# copyright 2003-2015 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/>.

"""some hooks to handle notification on entity's changes"""

from logilab.common.textutils import normalize_text

from cubicweb import RegistryNotFound

from cubicweb.predicates import is_instance

from cubicweb.server import hook

from cubicweb.sobjects.supervising import SupervisionMailOp

def notify_on_commit(cnx, view, viewargs=None):

    """register a notification view (see

    :class:`~cubicweb.sobjects.notification.NotificationView`) to be sent at

    post-commit time, ie only if the transaction has succeeded.

    `viewargs` is an optional dictionary containing extra argument to be given

    to :meth:`~cubicweb.sobjects.notification.NotificationView.render_and_send`

    """

    if viewargs is None:

        viewargs = {}

    notif_op = _RenderAndSendNotificationOp.get_instance(cnx)

    notif_op.add_data((view, viewargs))

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

    """End of the notification chain. Do render and send views after commit

    All others Operations end up adding data to this Operation.

    The notification are done on ``postcommit_event`` to make sure to prevent

    sending notification about rolled back data.

    """

    containercls = list

    def postcommit_event(self):

        deleted = self.cnx.deleted_in_transaction

        for view, viewargs in self.get_data():

            if view.cw_rset is not None:

                if not view.cw_rset:

                    # entity added and deleted in the same transaction

                    # (cache effect)

                    continue

                elif deleted(view.cw_rset[view.cw_row or 0][view.cw_col or 0]):

                    # entity added and deleted in the same transaction

                    continue

            try:

                view.render_and_send(**viewargs)

            except Exception:

                # error in post commit are not propagated

                # We keep this logic here to prevent a small notification error

                # to prevent them all.

                self.exception('Notification failed')

class NotificationHook(hook.Hook):

    __abstract__ = True

    category = 'notification'

    def select_view(self, vid, rset, row=0, col=0):

        try:

            return self._cw.vreg['views'].select_or_none(vid, self._cw, rset=rset,

                                                         row=row, col=col)

        except RegistryNotFound: # can happen in some config

                                 # (e.g. repo only config with no

                                 # notification views registered by

                                 # the instance's cubes)

            return None

class StatusChangeHook(NotificationHook):

    """notify when a workflowable entity has its state modified"""

    __regid__ = 'notifystatuschange'

    __select__ = NotificationHook.__select__ & is_instance('TrInfo')

    events = ('after_add_entity',)

    def __call__(self):

        entity = self.entity

        if not entity.from_state: # not a transition

            return

        rset = entity.related('wf_info_for')

        view = self.select_view('notif_status_change', rset=rset, row=0)

        if view is None:

            return

        comment = entity.printable_value('comment', format='text/plain')

        # XXX don't try to wrap rest until we've a proper transformation (see

        # #103822)

        if comment and entity.comment_format != 'text/rest':

            comment = normalize_text(comment, 80)

        viewargs = {'comment': comment,

                    'previous_state': entity.previous_state.name,

                    'current_state': entity.new_state.name}

        notify_on_commit(self._cw, view, viewargs=viewargs)

class RelationChangeHook(NotificationHook):

    __regid__ = 'notifyrelationchange'

    events = ('before_add_relation', 'after_add_relation',

              'before_delete_relation', 'after_delete_relation')

    def __call__(self):

        """if a notification view is defined for the event, send notification

        email defined by the view

        """

        rset = self._cw.eid_rset(self.eidfrom)

        view = self.select_view('notif_%s_%s' % (self.event,  self.rtype),

                                rset=rset, row=0)

        if view is None:

            return

        notify_on_commit(self._cw, view)

class EntityChangeHook(NotificationHook):

    """if a notification view is defined for the event, send notification

    email defined by the view

    """

    __regid__ = 'notifyentitychange'

    events = ('after_add_entity', 'after_update_entity')

    def __call__(self):

        rset = self.entity.as_rset()

        view = self.select_view('notif_%s' % self.event, rset=rset, row=0)

        if view is None:

            return

        notify_on_commit(self._cw, view)

class EntityUpdatedNotificationOp(hook.SingleLastOperation):

    """scrap all changed entity to prepare a Notification Operation for them"""

    def precommit_event(self):

        # precommit event that creates postcommit operation

        cnx = self.cnx

        for eid in cnx.transaction_data['changes']:

            view = cnx.vreg['views'].select('notif_entity_updated', cnx,

                                            rset=cnx.eid_rset(eid),

                                            row=0)

            notify_on_commit(self.cnx, view,

                    viewargs={'changes': cnx.transaction_data['changes'][eid]})

class EntityUpdateHook(NotificationHook):

    __regid__ = 'notifentityupdated'

    __abstract__ = True # do not register by default

    __select__ = NotificationHook.__select__ & hook.issued_from_user_query()

    events = ('before_update_entity',)

    skip_attrs = set(['modification_date'])

    def __call__(self):

        cnx = self._cw

        if cnx.added_in_transaction(self.entity.eid):

            return # entity is being created

        # then compute changes

        attrs = [k for k in self.entity.cw_edited

                 if not k in self.skip_attrs]

        if not attrs:

            return

        changes = cnx.transaction_data.setdefault('changes', {})

        thisentitychanges = changes.setdefault(self.entity.eid, set())

        rqlsel, rqlrestr = [], ['X eid %(x)s']

        for i, attr in enumerate(attrs):

            var = chr(65+i)

            rqlsel.append(var)

            rqlrestr.append('X %s %s' % (attr, var))

        rql = 'Any %s WHERE %s' % (','.join(rqlsel), ','.join(rqlrestr))

        rset = cnx.execute(rql, {'x': self.entity.eid})

        for i, attr in enumerate(attrs):

            oldvalue = rset[0][i]

            newvalue = self.entity.cw_edited[attr]

            if oldvalue != newvalue:

                thisentitychanges.add((attr, oldvalue, newvalue))

        if thisentitychanges:

            EntityUpdatedNotificationOp(cnx)

# supervising ##################################################################

class SomethingChangedHook(NotificationHook):

    __regid__ = 'supervising'

    __select__ = NotificationHook.__select__ & hook.issued_from_user_query()

    events = ('before_add_relation', 'before_delete_relation',

              'after_add_entity', 'before_update_entity')

    def __call__(self):

        dest = self._cw.vreg.config['supervising-addrs']

        if not dest: # no supervisors, don't do this for nothing...

            return

        if self._call():

            SupervisionMailOp(self._cw)

    def _call(self):

        event = self.event.split('_', 1)[1]

        if event == 'update_entity':

            if self._cw.added_in_transaction(self.entity.eid):

                return False

            if self.entity.e_schema == 'CWUser':

                if not (frozenset(self.entity.cw_edited)

                        - frozenset(('eid', 'modification_date',

                                     'last_login_time'))):

                    # don't record last_login_time update which are done

                    # automatically at login time

                    return False

        self._cw.transaction_data.setdefault('pendingchanges', []).append(

            (event, self))

        return True

class EntityDeleteHook(SomethingChangedHook):

    __regid__ = 'supervisingentitydel'

    events = ('before_delete_entity',)

    def _call(self):

        try:

            title = self.entity.dc_title()

        except Exception:

            # may raise an error during deletion process, for instance due to

            # missing required relation

            title = '#%s' % self.entity.eid

        self._cw.transaction_data.setdefault('pendingchanges', []).append(

            ('delete_entity', (self.entity.eid, self.entity.cw_etype, title)))

        return True