"""Manage access to the clients, including authenticating when needed.
"""

import logging

from openstackclient.common import exceptions as exc
from openstackclient.compute import client as compute_client
from openstackclient.identity import client as identity_client

LOG = logging.getLogger(__name__)


class ClientCache(object):
    """Descriptor class for caching created client handles.
    """

    def __init__(self, factory):
        self.factory = factory
        self._handle = None

    def __get__(self, instance, owner):
        # Tell the ClientManager to login to keystone
        if self._handle is None:
            self._handle = self.factory(instance)
        return self._handle


class ClientManager(object):
    """Manages access to API clients, including authentication.
    """

    identity = ClientCache(identity_client.make_client)
    compute = ClientCache(compute_client.make_client)

    def __init__(self, token=None, url=None,
                 auth_url=None,
                 tenant_name=None, tenant_id=None,
                 username=None, password=None,
                 region_name=None,
                 identity_api_version=None,
                 compute_api_version=None,
                 image_api_version=None,
                 ):
        self._token = token
        self._url = url
        self._auth_url = auth_url
        self._tenant_name = tenant_name
        self._tenant_id = tenant_id
        self._username = username
        self._password = password
        self._region_name = region_name
        self._identity_api_version = identity_api_version
        self._compute_api_version = compute_api_version
        self._image_api_version = image_api_version
        self._service_catalog = None

        # Create the identity client
        self.identity

        if not self._url:
            # Populate other password flow attributes
            self._token = self.identity.auth_token
            self._service_catalog = self.identity.service_catalog

        return

    def get_endpoint_for_service_type(self, service_type):
        """Return the endpoint URL for the service type.
        """
        # See if we are using password flow auth, i.e. we have a
        # service catalog to select endpoints from
        if self._service_catalog:
            endpoint = self._service_catalog.url_for(
                service_type=service_type)
        else:
            # Hope we were given the correct URL.
            endpoint = self._url
        return endpoint