# copyright 2003-2014 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: check for data integrity according to the instance'schema

validity

"""

__docformat__ = "restructuredtext en"

_ = unicode

from threading import Lock

from cubicweb import validation_error, neg_role

from cubicweb.schema import (META_RTYPES, WORKFLOW_RTYPES,

                             RQLConstraint, RQLUniqueConstraint)

from cubicweb.predicates import is_instance, composite_etype

from cubicweb.uilib import soup2xhtml

from cubicweb.server import hook

# 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 = META_RTYPES | WORKFLOW_RTYPES

DONT_CHECK_RTYPES_ON_DEL = META_RTYPES | WORKFLOW_RTYPES

_UNIQUE_CONSTRAINTS_LOCK = Lock()

_UNIQUE_CONSTRAINTS_HOLDER = None

def _acquire_unique_cstr_lock(session):

    """acquire the _UNIQUE_CONSTRAINTS_LOCK for the session.

    This lock used to avoid potential integrity pb when checking

    RQLUniqueConstraint in two different transactions, as explained in

    http://intranet.logilab.fr/jpl/ticket/36564

    """

    if 'uniquecstrholder' in session.transaction_data:

        return

    _UNIQUE_CONSTRAINTS_LOCK.acquire()

    session.transaction_data['uniquecstrholder'] = True

    # register operation responsible to release the lock on commit/rollback

    _ReleaseUniqueConstraintsOperation(session)

def _release_unique_cstr_lock(session):

    if 'uniquecstrholder' in session.transaction_data:

        del session.transaction_data['uniquecstrholder']

        _UNIQUE_CONSTRAINTS_LOCK.release()

class _ReleaseUniqueConstraintsOperation(hook.Operation):

    def postcommit_event(self):

        _release_unique_cstr_lock(self.session)

    def rollback_event(self):

        _release_unique_cstr_lock(self.session)

class _CheckRequiredRelationOperation(hook.DataOperationMixIn,

                                      hook.LateOperation):

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

    relation is being replaced

    """

    containercls = list

    role = key = base_rql = None

    def precommit_event(self):

        session = self.session

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

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

        for eid, rtype in self.get_data():

            # recheck pending eids / relation types

            if eid in pendingeids:

                continue

            if rtype in pendingrtypes:

                continue

            if not session.execute(self.base_rql % rtype, {'x': eid}):

                etype = session.entity_metas(eid)['type']

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

                        '%(etype)s (%(eid)s)')

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

                                       {'rtype': rtype, 'etype': etype, 'eid': eid},

                                       ['rtype', 'etype'])

class _CheckSRelationOp(_CheckRequiredRelationOperation):

    """check required subject relation"""

    role = 'subject'

    base_rql = 'Any O WHERE S eid %%(x)s, S %s O'

class _CheckORelationOp(_CheckRequiredRelationOperation):

    """check required object relation"""

    role = 'object'

    base_rql = 'Any S WHERE O eid %%(x)s, S %s O'

class IntegrityHook(hook.Hook):

    __abstract__ = True

    category = 'integrity'

class EnsureSymmetricRelationsAdd(hook.Hook):

    """ ensure X r Y => Y r X iff r is symmetric """

    __regid__ = 'cw.add_ensure_symmetry'

    category = 'activeintegrity'

    events = ('after_add_relation',)

    # __select__ is set in the registration callback

    def __call__(self):

        self._cw.repo.system_source.add_relation(self._cw, self.eidto,

                                                 self.rtype, self.eidfrom)

class EnsureSymmetricRelationsDelete(hook.Hook):

    """ ensure X r Y => Y r X iff r is symmetric """

    __regid__ = 'cw.delete_ensure_symmetry'

    category = 'activeintegrity'

    events = ('after_delete_relation',)

    # __select__ is set in the registration callback

    def __call__(self):

        self._cw.repo.system_source.delete_relation(self._cw, self.eidto,

                                                    self.rtype, self.eidfrom)

class CheckCardinalityHookBeforeDeleteRelation(IntegrityHook):

    """check cardinalities are satisfied"""

    __regid__ = 'checkcard_before_delete_relation'

    events = ('before_delete_relation',)

    def __call__(self):

        rtype = self.rtype

        if rtype in DONT_CHECK_RTYPES_ON_DEL:

            return

        session = self._cw

        eidfrom, eidto = self.eidfrom, self.eidto

        rdef = session.rtype_eids_rdef(rtype, eidfrom, eidto)

        if (rdef.subject, rtype, rdef.object) in session.transaction_data.get('pendingrdefs', ()):

            return

        card = rdef.cardinality

        if card[0] in '1+' and not session.deleted_in_transaction(eidfrom):

            _CheckSRelationOp.get_instance(session).add_data((eidfrom, rtype))

        if card[1] in '1+' and not session.deleted_in_transaction(eidto):

            _CheckORelationOp.get_instance(session).add_data((eidto, rtype))

class CheckCardinalityHookAfterAddEntity(IntegrityHook):

    """check cardinalities are satisfied"""

    __regid__ = 'checkcard_after_add_entity'

    events = ('after_add_entity',)

    def __call__(self):

        eid = self.entity.eid

        eschema = self.entity.e_schema

        for rschema, targetschemas, role in eschema.relation_definitions():

            # skip automatically handled relations

            if rschema.type in DONT_CHECK_RTYPES_ON_ADD:

                continue

            rdef = rschema.role_rdef(eschema, targetschemas[0], role)

            if rdef.role_cardinality(role) in '1+':

                if role == 'subject':

                    op = _CheckSRelationOp.get_instance(self._cw)

                else:

                    op = _CheckORelationOp.get_instance(self._cw)

                op.add_data((eid, rschema.type))

class _CheckConstraintsOp(hook.DataOperationMixIn, hook.LateOperation):

    """ check a new relation satisfy its constraints """

    containercls = list

    def precommit_event(self):

        session = self.session

        for values in self.get_data():

            eidfrom, rtype, eidto, constraints = values

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

            # transaction

            if session.deleted_in_transaction(eidfrom):

                continue

            if session.deleted_in_transaction(eidto):

                continue

            for constraint in constraints:

                # XXX

                # * lock RQLConstraint as well?

                # * use a constraint id to use per constraint lock and avoid

                #   unnecessary commit serialization ?

                if isinstance(constraint, RQLUniqueConstraint):

                    _acquire_unique_cstr_lock(session)

                try:

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

                except NotImplementedError:

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

                                  constraint)

class CheckConstraintHook(IntegrityHook):

    """check the relation satisfy its constraints

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

    will make constraint satisfied (or unsatisfied) may be added later.

    """

    __regid__ = 'checkconstraint'

    events = ('after_add_relation',)

    def __call__(self):

        # XXX get only RQL[Unique]Constraints?

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

        constraints = rdef.constraints

        if constraints:

            _CheckConstraintsOp.get_instance(self._cw).add_data(

                (self.eidfrom, self.rtype, self.eidto, constraints))

class CheckAttributeConstraintHook(IntegrityHook):

    """check the attribute relation satisfy its constraints

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

    will make constraint satisfied (or unsatisfied) may be added later.

    """

    __regid__ = 'checkattrconstraint'

    events = ('after_add_entity', 'after_update_entity')

    def __call__(self):

        eschema = self.entity.e_schema

        for attr in self.entity.cw_edited:

            if eschema.subjrels[attr].final:

                constraints = [c for c in eschema.rdef(attr).constraints

                               if isinstance(c, (RQLUniqueConstraint, RQLConstraint))]

                if constraints:

                    _CheckConstraintsOp.get_instance(self._cw).add_data(

                        (self.entity.eid, attr, None, constraints))

class CheckUniqueHook(IntegrityHook):

    __regid__ = 'checkunique'

    events = ('before_add_entity', 'before_update_entity')

    def __call__(self):

        entity = self.entity

        eschema = entity.e_schema

        for attr, val in entity.cw_edited.iteritems():

            if eschema.subjrels[attr].final and eschema.has_unique_values(attr):

                if val is None:

                    continue

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

                rset = self._cw.execute(rql, {'val': val})

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

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

                    raise validation_error(entity, {(attr, 'subject'): msg},

                                           (val,))

class DontRemoveOwnersGroupHook(IntegrityHook):

    """delete the composed of a composite relation when this relation is deleted

    """

    __regid__ = 'checkownersgroup'

    __select__ = IntegrityHook.__select__ & is_instance('CWGroup')

    events = ('before_delete_entity', 'before_update_entity')

    def __call__(self):

        entity = self.entity

        if self.event == 'before_delete_entity' and entity.name == 'owners':

            raise validation_error(entity, {None: _("can't be deleted")})

        elif self.event == 'before_update_entity' \

                 and 'name' in entity.cw_edited:

            oldname, newname = entity.cw_edited.oldnewvalue('name')

            if oldname == 'owners' and newname != oldname:

                raise validation_error(entity, {('name', 'subject'): _("can't be changed")})

class TidyHtmlFields(IntegrityHook):

    """tidy HTML in rich text strings"""

    __regid__ = 'htmltidy'

    events = ('before_add_entity', 'before_update_entity')

    def __call__(self):

        entity = self.entity

        metaattrs = entity.e_schema.meta_attributes()

        edited = entity.cw_edited

        for metaattr, (metadata, attr) in metaattrs.iteritems():

            if metadata == 'format' and attr in edited:

                try:

                    value = edited[attr]

                except KeyError:

                    continue # no text to tidy

                if isinstance(value, unicode): # filter out None and Binary

                    if getattr(entity, str(metaattr)) == 'text/html':

                        edited[attr] = soup2xhtml(value, self._cw.encoding)

class StripCWUserLoginHook(IntegrityHook):

    """ensure user logins are stripped"""

    __regid__ = 'stripuserlogin'

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

    events = ('before_add_entity', 'before_update_entity',)

    def __call__(self):

        login = self.entity.cw_edited.get('login')

        if login:

            self.entity.cw_edited['login'] = login.strip()

class DeleteCompositeOrphanHook(hook.Hook):

    """Delete the composed of a composite relation when the composite is

    deleted (this is similar to the cascading ON DELETE CASCADE

    semantics of sql).

    """

    __regid__ = 'deletecomposite'

    __select__ = hook.Hook.__select__ & composite_etype()

    events = ('before_delete_entity',)

    category = 'activeintegrity'

    def __call__(self):

        eid = self.entity.eid

        for rdef, role in self.entity.e_schema.composite_rdef_roles:

            rtype = rdef.rtype.type

            target = getattr(rdef, neg_role(role))

            expr = ('C %s X' % rtype) if role == 'subject' else ('X %s C' % rtype)

            self._cw.execute('DELETE %s X WHERE C eid %%(c)s, %s' % (target, expr),

                             {'c': eid})

def registration_callback(vreg):

    vreg.register_all(globals().values(), __name__)

    symmetric_rtypes = [rschema.type for rschema in vreg.schema.relations()

                        if rschema.symmetric]

    EnsureSymmetricRelationsAdd.__select__ = hook.Hook.__select__ & hook.match_rtype(*symmetric_rtypes)

    EnsureSymmetricRelationsDelete.__select__ = hook.Hook.__select__ & hook.match_rtype(*symmetric_rtypes)