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"""The Python implementation of the GRPC interoperability test client."""

import argparse
from oauth2client import client as oauth2client_client

import grpc
from grpc.beta import implementations
from src.proto.grpc.testing import test_pb2

from tests.interop import methods
from tests.interop import resources


def _args():
  parser = argparse.ArgumentParser()
  parser.add_argument(
      '--server_host', help='the host to which to connect', type=str)
  parser.add_argument(
      '--server_port', help='the port to which to connect', type=int)
  parser.add_argument(
      '--test_case', help='the test case to execute', type=str)
  parser.add_argument(
      '--use_tls', help='require a secure connection', default=False,
      type=resources.parse_bool)
  parser.add_argument(
      '--use_test_ca', help='replace platform root CAs with ca.pem',
      default=False, type=resources.parse_bool)
  parser.add_argument(
      '--server_host_override',
      help='the server host to which to claim to connect', type=str)
  parser.add_argument('--oauth_scope', help='scope for OAuth tokens', type=str)
  parser.add_argument(
      '--default_service_account',
      help='email address of the default service account', type=str)
  return parser.parse_args()


def _application_default_credentials():
  return oauth2client_client.GoogleCredentials.get_application_default()


def _stub(args):
  target = '{}:{}'.format(args.server_host, args.server_port)
  if args.test_case == 'oauth2_auth_token':
    google_credentials = _application_default_credentials()
    scoped_credentials = google_credentials.create_scoped([args.oauth_scope])
    access_token = scoped_credentials.get_access_token().access_token
    call_credentials = grpc.access_token_call_credentials(access_token)
  elif args.test_case == 'compute_engine_creds':
    google_credentials = _application_default_credentials()
    scoped_credentials = google_credentials.create_scoped([args.oauth_scope])
    # TODO(https://github.com/grpc/grpc/issues/6799): Eliminate this last
    # remaining use of the Beta API.
    call_credentials = implementations.google_call_credentials(
        scoped_credentials)
  elif args.test_case == 'jwt_token_creds':
    google_credentials = _application_default_credentials()
    # TODO(https://github.com/grpc/grpc/issues/6799): Eliminate this last
    # remaining use of the Beta API.
    call_credentials = implementations.google_call_credentials(
        google_credentials)
  else:
    call_credentials = None
  if args.use_tls:
    if args.use_test_ca:
      root_certificates = resources.test_root_certificates()
    else:
      root_certificates = None  # will load default roots.

    channel_credentials = grpc.ssl_channel_credentials(root_certificates)
    if call_credentials is not None:
      channel_credentials = grpc.composite_channel_credentials(
          channel_credentials, call_credentials)

    channel = grpc.secure_channel(
        target, channel_credentials,
        (('grpc.ssl_target_name_override', args.server_host_override,),))
  else:
    channel = grpc.insecure_channel(target)
  return test_pb2.TestServiceStub(channel)


def _test_case_from_arg(test_case_arg):
  for test_case in methods.TestCase:
    if test_case_arg == test_case.value:
      return test_case
  else:
    raise ValueError('No test case "%s"!' % test_case_arg)


def test_interoperability():
  args = _args()
  stub = _stub(args)
  test_case = _test_case_from_arg(args.test_case)
  test_case.test_interoperability(stub, args)


if __name__ == '__main__':
  test_interoperability()