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

 Implements the configuration related objects.

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

import os
import types
import errno

from werkzeug.utils import import_string
from ._compat import string_types, iteritems
from . import json


class ConfigAttribute(object):
 """Makes an attribute forward to the config"""

 def __init__(self, name, get_converter=None):
 self.__name__ = name
 self.get_converter = get_converter

 def __get__(self, obj, type=None):
 if obj is None:
 return self
 rv = obj.config[self.__name__]
 if self.get_converter is not None:
 rv = self.get_converter(rv)
 return rv

 def __set__(self, obj, value):
 obj.config[self.__name__] = value


class Config(dict):
 """Works exactly like a dict but provides ways to fill it from files
 or special dictionaries. There are two common patterns to populate the
 config.

 Either you can fill the config from a config file::

 app.config.from_pyfile('yourconfig.cfg')

 Or alternatively you can define the configuration options in the
 module that calls :meth:`from_object` or provide an import path to
 a module that should be loaded. It is also possible to tell it to
 use the same module and with that provide the configuration values
 just before the call::

 DEBUG = True
 SECRET_KEY = 'development key'
 app.config.from_object(__name__)

 In both cases (loading from any Python file or loading from modules),
 only uppercase keys are added to the config. This makes it possible to use
 lowercase values in the config file for temporary values that are not added
 to the config or to define the config keys in the same file that implements
 the application.

 Probably the most interesting way to load configurations is from an
 environment variable pointing to a file::

 app.config.from_envvar('YOURAPPLICATION_SETTINGS')

 In this case before launching the application you have to set this
 environment variable to the file you want to use. On Linux and OS X
 use the export statement::

 export YOURAPPLICATION_SETTINGS='/path/to/config/file'

 On windows use `set` instead.

 :param root_path: path to which files are read relative from. When the
 config object is created by the application, this is
 the application's :attr:`~flask.Flask.root_path`.
 :param defaults: an optional dictionary of default values
 """

 def __init__(self, root_path, defaults=None):
 dict.__init__(self, defaults or {})
 self.root_path = root_path

 def from_envvar(self, variable_name, silent=False):
 """Loads a configuration from an environment variable pointing to
 a configuration file. This is basically just a shortcut with nicer
 error messages for this line of code::

 app.config.from_pyfile(os.environ['YOURAPPLICATION_SETTINGS'])

 :param variable_name: name of the environment variable
 :param silent: set to ``True`` if you want silent failure for missing
 files.
 :return: bool. ``True`` if able to load config, ``False`` otherwise.
 """
 rv = os.environ.get(variable_name)
 if not rv:
 if silent:
 return False
 raise RuntimeError('The environment variable %r is not set '
 'and as such configuration could not be '
 'loaded. Set this variable and make it '
 'point to a configuration file' %
 variable_name)
 return self.from_pyfile(rv, silent=silent)

 def from_pyfile(self, filename, silent=False):
 """Updates the values in the config from a Python file. This function
 behaves as if the file was imported as module with the
 :meth:`from_object` function.

 :param filename: the filename of the config. This can either be an
 absolute filename or a filename relative to the
 root path.
 :param silent: set to ``True`` if you want silent failure for missing
 files.

 .. versionadded:: 0.7
 `silent` parameter.
 """
 filename = os.path.join(self.root_path, filename)
 d = types.ModuleType('config')
 d.__file__ = filename
 try:
 with open(filename, mode='rb') as config_file:
 exec(compile(config_file.read(), filename, 'exec'), d.__dict__)
 except IOError as e:
 if silent and e.errno in (
 errno.ENOENT, errno.EISDIR, errno.ENOTDIR
 ):
 return False
 e.strerror = 'Unable to load configuration file (%s)' % e.strerror
 raise
 self.from_object(d)
 return True

 def from_object(self, obj):
 """Updates the values from the given object. An object can be of one
 of the following two types:

 - a string: in this case the object with that name will be imported
 - an actual object reference: that object is used directly

 Objects are usually either modules or classes. :meth:`from_object`
 loads only the uppercase attributes of the module/class. A ``dict``
 object will not work with :meth:`from_object` because the keys of a
 ``dict`` are not attributes of the ``dict`` class.

 Example of module-based configuration::

 app.config.from_object('yourapplication.default_config')
 from yourapplication import default_config
 app.config.from_object(default_config)

 You should not use this function to load the actual configuration but
 rather configuration defaults. The actual config should be loaded
 with :meth:`from_pyfile` and ideally from a location not within the
 package because the package might be installed system wide.

 See :ref:`config-dev-prod` for an example of class-based configuration
 using :meth:`from_object`.

 :param obj: an import name or object
 """
 if isinstance(obj, string_types):
 obj = import_string(obj)
 for key in dir(obj):
 if key.isupper():
 self[key] = getattr(obj, key)

 def from_json(self, filename, silent=False):
 """Updates the values in the config from a JSON file. This function
 behaves as if the JSON object was a dictionary and passed to the
 :meth:`from_mapping` function.

 :param filename: the filename of the JSON file. This can either be an
 absolute filename or a filename relative to the
 root path.
 :param silent: set to ``True`` if you want silent failure for missing
 files.

 .. versionadded:: 0.11
 """
 filename = os.path.join(self.root_path, filename)

 try:
 with open(filename) as json_file:
 obj = json.loads(json_file.read())
 except IOError as e:
 if silent and e.errno in (errno.ENOENT, errno.EISDIR):
 return False
 e.strerror = 'Unable to load configuration file (%s)' % e.strerror
 raise
 return self.from_mapping(obj)

 def from_mapping(self, *mapping, **kwargs):
 """Updates the config like :meth:`update` ignoring items with non-upper
 keys.

 .. versionadded:: 0.11
 """
 mappings = []
 if len(mapping) == 1:
 if hasattr(mapping[0], 'items'):
 mappings.append(mapping[0].items())
 else:
 mappings.append(mapping[0])
 elif len(mapping) > 1:
 raise TypeError(
 'expected at most 1 positional argument, got %d' % len(mapping)
 )
 mappings.append(kwargs.items())
 for mapping in mappings:
 for (key, value) in mapping:
 if key.isupper():
 self[key] = value
 return True

 def get_namespace(self, namespace, lowercase=True, trim_namespace=True):
 """Returns a dictionary containing a subset of configuration options
 that match the specified namespace/prefix. Example usage::

 app.config['IMAGE_STORE_TYPE'] = 'fs'
 app.config['IMAGE_STORE_PATH'] = '/var/app/images'
 app.config['IMAGE_STORE_BASE_URL'] = 'http://img.website.com'
 image_store_config = app.config.get_namespace('IMAGE_STORE_')

 The resulting dictionary `image_store_config` would look like::

 {
 'type': 'fs',
 'path': '/var/app/images',
 'base_url': 'http://img.website.com'
 }

 This is often useful when configuration options map directly to
 keyword arguments in functions or class constructors.

 :param namespace: a configuration namespace
 :param lowercase: a flag indicating if the keys of the resulting
 dictionary should be lowercase
 :param trim_namespace: a flag indicating if the keys of the resulting
 dictionary should not include the namespace

 .. versionadded:: 0.11
 """
 rv = {}
 for k, v in iteritems(self):
 if not k.startswith(namespace):
 continue
 if trim_namespace:
 key = k[len(namespace):]
 else:
 key = k
 if lowercase:
 key = key.lower()
 rv[key] = v
 return rv

 def __repr__(self):
 return '<%s %s>' % (self.__class__.__name__, dict.__repr__(self))