from . import configs, _http, models

from flask import request, session, redirect
from oauthlib.common import add_params_to_uri


class DiscordOAuth2Session(_http.DiscordOAuth2HttpClient):
    """Main client class representing hypothetical OAuth2 session with discord.
    It uses Flask `session <http://flask.pocoo.org/docs/1.0/api/#flask.session>`_ local proxy object
    to save state, authorization token and keeps record of users sessions across different requests.
    This class inherits :py:class:`flask_discord._http.DiscordOAuth2HttpClient` class.

    Parameters
    ----------
    app : Flask
        An instance of your `flask application <http://flask.pocoo.org/docs/1.0/api/#flask.Flask>`_.

    """

    def create_session(self, scope: list = None, prompt: bool = True, params: dict = None):
        """Primary method used to create OAuth2 session and redirect users for
        authorization code grant.

        Parameters
        ----------
        scope : list, optional
            An optional list of valid `Discord OAuth2 Scopes
            <https://discordapp.com/developers/docs/topics/oauth2#shared-resources-oauth2-scopes>`_.
        prompt : bool, optional
            Determines if the OAuth2 grant should be explicitly prompted and re-approved. Defaults to True.
            Specify False for implicit grant which will skip the authorization screen and redirect to redirect URI.
        params : dict, optional
            An optional mapping of query parameters to supply to the authorization URL.

        Returns
        -------
        redirect
            Flask redirect to discord authorization servers to complete authorization code grant process.

        """
        scope = scope or request.args.get("scope", str()).split() or configs.DISCORD_OAUTH_DEFAULT_SCOPES

        if not prompt and set(scope) & set(configs.DISCORD_PASSTHROUGH_SCOPES):
            raise ValueError("You should use explicit OAuth grant for passthrough scopes like bot.")

        discord_session = self._make_session(scope=scope)
        authorization_url, state = discord_session.authorization_url(configs.DISCORD_AUTHORIZATION_BASE_URL)
        session["DISCORD_OAUTH2_STATE"] = state

        prompt = "consent" if prompt else "none"
        params = params or dict()
        params.update(prompt=prompt)
        authorization_url = add_params_to_uri(authorization_url, params)

        return redirect(authorization_url)

    def callback(self):
        """A method which should be always called after completing authorization code grant process
        usually in callback view.
        It fetches the authorization token and saves it flask
        `session <http://flask.pocoo.org/docs/1.0/api/#flask.session>`_ object.

        """
        if request.values.get("error"):
            return request.values["error"]
        discord = self._make_session(state=session.get("DISCORD_OAUTH2_STATE"))
        token = discord.fetch_token(
            configs.DISCORD_TOKEN_URL,
            client_secret=self.client_secret,
            authorization_response=request.url
        )
        self._token_updater(token)

    def revoke(self):
        """This method clears current discord token, state and all session data from flask
        `session <http://flask.pocoo.org/docs/1.0/api/#flask.session>`_. Which means user will have
        to go through discord authorization token grant flow again. Also tries to remove the user from internal
        cache if they exist.

        """

        self.users_cache.pop(self.user_id, None)

        for session_key in self.SESSION_KEYS:
            try:
                session.pop(session_key)
            except KeyError:
                pass

    @property
    def authorized(self):
        """A boolean indicating whether current session has authorization token or not."""
        return self._make_session().authorized

    @staticmethod
    def fetch_user() -> models.User:
        """This method returns user object from the internal cache if it exists otherwise makes an API call to do so.

        Returns
        -------
        flask_discord.models.User

        """
        return models.User.get_from_cache() or models.User.fetch_from_api()

    @staticmethod
    def fetch_connections() -> list:
        """This method returns list of user connection objects from internal cache if it exists otherwise
        makes an API call to do so.

        Returns
        -------
        list
            List of :py:class:`flask_discord.models.UserConnection` objects.

        """
        user = models.User.get_from_cache()
        try:
            if user.connections is not None:
                return user.connections
        except AttributeError:
            pass

        return models.UserConnection.fetch_from_api()

    @staticmethod
    def fetch_guilds() -> list:
        """This method returns list of guild objects from internal cache if it exists otherwise makes an API
        call to do so.

        Returns
        -------
        list
            List of :py:class:`flask_discord.models.Guild` objects.

        """
        user = models.User.get_from_cache()
        try:
            if user.guilds is not None:
                return user.guilds
        except AttributeError:
            pass

        return models.Guild.fetch_from_api()