from cubicweb import ValidationError

from cubicweb.selectors import is_instance

from cubicweb.server import hook

class SourceHook(hook.Hook):

    __abstract__ = True

    category = 'cw.sources'

class SourceAddedOp(hook.Operation):

    def precommit_event(self):

        self.session.repo.add_source(self.entity)

class SourceAddedHook(SourceHook):

    __regid__ = 'cw.sources.added'

    __select__ = SourceHook.__select__ & is_instance('CWSource')

    events = ('after_add_entity',)

    def __call__(self):

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

class SourceRemovedOp(hook.Operation):

    def precommit_event(self):

        self.session.repo.remove_source(self.uri)

class SourceRemovedHook(SourceHook):

    __regid__ = 'cw.sources.removed'

    __select__ = SourceHook.__select__ & is_instance('CWSource')

    events = ('before_delete_entity',)

    def __call__(self):

        if self.entity.name == 'system':

            raise ValidationError(self.entity.eid, {None: 'cant remove system source'})

        SourceRemovedOp(self._cw, uri=self.entity.name)