# copyright 2003-2014 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

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

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""web session: by default the session is actually the db connection """

__docformat__ = "restructuredtext en"

from time import time

from logging import getLogger

from logilab.common.registry import RegistrableObject

from cubicweb import RepositoryError, Unauthorized, BadConnectionId, set_log_methods

from cubicweb.predicates import yes

from cubicweb.web import InvalidSession

from cubicweb.web.views import authentication

class AbstractSessionManager(RegistrableObject):

    """manage session data associated to a session identifier"""

    __abstract__ = True

    __select__ = yes()

    __registry__ = 'sessions'

    __regid__ = 'sessionmanager'

    def __init__(self, repo):

        vreg = repo.vreg

        self.session_time = vreg.config['http-session-time'] or None

        self.authmanager = authentication.RepositoryAuthenticationManager(repo)

        interval = (self.session_time or 0) / 2.

        if vreg.config.anonymous_user()[0] is not None:

            self.cleanup_anon_session_time = vreg.config['cleanup-anonymous-session-time'] or 5 * 60

            assert self.cleanup_anon_session_time > 0

            if self.session_time is not None:

                self.cleanup_anon_session_time = min(self.session_time,

                                                     self.cleanup_anon_session_time)

            interval = self.cleanup_anon_session_time / 2.

        # we don't want to check session more than once every 5 minutes

        self.clean_sessions_interval = max(5 * 60, interval)

    def clean_sessions(self):

        """cleanup sessions which has not been unused since a given amount of

        time. Return the number of sessions which have been closed.

        """

        self.debug('cleaning http sessions')

        session_time = self.session_time

        closed, total = 0, 0

        for session in self.current_sessions():

            total += 1

            last_usage_time = session.mtime

            no_use_time = (time() - last_usage_time)

            if session.anonymous_session:

                if no_use_time >= self.cleanup_anon_session_time:

                    self.close_session(session)

                    closed += 1

            elif session_time is not None and no_use_time >= session_time:

                self.close_session(session)

                closed += 1

        return closed, total - closed

    def current_sessions(self):

        """return currently open sessions"""

        raise NotImplementedError()

    def get_session(self, req, sessionid):

        """return existing session for the given session identifier"""

        raise NotImplementedError()

    def open_session(self, req):

        """open and return a new session for the given request.

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

        (no authentication info found or wrong user/password)

        """

        raise NotImplementedError()

    def close_session(self, session):

        """close session on logout or on invalid session detected (expired out,

        corrupted...)

        """

        raise NotImplementedError()

set_log_methods(AbstractSessionManager, getLogger('cubicweb.sessionmanager'))

class InMemoryRepositorySessionManager(AbstractSessionManager):

    """manage session data associated to a session identifier"""

    def __init__(self, *args, **kwargs):

        super(InMemoryRepositorySessionManager, self).__init__(*args, **kwargs)

        # XXX require a RepositoryAuthenticationManager which violates

        #     authenticate interface by returning a session instead of a user

        #assert isinstance(self.authmanager, RepositoryAuthenticationManager)

        self._sessions = {}

    # dump_data / restore_data to avoid loosing open sessions on registry

    # reloading

    def dump_data(self):

        return self._sessions

    def restore_data(self, data):

        self._sessions = data

    def current_sessions(self):

        return self._sessions.values()

    def get_session(self, req, sessionid):

        """return existing session for the given session identifier"""

        if sessionid not in self._sessions:

            raise InvalidSession()

        session = self._sessions[sessionid]

        try:

            user = self.authmanager.validate_session(req, session)

        except InvalidSession:

            self.close_session(session)

            raise

        if session.closed:

            self.close_session(session)

            raise InvalidSession()

        return session

    def open_session(self, req):

        """open and return a new session for the given request. The session is

        also bound to the request.

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

        (no authentication info found or wrong user/password)

        """

        session, login = self.authmanager.authenticate(req)

        self._sessions[session.sessionid] = session

        session.mtime = time()

        return session

    def postlogin(self, req, session):

        """postlogin: the user have been related to a session

        Both req and session are passed to this function because actually

        linking the request to the session is not yet done and not the

        responsability of this object.

        """

        # Update last connection date

        # XXX: this should be in a post login hook in the repository, but there

        #      we can't differentiate actual login of automatic session

        #      reopening. Is it actually a problem?

        if 'last_login_time' in req.vreg.schema:

            self._update_last_login_time(session)

        req.set_message(req._('welcome %s!') % session.user.login)

    def _update_last_login_time(self, session):

        # XXX should properly detect missing permission / non writeable source

        # and avoid "except (RepositoryError, Unauthorized)" below

        try:

            with session.new_cnx() as cnx:

                cnx.execute('SET X last_login_time NOW WHERE X eid %(x)s',

                           {'x' : session.user.eid})

                cnx.commit()

        except (RepositoryError, Unauthorized):

            pass

    def close_session(self, session):

        """close session on logout or on invalid session detected (expired out,

        corrupted...)

        """

        self.info('closing http session %s' % session.sessionid)

        self._sessions.pop(session.sessionid, None)

        if not session.closed:

            session.repo.close(session.sessionid)