#!/usr/bin/env python
#
# Copyright 2007 Google LLC
#
# 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.
#


"""An APIProxy stub that communicates with VMEngine service bridges."""

from concurrent import futures
import imp
import logging
import os
import sys
from google.appengine.api import apiproxy_rpc
from google.appengine.api import apiproxy_stub_map
from google.appengine.ext.remote_api import remote_api_bytes_pb2 as remote_api_pb2
from google.appengine.runtime import apiproxy_errors
from google.appengine.runtime import context
import six.moves.urllib.parse
import urllib3


logging.getLogger('requests_nologs').setLevel(logging.ERROR)

TICKET_HEADER = 'HTTP_X_APPENGINE_API_TICKET'
DEV_TICKET_HEADER = 'HTTP_X_APPENGINE_DEV_REQUEST_ID'
DAPPER_ENV_KEY = 'HTTP_X_GOOGLE_DAPPERTRACEINFO'
SERVICE_BRIDGE_HOST = os.environ.get('API_HOST',
                                     'appengine.googleapis.internal')
API_PORT = os.environ.get('API_PORT', '10001')
SERVICE_ENDPOINT_NAME = 'app-engine-apis'
APIHOST_METHOD = '/VMRemoteAPI.CallRemoteAPI'
PROXY_PATH = '/rpc_http'
DAPPER_HEADER = 'X-Google-DapperTraceInfo'
SERVICE_DEADLINE_HEADER = 'X-Google-RPC-Service-Deadline'
SERVICE_ENDPOINT_HEADER = 'X-Google-RPC-Service-Endpoint'
SERVICE_METHOD_HEADER = 'X-Google-RPC-Service-Method'
RPC_CONTENT_TYPE = 'application/octet-stream'
DEFAULT_TIMEOUT = 60

DEADLINE_DELTA_SECONDS = 1


MAX_CONCURRENT_API_CALLS = 100

URLLIB3_POOL_COUNT = 10

URLLIB3_POOL_SIZE = 10


_EXCEPTIONS_MAP = {
    remote_api_pb2.RpcError.UNKNOWN:
        (apiproxy_errors.RPCFailedError,
         'The remote RPC to the application server failed for call %s.%s().'),
    remote_api_pb2.RpcError.CALL_NOT_FOUND:
        (apiproxy_errors.CallNotFoundError,
         'The API package \'%s\' or call \'%s()\' was not found.'),
    remote_api_pb2.RpcError.PARSE_ERROR:
        (apiproxy_errors.ArgumentError,
         'There was an error parsing arguments for API call %s.%s().'),
    remote_api_pb2.RpcError.OVER_QUOTA:
        (apiproxy_errors.OverQuotaError,
         'The API call %s.%s() required more quota than is available.'),
    remote_api_pb2.RpcError.REQUEST_TOO_LARGE:
        (apiproxy_errors.RequestTooLargeError,
         'The request to API call %s.%s() was too large.'),
    remote_api_pb2.RpcError.CAPABILITY_DISABLED:
        (apiproxy_errors.CapabilityDisabledError,
         'The API call %s.%s() is temporarily disabled.'),
    remote_api_pb2.RpcError.FEATURE_DISABLED:
        (apiproxy_errors.FeatureNotEnabledError,
         'The API call %s.%s() is currently not enabled.'),
    remote_api_pb2.RpcError.RESPONSE_TOO_LARGE:
        (apiproxy_errors.ResponseTooLargeError,
         'The response from API call %s.%s() was too large.'),
    remote_api_pb2.RpcError.CANCELLED:
        (apiproxy_errors.CancelledError,
         'The API call %s.%s() was explicitly cancelled.'),
    remote_api_pb2.RpcError.DEADLINE_EXCEEDED:
        (apiproxy_errors.DeadlineExceededError,
         'The API call %s.%s() took too long to respond and was cancelled.')
}

_DEFAULT_EXCEPTION = _EXCEPTIONS_MAP[remote_api_pb2.RpcError.UNKNOWN]

_DEADLINE_EXCEEDED_EXCEPTION = _EXCEPTIONS_MAP[
    remote_api_pb2.RpcError.DEADLINE_EXCEEDED]


class DefaultApiRPC(apiproxy_rpc.RPC):
  """A class representing an RPC to a remote server."""

  def _ErrorException(self, exception_class, error_details):
    return exception_class(error_details % (self.package, self.call))

  def _TranslateToError(self, response):
    """Translates a failed APIResponse into an exception."""


    if response.HasField('rpc_error'):
      code = response.rpc_error.code
      detail = response.rpc_error.detail
      exception_type, msg = _EXCEPTIONS_MAP.get(code, _DEFAULT_EXCEPTION)
      if detail:
        msg = '%s -- Additional details from server: %s' % (msg, detail)
      raise self._ErrorException(exception_type, msg)


    raise apiproxy_errors.ApplicationError(response.application_error.code,
                                           response.application_error.detail)

  def _MakeCallImpl(self):
    """Makes an asynchronous API call over the service bridge.

    For this to work the following must be set:
      self.package: the API package name;
      self.call: the name of the API call/method to invoke;
      self.request: the API request body as a serialized protocol buffer.

    The actual API call is made by urllib3.request via a thread pool
    (multiprocessing.dummy.Pool). The thread pool restricts the number of
    concurrent requests to MAX_CONCURRENT_API_CALLS, so this method will
    block if that limit is exceeded, until other asynchronous calls resolve.

    If the main thread holds the import lock, waiting on thread work can cause
    a deadlock:
    https://docs.python.org/2/library/threading.html#importing-in-threaded-code

    Therefore, we try to detect this error case and fall back to sync calls.
    """
    assert self._state == apiproxy_rpc.RPC.IDLE, self._state


    if context.READ_FROM_OS_ENVIRON:
      ticket = os.environ.get(TICKET_HEADER,
                              os.environ.get(DEV_TICKET_HEADER))
    else:


      ticket = context.gae_headers.API_TICKET.get(
          context.gae_headers.DEV_REQUEST_ID.get(None))

    request = remote_api_pb2.Request(
        service_name=self.package,
        method=self.call,
        request_id=ticket,
        request=self.request.SerializeToString())

    deadline = self.deadline or DEFAULT_TIMEOUT

    body_data = request.SerializeToString()
    headers = {
        SERVICE_DEADLINE_HEADER: str(deadline),
        SERVICE_ENDPOINT_HEADER: SERVICE_ENDPOINT_NAME,
        SERVICE_METHOD_HEADER: APIHOST_METHOD,
        'Content-type': RPC_CONTENT_TYPE,
    }


    dapper_header_value = context.get(DAPPER_ENV_KEY)
    if dapper_header_value:
      headers[DAPPER_HEADER] = dapper_header_value


    api_host = os.environ.get('API_HOST', SERVICE_BRIDGE_HOST)
    api_port = os.environ.get('API_PORT', API_PORT)

    if ':' in api_host:
      api_host = '[{}]'.format(api_host)
    endpoint_url = six.moves.urllib.parse.urlunparse(
        ('http', '%s:%s' % (api_host, api_port), PROXY_PATH, '', '', ''))

    self._state = apiproxy_rpc.RPC.RUNNING

    request_kwargs = dict(
        url=endpoint_url,
        method='POST',
        timeout=DEADLINE_DELTA_SECONDS + deadline,
        headers=headers,
        body=body_data)


    if six.PY2 and imp.lock_held():
      self.future = futures.Future()
      self.future.set_result(self._SendRequestAndFinish(**request_kwargs))

    else:


      self.future = self.stub.thread_pool.submit(self._SendRequestAndFinish,
                                                 **request_kwargs)

  def _WaitImpl(self):

    assert self.future is not None
    futures.wait([self.future])
    return True

  def _SendRequest(self, **kwargs):
    try:
      response = self.stub.http.request(**kwargs)

      if response.status != 200:
        raise apiproxy_errors.RPCFailedError(
            'Proxy returned HTTP status %s %s' %
            (response.status, response.reason))
    except urllib3.exceptions.TimeoutError:
      raise self._ErrorException(*_DEADLINE_EXCEEDED_EXCEPTION)
    except (urllib3.exceptions.RequestError,
            urllib3.exceptions.ConnectionError):

      raise self._ErrorException(*_DEFAULT_EXCEPTION)


    parsed_response = remote_api_pb2.Response.FromString(response.data)


    if (parsed_response.HasField('application_error') or
        parsed_response.HasField('rpc_error')):
      raise self._TranslateToError(parsed_response)


    self.response.ParseFromString(parsed_response.response)

  def _CaptureTrace(self, f, **kwargs):
    try:
      f(**kwargs)
    except Exception:


      _, exc, tb = sys.exc_info()
      self._exception = exc
      self._traceback = tb

  def _SendRequestAndFinish(self, **kwargs):
    try:
      self._CaptureTrace(self._SendRequest, **kwargs)
    finally:
      if self.callback:
        self._CaptureTrace(self.callback)
      self._state = apiproxy_rpc.RPC.FINISHING


class DefaultApiStub(object):
  """A stub for calling services through a VM service bridge.

  You can use this to stub out any service that the remote server supports.
  """


  def __init__(self):
    self.thread_pool = futures.ThreadPoolExecutor(MAX_CONCURRENT_API_CALLS)
    self.http = urllib3.PoolManager(
        num_pools=URLLIB3_POOL_COUNT, maxsize=URLLIB3_POOL_SIZE)

  def MakeSyncCall(self, service, call, request, response):
    """Make a synchronous API call.

    Args:
      service: The name of the service you are trying to use.
      call: The name of the method.
      request: The request protocol buffer
      response: The response protocol buffer to be filled.
    """
    rpc = self.CreateRPC()
    rpc.MakeCall(service, call, request, response)
    rpc.Wait()
    rpc.CheckSuccess()

  def CreateRPC(self):
    """Create a new RPC object."""
    return DefaultApiRPC(stub=self)


def Register(stub):
  """Insert stubs so App Engine services are accessed via the service bridge."""
  apiproxy_stub_map.apiproxy.SetDefaultStub(stub)