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# Copyright (c) 2016 Weitian LI <liweitianux@live.com>
# MIT license
#
# References:
# [1] https://configobj.readthedocs.io/en/latest/configobj.html
# [2] https://github.com/pazz/alot/blob/master/alot/settings/manager.py
"""
Configuration manager.
"""
import os
import sys
from glob import glob
import logging
from functools import reduce
from configobj import ConfigObj, ConfigObjError, flatten_errors
from validate import Validator
class ConfigError(Exception):
"""Could not parse user configurations"""
pass
CONFIGS_PATH = os.path.dirname(__file__)
class ConfigManager:
"""Manager the configurations"""
def __init__(self, configs=None):
"""Initialize the ConfigManager object with default configurations.
If user configs are given, they are also validated and get merged.
Parameters
----------
configs: list (of config files)
(optional) list of user config files to be merged
"""
configs_spec = sorted(glob(os.path.join(CONFIGS_PATH, "*.conf.spec")))
spec = "\n".join([open(f).read() for f in configs_spec]).split("\n")
self._configspec = ConfigObj(spec, interpolation=False,
list_values=False, _inspec=True)
configs_default = ConfigObj(interpolation=False,
configspec=self._configspec)
self._config = self._validate(configs_default)
if configs:
for config in configs:
self.read_config(config)
def read_config(self, config):
"""Read, validate and merge the input config.
Parameters
----------
config : str, list of str
Input config to be validated and merged.
This parameter can be the filename of the config file, or a list
contains the lines of the configs.
"""
newconfig = ConfigObj(config, interpolation=False,
configspec=self._configspec)
newconfig = self._validate(newconfig)
self._config.merge(newconfig)
def _validate(self, config):
"""Validate the config against the specification using a default
validator. The validated config values are returned if success,
otherwise, the ``ConfigError`` raised with details.
"""
validator = Validator()
try:
results = config.validate(validator, preserve_errors=True)
except ConfigObjError as e:
raise ConfigError(e.message)
if not results:
error_msg = ""
for (section_list, key, res) in flatten_errors(config, results):
if key is not None:
if res is False:
msg = 'key "%s" in section "%s" is missing.'
msg = msg % (key, ", ".join(section_list))
else:
msg = 'key "%s" in section "%s" failed validation: %s'
msg = msg % (key, ", ".join(section_list), res)
else:
msg = 'section "%s" is missing' % ".".join(section_list)
error_msg += msg + "\n"
raise ConfigError(error_msg)
return config
def get(self, key, fallback=None):
"""Get config value by key."""
return self._config.get(key, fallback)
def getn(self, keys, sep="/"):
"""Get the config value from the nested dictionary configs using
a list of keys or a "sep"-separated keys strings.
Parameters
----------
keys : str / list[str]
List of keys or a string separated by a specific character
(e.g., "/") to specify the item in the `self._config`, which
is a nested dictionary.
e.g., `["section1", "key2"]`, `"section1/key2"`
sep : str (len=1)
If the above "keys" is a string, then this parameter specify
the character used to separate the multi-level keys.
References
----------
- Stackoverflow: Checking a Dictionary using a dot notation string
https://stackoverflow.com/q/12414821/4856091
"""
if isinstance(keys, str):
keys = keys.split(sep)
return reduce(dict.get, keys, self._config)
@property
def logging(self):
"""Get and prepare the logging configurations for
``logging.basicConfig()`` to initialize the logging module.
NOTE
----
``basicConfig()`` will automatically create a ``Formatter`` with
the giving ``format`` and ``datefmt`` for each handlers if necessary,
and then adding the handlers to the "root" logger.
"""
from logging import FileHandler, StreamHandler
conf = self.get("logging")
# logging handlers
handlers = []
stream = conf["stream"]
if stream:
handlers.append(StreamHandler(getattr(sys, stream)))
logfile = conf["filename"]
filemode = conf["filemode"]
if logfile:
handlers.append(FileHandler(logfile, mode=filemode))
#
logconf = {
"level": getattr(logging, conf["level"]),
"format": conf["format"],
"datefmt": conf["datefmt"],
"filemode": filemode,
"handlers": handlers,
}
return logconf
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