"""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 datetime import datetime

from cubicweb import RepositoryError, ValidationError

from cubicweb.interfaces import IWorkflowable

from cubicweb.selectors import entity_implements

from cubicweb.server import hook

from cubicweb.entities.wfobjs import WorkflowTransition

def _change_state(session, x, oldstate, newstate):

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

    nocheck.add((x, 'in_state', oldstate))

    nocheck.add((x, 'in_state', newstate))

    # delete previous state first in case we're using a super session,

    # unless in_state isn't stored in the system source

    fromsource = session.describe(x)[1]

    if fromsource == 'system' or \

           not session.repo.sources_by_uri[fromsource].support_relation('in_state'):

        session.delete_relation(x, 'in_state', oldstate)

    session.add_relation(x, 'in_state', newstate)

# operations ###################################################################

class _SetInitialStateOp(hook.Operation):

    """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

        if not (session.deleted_in_transaction(entity.eid) or entity.in_state) \

               and entity.current_workflow:

            state = entity.current_workflow.initial

            if state:

                # use super session to by-pass security checks

                session.super_session.add_relation(entity.eid, 'in_state',

                                                   state.eid)

class _FireAutotransitionOp(hook.Operation):

    """try to fire auto transition after state changes"""

    def precommit_event(self):

        session = self.session

        entity = self.entity

        autotrs = list(entity.possible_transitions('auto'))

        if autotrs:

            assert len(autotrs) == 1

            entity.fire_transition(autotrs[0])

class _WorkflowChangedOp(hook.Operation):

    """fix entity current state when changing its workflow"""

    def precommit_event(self):

        # notice that enforcement that new workflow apply to the entity's type is

        # done by schema rule, no need to check it here

        session = self.session

        pendingeids = session.transaction_data.get('pendingeids', ())

        if self.eid in pendingeids:

            return

        entity = session.entity_from_eid(self.eid)

        # check custom workflow has not been rechanged to another one in the same

        # transaction

        mainwf = entity.main_workflow

        if mainwf.eid == self.wfeid:

            deststate = mainwf.initial

            if not deststate:

                msg = session._('workflow has no initial state')

                raise ValidationError(entity.eid, {'custom_workflow': msg})

            if mainwf.state_by_eid(entity.current_state.eid):

                # nothing to do

                return

            # if there are no history, simply go to new workflow's initial state

            if not entity.workflow_history:

                if entity.current_state.eid != deststate.eid:

                    _change_state(session, entity.eid,

                                  entity.current_state.eid, deststate.eid)

                return

            msg = session._('workflow changed to "%s"')

            msg %= session._(mainwf.name)

            session.transaction_data[(entity.eid, 'customwf')] = self.wfeid

            entity.change_state(deststate, msg, u'text/plain')

class _CheckTrExitPoint(hook.Operation):

    def precommit_event(self):

        tr = self.session.entity_from_eid(self.treid)

        outputs = set()

        for ep in tr.subworkflow_exit:

            if ep.subwf_state.eid in outputs:

                msg = self.session._("can't have multiple exits on the same state")

                raise ValidationError(self.treid, {'subworkflow_exit': msg})

            outputs.add(ep.subwf_state.eid)

class _SubWorkflowExitOp(hook.Operation):

    def precommit_event(self):

        session = self.session

        forentity = self.forentity

        trinfo = self.trinfo

        # we're in a subworkflow, check if we've reached an exit point

        wftr = forentity.subworkflow_input_transition()

        if wftr is None:

            # inconsistency detected

            msg = session._("state doesn't belong to entity's current workflow")

            raise ValidationError(self.trinfo.eid, {'to_state': msg})

        tostate = wftr.get_exit_point(forentity, trinfo['to_state'])

        if tostate is not None:

            # reached an exit point

            msg = session._('exiting from subworkflow %s')

            msg %= session._(forentity.current_workflow.name)

            session.transaction_data[(forentity.eid, 'subwfentrytr')] = True

            # XXX iirk

            req = forentity.req

            forentity.req = session.super_session

            try:

                trinfo = forentity.change_state(tostate, msg, u'text/plain',

                                                tr=wftr)

            finally:

                forentity.req = req

# hooks ########################################################################

class WorkflowHook(hook.Hook):

    __abstract__ = True

    category = 'worfklow'

class SetInitialStateHook(WorkflowHook):

    __regid__ = 'wfsetinitial'

    __select__ = WorkflowHook.__select__ & entity_implements(IWorkflowable)

    events = ('after_add_entity',)

    def __call__(self):

        _SetInitialStateOp(self._cw, entity=self.entity)

class PrepareStateChangeHook(WorkflowHook):

    """record previous state information"""

    __regid__ = 'cwdelstate'

    __select__ = WorkflowHook.__select__ & hook.match_rtype('in_state')

    events = ('before_delete_relation',)

    def __call__(self):

        self._cw.transaction_data.setdefault('pendingrelations', []).append(

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

class FireTransitionHook(WorkflowHook):

    """check the transition is allowed, add missing information. Expect that:

    * wf_info_for inlined relation is set

    * by_transition or to_state (managers only) inlined relation is set

    """

    __regid__ = 'wffiretransition'

    __select__ = WorkflowHook.__select__ & entity_implements('TrInfo')

    events = ('before_add_entity',)

    def __call__(self):

        session = self._cw

        entity = self.entity

        # first retreive entity to which the state change apply

        try:

            foreid = entity['wf_info_for']

        except KeyError:

            msg = session._('mandatory relation')

            raise ValidationError(entity.eid, {'wf_info_for': msg})

        forentity = session.entity_from_eid(foreid)

        # then check it has a workflow set, unless we're in the process of changing

        # entity's workflow

        if session.transaction_data.get((forentity.eid, 'customwf')):

            wfeid = session.transaction_data[(forentity.eid, 'customwf')]

            wf = session.entity_from_eid(wfeid)

        else:

            wf = forentity.current_workflow

        if wf is None:

            msg = session._('related entity has no workflow set')

            raise ValidationError(entity.eid, {None: msg})

        # then check it has a state set

        fromstate = forentity.current_state

        if fromstate is None:

            msg = session._('related entity has no state')

            raise ValidationError(entity.eid, {None: msg})

        # True if we are coming back from subworkflow

        swtr = session.transaction_data.pop((forentity.eid, 'subwfentrytr'), None)

        cowpowers = session.is_super_session or 'managers' in session.user.groups

        # no investigate the requested state change...

        try:

            treid = entity['by_transition']

        except KeyError:

            # no transition set, check user is a manager and destination state is

            # specified (and valid)

            if not cowpowers:

                msg = session._('mandatory relation')

                raise ValidationError(entity.eid, {'by_transition': msg})

            deststateeid = entity.get('to_state')

            if not deststateeid:

                msg = session._('mandatory relation')

                raise ValidationError(entity.eid, {'by_transition': msg})

            deststate = wf.state_by_eid(deststateeid)

                msg = session._("state doesn't belong to entity's workflow")

                raise ValidationError(entity.eid, {'to_state': msg})

        else:

            # check transition is valid and allowed, unless we're coming back from

            # subworkflow

            tr = session.entity_from_eid(treid)

            if swtr is None:

                if tr is None:

                    msg = session._("transition doesn't belong to entity's workflow")

                    raise ValidationError(entity.eid, {'by_transition': msg})

                if not tr.has_input_state(fromstate):

                    msg = session._("transition isn't allowed")

                    raise ValidationError(entity.eid, {'by_transition': msg})

                if not tr.may_be_fired(foreid):

                    msg = session._("transition may not be fired")

                    raise ValidationError(entity.eid, {'by_transition': msg})

            if entity.get('to_state'):

                deststateeid = entity['to_state']

                if not cowpowers and deststateeid != tr.destination().eid:

                    msg = session._("transition isn't allowed")

                    raise ValidationError(entity.eid, {'by_transition': msg})

                if swtr is None:

                    deststate = session.entity_from_eid(deststateeid)

                    if not cowpowers and deststate is None:

                        msg = session._("state doesn't belong to entity's workflow")

                        raise ValidationError(entity.eid, {'to_state': msg})

            else:

                deststateeid = tr.destination().eid

        # everything is ok, add missing information on the trinfo entity

        entity['from_state'] = fromstate.eid

        entity['to_state'] = deststateeid

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

        nocheck.add((entity.eid, 'from_state', fromstate.eid))

        nocheck.add((entity.eid, 'to_state', deststateeid))

        _FireAutotransitionOp(session, entity=forentity)

class FiredTransitionHook(WorkflowHook):

    """change related entity state"""

    __regid__ = 'wffiretransition'

    __select__ = WorkflowHook.__select__ & entity_implements('TrInfo')

    events = ('after_add_entity',)

    def __call__(self):

        trinfo = self.entity

        _change_state(self._cw, trinfo['wf_info_for'],

                      trinfo['from_state'], trinfo['to_state'])

        forentity = self._cw.entity_from_eid(trinfo['wf_info_for'])

        assert forentity.current_state.eid == trinfo['to_state']

        if forentity.main_workflow.eid != forentity.current_workflow.eid:

            _SubWorkflowExitOp(self._cw, forentity=forentity, trinfo=trinfo)

class CheckInStateChangeAllowed(WorkflowHook):

    """check state apply, in case of direct in_state change using unsafe_execute

    """

    __regid__ = 'wfcheckinstate'

    __select__ = WorkflowHook.__select__ & hook.match_rtype('in_state')

    events = ('before_add_relation',)

    def __call__(self):

        session = self._cw

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

        if (self.eidfrom, 'in_state', self.eidto) in nocheck:

            # state changed through TrInfo insertion, so we already know it's ok

            return

        entity = session.entity_from_eid(self.eidfrom)

        mainwf = entity.main_workflow

        if mainwf is None:

            msg = session._('entity has no workflow set')

            raise ValidationError(entity.eid, {None: msg})

        for wf in mainwf.iter_workflows():

            if wf.state_by_eid(self.eidto):

                break

        else:

            msg = session._("state doesn't belong to entity's workflow. You may "

                            "want to set a custom workflow for this entity first.")

            raise ValidationError(self.eidfrom, {'in_state': msg})

        if entity.current_workflow and wf.eid != entity.current_workflow.eid:

            msg = session._("state doesn't belong to entity's current workflow")

            raise ValidationError(self.eidfrom, {'in_state': msg})

class SetModificationDateOnStateChange(WorkflowHook):

    """update entity's modification date after changing its state"""

    __regid__ = 'wfsyncmdate'

    __select__ = WorkflowHook.__select__ & hook.match_rtype('in_state')

    events = ('after_add_relation',)

    def __call__(self):

        if self._cw.added_in_transaction(self.eidfrom):

            # new entity, not needed

            return

        entity = self._cw.entity_from_eid(self.eidfrom)

        try:

            entity.set_attributes(modification_date=datetime.now(),

                                  _cw_unsafe=True)

        except RepositoryError, ex:

            # usually occurs if entity is coming from a read-only source

            # (eg ldap user)

            self.warning('cant change modification date for %s: %s', entity, ex)

class CheckWorkflowTransitionExitPoint(WorkflowHook):

    """check that there is no multiple exits from the same state"""

    __regid__ = 'wfcheckwftrexit'

    __select__ = WorkflowHook.__select__ & hook.match_rtype('subworkflow_exit')

    events = ('after_add_relation',)

    def __call__(self):

        _CheckTrExitPoint(self._cw, treid=self.eidfrom)

class SetCustomWorkflow(WorkflowHook):

    __regid__ = 'wfsetcustom'

    __select__ = WorkflowHook.__select__ & hook.match_rtype('custom_workflow')

    events = ('after_add_relation',)

    def __call__(self):

        _WorkflowChangedOp(self._cw, eid=self.eidfrom, wfeid=self.eidto)

class DelCustomWorkflow(SetCustomWorkflow):

    __regid__ = 'wfdelcustom'

    events = ('after_delete_relation',)

    def __call__(self):

        entity = self._cw.entity_from_eid(self.eidfrom)

        typewf = entity.cwetype_workflow()

        if typewf is not None:

            _WorkflowChangedOp(self._cw, eid=self.eidfrom, wfeid=typewf.eid)