"""Core hooks: workflow related hooks

: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 ValidationError
from cubicweb.interfaces import IWorkflowable
from cubicweb.selectors import entity_implements
from cubicweb.server.hook import Hook, match_rtype
from cubicweb.server.pool import PreCommitOperation
from cubicweb.server.hookhelper import previous_state


def relation_deleted(session, eidfrom, rtype, eidto):
    session.transaction_data.setdefault('pendingrelations', []).append(
        (eidfrom, rtype, eidto))


class _SetInitialStateOp(PreCommitOperation):
    """make initial state be a default state"""

    def precommit_event(self):
        session = self.session
        entity = self.entity
        # if there is an initial state and the entity's state is not set,
        # use the initial state as a default state
        pendingeids = session.transaction_data.get('pendingeids', ())
        if not entity.eid in pendingeids and not entity.in_state:
            rset = session.execute('Any S WHERE ET initial_state S, ET name %(name)s',
                                   {'name': entity.id})
            if rset:
                session.add_relation(entity.eid, 'in_state', rset[0][0])


class SetInitialStateHook(Hook):
    __id__ = 'wfsetinitial'
    __select__ = Hook.__select__ & entity_implements(IWorkflowable)
    category = 'worfklow'
    events = ('after_add_entity',)

    def __call__(self):
        _SetInitialStateOp(self.cw_req, entity=self.entity)


class PrepareStateChangeHook(Hook):
    """record previous state information"""
    __id__ = 'cwdelstate'
    __select__ = Hook.__select__ & match_rtype('in_state')
    category = 'worfklow'
    events = ('before_delete_relation',)

    def __call__(self):
        self.cw_req.transaction_data.setdefault('pendingrelations', []).append(
            (self.eidfrom, self.rtype, self.eidto))


class FireTransitionHook(PrepareStateChangeHook):
    """check the transition is allowed and record transition information"""
    __id__ = 'wffiretransition'
    events = ('before_add_relation',)

    def __call__(self):
        session = self.cw_req
        eidfrom = self.eidfrom
        eidto = self.eidto
        state = previous_state(session, eidfrom)
        etype = session.describe(eidfrom)[0]
        if not (session.is_super_session or 'managers' in session.user.groups):
            if not state is None:
                entity = session.entity_from_eid(eidfrom)
                # we should find at least one transition going to this state
                try:
                    iter(state.transitions(entity, eidto)).next()
                except StopIteration:
                    msg = session._('transition is not allowed')
                    raise ValidationError(eidfrom, {'in_state': msg})
            else:
                # not a transition
                # check state is initial state if the workflow defines one
                isrset = session.unsafe_execute('Any S WHERE ET initial_state S, ET name %(etype)s',
                                                {'etype': etype})
                if isrset and not eidto == isrset[0][0]:
                    msg = session._('not the initial state for this entity')
                    raise ValidationError(eidfrom, {'in_state': msg})
        eschema = session.repo.schema[etype]
        if not 'wf_info_for' in eschema.object_relations():
            # workflow history not activated for this entity type
            return
        rql = 'INSERT TrInfo T: T wf_info_for E, T to_state DS, T comment %(comment)s'
        args = {'comment': session.get_shared_data('trcomment', None, pop=True),
                'e': eidfrom, 'ds': eidto}
        cformat = session.get_shared_data('trcommentformat', None, pop=True)
        if cformat is not None:
            args['comment_format'] = cformat
            rql += ', T comment_format %(comment_format)s'
        restriction = ['DS eid %(ds)s, E eid %(e)s']
        if not state is None: # not a transition
            rql += ', T from_state FS'
            restriction.append('FS eid %(fs)s')
            args['fs'] = state.eid
        rql = '%s WHERE %s' % (rql, ', '.join(restriction))
        session.unsafe_execute(rql, args, 'e')