# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2012 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
# Copyright 2012 Nebula, Inc.
#
#    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 logging

from horizon import exceptions


__all__ = ('APIResourceWrapper', 'APIDictWrapper',
           'get_service_from_catalog', 'url_for',)


LOG = logging.getLogger(__name__)


class APIResourceWrapper(object):
    """ Simple wrapper for api objects

        Define _attrs on the child class and pass in the
        api object as the only argument to the constructor
    """
    _attrs = []

    def __init__(self, apiresource):
        self._apiresource = apiresource

    def __getattr__(self, attr):
        if attr in self._attrs:
            # __getattr__ won't find properties
            return self._apiresource.__getattribute__(attr)
        else:
            LOG.debug('Attempted to access unknown attribute "%s" on'
                      ' APIResource object of type "%s" wrapping resource of'
                      ' type "%s"' % (attr, self.__class__,
                                      self._apiresource.__class__))
            raise AttributeError(attr)


class APIDictWrapper(object):
    """ Simple wrapper for api dictionaries

        Some api calls return dictionaries.  This class provides identical
        behavior as APIResourceWrapper, except that it will also behave as a
        dictionary, in addition to attribute accesses.

        Attribute access is the preferred method of access, to be
        consistent with api resource objects from novclient.
    """
    def __init__(self, apidict):
        self._apidict = apidict

    def __getattr__(self, attr):
        try:
            return self._apidict[attr]
        except KeyError:
            msg = 'Unknown attribute "%(attr)s" on APIResource object ' \
                  'of type "%(cls)s"' % {'attr': attr, 'cls': self.__class__}
            LOG.debug(msg)
            raise AttributeError(msg)

    def __getitem__(self, item):
        try:
            return self.__getattr__(item)
        except AttributeError, e:
            # caller is expecting a KeyError
            raise KeyError(e)

    def get(self, item, default=None):
        try:
            return self.__getattr__(item)
        except AttributeError:
            return default


def get_service_from_catalog(catalog, service_type):
    if catalog:
        for service in catalog:
            if service['type'] == service_type:
                return service
    return None


def url_for(request, service_type, admin=False, endpoint_type='internalURL'):
    catalog = request.user.service_catalog
    service = get_service_from_catalog(catalog, service_type)
    if service:
        try:
            if admin:
                return service['endpoints'][0]['adminURL']
            else:
                return service['endpoints'][0][endpoint_type]
        except (IndexError, KeyError):
            raise exceptions.ServiceCatalogException(service_type)
    else:
        raise exceptions.ServiceCatalogException(service_type)