ];
  }

  /**
   * Sets a message to me displayed on the following page.
   *
   * @return string
   *   A notification message.
   */
  public function setMessage() {
    $this
      ->messenger()
      ->addStatus($this
      ->t('This is a dummy message.'));
    return new Response($this
      ->t('A message was set.'));

    // Do not return anything, so the current request does not result in a themed
    // page with messages. The message will be displayed in the following request
    // instead.
  }

  /**
   * Sets a message but call drupal_save_session(FALSE).
   *
   * @return string
   *   A notification message.
   */
  public function setMessageButDoNotSave() {
    \Drupal::service('session_handler.write_safe')
      ->setSessionWritable(FALSE);
    $this
      ->setMessage();
    return [
      '#markup' => '',
    ];
  }

  /**
   * Only available if current user is logged in.
   *
   * @return string
   *   A notification message.
   */
  public function isLoggedIn() {
    return [
      '#markup' => $this
        ->t('User is logged in.'),
    ];
  }

  /**
   * Returns the trace recorded by test proxy session handlers as JSON.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The incoming request.
   *
   * @return \Symfony\Component\HttpFoundation\JsonResponse
   *   The response.
   */
  public function traceHandler(Request $request) {

    // Start a session if necessary, set a value and then save and close it.
    $request
      ->getSession()
      ->start();
    if (empty($_SESSION['trace-handler'])) {
      $_SESSION['trace-handler'] = 1;
    }
    else {
      $_SESSION['trace-handler']++;
    }
    $request
      ->getSession()
      ->save();

    // Collect traces and return them in JSON format.
    $trace = \Drupal::service('session_test.session_handler_proxy_trace')
      ->getArrayCopy();
    return new JsonResponse($trace);
  }

  /**
   * Returns the values stored in the active session and the user ID.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   *
   * @return \Symfony\Component\HttpFoundation\JsonResponse
   *   A response object containing the session values and the user ID.
   */
  public function getSession(Request $request) {
    return new JsonResponse([
      'session' => $request
        ->getSession()
        ->all(),
      'user' => $this
        ->currentUser()
        ->id(),
    ]);
  }

  /**
   * Sets a test value on the session.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   * @param string $test_value
   *   A value to set on the session.
   *
   * @return \Symfony\Component\HttpFoundation\JsonResponse
   *   A response object containing the session values and the user ID.
   */
  public function setSession(Request $request, $test_value) {
    $session = $request
      ->getSession();
    $session
      ->set('test_value', $test_value);
    return new JsonResponse([
      'session' => $session
        ->all(),
      'user' => $this
        ->currentUser()
        ->id(),
    ]);
  }

  /**
   * Sets the test flag in the session test bag.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   *
   * @return \Symfony\Component\HttpFoundation\Response
   *   The response object.
   */
  public function setSessionBagFlag(Request $request) {

    /** @var \Drupal\session_test\Session\TestSessionBag */
    $bag = $request
      ->getSession()
      ->getBag(TestSessionBag::BAG_NAME);
    $bag
      ->setFlag();
    return new Response();
  }

  /**
   * Clears the test flag from the session test bag.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   *
   * @return \Symfony\Component\HttpFoundation\Response
   *   The response object.
   */
  public function clearSessionBagFlag(Request $request) {

    /** @var \Drupal\session_test\Session\TestSessionBag */
    $bag = $request
      ->getSession()
      ->getBag(TestSessionBag::BAG_NAME);
    $bag
      ->clearFlag();
    return new Response();
  }

  /**
   * Prints a message if the flag in the session bag is set.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   *
   * @return \Symfony\Component\HttpFoundation\Response
   *   The response object.
   */
  public function hasSessionBagFlag(Request $request) {

    /** @var \Drupal\session_test\Session\TestSessionBag */
    $bag = $request
      ->getSession()
      ->getBag(TestSessionBag::BAG_NAME);
    return new Response(empty($bag
      ->hasFlag()) ? $this
      ->t('Flag is absent from session bag') : $this
      ->t('Flag is present in session bag'));
  }

  /**
   * Trigger an exception when the session is written.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   */
  public function triggerWriteException(Request $request) {
    $session = $request
      ->getSession();
    $session
      ->set('test_value', 'Ensure session contains some data');

    // Move sessions table out of the way.
    $schema = \Drupal::database()
      ->schema();
    $schema
      ->renameTable('sessions', 'sessions_tmp');

    // There needs to be a session table, otherwise
    // InstallerRedirectTrait::shouldRedirectToInstaller() will instruct the
    // handleException::handleException to redirect to the installer.
    $schema
      ->createTable('sessions', [
      'description' => "Fake sessions table missing some columns.",
      'fields' => [
        'sid' => [
          'description' => "A fake session ID column.",
          'type' => 'varchar_ascii',
          'length' => 128,
          'not null' => TRUE,
        ],
      ],
      'primary key' => [
        'sid',
      ],
    ]);
    drupal_register_shutdown_function(function () {
      $schema = \Drupal::database()
        ->schema();
      $schema
        ->dropTable('sessions');
      $schema
        ->renameTable('sessions_tmp', 'sessions');
    });
    return new Response();
  }

}