"""workflow definition and history related entities

: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.entities import AnyEntity, fetch_config

class Transition(AnyEntity):

    """customized class for Transition entities

    provides a specific may_be_passed method to check if the relation may be

    passed by the logged user

    """

    id = 'Transition'

    fetch_attrs, fetch_order = fetch_config(['name'])

    def may_be_passed(self, eid, stateeid):

        """return true if the logged user may pass this transition

        `eid` is the eid of the object on which we may pass the transition

        `stateeid` is the eid of the current object'state XXX unused

        """

        user = self.req.user

        # check user is at least in one of the required groups if any

        groups = frozenset(g.name for g in self.require_group)

        if groups:

            matches = user.matching_groups(groups)

            if matches:

                return matches

            if 'owners' in groups and user.owns(eid):

                return True

        # check one of the rql expression conditions matches if any

        if self.condition:

            for rqlexpr in self.condition:

                if rqlexpr.check_expression(self.req, eid):

                    return True

        if self.condition or groups:

            return False

        return True

    def destination(self):

        return self.destination_state[0]

    def after_deletion_path(self):

        """return (path, parameters) which should be used as redirect

        information when this entity is being deleted

        """

        if self.transition_of:

            return self.transition_of[0].rest_path(), {'vid': 'workflow'}

        return super(Transition, self).after_deletion_path()

class State(AnyEntity):

    """customized class for State entities

    provides a specific transitions method returning transitions that may be

    passed by the current user for the given entity

    """

    id = 'State'

    fetch_attrs, fetch_order = fetch_config(['name'])

    rest_attr = 'eid'

    def transitions(self, entity, desteid=None):

        rql = ('Any T,N,DS where S allowed_transition T, S eid %(x)s, '

               'T name N, T destination_state DS, '

               'T transition_of ET, ET name %(et)s')

        if desteid is not None:

            rql += ', DS eid %(ds)s'

        rset = self.req.execute(rql, {'x': self.eid, 'et': str(entity.e_schema),

                                         'ds': desteid}, 'x')

        for tr in rset.entities():

            if tr.may_be_passed(entity.eid, self.eid):

                yield tr

    def after_deletion_path(self):

        """return (path, parameters) which should be used as redirect

        information when this entity is being deleted

        """

        if self.state_of:

            return self.state_of[0].rest_path(), {'vid': 'workflow'}

        return super(State, self).after_deletion_path()

class TrInfo(AnyEntity):

    """customized class for Transition information entities

    """

    id = 'TrInfo'

    fetch_attrs, fetch_order = fetch_config(['creation_date', 'comment'],

                                            pclass=None) # don't want modification_date

    @property

    def for_entity(self):

        return self.wf_info_for and self.wf_info_for[0]

    @property

    def previous_state(self):

        return self.from_state and self.from_state[0]

    @property

    def new_state(self):

        return self.to_state[0]

    def after_deletion_path(self):

        """return (path, parameters) which should be used as redirect

        information when this entity is being deleted

        """

        if self.for_entity:

            return self.for_entity.rest_path(), {}

        return 'view', {}