libervia-backend/libervia/backend/tools/trigger.py

#!/usr/bin/env python3


# SAT: a jabber client
# Copyright (C) 2009-2026 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"""

import inspect
from typing import Any, Callable
from libervia.backend.core.i18n import _
from libervia.backend.core.log import getLogger
from libervia.backend.core.core_types import SatXMPPEntity

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: str, callback: Callable[..., Any], priority: int = 0
    ) -> None:
        """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 add_with_check(
        self,
        point_name: str,
        plugin: object,
        callback: Callable[..., Any],
        priority: int = 0,
    ) -> None:
        """Like [add], but checks session before running the trigger.

        This method is to be used for triggers which can run in components and are
        expecting a ``client``: as all plugins are not run for component, a check will be
        added before running the trigger, if the plugin is not valid for this component,
        the trigger is ignored. ``client`` must be the first positional argument.

        @param point_name: name of the trigger point
        @param plugin: instance of the plugin using this trigger. This is necessary to
            check if the plugin is available in the session.
        @param callback: method to call at the trigger point
        @param priority: callback will be called in priority order, biggest first
        """
        if inspect.iscoroutinefunction(callback):

            async def async_wrapper(client: SatXMPPEntity, *args, **kwargs):
                if client.is_component and plugin not in client.plugins:
                    log.debug(f"Ignoring {callback} as parent plugin is not available")
                    return True
                else:
                    return await callback(client, *args, **kwargs)

            self.add(point_name, async_wrapper, priority)
        else:

            def sync_wrapper(client: SatXMPPEntity, *args, **kwargs):
                if client.is_component and plugin not in client.plugins:
                    log.debug(f"Ignoring {callback} as parent plugin is not available")
                    return True
                else:
                    return callback(client, *args, **kwargs)

            self.add(point_name, sync_wrapper, priority)

    def remove(self, point_name: str, callback: Callable[..., Any]) -> None:
        """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 exist 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: str, *args: Any, **kwargs: Any) -> bool:
        """Put a trigger point.

        All the triggers for that point will be run.
        @param point_name: name of the trigger point
        @param args: arguments to transmit to triggers
        @param kwargs: keyword arguments to transmit to triggers. If
            ``triggers_no_cancel`` is present and set to True, it will be
            popped and triggers cannot stop the workflow.
        @return: True if the action must be continued, False otherwise
        """
        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 return_point(
        self, point_name: str, *args: Any, **kwargs: Any
    ) -> tuple[bool, Any | None]:
        """Like [point] but triggers 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
        @param args: arguments to transmit to triggers
        @param kwargs: keyword arguments to transmit to triggers
        @return: tuple of (continue, return_value); True/None if continued,
            False/value if a trigger stopped the workflow
        """

        if point_name not in self.__triggers:
            return True, None

        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