# -*- coding:utf-8 -*-

from tornado.ioloop import IOLoop

from tornado.web import RequestHandler, Application

class MiddleWare(object):

    def process_request(self, handler):

        pass

    def process_response(self, handler):

        pass

class CheckLogin(MiddleWare):

    def is_login(self, handler):

        pwd = handler.get_argument("pwd", "")

        if not pwd:

            raise Exception("login required")

        else:

            return True

    def process_request(self, handler):

        self.is_login(handler)

session_counter = 0

class Counter(MiddleWare):

    def process_request(self, handler):

        global session_counter

        session_counter = session_counter + 1

class MiddleHandler(RequestHandler):

    def initialize(self, middleware):

        self.middleware = middleware

    def prepare(self):

        for middleware in self.middleware:

            middleware.process_request(self)

    def finish(self, chunk=None):

        super(MiddleHandler, self).finish(chunk)

    def write_error(self, status_code, **kwargs):

        exc_cls, exc_instance, trace = kwargs.get("exc_info")

        if status_code != 200:

            self.set_status(status_code)

            self.write({"msg": str(exc_instance)})

class EchoHandler(MiddleHandler):

    def get(self):

        message = self.get_argument("msg", "world")

        self.write("hello, %s, current online: %d" % (message, session_counter))

def get_middleware():

    return (CheckLogin(), Counter())

if __name__ == '__main__':

    loop = IOLoop.instance()

    middleware_list = get_middleware()

    app = Application([(r"/echo", EchoHandler, dict(middleware=middleware_list))])

    app.listen(8888)

    loop.start()