#
#    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 itertools

from heat.api.openstack.v1 import util
from heat.common import identifier
from heat.common import serializers
from heat.common import wsgi
from heat.rpc import api as engine_api
from heat.rpc import client as rpc_client


def format_resource(req, res, keys=None):
    keys = keys or []
    include_key = lambda k: k in keys if keys else True

    def transform(key, value):
        if not include_key(key):
            return

        if key == engine_api.RES_ID:
            identity = identifier.ResourceIdentifier(**value)
            links = [util.make_link(req, identity),
                     util.make_link(req, identity.stack(), 'stack')]

            nested_id = res.get(engine_api.RES_NESTED_STACK_ID)
            if nested_id:
                nested_identity = identifier.HeatIdentifier(**nested_id)
                links.append(util.make_link(req, nested_identity, 'nested'))

            yield ('links', links)
        elif (key == engine_api.RES_STACK_NAME or
              key == engine_api.RES_STACK_ID or
              key == engine_api.RES_ACTION or
              key == engine_api.RES_NESTED_STACK_ID):
            return
        elif (key == engine_api.RES_METADATA):
            return
        elif (key == engine_api.RES_STATUS and engine_api.RES_ACTION in res):
            # To avoid breaking API compatibility, we join RES_ACTION
            # and RES_STATUS, so the API format doesn't expose the
            # internal split of state into action/status
            yield (key, '_'.join((res[engine_api.RES_ACTION], value)))
        elif (key == engine_api.RES_NAME):
            yield ('logical_resource_id', value)
            yield (key, value)

        else:
            yield (key, value)

    return dict(itertools.chain.from_iterable(
        transform(k, v) for k, v in res.items()))


class ResourceController(object):
    """
    WSGI controller for Resources in Heat v1 API
    Implements the API actions
    """
    # Define request scope (must match what is in policy.json)
    REQUEST_SCOPE = 'resource'

    def __init__(self, options):
        self.options = options
        self.rpc_client = rpc_client.EngineClient()

    @util.identified_stack
    def index(self, req, identity):
        """
        Lists summary information for all resources
        """

        # Though nested_depth is defaulted in the RPC API, this prevents empty
        # strings from being passed, thus breaking the code in the engine.
        nested_depth = int(req.params.get('nested_depth') or 0)
        res_list = self.rpc_client.list_stack_resources(req.context,
                                                        identity,
                                                        nested_depth)

        return {'resources': [format_resource(req, res) for res in res_list]}

    @util.identified_stack
    def show(self, req, identity, resource_name):
        """
        Gets detailed information for a resource
        """

        res = self.rpc_client.describe_stack_resource(req.context,
                                                      identity,
                                                      resource_name)

        return {'resource': format_resource(req, res)}

    @util.identified_stack
    def metadata(self, req, identity, resource_name):
        """
        Gets metadata information for a resource
        """

        res = self.rpc_client.describe_stack_resource(req.context,
                                                      identity,
                                                      resource_name)

        return {engine_api.RES_METADATA: res[engine_api.RES_METADATA]}

    @util.identified_stack
    def signal(self, req, identity, resource_name, body=None):
        self.rpc_client.resource_signal(req.context,
                                        stack_identity=identity,
                                        resource_name=resource_name,
                                        details=body)


def create_resource(options):
    """
    Resources resource factory method.
    """
    deserializer = wsgi.JSONRequestDeserializer()
    serializer = serializers.JSONResponseSerializer()
    return wsgi.Resource(ResourceController(options), deserializer, serializer)
