#!/usr/bin/env python

#

# Copyright 2007 Google 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.

#

"""Base class for implementing API proxy stubs."""

from google.appengine.api import apiproxy_rpc

from google.appengine.runtime import apiproxy_errors

MAX_REQUEST_SIZE = 1 << 20

class APIProxyStub(object):

  """Base class for implementing API proxy stub classes.

  To implement an API proxy stub:

    - Extend this class.

    - Override __init__ to pass in appropriate default service name.

    - Implement service methods as _Dynamic_<method>(request, response).

  """

  def __init__(self, service_name, max_request_size=MAX_REQUEST_SIZE):

    """Constructor.

    Args:

      service_name: Service name expected for all calls.

      max_request_size: int, maximum allowable size of the incoming request.  A

        apiproxy_errors.RequestTooLargeError will be raised if the inbound

        request exceeds this size.  Default is 1 MB.

    """

    self.__service_name = service_name

    self.__max_request_size = max_request_size

  def CreateRPC(self):

    """Creates RPC object instance.

    Returns:

      a instance of RPC.

    """

    return apiproxy_rpc.RPC(stub=self)

  def MakeSyncCall(self, service, call, request, response):

    """The main RPC entry point.

    Args:

      service: Must be name as provided to service_name of constructor.

      call: A string representing the rpc to make.  Must be part of

        the underlying services methods and impemented by _Dynamic_<call>.

      request: A protocol buffer of the type corresponding to 'call'.

      response: A protocol buffer of the type corresponding to 'call'.

    """

    assert service == self.__service_name, ('Expected "%s" service name, '

                                            'was "%s"' % (self.__service_name,

                                                          service))

    if request.ByteSize() > self.__max_request_size:

      raise apiproxy_errors.RequestTooLargeError(

          'The request to API call %s.%s() was too large.' % (service, call))

    messages = []

    assert request.IsInitialized(messages), messages

    method = getattr(self, '_Dynamic_' + call)

    method(request, response)