# copyright 2003-2013 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: set generic metadata"""

__docformat__ = "restructuredtext en"

from datetime import datetime

from base64 import b64encode

from pytz import utc

from cubicweb.predicates import is_instance

from cubicweb.server import hook

from cubicweb.server.edition import EditedEntity

class MetaDataHook(hook.Hook):

    __abstract__ = True

    category = 'metadata'

class InitMetaAttrsHook(MetaDataHook):

    """before create a new entity -> set creation and modification date

    this is a conveniency hook, you shouldn't have to disable it

    """

    __regid__ = 'metaattrsinit'

    events = ('before_add_entity',)

    def __call__(self):

        timestamp = datetime.now(utc)

        edited = self.entity.cw_edited

        if not edited.get('creation_date'):

            edited['creation_date'] = timestamp

        if not edited.get('modification_date'):

            edited['modification_date'] = timestamp

        if not self._cw.transaction_data.get('do-not-insert-cwuri'):

            cwuri = u'%s%s' % (self._cw.base_url(), self.entity.eid)

            edited.setdefault('cwuri', cwuri)

class UpdateMetaAttrsHook(MetaDataHook):

    """update an entity -> set modification date"""

    __regid__ = 'metaattrsupdate'

    events = ('before_update_entity',)

    def __call__(self):

        # repairing is true during c-c upgrade/shell and similar commands. We

        # usually don't want to update modification date in such cases.

        #

        # XXX to be really clean, we should turn off modification_date update

        # explicitly on each command where we do not want that behaviour.

        if not self._cw.vreg.config.repairing:

            self.entity.cw_edited.setdefault('modification_date', datetime.now(utc))

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

    def precommit_event(self):

        cnx = self.cnx

        relations = [(eid, cnx.user.eid) for eid in self.get_data()

                # don't consider entities that have been created and deleted in

                # the same transaction, nor ones where created_by has been

                # explicitly set

                if not cnx.deleted_in_transaction(eid) and \

                   not cnx.entity_from_eid(eid).created_by]

        cnx.add_relations([('created_by', relations)])

class SetOwnershipHook(MetaDataHook):

    """create a new entity -> set owner and creator metadata"""

    __regid__ = 'setowner'

    events = ('after_add_entity',)

    def __call__(self):

        if not self._cw.is_internal_session:

            self._cw.add_relation(self.entity.eid, 'owned_by', self._cw.user.eid)

            SetCreatorOp.get_instance(self._cw).add_data(self.entity.eid)

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

    def precommit_event(self):

        for compositeeid, composedeid in self.get_data():

            if self.cnx.deleted_in_transaction(compositeeid):

                continue

            if self.cnx.deleted_in_transaction(composedeid):

                continue

            self.cnx.execute('SET X owned_by U WHERE C owned_by U, C eid %(c)s,'

                                 'NOT EXISTS(X owned_by U, X eid %(x)s)',

                                 {'c': compositeeid, 'x': composedeid})

class SyncCompositeOwner(MetaDataHook):

    """when adding composite relation, the composed should have the same owners

    has the composite

    """

    __regid__ = 'synccompositeowner'

    events = ('after_add_relation',)

    def __call__(self):

        if self.rtype == 'wf_info_for':

            # skip this special composite relation # XXX (syt) why?

            return

        eidfrom, eidto = self.eidfrom, self.eidto

        composite = self._cw.rtype_eids_rdef(self.rtype, eidfrom, eidto).composite

        if composite == 'subject':

            SyncOwnersOp.get_instance(self._cw).add_data( (eidfrom, eidto) )

        elif composite == 'object':

            SyncOwnersOp.get_instance(self._cw).add_data( (eidto, eidfrom) )

class FixUserOwnershipHook(MetaDataHook):

    """when a user has been created, add owned_by relation on itself"""

    __regid__ = 'fixuserowner'

    __select__ = MetaDataHook.__select__ & is_instance('CWUser')

    events = ('after_add_entity',)

    def __call__(self):

        self._cw.add_relation(self.entity.eid, 'owned_by', self.entity.eid)

class UpdateFTIHook(MetaDataHook):

    """sync fulltext index text index container when a relation with

    fulltext_container set is added / removed

    """

    __regid__ = 'updateftirel'

    events = ('after_add_relation', 'after_delete_relation')

    def __call__(self):

        rtype = self.rtype

        cnx = self._cw

        ftcontainer = cnx.vreg.schema.rschema(rtype).fulltext_container

        if ftcontainer == 'subject':

            cnx.repo.system_source.index_entity(

                cnx, cnx.entity_from_eid(self.eidfrom))

        elif ftcontainer == 'object':

            cnx.repo.system_source.index_entity(

                cnx, cnx.entity_from_eid(self.eidto))

# entity source handling #######################################################

class ChangeEntitySourceUpdateCaches(hook.Operation):

    oldsource = newsource = entity = None # make pylint happy

    def postcommit_event(self):

        self.oldsource.reset_caches()

        repo = self.cnx.repo

        entity = self.entity

        extid = entity.cw_metainformation()['extid']

        repo._type_source_cache[entity.eid] = (

            entity.cw_etype, None, self.newsource.uri)

        repo._extid_cache[extid] = -entity.eid

class ChangeEntitySourceDeleteHook(MetaDataHook):

    """support for moving an entity from an external source by watching 'Any

    cw_source CWSource' relation

    """

    __regid__ = 'cw.metadata.source-change'

    __select__ = MetaDataHook.__select__ & hook.match_rtype('cw_source')

    events = ('before_delete_relation',)

    def __call__(self):

        if (self._cw.deleted_in_transaction(self.eidfrom)

            or self._cw.deleted_in_transaction(self.eidto)):

            return

        schange = self._cw.transaction_data.setdefault('cw_source_change', {})

        schange[self.eidfrom] = self.eidto

class ChangeEntitySourceAddHook(MetaDataHook):

    __regid__ = 'cw.metadata.source-change'

    __select__ = MetaDataHook.__select__ & hook.match_rtype('cw_source')

    events = ('before_add_relation',)

    def __call__(self):

        schange = self._cw.transaction_data.get('cw_source_change')

        if schange is not None and self.eidfrom in schange:

            newsource = self._cw.entity_from_eid(self.eidto)

            if newsource.name != 'system':

                raise Exception('changing source to something else than the '

                                'system source is unsupported')

            syssource = newsource.repo_source

            oldsource = self._cw.entity_from_eid(schange[self.eidfrom])

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

            # we don't want the moved entity to be reimported later.  To

            # distinguish this state, move the record from the 'entities' table

            # to 'moved_entities'.  External source will then have consider

            # case where `extid2eid` returns a negative eid as 'this entity was

            # known but has been moved, ignore it'.

            extid = self._cw.entity_metas(entity.eid)['extid']

            assert extid is not None

            attrs = {'eid': entity.eid, 'extid': b64encode(extid).decode('ascii')}

            self._cw.system_sql(syssource.sqlgen.insert('moved_entities', attrs), attrs)

            attrs = {'type': entity.cw_etype, 'eid': entity.eid, 'extid': None,

                     'asource': 'system'}

            self._cw.system_sql(syssource.sqlgen.update('entities', attrs, ['eid']), attrs)

            # register an operation to update repository/sources caches

            ChangeEntitySourceUpdateCaches(self._cw, entity=entity,

                                           oldsource=oldsource.repo_source,

                                           newsource=syssource)