# Copyright (c) 2013 Rackspace, 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.


from marconiclient.common import api


class Request(object):
    """General data for a Marconi request, passed to the transport layer.
    The idea is to be declarative i.e. specify *what* is desired. It's up to
    the respective transport to turn this into a layer-specific request.
    """

    def __init__(self, endpoint='', operation='', params=None, headers=None):
        self.endpoint = endpoint
        self.operation = operation
        self.params = params or {}
        self.headers = headers or {}

    def validate(self):
        """`None` if the request data is valid, an error message otherwise.
        Checks the `operation` and the presence of the `params`.
        """
        api_info_data = api.info()
        if self.operation not in api_info_data:
            return "Invalid operation '%s'" % self.operation

        api_info = api_info_data[self.operation]

        param_names = set() if not self.params else set(self.params.keys())
        # NOTE(al-maisan) Do we have all the mandatory params?
        if not api_info.mandatory.issubset(param_names):
            missing = sorted(api_info.mandatory - param_names)
            return "Missing mandatory params: '%s'" % ', '.join(missing)

        # NOTE(al-maisan) Our params must be either in the mandatory or the
        # optional subset.
        all_permissible_params = api_info.mandatory.union(api_info.optional)
        if not param_names.issubset(all_permissible_params):
            invalid = sorted(param_names - all_permissible_params)
            return "Invalid params: '%s'" % ', '.join(invalid)

        return None