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((string) $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()) ? (string) $this->t('Flag is absent from session bag') : (string) $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();
    }

}