##############################################################################
# Copyright (c) 2017 NEC Corporation and others.
#
# All rights reserved. This program and the accompanying materials
# are made available under the terms of the Apache License, Version 2.0
# which accompanies this distribution, and is available at
# http://www.apache.org/licenses/LICENSE-2.0
##############################################################################

import os

from keystoneauth1 import loading
from keystoneauth1 import session


def get_identity_auth(username=None, password=None, project=None):
    auth_url = os.environ['OS_AUTH_URL']
    username = username or os.environ['OS_USERNAME']
    password = password or os.environ['OS_PASSWORD']
    user_domain_name = os.environ.get('OS_USER_DOMAIN_NAME') or 'default'
    user_domain_id = os.environ.get('OS_USER_DOMAIN_ID') or 'default'
    project_name = project or os.environ.get('OS_PROJECT_NAME') \
                   or os.environ.get('OS_TENANT_NAME')
    project_domain_name = os.environ.get('OS_PROJECT_DOMAIN_NAME') or 'default'
    project_domain_id = os.environ.get('OS_PROJECT_DOMAIN_ID') or 'default'

    loader = loading.get_plugin_loader('password')
    return loader.load_from_options(
        auth_url=auth_url,
        username=username,
        password=password,
        user_domain_name=user_domain_name,
        user_domain_id=user_domain_id,
        project_name=project_name,
        tenant_name=project_name,
        project_domain_name=project_domain_name,
        project_domain_id=project_domain_id)


def get_session(auth=None):
    """Get a user credentials auth session."""
    if auth is None:
        auth = get_identity_auth()
    return session.Session(auth=auth)