import warnings

import logging

from pyramid.compat import pickle

from pyramid.session import SignedCookieSessionFactory

from cubicweb import Binary

log = logging.getLogger(__name__)

def logerrors(logger):

    def wrap(fn):

        def newfn(*args, **kw):

            try:

                return fn(*args, **kw)

            except:

                logger.exception("Error in %s" % fn.__name__)

        return newfn

    return wrap

def CWSessionFactory(

        secret,

        cookie_name='session',

        max_age=None,

        path='/',

        domain=None,

        secure=False,

        httponly=False,

        set_on_exception=True,

        timeout=1200,

        reissue_time=120,

        hashalg='sha512',

        salt='pyramid.session.',

        serializer=None):

    """ A pyramid session factory that store session data in the CubicWeb

    database.

    Storage is done with the 'CWSession' entity, which is provided by the

    'pyramid' cube.

    .. warning::

        Although it provides a sane default behavior, this session storage has

        a serious overhead because it uses RQL to access the database.

        Using pure SQL would improve a bit (it is roughly twice faster), but it

        is still pretty slow and thus not an immediate priority.

        It is recommended to use faster session factory

        (pyramid_redis_sessions_ for example) if you need speed.

    .. _pyramid_redis_sessions: http://pyramid-redis-sessions.readthedocs.org/

                                en/latest/index.html

    """

    SignedCookieSession = SignedCookieSessionFactory(

        secret,

        cookie_name=cookie_name,

        max_age=max_age,

        path=path,

        domain=domain,

        secure=secure,

        httponly=httponly,

        set_on_exception=set_on_exception,

        timeout=timeout,

        reissue_time=reissue_time,

        hashalg=hashalg,

        salt=salt,

        serializer=serializer)

    class CWSession(SignedCookieSession):

        def __init__(self, request):

            # _set_accessed will be called by the super __init__.

            # Setting _loaded to True inhibates it.

            self._loaded = True

            # the super __init__ will load a single value in the dictionnary,

            # the session id.

            super(CWSession, self).__init__(request)

            # Remove the session id from the dict

            self.sessioneid = self.pop('sessioneid', None)

            self.repo = request.registry['cubicweb.repository']

            # We need to lazy-load only for existing sessions

            self._loaded = self.sessioneid is None

        @logerrors(log)

        def _set_accessed(self, value):

            self._accessed = value

            if self._loaded:

                return

            with self.repo.internal_cnx() as cnx:

                session = cnx.find('CWSession', eid=self.sessioneid).one()

                value = session.cwsessiondata

                if value:

                    # Use directly dict.update to avoir _set_accessed to be

                    # recursively called

                    dict.update(self, pickle.load(value))

            self._loaded = True

        def _get_accessed(self):

            return self._accessed

        accessed = property(_get_accessed, _set_accessed)

        @logerrors(log)

        def _set_cookie(self, response):

            # Save the value in the database

            data = Binary(pickle.dumps(dict(self)))

            sessioneid = self.sessioneid

            with self.repo.internal_cnx() as cnx:

                if not sessioneid:

                    session = cnx.create_entity(

                        'CWSession', cwsessiondata=data)

                    sessioneid = session.eid

                else:

                    session = cnx.entity_from_eid(sessioneid)

                    session.cw_set(cwsessiondata=data)

                cnx.commit()

            # Only if needed actually set the cookie

            if self.new or self.accessed - self.renewed > self._reissue_time:

                dict.clear(self)

                dict.__setitem__(self, 'sessioneid', sessioneid)

                return super(CWSession, self)._set_cookie(response)

            return True

    return CWSession

def includeme(config):

    """ Activate the CubicWeb session factory.

    Usually called via ``config.include('pyramid_cubicweb.auth')``.

    See also :ref:`defaults_module`

    """

    secret = config.registry['cubicweb.config']['pyramid-session-secret']

    if not secret:

        secret = 'notsosecret'

        warnings.warn('''

            !! WARNING !! !! WARNING !!

            The session cookies are signed with a static secret key.

            To put your own secret key, edit your all-in-one.conf file

            and set the 'pyramid-session-secret' key.

            YOU SHOULD STOP THIS INSTANCE unless your really know what you

            are doing !!

        ''')

    session_factory = CWSessionFactory(secret)

    config.set_session_factory(session_factory)