# -*- coding: utf-8 -*-
"""
flask.logging
~~~~~~~~~~~~~

:copyright: © 2010 by the Pallets team.
:license: BSD, see LICENSE for more details.
"""

from __future__ import absolute_import

import logging
import sys

from werkzeug.local import LocalProxy

from .globals import request


@LocalProxy
def wsgi_errors_stream():
 """Find the most appropriate error stream for the application. If a request
 is active, log to ``wsgi.errors``, otherwise use ``sys.stderr``.

 If you configure your own :class:`logging.StreamHandler`, you may want to
 use this for the stream. If you are using file or dict configuration and
 can't import this directly, you can refer to it as
 ``ext://flask.logging.wsgi_errors_stream``.
 """
 return request.environ['wsgi.errors'] if request else sys.stderr


def has_level_handler(logger):
 """Check if there is a handler in the logging chain that will handle the
 given logger's :meth:`effective level <~logging.Logger.getEffectiveLevel>`.
 """
 level = logger.getEffectiveLevel()
 current = logger

 while current:
 if any(handler.level <= level for handler in current.handlers):
 return True

 if not current.propagate:
 break

 current = current.parent

 return False


#: Log messages to :func:`~flask.logging.wsgi_errors_stream` with the format
#: ``[%(asctime)s] %(levelname)s in %(module)s: %(message)s``.
default_handler = logging.StreamHandler(wsgi_errors_stream)
default_handler.setFormatter(logging.Formatter(
 '[%(asctime)s] %(levelname)s in %(module)s: %(message)s'
))


def create_logger(app):
 """Get the ``'flask.app'`` logger and configure it if needed.

 When :attr:`~flask.Flask.debug` is enabled, set the logger level to
 :data:`logging.DEBUG` if it is not set.

 If there is no handler for the logger's effective level, add a
 :class:`~logging.StreamHandler` for
 :func:`~flask.logging.wsgi_errors_stream` with a basic format.
 """
 logger = logging.getLogger('flask.app')

 if app.debug and logger.level == logging.NOTSET:
 logger.setLevel(logging.DEBUG)

 if not has_level_handler(logger):
 logger.addHandler(default_handler)

 return logger