# Copyright (C) 2012 Canonical Ltd.
# Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
# Copyright (C) 2012 Yahoo! Inc.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
# Author: Joshua Harlow <harlowja@yahoo-inc.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

import collections
import io
import logging
import logging.config
import logging.handlers
import os
import sys
import time

# Logging levels for easy access
CRITICAL = logging.CRITICAL
FATAL = logging.FATAL
ERROR = logging.ERROR
WARNING = logging.WARNING
WARN = logging.WARN
INFO = logging.INFO
DEBUG = logging.DEBUG
NOTSET = logging.NOTSET

# Default basic format
DEF_CON_FORMAT = '%(asctime)s - %(filename)s[%(levelname)s]: %(message)s'

# Always format logging timestamps as UTC time
logging.Formatter.converter = time.gmtime


def setupBasicLogging(level=DEBUG, formatter=None):
    if not formatter:
        formatter = logging.Formatter(DEF_CON_FORMAT)
    root = logging.getLogger()
    for handler in root.handlers:
        if hasattr(handler, 'stream') and hasattr(handler.stream, 'name'):
            if handler.stream.name == '<stderr>':
                handler.setLevel(level)
                return
    # Didn't have an existing stderr handler; create a new handler
    console = logging.StreamHandler(sys.stderr)
    console.setFormatter(formatter)
    console.setLevel(level)
    root.addHandler(console)
    root.setLevel(level)


def flushLoggers(root):
    if not root:
        return
    for h in root.handlers:
        if isinstance(h, (logging.StreamHandler)):
            try:
                h.flush()
            except IOError:
                pass
    flushLoggers(root.parent)


def setupLogging(cfg=None):
    # See if the config provides any logging conf...
    if not cfg:
        cfg = {}

    log_cfgs = []
    log_cfg = cfg.get('logcfg')
    if log_cfg and isinstance(log_cfg, str):
        # If there is a 'logcfg' entry in the config,
        # respect it, it is the old keyname
        log_cfgs.append(str(log_cfg))
    elif "log_cfgs" in cfg:
        for a_cfg in cfg['log_cfgs']:
            if isinstance(a_cfg, str):
                log_cfgs.append(a_cfg)
            elif isinstance(a_cfg, (collections.Iterable)):
                cfg_str = [str(c) for c in a_cfg]
                log_cfgs.append('\n'.join(cfg_str))
            else:
                log_cfgs.append(str(a_cfg))

    # See if any of them actually load...
    am_tried = 0
    for log_cfg in log_cfgs:
        try:
            am_tried += 1
            # Assume its just a string if not a filename
            if log_cfg.startswith("/") and os.path.isfile(log_cfg):
                # Leave it as a file and do not make it look like
                # something that is a file (but is really a buffer that
                # is acting as a file)
                pass
            else:
                log_cfg = io.StringIO(log_cfg)
            # Attempt to load its config
            logging.config.fileConfig(log_cfg)
            # The first one to work wins!
            return
        except Exception:
            # We do not write any logs of this here, because the default
            # configuration includes an attempt at using /dev/log, followed
            # up by writing to a file.  /dev/log will not exist in very early
            # boot, so an exception on that is expected.
            pass

    # If it didn't work, at least setup a basic logger (if desired)
    basic_enabled = cfg.get('log_basic', True)

    sys.stderr.write(("WARN: no logging configured!"
                      " (tried %s configs)\n") % (am_tried))
    if basic_enabled:
        sys.stderr.write("Setting up basic logging...\n")
        setupBasicLogging()


def getLogger(name='cloudinit'):
    return logging.getLogger(name)


def _resetLogger(log):
    """Remove all current handlers, unset log level and add a NullHandler.

    (Adding the NullHandler avoids "No handlers could be found for logger XXX"
    messages.)
    """
    if not log:
        return
    handlers = list(log.handlers)
    for h in handlers:
        h.flush()
        h.close()
        log.removeHandler(h)
    log.setLevel(NOTSET)
    log.addHandler(logging.NullHandler())


def resetLogging():
    _resetLogger(logging.getLogger())
    _resetLogger(getLogger())


resetLogging()

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