"""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.pool import LateOperation

from cubicweb.server import BEFORE_ADD_RELATIONS, ON_COMMIT_ADD_RELATIONS

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.keys()

    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(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(LateOperation):

    def precommit_event(self):

        self.rschema.check_perm(self.session, self.action, self.fromeid, self.toeid)

    def commit_event(self):

        pass

def after_add_entity(session, entity):

    if not session.is_super_session:

        CheckEntityPermissionOp(session, entity=entity, action='add')

def after_update_entity(session, entity):

    if not session.is_super_session:

        try:

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

            entity.check_perm('update')

            check_entity_attributes(session, entity)

        except Unauthorized:

            entity.clear_local_perm_cache('update')

            CheckEntityPermissionOp(session, entity=entity, action='update')

def before_del_entity(session, eid):

    if not session.is_super_session:

        eschema = session.repo.schema[session.describe(eid)[0]]

        eschema.check_perm(session, 'delete', eid)

def before_add_relation(session, fromeid, rtype, toeid):

    if rtype in BEFORE_ADD_RELATIONS and not session.is_super_session:

        nocheck = session.transaction_data.get('skip-security', ())

        if (fromeid, rtype, toeid) in nocheck:

            return

        rschema = session.repo.schema[rtype]

        rschema.check_perm(session, 'add', fromeid, toeid)

def after_add_relation(session, fromeid, rtype, toeid):

    if not rtype in BEFORE_ADD_RELATIONS and not session.is_super_session:

        nocheck = session.transaction_data.get('skip-security', ())

        if (fromeid, rtype, toeid) in nocheck:

            return

        rschema = session.repo.schema[rtype]

        if rtype in ON_COMMIT_ADD_RELATIONS:

            CheckRelationPermissionOp(session, action='add', rschema=rschema,

                                      fromeid=fromeid, toeid=toeid)

        else:

            rschema.check_perm(session, 'add', fromeid, toeid)

def before_del_relation(session, fromeid, rtype, toeid):

    if not session.is_super_session:

        nocheck = session.transaction_data.get('skip-security', ())

        if (fromeid, rtype, toeid) in nocheck:

            return

        session.repo.schema[rtype].check_perm(session, 'delete', fromeid, toeid)

def register_security_hooks(hm):

    """register meta-data related hooks on the hooks manager"""

    hm.register_hook(after_add_entity, 'after_add_entity', '')

    hm.register_hook(after_update_entity, 'after_update_entity', '')

    hm.register_hook(before_del_entity, 'before_delete_entity', '')

    hm.register_hook(before_add_relation, 'before_add_relation', '')

    hm.register_hook(after_add_relation, 'after_add_relation', '')

    hm.register_hook(before_del_relation, 'before_delete_relation', '')