"""user authentication component

:organization: Logilab

:copyright: 2001-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

"""

from __future__ import with_statement

__docformat__ = "restructuredtext en"

from threading import Lock

from logilab.common.decorators import clear_cache

from cubicweb import AuthenticationError, BadConnectionId

from cubicweb.view import Component

from cubicweb.dbapi import repo_connect, ConnectionProperties

from cubicweb.web import InvalidSession

from cubicweb.web.application import AbstractAuthenticationManager

class NoAuthInfo(Exception): pass

class WebAuthInfoRetreiver(Component):

    __registry__ = 'webauth'

    order = None

    def authentication_information(self, req):

        """retreive authentication information from the given request, raise

        NoAuthInfo if expected information is not found.

        """

        raise NotImplementedError()

    def authenticated(self, retreiver, req, cnx, login, authinfo):

        """callback when return authentication information have opened a

        repository connection successfully. Take care req has no session

        attached yet, hence req.execute isn't available.

        """

        pass

class LoginPasswordRetreiver(WebAuthInfoRetreiver):

    __regid__ = 'loginpwdauth'

    order = 10

    def authentication_information(self, req):

        """retreive authentication information from the given request, raise

        NoAuthInfo if expected information is not found.

        """

        login, password = req.get_authorization()

        if not login:

            raise NoAuthInfo()

        return login, {'password': password}

class RepositoryAuthenticationManager(AbstractAuthenticationManager):

    """authenticate user associated to a request and check session validity"""

    def __init__(self, vreg):

        super(RepositoryAuthenticationManager, self).__init__(vreg)

        self.repo = vreg.config.repository(vreg)

        self.log_queries = vreg.config['query-log-file']

        self.authinforetreivers = sorted(vreg['webauth'].possible_objects(vreg),

                                    key=lambda x: x.order)

        assert self.authinforetreivers

        # 2-uple login / password, login is None when no anonymous access

        # configured

        self.anoninfo = vreg.config.anonymous_user()

        if self.anoninfo[0]:

            self.anoninfo = (self.anoninfo[0], {'password': self.anoninfo[1]})

    def validate_session(self, req, session):

        """check session validity, reconnecting it to the repository if the

        associated connection expired in the repository side (hence the

        necessity for this method). Return the connected user on success.

        raise :exc:`InvalidSession` if session is corrupted for a reason or

        another and should be closed

        """

        # with this authentication manager, session is actually a dbapi

        # connection

        login = req.get_authorization()[0]

        # check session.login and not user.login, since in case of login by

        # email, login and cnx.login are the email while user.login is the

        # actual user login

        if login and session.login != login:

            raise InvalidSession('login mismatch')

        try:

            lock = session.reconnection_lock

        except AttributeError:

            lock = session.reconnection_lock = Lock()

        # need to be locked two avoid duplicated reconnections on concurrent

        # requests

        with lock:

            cnx = session.cnx

            try:

                # calling cnx.user() check connection validity, raise

                # BadConnectionId on failure

                user = cnx.user(req)

            except BadConnectionId:

                # check if a connection should be automatically restablished

                if (login is None or login == session.login):

                    cnx = self._authenticate(session.login, session.authinfo)

                    user = cnx.user(req)

                    session.cnx = cnx

                else:

                    raise InvalidSession('bad connection id')

        return user

    def authenticate(self, req):

        """authenticate user using connection information found in the request,

        and return corresponding a :class:`~cubicweb.dbapi.Connection` instance,

        as well as login and authentication information dictionary used to open

        the connection.

        raise :exc:`cubicweb.AuthenticationError` if authentication failed

        (no authentication info found or wrong user/password)

        """

        for retreiver in self.authinforetreivers:

            try:

                login, authinfo = retreiver.authentication_information(req)

            except NoAuthInfo:

                continue

            try:

                cnx = self._authenticate(login, authinfo)

            except AuthenticationError:

                continue # the next one may succeed

            for retreiver_ in self.authinforetreivers:

                retreiver_.authenticated(retreiver, req, cnx, login, authinfo)

            return cnx, login, authinfo

        # false if no authentication info found, eg this is not an

        # authentication failure

        if 'login' in locals():

            req.set_message(req._('authentication failure'))

        login, authinfo = self.anoninfo

        if login:

            cnx = self._authenticate(login, authinfo)

            cnx.anonymous_connection = True

            return cnx, login, authinfo

        raise AuthenticationError()

    def _authenticate(self, login, authinfo):

        cnxprops = ConnectionProperties(self.vreg.config.repo_method,

                                        close=False, log=self.log_queries)

        cnx = repo_connect(self.repo, login, cnxprops=cnxprops, **authinfo)

        # decorate connection

        cnx.vreg = self.vreg

        return cnx