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# Source code for astropy.config.configuration

    # Licensed under a 3-clause BSD style license - see LICENSE.rst
    """This module contains classes and functions to standardize access to
    configuration files for Astropy and affiliated packages.

    .. note::
        The configuration system makes use of the 'configobj' package, which stores
        configuration in a text format like that used in the standard library
        `ConfigParser`. More information and documentation for configobj can be
        found at http://www.voidspace.org.uk/python/configobj.html.
    """
    from __future__ import (absolute_import, division, print_function,
                            unicode_literals)
    from ..extern import six

    import inspect
    import pkgutil
    import re
    import sys
    import textwrap
    import types

    from contextlib import contextmanager
    from os import path
    from warnings import warn

    from ..extern import six
    from ..extern.configobj import configobj, validate
    from ..utils.exceptions import AstropyWarning

    __all__ = ['ConfigurationItem', 'InvalidConfigurationItemWarning',
               'ConfigurationMissingWarning', 'get_config', 'save_config',
               'reload_config']

    class InvalidConfigurationItemWarning(AstropyWarning):
        """ A Warning that is issued when the configuration value specified in the
        astropy configuration file does not match the type expected for that
        configuration value.
        """

    class ConfigurationMissingWarning(AstropyWarning):
        """ A Warning that is issued when the configuration directory cannot be
        accessed (usually due to a permissions problem). If this warning appears,
        configuration items will be set to their defaults rather than read from the
        configuration file, and no configuration will persist across sessions.
        """

    # these are not in __all__ because it's not intended that a user ever see them
    class ConfigurationDefaultMissingError(ValueError):
        """ An exception that is raised when the configuration defaults (which
        should be generated at build-time) are missing.
        """

    # this is used in astropy/__init__.py
    class ConfigurationDefaultMissingWarning(AstropyWarning):
        """ A warning that is issued when the configuration defaults (which
        should be generated at build-time) are missing.
        """

    class ConfigurationItem(object):
        """ A setting and associated value stored in the astropy configuration
        files.

        These objects are typically defined at the top of astropy subpackages
        or affiliated packages, and store values or option settings that can be
        modified by the user to

        Parameters
        ----------
        name : str
            The (case-sensitive) name of this parameter, as shown in the
            configuration file.
        defaultvalue
            The default value for this item. If this is a list of strings, this
            item will be interpreted as an 'options' value - this item must be one
            of those values, and the first in the list will be taken as the default
            value.
        description : str or None
            A description of this item (will be shown as a comment in the
            configuration file)
        cfgtype : str or None
            A type specifier like those used as the *values* of a particular key in
            a `configspec` file of `configobj`. If None, the type will be inferred
            from the default value.
        module : str or None
            The full module name that this item is associated with. The first
            element (e.g. 'astropy' if this is 'astropy.config.configuration')
            will be used to determine the name of the configuration file, while
            the remaining items determine the section. If None, the package will be
            inferred from the package within whiich this object's initializer is
            called.

        Raises
        ------
        RuntimeError
            If `module` is None, but the module this item is created from cannot
            be determined.

        Examples
        --------
        The following example will create an item 'cfgoption = 42' in the
        '[configuration]' section of astropy.cfg (located in the directory that
        `astropy.config.paths.get_config_dir` returns), or if the option is already
        set, it will take the value from the configuration file::

            from astropy.config import ConfigurationItem

            CFG_OPTION = ConfigurationItem('cfgoption',42,module='astropy.configuration')

        If called as ``CFG_OPTION()``, this will return the value ``42``, or some
        other integer if the ``astropy.cfg`` file specifies a different value.

        If this were a file ``astropy/configuration/__init__.py``, the `module`
        option would not be necessary, as it would automatically detect the correct
        module.

        """

        # this is used to make validation faster so a Validator object doesn't
        # have to be created every time
        _validator = validate.Validator()

        def __init__(self, name, defaultvalue='', description=None, cfgtype=None,
                     module=None):
            from ..utils import find_current_module
            from ..utils import isiterable

            if module is None:
                module = find_current_module(2)
                if module is None:
                    msg1 = 'Cannot automatically determine get_config module, '
                    msg2 = 'because it is not called from inside a valid module'
                    raise RuntimeError(msg1 + msg2)
                else:
                    module = module.__name__

            self.name = name
            self.module = module
            self.description = description

            # now determine cfgtype if it is not given
            if cfgtype is None:
                if (isiterable(defaultvalue) and not
                        isinstance(defaultvalue, six.string_types)):
                    # it is an options list
                    dvstr = [str(v) for v in defaultvalue]
                    cfgtype = 'option(' + ', '.join(dvstr) + ')'
                    defaultvalue = dvstr[0]
                elif isinstance(defaultvalue, bool):
                    cfgtype = 'boolean'
                elif isinstance(defaultvalue, int):
                    cfgtype = 'integer'
                elif isinstance(defaultvalue, float):
                    cfgtype = 'float'
                else:
                    cfgtype = 'string'
                    defaultvalue = str(defaultvalue)

            self.cfgtype = cfgtype

            self._validate_val(defaultvalue)
            self.defaultvalue = defaultvalue

            # note that the actual value is stored in the ConfigObj file for this
            # package

            # this checks the current value to make sure it's valid for the type
            # as well as updating the ConfigObj with the default value, if it's not
            # actually in the ConfigObj
            try:
                self()
            except TypeError as e:
                # make sure it's a TypeError from __call__
                if 'Configuration value not valid:' in e.args[0]:
                    warn(InvalidConfigurationItemWarning(*e.args))
                else:
                    raise

        def set(self, value):
            """ Sets the current value of this `ConfigurationItem`.

            This also updates the comments that give the description and type
            information.

            .. note::
                This does *not* save the value of this `ConfigurationItem` to the
                configuration file.  To do that, use `ConfigurationItem.save` or
                `save_config`.

            Parameters
            ----------
            value
                The value this item should be set to.

            Raises
            ------
            TypeError
                If the provided `value` is not valid for this `ConfigurationItem`.
            """
            try:
                value = self._validate_val(value)
            except validate.ValidateError as e:
                msg = 'Provided value for configuration item {0} not valid: {1}'
                raise TypeError(msg.format(self.name, e.args[0]))

            sec = get_config(self.module)

            sec[self.name] = value
            sec.comments[self.name] = self._generate_comments()

        @contextmanager
        def set_temp(self, value):
            """
            Sets this item to a specified value only inside a while loop.

            Use as::
                ITEM = ConfigurationItem('ITEM', 'default', 'description')

                with ITEM.set_temp('newval'):
                    ... do something that wants ITEM's value to be 'newval' ...

                 # ITEM is now 'default' after the with block

            Parameters
            ----------
            value
                The value to set this item to inside the with block.

            """
            initval = self()
            self.set(value)
            yield
            self.set(initval)

        def save(self, value=None):
            """ Writes a value for this `ConfigurationItem` to the relevant
            configuration file.

            This also writes updated versions of the comments that give the
            description and type information.

            .. note::
                This only saves the value of this *particular* `ConfigurationItem`.
                To save all configuration settings for this package at once, see
                `save_config`.

            Parameters
            ----------
            value
                Save this value to the configuration file. If None, the current
                value of this `ConfigurationItem` will be saved.

            Raises
            ------
            TypeError
                If the provided `value` is not valid for this `ConfigurationItem`.
            """
            try:
                value = self() if value is None else self._validate_val(value)
            except validate.ValidateError as e:
                msg = 'Provided value for configuration item {0} not valid: {1}'
                raise TypeError(msg.format(self.name, e.args[0]))

            # Now find the  ConfigObj that this is based on
            baseobj = get_config(self.module)
            secname = baseobj.name
            cobj = baseobj
            # a ConfigObj's parent is itself, so we look for the parent with that
            while cobj.parent is not cobj:
                cobj = cobj.parent

            # use the current on disk version, which will be modified with the
            # given value and type/description
            newobj = configobj.ConfigObj(cobj.filename, interpolation=False)
            if secname is not None:
                if secname not in newobj:
                    newobj[secname] = {}
                newsec = newobj[secname]

            newsec[self.name] = value
            newsec.comments[self.name] = self._generate_comments()
            newobj.write()

        def reload(self):
            """ Reloads the value of this `ConfigurationItem` from the relevant
            configuration file.

            Returns
            -------
            val
                The new value loaded from the configuration file.
            """
            baseobj = get_config(self.module)
            secname = baseobj.name

            cobj = baseobj
            # a ConfigObj's parent is itself, so we look for the parent with that
            while cobj.parent is not cobj:
                cobj = cobj.parent

            newobj = configobj.ConfigObj(cobj.filename, interpolation=False)
            if secname is not None:
                newobj = newobj[secname]

            baseobj[self.name] = newobj[self.name]

        def __repr__(self):
            out = '<{0}: name={1!r} value={2!r} at 0x{3:x}>'.format(
                self.__class__.__name__, self.name, self(), id(self))
            return out

        def __str__(self):
            out = '\n'.join(('{0}: {1}',
                             '  cfgtype={2!r}',
                             '  defaultvalue={3!r}',
                             '  description={4!r}',
                             '  module={5}',
                             '  value={6!r}'))
            out = out.format(self.__class__.__name__, self.name, self.cfgtype,
                             self.defaultvalue, self.description, self.module,
                             self())
            return out

        def __call__(self):
            """ Returns the value of this `ConfigurationItem`

            Returns
            -------
            val
                This item's value, with a type determined by the `cfgtype`
                attribute.

            Raises
            ------
            TypeError
                If the configuration value as stored is not this item's type.
            """

            # get the value from the relevant `configobj.ConfigObj` object
            sec = get_config(self.module)
            if self.name not in sec:
                self.set(self.defaultvalue)
            val = sec[self.name]

            try:
                return self._validate_val(val)
            except validate.ValidateError as e:
                raise TypeError('Configuration value not valid:' + e.args[0])

        def _validate_val(self, val):
            """ Validates the provided value based on cfgtype and returns the
            type-cast value

            throws the underlying configobj exception if it fails
            """
            # note that this will normally use the *class* attribute `_validator`,
            # but if some arcane reason is needed for making a special one for an
            # instance or sub-class, it will be used
            return self._validator.check(self.cfgtype, val)

        def _generate_comments(self):
            comments = []
            comments.append('')  # adds a blank line before every entry
            if self.description is not None:
                for line in textwrap.wrap(self.description, width=76):
                    comments.append(line)
            if self.cfgtype.startswith('option'):
                comments.append("Options: " + self.cfgtype[7:-1])
            return comments

    # this dictionary stores the master copy of the ConfigObj's for each
    # root package
    _cfgobjs = {}

    def get_config(packageormod=None, reload=False):
        """ Gets the configuration object or section associated with a particular
        package or module.

        Parameters
        -----------
        packageormod : str or None
            The package for which to retrieve the configuration object. If a
            string, it must be a valid package name, or if None, the package from
            which this function is called will be used.

        Returns
        -------
        cfgobj : `configobj.ConfigObj` or `configobj.Section`
            If the requested package is a base package, this will be the
            `configobj.ConfigObj` for that package, or if it is a subpackage or
            module, it will return the relevant `configobj.Section` object.

        Raises
        ------
        RuntimeError
            If `package` is None, but the package this item is created from cannot
            be determined.

        """

        from .paths import get_config_dir
        from ..utils import find_current_module

        if packageormod is None:
            packageormod = find_current_module(2)
            if packageormod is None:
                msg1 = 'Cannot automatically determine get_config module, '
                msg2 = 'because it is not called from inside a valid module'
                raise RuntimeError(msg1 + msg2)
            else:
                packageormod = packageormod.__name__

        packageormodspl = packageormod.split('.')
        rootname = packageormodspl[0]
        secname = '.'.join(packageormodspl[1:])

        cobj = _cfgobjs.get(rootname, None)

        if cobj is None:
            if _ASTROPY_SETUP_:
                # There's no reason to use anything but the default config
                cobj = configobj.ConfigObj(interpolation=False)
            else:
                try:
                    cfgfn = path.join(get_config_dir(), rootname + '.cfg')
                    cobj = configobj.ConfigObj(cfgfn, interpolation=False)
                except (IOError, OSError) as e:
                    msg = ('Configuration defaults will be used, and '
                           'configuration cannot be saved due to ')
                    errstr = '' if len(e.args) < 1 else (':' + str(e.args[0]))
                    msg += e.__class__.__name__ + errstr
                    warn(ConfigurationMissingWarning(msg))

                    # This caches the object, so if the file becomes accessible, this
                    # function won't see it unless the module is reloaded
                    cobj = configobj.ConfigObj(interpolation=False)

            _cfgobjs[rootname] = cobj

        if secname:  # not the root package
            if secname not in cobj:
                cobj[secname] = {}
            return cobj[secname]
        else:
            return cobj

    def save_config(packageormod=None, filename=None):
        """ Saves all configuration settings to the configuration file for the
        root package of the requested package/module.

        This overwrites any configuration items that have been changed in
        `ConfigurationItem` objects that are based on the configuration file
        determined by the *root* package of `packageormod` (e.g. 'astropy.cfg' for
        the 'astropy.config.configuration' module).

        .. note::
            To save only a single item, use the `ConfigurationItem.save` method -
            this will save all options in the current session that may have been
            changed.

        Parameters
        ----------
        packageormod : str or None
            The package or module name - see `get_config` for details.

        filename : str, optional
            Save the config to a given filename instead of to the default location.

        """

        sec = get_config(packageormod)
        # look for the section that is its own parent - that's the base object
        while sec.parent is not sec:
            sec = sec.parent
        if filename is not None:
            with open(filename, 'w') as f:
                sec.write(outfile=f)
        else:
            sec.write()

    def reload_config(packageormod=None):
        """ Reloads configuration settings from a configuration file for the root
        package of the requested package/module.

        This overwrites any changes that may have been made in `ConfigurationItem`
        objects.  This applies for any items that are based on this file, which is
        determined by the *root* package of `packageormod` (e.g. 'astropy.cfg' for
        the 'astropy.config.configuration' module).

        Parameters
        ----------
        packageormod : str or None
            The package or module name - see `get_config` for details.
        """
        sec = get_config(packageormod)
        # look for the section that is its own parent - that's the base object
        while sec.parent is not sec:
            sec = sec.parent
        sec.reload()

    def get_config_items(packageormod=None):
        """ Returns the `ConfigurationItem` objects associated with a particular
        module.

        Parameters
        ----------
        packageormod : str or None
            The package or module name or None to get the current module's items.

        Returns
        -------
        configitems : dict
            A dictionary where the keys are the name of the items as the are named
            in the module, and the values are the associated `ConfigurationItem`
            objects.

        """

        from ..utils import find_current_module

        if packageormod is None:
            packageormod = find_current_module(2)
            if packageormod is None:
                msg1 = 'Cannot automatically determine get_config module, '
                msg2 = 'because it is not called from inside a valid module'
                raise RuntimeError(msg1 + msg2)
        elif isinstance(packageormod, six.string_types):
            __import__(packageormod)
            packageormod = sys.modules[packageormod]
        elif inspect.ismodule(packageormod):
            pass
        else:
            raise TypeError('packageormod in get_config_items is invalid')

        configitems = {}
        for n, obj in six.iteritems(packageormod.__dict__):
            # if it's not a new-style object, it's certainly not a ConfigurationItem
            if hasattr(obj, '__class__'):
                fqn = obj.__class__.__module__ + '.' + obj.__class__.__name__
                if fqn == 'astropy.config.configuration.ConfigurationItem':
                    configitems[n] = obj

        return configitems

    def _fix_section_blank_lines(sec, recurse=True, gotoroot=True):
        """
        Adds a blank line to the comments of any sections in the requested sections,
        recursing into subsections if `recurse` is True. If `gotoroot` is True,
        this first goes to the root of the requested section, just like
        `save_config` and `reload_config` - this does nothing if `sec` is a
        configobj already.
        """

        if not hasattr(sec, 'sections'):
            sec = get_config(sec)

            # look for the section that is its own parent - that's the base object
            if gotoroot:
                while sec.parent is not sec:
                    sec = sec.parent

        for isec, snm in enumerate(sec.sections):
            comm = sec.comments[snm]
            if len(comm) == 0 or comm[-1] != '':
                if sec.parent is sec and isec == 0:
                    pass  # don't do it for first section
                else:
                    comm.append('')
            if recurse:
                _fix_section_blank_lines(sec[snm], True, False)

    _unsafe_import_regex = [r'astropy\.sphinx\.ext.*',
                            r'astropy\.utils\.compat\._gzip_32',
                            r'astropy\.utils\.compat\._fractions_27',
                            r'.*.setup_package',
                            r'astropy\.version_helpers',
                            r'astropy\.setup_helpers'
                            ]
    _unsafe_import_regex = [('(' + pat + ')') for pat in _unsafe_import_regex]
    _unsafe_import_regex = re.compile('|'.join(_unsafe_import_regex))

    def generate_all_config_items(pkgornm=None, reset_to_default=False,
                                  filename=None):
        """ Given a root package name or package, this function walks
        through all the subpackages and modules, which should populate any
        ConfigurationItem objects defined at the module level. If
        `reset_to_default` is True, it also sets all of the items to their default
        values, regardless of what the file's value currently is. It then saves the
        `ConfigObj`.

        Parameters
        ----------
        pkgname : str, module, or None
            The package for which to generate configuration items.  If None,
            the package of the function that calls this one will be used.

        reset_to_default : bool
            If True, the configuration items will all be set to their defaults.

        filename : str, optional
            Save the generated config items to the given filename instead of to
            the default config file path.

        Returns
        -------
        cfgfn : str
            The filename of the generated configuration item.

        """

        from ..utils import find_current_module

        if pkgornm is None:
            pkgornm = find_current_module(1).__name__.split('.')[0]

        if isinstance(pkgornm, six.string_types):
            package = pkgutil.get_loader(pkgornm).load_module(pkgornm)
        elif (isinstance(pkgornm, types.ModuleType) and
                '__init__' in pkgornm.__file__):
            package = pkgornm
        else:
            msg = 'generate_all_config_items was not given a package/package name'
            raise TypeError(msg)

        if hasattr(package, '__path__'):
            pkgpath = package.__path__
        elif hasattr(package, '__file__'):
            pkgpath = path.split(package.__file__)[0]
        else:
            raise AttributeError('package to generate config items for does not '
                                 'have __file__ or __path__')

        prefix = package.__name__ + '.'
        for imper, nm, ispkg in pkgutil.walk_packages(pkgpath, prefix):
            if nm == 'astropy.config.tests.test_configs':
                continue
            if not _unsafe_import_regex.match(nm):
                imper.find_module(nm)
                if reset_to_default:
                    for cfgitem in six.itervalues(get_config_items(nm)):
                        cfgitem.set(cfgitem.defaultvalue)

        _fix_section_blank_lines(package.__name__, True, True)

        save_config(package.__name__, filename=filename)

        if filename is None:
            return get_config(package.__name__).filename
        else:
            return filename

    # this is not in __all__ because it's not intended that a user uses it
    def update_default_config(pkg, default_cfg_dir_or_fn):
        """
        Checks if the configuration file for the specified package exists, and if
        not, copy over the default configuration.

        Parameters
        ----------
        pkg : str
            The package to be updated.
        default_cfg_dir_or_fn : str
            The filename or directory name where the default configuration file is.
            If a directory name, `pkg`.cfg will be used in that directory.

        Returns
        -------
        updated : bool
            If the profile needed to be updated, True, otherwise False.

        Raises
        ------
        ConfigurationDefaultMissingError
            If the default configuration could not be found.

        """

        cfgfn = get_config(pkg).filename

        if path.exists(cfgfn):
            with open(cfgfn) as f:
                doupdate = f.read() == ''
        else:
            doupdate = True

        if doupdate:
            if path.isdir(default_cfg_dir_or_fn):
                default_cfgfn = path.join(default_cfg_dir_or_fn, pkg + '.cfg')
            else:
                default_cfgfn = default_cfg_dir_or_fn

            if not path.isfile(default_cfgfn):
                raise ConfigurationDefaultMissingError(
                    'Requested default configuration file {0} is '
                    'not a file.'.format(default_cfgfn))

            with open(cfgfn, 'w') as fw:
                with open(default_cfgfn) as fr:
                    fw.write(fr.read())
            return True

        else:
            return False