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

"""

__docformat__ = "restructuredtext en"

from logilab.common.textutils import normalize_text

from cubicweb.selectors import implements

from cubicweb.server import hook

from cubicweb.sobjects.supervising import SupervisionMailOp

class RenderAndSendNotificationView(hook.Operation):

    """delay rendering of notification view until precommit"""

    def precommit_event(self):

        view = self.view

        if view.cw_rset is not None and not view.cw_rset:

            return # entity added and deleted in the same transaction (cache effect)

        if view.cw_rset and self.session.deleted_in_transaction(view.cw_rset[view.cw_row or 0][view.cw_col or 0]):

            return # entity added and deleted in the same transaction

        self.view.render_and_send(**getattr(self, 'viewargs', {}))

class NotificationHook(hook.Hook):

    __abstract__ = True

    category = 'notification'

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

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

                                                     row=row, col=col)

class StatusChangeHook(NotificationHook):

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

    __regid__ = 'notifystatuschange'

    __select__ = NotificationHook.__select__ & implements('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)

        RenderAndSendNotificationView(self._cw, view=view, viewargs={

            'comment': comment, 'previous_state': entity.previous_state.name,

            'current_state': entity.new_state.name})

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

        RenderAndSendNotificationView(self._cw, view=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

        RenderAndSendNotificationView(self._cw, view=view)

class EntityUpdatedNotificationOp(hook.SingleLastOperation):

    def precommit_event(self):

        session = self.session

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

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

                                                rset=session.eid_rset(eid),

                                                row=0)

            RenderAndSendNotificationView(session, view=view)

class EntityUpdateHook(NotificationHook):

    __regid__ = 'notifentityupdated'

    __abstract__ = True # do not register by default

    __select__ = NotificationHook.__select__ & hook.from_dbapi_query()

    events = ('before_update_entity',)

    skip_attrs = set()

    def __call__(self):

        session = self._cw

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

            return # entity is being created

        # then compute changes

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

                 if not k in self.skip_attrs]

        if not attrs:

            return

        changes = session.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 = session.execute(rql, {'x': self.entity.eid}, 'x')

        for i, attr in enumerate(attrs):

            oldvalue = rset[0][i]

            newvalue = self.entity[attr]

            if oldvalue != newvalue:

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

        if thisentitychanges:

            EntityUpdatedNotificationOp(session)

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

class SomethingChangedHook(NotificationHook):

    __regid__ = 'supervising'

    __select__ = NotificationHook.__select__ & hook.from_dbapi_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 (self.entity.edited_attributes - 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:

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

            # missing required relation

            title = '#%s' % eid

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

            ('delete_entity', (self.entity.eid, str(self.entity.e_schema), title)))

        return True