# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

import argparse
import os

from keystoneclient.auth import base

# NOTE(jamielennox): ideally oslo.config would be smart enough to handle all
# the Opt manipulation that goes on in this file. However it is currently not.
# Options are handled in as similar a way as possible to oslo.config such that
# when available we should be able to transition.


def register_argparse_arguments(parser, argv):
    """Register CLI options needed to create a plugin.

    The function inspects the provided arguments so that it can also register
    the options required for that specific plugin if available.

    :param argparse.ArgumentParser: the parser to attach argparse options to.
    :param list argv: the arguments provided to the appliation.

    :returns: The plugin class that will be loaded or None if not provided.

    :raises exceptions.NoMatchingPlugin: if a plugin cannot be created.
    """
    in_parser = argparse.ArgumentParser(add_help=False)
    env_plugin = os.environ.get('OS_AUTH_PLUGIN')
    for p in (in_parser, parser):
        p.add_argument('--os-auth-plugin',
                       metavar='<name>',
                       default=env_plugin,
                       help='The auth plugin to load')

    options, _args = in_parser.parse_known_args(argv)

    if not options.os_auth_plugin:
        return None

    msg = 'Options specific to the %s plugin.' % options.os_auth_plugin
    group = parser.add_argument_group('Authentication Options', msg)
    plugin = base.get_plugin_class(options.os_auth_plugin)

    for opt in plugin.get_options():
        if opt.default is None:
            env_name = opt.name.replace('-', '_').upper()
            default = os.environ.get('OS_' + env_name)
        else:
            default = opt.default

        group.add_argument('--os-' + opt.name,
                           default=default,
                           metavar=opt.metavar,
                           help=opt.help,
                           dest=opt.dest)

    return plugin


def load_from_argparse_arguments(namespace, **kwargs):
    """Retrieve the created plugin from the completed argparse results.

    Loads and creates the auth plugin from the information parsed from the
    command line by argparse.

    :param Namespace namespace: The result from CLI parsing.

    :returns: An auth plugin, or None if a name is not provided.

    :raises exceptions.NoMatchingPlugin: if a plugin cannot be created.
    """
    if not namespace.os_auth_plugin:
        return None

    plugin_class = base.get_plugin_class(namespace.os_auth_plugin)

    for opt in plugin_class.get_options():
        val = getattr(namespace, opt.dest)
        if val is not None:
            val = opt.type(val)
        kwargs.setdefault(opt.dest, val)

    return plugin_class.load_from_options(**kwargs)