view sat/tools/trigger.py @ 3178:98b321234068

plugin aesgcm: use 12 bytes Initialisation Vector: SàT was using 16 bytes IV when sending files withr AES-GCM, due to ChatSecure being only compatible with that. Monal, an other iOS client is only compatible with 12 bytes IV, and ChatSecure has fixed its code to also handle 12 bytes IV, so there is not reason anymore to use 16 bytes, and SàT now uses 12 bytes.
author Goffi <goffi@goffi.org>
date Tue, 18 Feb 2020 18:17:18 +0100
parents 559a625a236b
children be6d91572633
line wrap: on
line source

#!/usr/bin/env python3


# SAT: a jabber client
# Copyright (C) 2009-2020 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program 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 Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""Misc usefull classes"""

from sat.core.i18n import _
from sat.core.log import getLogger

log = getLogger(__name__)


class TriggerException(Exception):
    pass


class SkipOtherTriggers(Exception):
    """ Exception to raise if normal behaviour must be followed instead of following triggers list """

    pass


class TriggerManager(object):
    """This class manage triggers: code which interact to change the behaviour of SàT"""

    try:  # FIXME: to be removed when a better solution is found
        MIN_PRIORITY = float("-inf")
        MAX_PRIORITY = float("+inf")
    except:  # XXX: Pyjamas will bug if you specify ValueError here
        # Pyjamas uses the JS Float class
        MIN_PRIORITY = Number.NEGATIVE_INFINITY
        MAX_PRIORITY = Number.POSITIVE_INFINITY

    def __init__(self):
        self.__triggers = {}

    def add(self, point_name, callback, priority=0):
        """Add a trigger to a point

        @param point_name: name of the point when the trigger should be run
        @param callback: method to call at the trigger point
        @param priority: callback will be called in priority order, biggest
        first
        """
        if point_name not in self.__triggers:
            self.__triggers[point_name] = []
        if priority != 0 and priority in [
            trigger_tuple[0] for trigger_tuple in self.__triggers[point_name]
        ]:
            if priority in (self.MIN_PRIORITY, self.MAX_PRIORITY):
                log.warning(_("There is already a bound priority [%s]") % point_name)
            else:
                log.debug(
                    _("There is already a trigger with the same priority [%s]")
                    % point_name
                )
        self.__triggers[point_name].append((priority, callback))
        self.__triggers[point_name].sort(
            key=lambda trigger_tuple: trigger_tuple[0], reverse=True
        )

    def remove(self, point_name, callback):
        """Remove a trigger from a point

        @param point_name: name of the point when the trigger should be run
        @param callback: method to remove, must exists in the trigger point
        """
        for trigger_tuple in self.__triggers[point_name]:
            if trigger_tuple[1] == callback:
                self.__triggers[point_name].remove(trigger_tuple)
                return
        raise TriggerException("Trying to remove an unexisting trigger")

    def point(self, point_name, *args, **kwargs):
        """This put a trigger point

        All the triggers for that point will be run
        @param point_name: name of the trigger point
        @param *args: args to transmit to trigger
        @param *kwargs: kwargs to transmit to trigger
            if "triggers_no_cancel" is present, it will be popup out
                when set to True, this argument don't let triggers stop
                the workflow
        @return: True if the action must be continued, False else
        """
        if point_name not in self.__triggers:
            return True

        can_cancel = not kwargs.pop('triggers_no_cancel', False)

        for priority, trigger in self.__triggers[point_name]:
            try:
                if not trigger(*args, **kwargs) and can_cancel:
                    return False
            except SkipOtherTriggers:
                break
        return True

    def returnPoint(self, point_name, *args, **kwargs):
        """Like point but trigger must return (continue, return_value)

        All triggers for that point must return a tuple with 2 values:
            - continue, same as for point, if False action must be finished
            - return_value: value to return ONLY IF CONTINUE IS FALSE
        @param point_name: name of the trigger point
        @return: True if the action must be continued, False else
        """

        if point_name not in self.__triggers:
            return True

        for priority, trigger in self.__triggers[point_name]:
            try:
                cont, ret_value = trigger(*args, **kwargs)
                if not cont:
                    return False, ret_value
            except SkipOtherTriggers:
                break
        return True, None