"""Core hooks: check schema validity, unsure we are not deleting necessary

entities...

: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 UnknownProperty, ValidationError, BadConnectionId

from cubicweb.server.pool import Operation, LateOperation, PreCommitOperation

from cubicweb.server.hookhelper import (check_internal_entity, 

                                        get_user_sessions, rproperty)

from cubicweb.server.repository import FTIndexEntityOp

# special relations that don't have to be checked for integrity, usually

# because they are handled internally by hooks (so we trust ourselves)

DONT_CHECK_RTYPES_ON_ADD = set(('owned_by', 'created_by',

                                'is', 'is_instance_of',

                                'wf_info_for', 'from_state', 'to_state'))

DONT_CHECK_RTYPES_ON_DEL = set(('is', 'is_instance_of',

                                'wf_info_for', 'from_state', 'to_state'))

def relation_deleted(session, eidfrom, rtype, eidto):

    session.transaction_data.setdefault('pendingrelations', []).append(

        (eidfrom, rtype, eidto))

def eschema_type_eid(session, etype):

    """get eid of the CWEType entity for the given yams type"""

    eschema = session.repo.schema.eschema(etype)

    # eschema.eid is None if schema has been readen from the filesystem, not

    # from the database (eg during tests)

    if eschema.eid is None:

        eschema.eid = session.unsafe_execute(

            'Any X WHERE X is CWEType, X name %(name)s',

            {'name': str(etype)})[0][0]

    return eschema.eid

# base meta-data handling ######################################################

def setctime_before_add_entity(session, entity):

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

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

    """

    timestamp = datetime.now()

    entity.setdefault('creation_date', timestamp)

    entity.setdefault('modification_date', timestamp)

    if not session.get_shared_data('do-not-insert-cwuri'):

        entity.setdefault('cwuri', u'%seid/%s' % (session.base_url(), entity.eid))

def setmtime_before_update_entity(session, entity):

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

    entity.setdefault('modification_date', datetime.now())

class SetCreatorOp(PreCommitOperation):

    def precommit_event(self):

        session = self.session

        if self.entity.eid in session.transaction_data.get('pendingeids', ()):

            # entity have been created and deleted in the same transaction

            return

        if not self.entity.created_by:

            session.add_relation(self.entity.eid, 'created_by', session.user.eid)

def setowner_after_add_entity(session, entity):

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

    asession = session.actual_session()

    if not asession.is_internal_session:

        session.add_relation(entity.eid, 'owned_by', asession.user.eid)

        SetCreatorOp(asession, entity=entity)

def setis_after_add_entity(session, entity):

    """create a new entity -> set is relation"""

    if hasattr(entity, '_cw_recreating'):

        return

    try:

        session.add_relation(entity.eid, 'is',

                             eschema_type_eid(session, entity.id))

    except IndexError:

        # during schema serialization, skip

        return

    # XXX < 2.50 bw compat

    if not session.get_shared_data('do-not-insert-is_instance_of'):

        for etype in entity.e_schema.ancestors() + [entity.e_schema]:

            session.add_relation(entity.eid, 'is_instance_of',

                                 eschema_type_eid(session, etype))

def setowner_after_add_user(session, entity):

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

    session.add_relation(entity.eid, 'owned_by', entity.eid)

def fti_update_after_add_relation(session, eidfrom, rtype, eidto):

    """sync fulltext index when relevant relation is added. Reindexing the

    contained entity is enough since it will implicitly reindex the container

    entity.

    """

    ftcontainer = session.repo.schema.rschema(rtype).fulltext_container

    if ftcontainer == 'subject':

        FTIndexEntityOp(session, entity=session.entity_from_eid(eidto))

    elif ftcontainer == 'object':

        FTIndexEntityOp(session, entity=session.entity_from_eid(eidfrom))

def fti_update_after_delete_relation(session, eidfrom, rtype, eidto):

    """sync fulltext index when relevant relation is deleted. Reindexing both

    entities is necessary.

    """

    if session.repo.schema.rschema(rtype).fulltext_container:

        FTIndexEntityOp(session, entity=session.entity_from_eid(eidto))

        FTIndexEntityOp(session, entity=session.entity_from_eid(eidfrom))

class SyncOwnersOp(PreCommitOperation):

    def precommit_event(self):

        self.session.unsafe_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': self.compositeeid, 'x': self.composedeid},

                                    ('c', 'x'))

def sync_owner_after_add_composite_relation(session, eidfrom, rtype, eidto):

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

    has the composite

    """

    if rtype == 'wf_info_for':

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

        return

    composite = rproperty(session, rtype, eidfrom, eidto, 'composite')

    if composite == 'subject':

        SyncOwnersOp(session, compositeeid=eidfrom, composedeid=eidto)

    elif composite == 'object':

        SyncOwnersOp(session, compositeeid=eidto, composedeid=eidfrom)

def _register_metadata_hooks(hm):

    """register meta-data related hooks on the hooks manager"""

    hm.register_hook(setctime_before_add_entity, 'before_add_entity', '')

    hm.register_hook(setmtime_before_update_entity, 'before_update_entity', '')

    hm.register_hook(setowner_after_add_entity, 'after_add_entity', '')

    hm.register_hook(sync_owner_after_add_composite_relation, 'after_add_relation', '')

    hm.register_hook(fti_update_after_add_relation, 'after_add_relation', '')

    hm.register_hook(fti_update_after_delete_relation, 'after_delete_relation', '')

    if 'is' in hm.schema:

        hm.register_hook(setis_after_add_entity, 'after_add_entity', '')

    if 'CWUser' in hm.schema:

        hm.register_hook(setowner_after_add_user, 'after_add_entity', 'CWUser')

# core hooks ##################################################################

class DelayedDeleteOp(PreCommitOperation):

    """delete the object of composite relation except if the relation

    has actually been redirected to another composite

    """

    def precommit_event(self):

        session = self.session

        # don't do anything if the entity is being created or deleted

        if not (self.eid in session.transaction_data.get('pendingeids', ()) or

                self.eid in session.transaction_data.get('neweids', ())):

            etype = session.describe(self.eid)[0]

            session.unsafe_execute('DELETE %s X WHERE X eid %%(x)s, NOT %s'

                                   % (etype, self.relation),

                                   {'x': self.eid}, 'x')

def handle_composite_before_del_relation(session, eidfrom, rtype, eidto):

    """delete the object of composite relation"""

    composite = rproperty(session, rtype, eidfrom, eidto, 'composite')

    if composite == 'subject':

        DelayedDeleteOp(session, eid=eidto, relation='Y %s X' % rtype)

    elif composite == 'object':

        DelayedDeleteOp(session, eid=eidfrom, relation='X %s Y' % rtype)

def before_del_group(session, eid):

    """check that we don't remove the owners group"""

    check_internal_entity(session, eid, ('owners',))

# schema validation hooks #####################################################

class CheckConstraintsOperation(LateOperation):

    """check a new relation satisfy its constraints

    """

    def precommit_event(self):

        eidfrom, rtype, eidto = self.rdef

        # first check related entities have not been deleted in the same

        # transaction

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

        if eidfrom in pending:

            return

        if eidto in pending:

            return

        for constraint in self.constraints:

            try:

                constraint.repo_check(self.session, eidfrom, rtype, eidto)

            except NotImplementedError:

                self.critical('can\'t check constraint %s, not supported',

                              constraint)

    def commit_event(self):

        pass

def cstrcheck_after_add_relation(session, eidfrom, rtype, eidto):

    """check the relation satisfy its constraints

    this is delayed to a precommit time operation since other relation which

    will make constraint satisfied may be added later.

    """

    constraints = rproperty(session, rtype, eidfrom, eidto, 'constraints')

    if constraints:

        CheckConstraintsOperation(session, constraints=constraints,

                                  rdef=(eidfrom, rtype, eidto))

def uniquecstrcheck_before_modification(session, entity):

    eschema = entity.e_schema

    for attr, val in entity.items():

        if val is None:

            continue

        if eschema.subject_relation(attr).is_final() and \

               eschema.has_unique_values(attr):

            rql = '%s X WHERE X %s %%(val)s' % (entity.e_schema, attr)

            rset = session.unsafe_execute(rql, {'val': val})

            if rset and rset[0][0] != entity.eid:

                msg = session._('the value "%s" is already used, use another one')

                raise ValidationError(entity.eid, {attr: msg % val})

class CheckRequiredRelationOperation(LateOperation):

    """checking relation cardinality has to be done after commit in

    case the relation is being replaced

    """

    eid, rtype = None, None

    def precommit_event(self):

        # recheck pending eids

        if self.eid in self.session.transaction_data.get('pendingeids', ()):

            return

        if self.session.unsafe_execute(*self._rql()).rowcount < 1:

            etype = self.session.describe(self.eid)[0]

            _ = self.session._

            msg = _('at least one relation %(rtype)s is required on %(etype)s (%(eid)s)')

            msg %= {'rtype': _(self.rtype), 'etype': _(etype), 'eid': self.eid}

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

    def commit_event(self):

        pass

    def _rql(self):

        raise NotImplementedError()

class CheckSRelationOp(CheckRequiredRelationOperation):

    """check required subject relation"""

    def _rql(self):

        return 'Any O WHERE S eid %%(x)s, S %s O' % self.rtype, {'x': self.eid}, 'x'

class CheckORelationOp(CheckRequiredRelationOperation):

    """check required object relation"""

    def _rql(self):

        return 'Any S WHERE O eid %%(x)s, S %s O' % self.rtype, {'x': self.eid}, 'x'

def checkrel_if_necessary(session, opcls, rtype, eid):

    """check an equivalent operation has not already been added"""

    for op in session.pending_operations:

        if isinstance(op, opcls) and op.rtype == rtype and op.eid == eid:

            break

    else:

        opcls(session, rtype=rtype, eid=eid)

def cardinalitycheck_after_add_entity(session, entity):

    """check cardinalities are satisfied"""

    eid = entity.eid

    for rschema, targetschemas, x in entity.e_schema.relation_definitions():

        # skip automatically handled relations

        if rschema.type in DONT_CHECK_RTYPES_ON_ADD:

            continue

        if x == 'subject':

            subjtype = entity.e_schema

            objtype = targetschemas[0].type

            cardindex = 0

            opcls = CheckSRelationOp

        else:

            subjtype = targetschemas[0].type

            objtype = entity.e_schema

            cardindex = 1

            opcls = CheckORelationOp

        card = rschema.rproperty(subjtype, objtype, 'cardinality')

        if card[cardindex] in '1+':

            checkrel_if_necessary(session, opcls, rschema.type, eid)

def cardinalitycheck_before_del_relation(session, eidfrom, rtype, eidto):

    """check cardinalities are satisfied"""

    if rtype in DONT_CHECK_RTYPES_ON_DEL:

        return

    card = rproperty(session, rtype, eidfrom, eidto, 'cardinality')

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

    if (session.describe(eidfrom)[0], rtype, session.describe(eidto)[0]) in pendingrdefs:

        return

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

    if card[0] in '1+' and not eidfrom in pendingeids:

        checkrel_if_necessary(session, CheckSRelationOp, rtype, eidfrom)

    if card[1] in '1+' and not eidto in pendingeids:

        checkrel_if_necessary(session, CheckORelationOp, rtype, eidto)

def _register_core_hooks(hm):

    hm.register_hook(handle_composite_before_del_relation, 'before_delete_relation', '')

    hm.register_hook(before_del_group, 'before_delete_entity', 'CWGroup')

    #hm.register_hook(cstrcheck_before_update_entity, 'before_update_entity', '')

    hm.register_hook(cardinalitycheck_after_add_entity, 'after_add_entity', '')

    hm.register_hook(cardinalitycheck_before_del_relation, 'before_delete_relation', '')

    hm.register_hook(cstrcheck_after_add_relation, 'after_add_relation', '')

    hm.register_hook(uniquecstrcheck_before_modification, 'before_add_entity', '')

    hm.register_hook(uniquecstrcheck_before_modification, 'before_update_entity', '')

# user/groups synchronisation #################################################

class GroupOperation(Operation):

    """base class for group operation"""

    geid = None

    def __init__(self, session, *args, **kwargs):

        """override to get the group name before actual groups manipulation:

        we may temporarily loose right access during a commit event, so

        no query should be emitted while comitting

        """

        rql = 'Any N WHERE G eid %(x)s, G name N'

        result = session.execute(rql, {'x': kwargs['geid']}, 'x', build_descr=False)

        Operation.__init__(self, session, *args, **kwargs)

        self.group = result[0][0]

class DeleteGroupOp(GroupOperation):

    """synchronize user when a in_group relation has been deleted"""

    def commit_event(self):

        """the observed connections pool has been commited"""

        groups = self.cnxuser.groups

        try:

            groups.remove(self.group)

        except KeyError:

            self.error('user %s not in group %s',  self.cnxuser, self.group)

            return