#!/usr/bin/env python3
#
# Copyright (c) 2016 Jon Turney
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#

import logging


# trivial log filter (which can be used as a context manager) to annotate log
# record with extra attributes.
class AttrFilter(logging.Filter):
    def __init__(self, **kwargs):
        self.attributes = kwargs

    def filter(self, record):
        for a in self.attributes:
            setattr(record, a, self.attributes[a])
        return True

    def __enter__(self):
        logging.getLogger().addFilter(self)
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        logging.getLogger().removeFilter(self)

        # process any exception in the with-block normally
        return False
