# Source code for cassandra.auth

    # Copyright DataStax, Inc.
    #
    # Licensed under the Apache License, Version 2.0 (the "License");
    # you may not use this file except in compliance with the License.
    # You may obtain a copy of the License at
    #
    # http://www.apache.org/licenses/LICENSE-2.0
    #
    # Unless required by applicable law or agreed to in writing, software
    # distributed under the License is distributed on an "AS IS" BASIS,
    # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    # See the License for the specific language governing permissions and
    try:
        from puresasl.client import SASLClient
    except ImportError:
        SASLClient = None

    class AuthProvider(object):
        """
        An abstract class that defines the interface that will be used for
        creating :class:`~.Authenticator` instances when opening new
        connections to Cassandra.

        .. versionadded:: 2.0.0
        """

        def new_authenticator(self, host):
            """
            Implementations of this class should return a new instance
            of :class:`~.Authenticator` or one of its subclasses.
            """
            raise NotImplementedError()

    class Authenticator(object):
        """
        An abstract class that handles SASL authentication with Cassandra servers.

        Each time a new connection is created and the server requires authentication,
        a new instance of this class will be created by the corresponding
        :class:`~.AuthProvider` to handler that authentication. The lifecycle of the
        new :class:`~.Authenticator` will the be:

        1) The :meth:`~.initial_response()` method will be called. The return
        value will be sent to the server to initiate the handshake.

        2) The server will respond to each client response by either issuing a
        challenge or indicating that the authentication is complete (successful or not).
        If a new challenge is issued, :meth:`~.evaluate_challenge()`
        will be called to produce a response that will be sent to the
        server. This challenge/response negotiation will continue until the server
        responds that authentication is successful (or an :exc:`~.AuthenticationFailed`
        is raised).

        3) When the server indicates that authentication is successful,
        :meth:`~.on_authentication_success` will be called a token string that
        that the server may optionally have sent.

        The exact nature of the negotiation between the client and server is specific
        to the authentication mechanism configured server-side.

        .. versionadded:: 2.0.0
        """

        server_authenticator_class = None
        """ Set during the connection AUTHENTICATE phase """

        def initial_response(self):
            """
            Returns an message to send to the server to initiate the SASL handshake.
            :const:`None` may be returned to send an empty message.
            """
            return None

        def evaluate_challenge(self, challenge):
            """
            Called when the server sends a challenge message.  Generally, this method
            should return :const:`None` when authentication is complete from a
            client perspective.  Otherwise, a string should be returned.
            """
            raise NotImplementedError()

        def on_authentication_success(self, token):
            """
            Called when the server indicates that authentication was successful.
            Depending on the authentication mechanism, `token` may be :const:`None`
            or a string.
            """
            pass

    class PlainTextAuthProvider(AuthProvider):
        """
        An :class:`~.AuthProvider` that works with Cassandra's PasswordAuthenticator.

        Example usage::

            from cassandra.cluster import Cluster
            from cassandra.auth import PlainTextAuthProvider

            auth_provider = PlainTextAuthProvider(
                    username='cassandra', password='cassandra')
            cluster = Cluster(auth_provider=auth_provider)

        .. versionadded:: 2.0.0
        """

        def __init__(self, username, password):
            self.username = username
            self.password = password

        def new_authenticator(self, host):
            return PlainTextAuthenticator(self.username, self.password)

    class PlainTextAuthenticator(Authenticator):
        """
        An :class:`~.Authenticator` that works with Cassandra's PasswordAuthenticator.

        .. versionadded:: 2.0.0
        """

        def __init__(self, username, password):
            self.username = username
            self.password = password

        def initial_response(self):
            return "\x00%s\x00%s" % (self.username, self.password)

        def evaluate_challenge(self, challenge):
            return None

    class SaslAuthProvider(AuthProvider):
        """
        An :class:`~.AuthProvider` supporting general SASL auth mechanisms

        Suitable for GSSAPI or other SASL mechanisms

        Example usage::

            from cassandra.cluster import Cluster
            from cassandra.auth import SaslAuthProvider

            sasl_kwargs = {'service': 'something',
                           'mechanism': 'GSSAPI',
                           'qops': 'auth'.split(',')}
            auth_provider = SaslAuthProvider(**sasl_kwargs)
            cluster = Cluster(auth_provider=auth_provider)

        .. versionadded:: 2.1.4
        """

        def __init__(self, **sasl_kwargs):
            if SASLClient is None:
                raise ImportError('The puresasl library has not been installed')
            if 'host' in sasl_kwargs:
                raise ValueError("kwargs should not contain 'host' since it is passed dynamically to new_authenticator")
            self.sasl_kwargs = sasl_kwargs

        def new_authenticator(self, host):
            return SaslAuthenticator(host, **self.sasl_kwargs)

    class SaslAuthenticator(Authenticator):
        """
        A pass-through :class:`~.Authenticator` using the third party package
        'pure-sasl' for authentication

        .. versionadded:: 2.1.4
        """

        def __init__(self, host, service, mechanism='GSSAPI', **sasl_kwargs):
            if SASLClient is None:
                raise ImportError('The puresasl library has not been installed')
            self.sasl = SASLClient(host, service, mechanism, **sasl_kwargs)

        def initial_response(self):
            return self.sasl.process()

        def evaluate_challenge(self, challenge):
            return self.sasl.process(challenge)