# Copyright (c) 2016 Weitian LI <liweitianux@live.com>
# MIT license

"""
Web user interface (UI) of "fg21sim" based upon Tornado_ web server.

.. _Tornado: http://www.tornadoweb.org/
"""

import os
from concurrent.futures import ThreadPoolExecutor

import tornado.web
from tornado.web import url
from tornado.options import define, options

from .handlers import (IndexHandler,
                       LoginHandler,
                       ConfigsAJAXHandler,
                       ConsoleAJAXHandler,
                       WSHandler)
from .utils import gen_cookie_secret
from ..configs import ConfigManager


# Each module defines its own options, which are added to the global namespace
define("max_workers", default=1, type=int,
       help="Maximum number of threads to execute the submitted tasks")


class Application(tornado.web.Application):
    """
    Application of the "fg21sim" Web UI.

    Attributes
    ----------
    configmanager : `~fg21sim.configs.ConfigManager`
        A ``ConfigManager`` instance, which saves the current configurations
        status.  The configuration operations (e.g., "set", "get", "load")
        are performed on this instance, which is also passed to the
        foregrounds simulation programs.
    websockets : set of `~tornado.websocket.WebSocketHandler`
        Current active WebSockets opened by clients.
        When a new WebSocket connection established, it is added to this
        list, which is also removed from this list when the connection lost.
    executor : `~concurrent.futures.ThreadPoolExecutor`
        An executor that uses a pool of threads to execute the submitted
        tasks asynchronously.
    task_status : dict
        Whether the task is running and/or finished?
        1. running=False, finished=False: not started
        2. running=False, finished=True:  finished
        3. running=True,  finished=False: running
        4. running=True,  finished=True:  ?? error ??
    """

    def __init__(self, **kwargs):
        self.configmanager = ConfigManager()
        self.websockets = set()
        self.executor = ThreadPoolExecutor(max_workers=options.max_workers)
        self.task_status = {"running": False, "finished": False}
        # URL handlers
        handlers = [
            url(r"/", IndexHandler, name="index"),
            url(r"/login", LoginHandler, name="login"),
            url(r"/ajax/configs", ConfigsAJAXHandler),
            url(r"/ajax/console", ConsoleAJAXHandler),
            url(r"/ws", WSHandler),
        ]
        # Application settings
        settings = {
            # The static files will be served from the default "/static/" URI.
            # Recommend to use `{{ static_url(filepath) }}` in the templates.
            "static_path": os.path.join(os.path.dirname(__file__),
                                        "static"),
            "template_path": os.path.join(os.path.dirname(__file__),
                                          "templates"),
            # URL to be redirected to if the user is not logged in
            "login_url": r"/login",
            # Secret key used to sign the cookies
            "cookie_secret": gen_cookie_secret(),
            # Enable "cross-site request forgery" (XSRF) protection
            "xsrf_cookies": True,
        }
        settings.update(kwargs)
        super().__init__(handlers, **settings)