from yams.schema import role_name

from cubicweb import ValidationError

from cubicweb.selectors import is_instance

from cubicweb.server import SOURCE_TYPES, hook

class SourceHook(hook.Hook):

    __abstract__ = True

    category = 'cw.sources'

class SourceAddedOp(hook.Operation):

    def postcommit_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):

            msg = self._cw._('unknown source type')

            raise ValidationError(self.entity.eid,

                                  {role_name('type', 'subject'): msg})

        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)

# source mapping synchronization. Expect cw_for_source/cw_schema are immutable

# relations (i.e. can't change from a source or schema to another).

class SourceMappingDeleteHook(SourceHook):

    """check cw_for_source and cw_schema are immutable relations

    XXX empty delete perms would be enough?

    """

    __regid__ = 'cw.sources.delschemaconfig'

    __select__ = SourceHook.__select__ & hook.match_rtype('cw_for_source', 'cw_schema')

    events = ('before_add_relation',)

    def __call__(self):

        if not self._cw.added_in_transaction(self.eidfrom):

            msg = self._cw._("can't change this relation")

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

class SourceMappingChangedOp(hook.DataOperationMixIn, hook.Operation):

    def check_or_update(self, checkonly):

        session = self.session

        # take care, can't call get_data() twice

        try:

            data = self.__data

        except AttributeError:

            data = self.__data = self.get_data()

        for schemacfg, source in data:

            if source is None:

                source = schemacfg.source

            if session.added_in_transaction(schemacfg.eid):

                if not session.deleted_in_transaction(schemacfg.eid):

                    source.add_schema_config(schemacfg, checkonly=checkonly)

            elif session.deleted_in_transaction(schemacfg.eid):

                source.delete_schema_config(schemacfg, checkonly=checkonly)

            else:

                source.update_schema_config(schemacfg, checkonly=checkonly)

    def precommit_event(self):

        self.check_or_update(True)

    def postcommit_event(self):

        self.check_or_update(False)

class SourceMappingChangedHook(SourceHook):

    __regid__ = 'cw.sources.schemaconfig'

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

    events = ('after_add_entity', 'after_update_entity')

    def __call__(self):

        if self.event == 'after_add_entity' or (

            self.event == 'after_update_entity' and 'options' in self.entity.cw_edited):

            SourceMappingChangedOp.get_instance(self._cw).add_data(

                (self.entity, None) )

class SourceMappingDeleteHook(SourceHook):

    __regid__ = 'cw.sources.delschemaconfig'

    __select__ = SourceHook.__select__ & hook.match_rtype('cw_for_source')

    events = ('before_delete_relation',)

    def __call__(self):

        SourceMappingChangedOp.get_instance(self._cw).add_data(

            (self._cw.entity_from_eid(self.eidfrom),

             self._cw.entity_from_eid(self.eidto)) )