# copyright 2003-2016 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/>.

"""Core hooks: synchronize living session on persistent data changes"""

from cubicweb import _

from cubicweb import UnknownProperty, BadConnectionId, validation_error

from cubicweb.predicates import is_instance

from cubicweb.server import hook

from cubicweb.entities.authobjs import user_session_cache_key

def get_user_sessions(cnx, user_eid):

    if cnx.user.eid == user_eid:

        yield cnx

class CachedValueMixin(object):

    """Mixin class providing methods to retrieve some value, specified through

    `value_name` attribute, in session data.

    """

    value_name = None

    session = None  # make pylint happy

    @property

    def cached_value(self):

        """Return cached value for the user, or None"""

        key = user_session_cache_key(self.session.user.eid, self.value_name)

        return self.session.data.get(key, None)

    def update_cached_value(self, value):

        """Update cached value for the user (modifying the set returned by cached_value may not be

        necessary depending on session data implementation, e.g. redis)

        """

        key = user_session_cache_key(self.session.user.eid, self.value_name)

        self.session.data[key] = value

class SyncSessionHook(hook.Hook):

    __abstract__ = True

    category = 'syncsession'

# user/groups synchronisation #################################################

class _GroupOperation(CachedValueMixin, hook.Operation):

    """Base class for group operation"""

    value_name = 'groups'

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

        """Override to get the group name before actual groups manipulation

        we may temporarily loose right access during a commit event, so

        no query should be emitted while comitting

        """

        rql = 'Any N WHERE G eid %(x)s, G name N'

        result = cnx.execute(rql, {'x': kwargs['group_eid']}, build_descr=False)

        hook.Operation.__init__(self, cnx, *args, **kwargs)

        self.group = result[0][0]

class _DeleteGroupOp(_GroupOperation):

    """Synchronize user when a in_group relation has been deleted"""

    def postcommit_event(self):

        cached_groups = self.cached_value

        if cached_groups is not None:

            cached_groups.remove(self.group)

            self.update_cached_value(cached_groups)

class _AddGroupOp(_GroupOperation):

    """Synchronize user when a in_group relation has been added"""

    def postcommit_event(self):

        cached_groups = self.cached_value

        if cached_groups is not None:

            cached_groups.add(self.group)

            self.update_cached_value(cached_groups)

class SyncInGroupHook(SyncSessionHook):

    """Watch addition/removal of in_group relation to synchronize living sessions accordingly"""

    __regid__ = 'syncingroup'

    __select__ = SyncSessionHook.__select__ & hook.match_rtype('in_group')

    events = ('after_delete_relation', 'after_add_relation')

    def __call__(self):

        if self.event == 'after_delete_relation':

            opcls = _DeleteGroupOp

        else:

            opcls = _AddGroupOp

        for session in get_user_sessions(self._cw, self.eidfrom):

            opcls(self._cw, session=session, group_eid=self.eidto)

class _CloseSessionOp(hook.Operation):

    """Close user's session when it has been deleted"""

    def postcommit_event(self):

        try:

            # remove cached groups for the user

            key = user_session_cache_key(self.session.user.eid, 'groups')

            self.session.data.pop(key, None)

        except BadConnectionId:

            pass  # already closed

class UserDeletedHook(SyncSessionHook):

    """Watch deletion of user to close its opened session"""

    __regid__ = 'closession'

    __select__ = SyncSessionHook.__select__ & is_instance('CWUser')

    events = ('after_delete_entity',)

    def __call__(self):

        for session in get_user_sessions(self._cw, self.entity.eid):

            _CloseSessionOp(self._cw, session=session)

# CWProperty hooks #############################################################

class _UserPropertyOperation(CachedValueMixin, hook.Operation):

    """Base class for property operation"""

    value_name = 'properties'

    key = None  # make pylint happy

class _ChangeUserCWPropertyOp(_UserPropertyOperation):

    """Synchronize cached user's properties when one has been added/updated"""

    value = None  # make pylint happy

    def postcommit_event(self):

        cached_props = self.cached_value

        if cached_props is not None:

            cached_props[self.key] = self.value

            self.update_cached_value(cached_props)

class _DelUserCWPropertyOp(_UserPropertyOperation):

    """Synchronize cached user's properties when one has been deleted"""

    def postcommit_event(self):

        cached_props = self.cached_value

        if cached_props is not None:

            cached_props.pop(self.key, None)

            self.update_cached_value(cached_props)

class _ChangeSiteWideCWPropertyOp(hook.Operation):

    """Synchronize site wide properties when one has been added/updated"""

    cwprop = None  # make pylint happy

    def postcommit_event(self):

        cwprop = self.cwprop

        if not cwprop.for_user:

            self.cnx.vreg['propertyvalues'][cwprop.pkey] = \

                self.cnx.vreg.typed_value(cwprop.pkey, cwprop.value)

        # if for_user is set, update is handled by a ChangeUserCWPropertyOp operation

class _DelSiteWideCWPropertyOp(hook.Operation):

    """Synchronize site wide properties when one has been deleted"""

    key = None  # make pylint happy

    def postcommit_event(self):

        self.cnx.vreg['propertyvalues'].pop(self.key, None)

class AddCWPropertyHook(SyncSessionHook):

    __regid__ = 'addcwprop'

    __select__ = SyncSessionHook.__select__ & is_instance('CWProperty')

    events = ('after_add_entity',)

    def __call__(self):

        key, value = self.entity.pkey, self.entity.value

        if key.startswith('sources.'):

            return

        cnx = self._cw

        try:

            value = cnx.vreg.typed_value(key, value)

        except UnknownProperty:

            msg = _('unknown property key %s')

            raise validation_error(self.entity, {('pkey', 'subject'): msg}, (key,))

        except ValueError as ex:

            raise validation_error(self.entity, {('value', 'subject'): str(ex)})

        if cnx.user.matching_groups('managers'):

            _ChangeSiteWideCWPropertyOp(cnx, cwprop=self.entity)

        else:

            cnx.add_relation(self.entity.eid, 'for_user', cnx.user.eid)

class UpdateCWPropertyHook(AddCWPropertyHook):

    __regid__ = 'updatecwprop'

    events = ('after_update_entity',)

    def __call__(self):

        entity = self.entity

        if not ('pkey' in entity.cw_edited or

                'value' in entity.cw_edited):

            return

        key, value = entity.pkey, entity.value

        if key.startswith('sources.'):

            return

        cnx = self._cw

        try:

            value = cnx.vreg.typed_value(key, value)

        except UnknownProperty:

            return

        except ValueError as ex:

            raise validation_error(entity, {('value', 'subject'): str(ex)})

        if entity.for_user:

            for session in get_user_sessions(cnx, entity.for_user[0].eid):

                _ChangeUserCWPropertyOp(cnx, session=session, key=key, value=value)

        else:

            _ChangeSiteWideCWPropertyOp(cnx, cwprop=self.entity)

class DeleteCWPropertyHook(AddCWPropertyHook):

    __regid__ = 'delcwprop'

    events = ('before_delete_entity',)

    def __call__(self):

        cnx = self._cw

        for eidfrom, rtype, eidto in cnx.transaction_data.get('pendingrelations', ()):

            if rtype == 'for_user' and eidfrom == self.entity.eid:

                # if for_user was set, delete already handled by hook on for_user deletion

                break

        else:

            _DelSiteWideCWPropertyOp(cnx, key=self.entity.pkey)

class AddForUserRelationHook(SyncSessionHook):

    __regid__ = 'addcwpropforuser'

    __select__ = SyncSessionHook.__select__ & hook.match_rtype('for_user')

    events = ('after_add_relation',)

    def __call__(self):

        cnx = self._cw

        eidfrom = self.eidfrom

        if not cnx.entity_type(eidfrom) == 'CWProperty':

            return

        key, value = cnx.execute('Any K,V WHERE P eid %(x)s,P pkey K,P value V',

                                 {'x': eidfrom})[0]

        if cnx.vreg.property_info(key)['sitewide']:

            msg = _("site-wide property can't be set for user")

            raise validation_error(eidfrom, {('for_user', 'subject'): msg})

        for session in get_user_sessions(cnx, self.eidto):

            _ChangeUserCWPropertyOp(cnx, session=session, key=key, value=value)

class DelForUserRelationHook(AddForUserRelationHook):

    __regid__ = 'delcwpropforuser'

    events = ('after_delete_relation',)

    def __call__(self):

        cnx = self._cw

        key = cnx.execute('Any K WHERE P eid %(x)s, P pkey K', {'x': self.eidfrom})[0][0]

        cnx.transaction_data.setdefault('pendingrelations', []).append(

            (self.eidfrom, self.rtype, self.eidto))

        for session in get_user_sessions(cnx, self.eidto):

            _DelUserCWPropertyOp(cnx, session=session, key=key)