"""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

"""

__docformat__ = "restructuredtext en"

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 ExplicitLogin, 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, req, cnx, retreiver):

        """callback when return authentication information have opened a

        repository connection successfully

        """

        pass

class LoginPasswordRetreiver(WebAuthInfoRetreiver):

    __regid__ = 'loginpwdauth'

    order = 10

    def __init__(self, vreg):

        self.anoninfo = vreg.config.anonymous_user()

    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:

            # No session and no login -> try anonymous

            login, password = self.anoninfo

            if not login: # anonymous not authorized

                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

    def validate_session(self, req, session):

        """check session validity, and return eventually hijacked session

        :raise InvalidSession:

          if session is corrupted for a reason or another and should be closed

        """

        # with this authentication manager, session is actually a dbapi

        # connection

        cnx = session

        login = req.get_authorization()[0]

        try:

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

            # BadConnectionId on failure

            user = cnx.user(req)

            # check cnx.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 cnx.login != login:

                cnx.close()

                raise InvalidSession('login mismatch')

        except BadConnectionId:

            # check if a connection should be automatically restablished

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

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

                user = cnx.user(req)

                # backport session's data

                cnx.data = session.data

            else:

                raise InvalidSession('bad connection id')

        # associate the connection to the current request

        req.set_connection(cnx, user)

        return cnx

    def authenticate(self, req):

        """authenticate user and return corresponding user object

        :raise ExplicitLogin: if authentication is required (no authentication

        info found or wrong user/password)

        Note: this method is violating AuthenticationManager interface by

        returning a session instance instead of the user. This is expected by

        the InMemoryRepositorySessionManager.

        """

        for retreiver in self.authinforetreivers:

            try:

                login, authinfo = retreiver.authentication_information(req)

            except NoAuthInfo:

                continue

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

            break

        else:

            raise ExplicitLogin()

        for retreiver_ in self.authinforetreivers:

            retreiver_.authenticated(req, cnx, retreiver)

        return cnx

    def _authenticate(self, req, login, authinfo):

        # remove possibly cached cursor coming from closed connection

        clear_cache(req, 'cursor')

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

                                        close=False, log=self.log_queries)

        try:

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

        except AuthenticationError:

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

            # restore an anonymous connection if possible

            anonlogin, anonpassword = self.vreg.config.anonymous_user()

            if anonlogin and anonlogin != login:

                cnx = repo_connect(self.repo, anonlogin, password=anonpassword,

                                   cnxprops=cnxprops)

                self._init_cnx(cnx, anonlogin, {'password': anonpassword})

            else:

                raise ExplicitLogin()

        else:

            self._init_cnx(cnx, login, authinfo)

        # associate the connection to the current request

        req.set_connection(cnx)

        return cnx

    def _init_cnx(self, cnx, login, authinfo):

        # decorate connection

        if login == self.vreg.config.anonymous_user()[0]:

            cnx.anonymous_connection = True

        cnx.vreg = self.vreg

        cnx.login = login

        cnx.authinfo = authinfo