# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""Core hooks: workflow related hooks

"""

__docformat__ = "restructuredtext en"

from datetime import datetime

from yams.schema import role_name

from cubicweb import RepositoryError, ValidationError

from cubicweb.interfaces import IWorkflowable

from cubicweb.selectors import implements

from cubicweb.server import hook

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 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:

                session.add_relation(entity.eid, 'in_state', state.eid)

                _FireAutotransitionOp(session, entity=entity)

class _FireAutotransitionOp(hook.Operation):

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

    def precommit_event(self):

        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:

                qname = role_name('custom_workflow', 'subject')

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

                raise ValidationError(entity.eid, {qname: 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)

                    _FireAutotransitionOp(session, entity=entity)

                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:

                qname = role_name('subworkflow_exit', 'subject')

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

                raise ValidationError(self.treid, {qname: 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

            qname = role_name('to_state', 'subject')

            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

            forentity.change_state(tostate, msg, u'text/plain', tr=wftr)

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

class WorkflowHook(hook.Hook):

    __abstract__ = True

    category = 'worfklow'

class SetInitialStateHook(WorkflowHook):

    __regid__ = 'wfsetinitial'

    __select__ = WorkflowHook.__select__ & 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__ & 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:

            qname = role_name('wf_info_for', 'subject')

            msg = session._('mandatory relation')

            raise ValidationError(entity.eid, {qname: 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.user.is_in_group('managers')

                     or not session.write_security)

        # 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:

                qname = role_name('by_transition', 'subject')

                msg = session._('mandatory relation')

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

            deststateeid = entity.get('to_state')

            if not deststateeid:

                qname = role_name('by_transition', 'subject')

                msg = session._('mandatory relation')

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

            deststate = wf.state_by_eid(deststateeid)

            if deststate is None:

                qname = role_name('to_state', 'subject')

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

                raise ValidationError(entity.eid, {qname: 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:

                qname = role_name('by_transition', 'subject')

                if tr is None:

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

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

                if not tr.has_input_state(fromstate):

                    msg = session._("transition %(tr)s isn't allowed from %(st)s") % {

                        'tr': session._(tr.name), 'st': session._(fromstate.name)}

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

                if not tr.may_be_fired(foreid):

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

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

            if entity.get('to_state'):

                deststateeid = entity['to_state']

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

                    qname = role_name('by_transition', 'subject')

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

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

                if swtr is None:

                    deststate = session.entity_from_eid(deststateeid)

                    if not cowpowers and deststate is None:

                        qname = role_name('to_state', 'subject')

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

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

            else:

                deststateeid = tr.destination(forentity).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__ & 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.get('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:

            qname = role_name('in_state', 'subject')

            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, {qname: msg})

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

            qname = role_name('in_state', 'subject')

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

            raise ValidationError(self.eidfrom, {qname: 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())

        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()