import functools

from channels.handler import AsgiRequest
from rest_framework.exceptions import AuthenticationFailed
from rest_framework.settings import api_settings


authenticators = [auth() for auth in api_settings.DEFAULT_AUTHENTICATION_CLASSES]


def rest_auth(func):
    """
    Wraps a HTTP or WebSocket connect consumer (or any consumer of messages
    that provides a "cookies" or "get" attribute) to provide a "http_session"
    attribute that behaves like request.session; that is, it's hung off of
    a per-user session key that is saved in a cookie or passed as the
    "session_key" GET parameter.

    It won't automatically create and set a session cookie for users who
    don't have one - that's what SessionMiddleware is for, this is a simpler
    read-only version for more low-level code.

    If a message does not have a session we can inflate, the "session" attribute
    will be None, rather than an empty session you can write to.

    Does not allow a new session to be set; that must be done via a view. This
    is only an accessor for any existing session.
    """
    @functools.wraps(func)
    def inner(message, *args, **kwargs):
        # Make sure there's NOT a http_session already
        try:
            # We want to parse the WebSocket (or similar HTTP-lite) message
            # to get cookies and GET, but we need to add in a few things that
            # might not have been there.
            if "method" not in message.content:
                message.content['method'] = "FAKE"
            request = AsgiRequest(message)

        except Exception as e:
            raise ValueError("Cannot parse HTTP message - are you sure this is a HTTP consumer? %s" % e)
        # Make sure there's a session key
        user = None
        auth = None
        auth_token = request.GET.get("token", None)

        if auth_token:
            # comptatibility with rest framework
            request._request = {}
            request.META["HTTP_AUTHORIZATION"] = "token {}".format(auth_token)
            for authenticator in authenticators:
                try:
                    user_auth_tuple = authenticator.authenticate(request)
                except AuthenticationFailed:
                    pass

                if user_auth_tuple is not None:
                    message._authenticator = authenticator
                    user, auth = user_auth_tuple
                    break
        message.user, message.auth = user, auth
        # Make sure there's a session key
        # Run the consumer
        result = func(message, *args, **kwargs)
        return result
    return inner


def rest_token_user(func):
    """
saf    Wraps a HTTP or WebSocket consumer (or any consumer of messages
    that provides a "COOKIES" attribute) to provide both a "session"
    attribute and a "user" attibute, like AuthMiddleware does.

    This runs http_session() to get a session to hook auth off of.
    If the user does not have a session cookie set, both "session"
    and "user" will be None.
    """
    @rest_auth
    @functools.wraps(func)
    def inner(message, *args, **kwargs):
        # If we didn't get a session, then we don't get a user
        if not hasattr(message, "auth"):
            raise ValueError("Did not see a http session to get auth from")
        return func(message, *args, **kwargs)
    return inner


class RestTokenConsumerMixin(object):
    rest_user = False

    def get_handler(self, message, **kwargs):
        handler = super(RestTokenConsumerMixin, self).get_handler(message, **kwargs)
        if self.rest_user:
            handler = rest_token_user(handler)
        return handler

    def connect(self, message, **kwargs):
        if self.rest_user and not self.message.user:
            self.close()
        return message
