"""Security hooks: check permissions to add/delete/update entities according to

the user connected to a session

:organization: Logilab

:copyright: 2001-2009 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 cubicweb import Unauthorized

from cubicweb.server import BEFORE_ADD_RELATIONS, ON_COMMIT_ADD_RELATIONS, hook

def check_entity_attributes(session, entity):

    eid = entity.eid

    eschema = entity.e_schema

    # ._default_set is only there on entity creation to indicate unspecified

    # attributes which has been set to a default value defined in the schema

    defaults = getattr(entity, '_default_set', ())

    try:

        editedattrs = entity.edited_attributes

    except AttributeError:

        editedattrs = entity

    for attr in editedattrs:

        if attr in defaults:

            continue

        rschema = eschema.subject_relation(attr)

        if rschema.is_final(): # non final relation are checked by other hooks

            # add/delete should be equivalent (XXX: unify them into 'update' ?)

            rschema.check_perm(session, 'add', eid)

class _CheckEntityPermissionOp(hook.LateOperation):

    def precommit_event(self):

        #print 'CheckEntityPermissionOp', self.session.user, self.entity, self.action

        self.entity.check_perm(self.action)

        check_entity_attributes(self.session, self.entity)

    def commit_event(self):

        pass

class _CheckRelationPermissionOp(hook.LateOperation):

    def precommit_event(self):

        self.rschema.check_perm(self.session, self.action, self.eidfrom, self.eidto)

    def commit_event(self):

        pass

class SecurityHook(hook.Hook):

    __abstract__ = True

    category = 'security'

    __select__ = hook.Hook.__select__ & hook.regular_session()

class AfterAddEntitySecurityHook(SecurityHook):

    __id__ = 'securityafteraddentity'

    events = ('after_add_entity',)

    def __call__(self):

        _CheckEntityPermissionOp(self._cw, entity=self.entity, action='add')

class AfterUpdateEntitySecurityHook(SecurityHook):

    __id__ = 'securityafterupdateentity'

    events = ('after_update_entity',)

    def __call__(self):

        try:

            # check user has permission right now, if not retry at commit time

            self.entity.check_perm('update')

            check_entity_attributes(self._cw, self.entity)

        except Unauthorized:

            self.entity.clear_local_perm_cache('update')

            _CheckEntityPermissionOp(self._cw, entity=self.entity, action='update')

class BeforeDelEntitySecurityHook(SecurityHook):

    __id__ = 'securitybeforedelentity'

    events = ('before_delete_entity',)

    def __call__(self):

        self.entity.check_perm('delete')

class BeforeAddRelationSecurityHook(SecurityHook):

    __id__ = 'securitybeforeaddrelation'

    events = ('before_add_relation',)

    def __call__(self):

        if self.rtype in BEFORE_ADD_RELATIONS:

            rschema = self._cw.repo.schema[self.rtype]

            rschema.check_perm(self._cw, 'add', self.eidfrom, self.eidto)

class AfterAddRelationSecurityHook(SecurityHook):

    __id__ = 'securityafteraddrelation'

    events = ('after_add_relation',)

    def __call__(self):

        if not self.rtype in BEFORE_ADD_RELATIONS:

            rschema = self._cw.repo.schema[self.rtype]

            if self.rtype in ON_COMMIT_ADD_RELATIONS:

                _CheckRelationPermissionOp(self._cw, action='add',

                                           rschema=rschema,

                                           eidfrom=self.eidfrom,

                                           eidto=self.eidto)

            else:

                rschema.check_perm(self._cw, 'add', self.eidfrom, self.eidto)

class BeforeDelRelationSecurityHook(SecurityHook):

    __id__ = 'securitybeforedelrelation'

    events = ('before_delete_relation',)

    def __call__(self):

            return

        self._cw.repo.schema[self.rtype].check_perm(self._cw, 'delete',

                                                       self.eidfrom, self.eidto)