"""Provide the Auth class."""
from typing import Dict, List, Optional, Set, Union

from prawcore import (
    Authorizer,
    ImplicitAuthorizer,
    UntrustedAuthenticator,
    session,
)

from ..exceptions import InvalidImplicitAuth, MissingRequiredAttributeException
from .base import PRAWBase


class Auth(PRAWBase):
    """Auth provides an interface to Reddit's authorization."""

    @property
    def limits(self) -> Dict[str, Optional[Union[str, int]]]:
        """Return a dictionary containing the rate limit info.

        The keys are:

        :remaining: The number of requests remaining to be made in the
            current rate limit window.
        :reset_timestamp: A unix timestamp providing an upper bound on when the
            rate limit counters will reset.
        :used: The number of requests made in the current rate limit
            window.

        All values are initially ``None`` as these values are set in response
        to issued requests.

        The ``reset_timestamp`` value is an upper bound as the real timestamp
        is computed on Reddit's end in preparation for sending the
        response. This value may change slightly within a given window due to
        slight changes in response times and rounding.

        """
        data = self._reddit._core._rate_limiter
        return {
            "remaining": data.remaining,
            "reset_timestamp": data.reset_timestamp,
            "used": data.used,
        }

    def authorize(self, code: str) -> Optional[str]:
        """Complete the web authorization flow and return the refresh token.

        :param code: The code obtained through the request to the redirect uri.
        :returns: The obtained refresh token, if available, otherwise ``None``.

        The session's active authorization will be updated upon success.

        """
        authenticator = self._reddit._read_only_core._authorizer._authenticator
        authorizer = Authorizer(authenticator)
        authorizer.authorize(code)
        authorized_session = session(authorizer)
        self._reddit._core = self._reddit._authorized_core = authorized_session
        return authorizer.refresh_token

    def implicit(self, access_token: str, expires_in: int, scope: str) -> None:
        """Set the active authorization to be an implicit authorization.

        :param access_token: The access_token obtained from Reddit's callback.
        :param expires_in: The number of seconds the ``access_token`` is valid
            for. The origin of this value was returned from Reddit's callback.
            You may need to subtract an offset before passing in this number to
            account for a delay between when Reddit prepared the response, and
            when you make this function call.
        :param scope: A space-delimited string of Reddit OAuth2 scope names as
            returned from Reddit's callback.

        :raises: :class:`.InvalidImplicitAuth` if :class:`.Reddit` was
            initialized for a non-installed application type.

        """
        authenticator = self._reddit._read_only_core._authorizer._authenticator
        if not isinstance(authenticator, UntrustedAuthenticator):
            raise InvalidImplicitAuth
        implicit_session = session(
            ImplicitAuthorizer(authenticator, access_token, expires_in, scope)
        )
        self._reddit._core = self._reddit._authorized_core = implicit_session

    def scopes(self) -> Set[str]:
        """Return a set of scopes included in the current authorization.

        For read-only authorizations this should return ``{"*"}``.

        """
        authorizer = self._reddit._core._authorizer
        if not authorizer.is_valid():
            authorizer.refresh()
        return authorizer.scopes

    def url(
        self,
        scopes: List[str],
        state: str,
        duration: str = "permanent",
        implicit: bool = False,
    ) -> str:
        """Return the URL used out-of-band to grant access to your application.

        :param scopes: A list of OAuth scopes to request authorization for.
        :param state: A string that will be reflected in the callback to
            ``redirect_uri``. This value should be temporarily unique to the
            client for whom the URL was generated for.
        :param duration: Either ``permanent`` or ``temporary`` (default:
            permanent). ``temporary`` authorizations generate access tokens
            that last only 1 hour. ``permanent`` authorizations additionally
            generate a refresh token that can be indefinitely used to generate
            new hour-long access tokens. This value is ignored when
            ``implicit=True``.
        :param implicit: For **installed** applications, this value can be set
            to use the implicit, rather than the code flow. When True, the
            ``duration`` argument has no effect as only temporary tokens can be
            retrieved.

        """
        authenticator = self._reddit._read_only_core._authorizer._authenticator
        if authenticator.redirect_uri is self._reddit.config.CONFIG_NOT_SET:
            raise MissingRequiredAttributeException("redirect_uri must be provided")
        if isinstance(authenticator, UntrustedAuthenticator):
            return authenticator.authorize_url(
                "temporary" if implicit else duration, scopes, state, implicit=implicit,
            )
        if implicit:
            raise InvalidImplicitAuth
        return authenticator.authorize_url(duration, scopes, state)
