# Copyright 2017 gRPC authors.
#
# 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 interceptors that operate on all RPC types."""

import grpc


class _GenericClientInterceptor(
        grpc.UnaryUnaryClientInterceptor, grpc.UnaryStreamClientInterceptor,
        grpc.StreamUnaryClientInterceptor, grpc.StreamStreamClientInterceptor):

    def __init__(self, interceptor_function):
        self._fn = interceptor_function

    def intercept_unary_unary(self, continuation, client_call_details, request):
        new_details, new_request_iterator, postprocess = self._fn(
            client_call_details, iter((request,)), False, False)
        response = continuation(new_details, next(new_request_iterator))
        return postprocess(response) if postprocess else response

    def intercept_unary_stream(self, continuation, client_call_details,
                               request):
        new_details, new_request_iterator, postprocess = self._fn(
            client_call_details, iter((request,)), False, True)
        response_it = continuation(new_details, next(new_request_iterator))
        return postprocess(response_it) if postprocess else response_it

    def intercept_stream_unary(self, continuation, client_call_details,
                               request_iterator):
        new_details, new_request_iterator, postprocess = self._fn(
            client_call_details, request_iterator, True, False)
        response = continuation(new_details, new_request_iterator)
        return postprocess(response) if postprocess else response

    def intercept_stream_stream(self, continuation, client_call_details,
                                request_iterator):
        new_details, new_request_iterator, postprocess = self._fn(
            client_call_details, request_iterator, True, True)
        response_it = continuation(new_details, new_request_iterator)
        return postprocess(response_it) if postprocess else response_it


def create(intercept_call):
    return _GenericClientInterceptor(intercept_call)