# copyright 2019 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/>.

from logging import getLogger

logger = getLogger('cubicweb')

SUBSCRIBERS = {

    "controller": [],

    "rql": [],

    "sql": [],

    "vreg": [],

    "registry_decisions": [],

}

def subscribe_to_debug_channel(channel, subscriber):

    """

    Allow to subscribe a callable to one of the debug channels.

    The channel must be one of: %s

    And the callable need to accept one argument.

    It will raise Exception if the channel doesn't exist.

    """ % SUBSCRIBERS.keys()

    if channel not in SUBSCRIBERS.keys():

        raise Exception("debug channel '%s' doesn't exist" % channel)

    SUBSCRIBERS[channel].append(subscriber)

def unsubscribe_to_debug_channel(channel, subscriber):

    """

    Unsubscribe a callable from a channel. It will raise Exception if the

    channel doesn't exist nor

    """

    if channel not in SUBSCRIBERS.keys():

        raise Exception("debug channel '%s' doesn't exist" % channel)

    if subscriber not in SUBSCRIBERS[channel]:

        raise Exception("subscriber '%s' is not in debug channel '%s'" % (subscriber, channel))

    SUBSCRIBERS[channel].remove(subscriber)

def emit_to_debug_channel(channel, message):

    """

    Send a message to a specified debug channel that will call all its

    subscribers.

    It will raise Exception if the channel doesn't exist.

    """

    if channel not in SUBSCRIBERS.keys():

        raise Exception("debug channel '%s' doesn't exist" % channel)

    for subscriber in SUBSCRIBERS[channel]:

        try:

            subscriber(message)

        except Exception:

            logger.error("Failed to send debug message '%s' to subscriber '%s'", message, subscriber, exc_info=True)