# Copyright 2012 OpenStack Foundation
# All Rights Reserved.
#
#    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.

"""
Base utilities to build API operation managers and objects on top of.
"""

import copy

from glanceclient.openstack.common.apiclient import base

# Python 2.4 compat
try:
    all
except NameError:
    def all(iterable):
        return True not in (not x for x in iterable)


def getid(obj):
    """
    Abstracts the common pattern of allowing both an object or an object's ID
    (UUID) as a parameter when dealing with relationships.
    """
    try:
        return obj.id
    except AttributeError:
        return obj


class Manager(object):
    """
    Managers interact with a particular type of API (servers, flavors, images,
    etc.) and provide CRUD operations for them.
    """
    resource_class = None

    def __init__(self, api):
        self.api = api

    def _list(self, url, response_key, obj_class=None, body=None):
        resp, body = self.api.json_request('GET', url)

        if obj_class is None:
            obj_class = self.resource_class

        data = body[response_key]
        return [obj_class(self, res, loaded=True) for res in data if res]

    def _delete(self, url):
        self.api.raw_request('DELETE', url)

    def _update(self, url, body, response_key=None):
        resp, body = self.api.json_request('PUT', url, body=body)
        # PUT requests may not return a body
        if body:
            return self.resource_class(self, body[response_key])


class Resource(base.Resource):
    """
    A resource represents a particular instance of an object (tenant, user,
    etc). This is pretty much just a bag for attributes.
    """

    def to_dict(self):
        # Note(akurilin): There is a patch in Oslo, that adds to_dict() method
        # to common Resource - I1db6c12a1f798de7f7fafd0c34fb0ef523610153.
        # When Oslo code comes, we will be in able to remove this method
        # and class at all.
        return copy.deepcopy(self._info)