text: #!/usr/bin/env python3.9
  # Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
  # SPDX-License-Identifier: Apache-2.0
  """ Call Event DynamoDB stream Lambda Processor
  """
  import asyncio
  import logging
  from os import environ, getenv
  from typing import TYPE_CHECKING, Dict, List, TypedDict, Union
  from urllib.parse import urlparse
  
  # third-party imports from Lambda layer
  from aws_lambda_powertools import Logger, Metrics, Tracer
  from aws_lambda_powertools.metrics import MetricUnit
  from aws_lambda_powertools.utilities.data_classes import DynamoDBStreamEvent
  from aws_lambda_powertools.utilities.typing import LambdaContext
  import boto3
  from botocore.config import Config as BotoCoreConfig
  from gql.client import Client
  from gql.transport.aiohttp import AIOHTTPTransport
  from gql.transport.appsync_auth import AppSyncIAMAuthentication
  
  # local imports
  # pylint: disable=import-error
  from dynamodb_stream_event import DynamoDBDeserializedStreamEvent
  from mapping import is_call_event_record
  from call_event_handler import CallEventHandler
  from tumbling_window_state import CallState, CallStateManager
  
  # pylint: enable=import-error
  
  if TYPE_CHECKING:
      from mypy_boto3_dynamodb.service_resource import DynamoDBServiceResource, Table as DynamoDbTable
      from mypy_boto3_comprehend.client import ComprehendClient
      from boto3 import Session as Boto3Session
  else:
      Boto3Session = object
      ComprehendClient = object
      DynamoDBServiceResource = object
      DynamoDbTable = object
  
  LOGGER = Logger(location="%(filename)s:%(lineno)d - %(funcName)s()")
  TRACER = Tracer()
  METRICS = Metrics(
      namespace=getenv("POWERTOOLS_METRICS_NAMESPACE", "CallAnalytics"),
      service=getenv("POWERTOOLS_SERVICE_NAME", "CallEventStreamProcessor"),
  )
  
  APPSYNC_GRAPHQL_URL = environ["APPSYNC_GRAPHQL_URL"]
  BOTO3_SESSION: Boto3Session = boto3.Session()
  CLIENT_CONFIG = BotoCoreConfig(
      retries={"mode": "adaptive", "max_attempts": 3},
  )
  IS_SENTIMENT_ANALYSIS_ENABLED = getenv("IS_SENTIMENT_ANALYSIS_ENABLED", "true").lower() == "true"
  if IS_SENTIMENT_ANALYSIS_ENABLED:
      COMPREHEND_CLIENT: ComprehendClient = BOTO3_SESSION.client("comprehend", config=CLIENT_CONFIG)
      COMPREHEND_LANGUAGE_CODE = getenv("COMPREHEND_LANGUAGE_CODE", "en")
  
  EVENT_SOURCING_TABLE_NAME = environ["EVENT_SOURCING_TABLE_NAME"]
  DYNAMODB_RESOURCE: DynamoDBServiceResource = BOTO3_SESSION.resource(
      "dynamodb",
      config=CLIENT_CONFIG,
  )
  EVENT_SOURCING_TABLE: DynamoDbTable = DYNAMODB_RESOURCE.Table(EVENT_SOURCING_TABLE_NAME)
  
  EVENT_LOOP = asyncio.get_event_loop()
  
  
  class EventHandlerResult(TypedDict):
      """Event Handler Result Type"""
  
      results: List[Union[Dict, Exception]]
      state: CallState
      event_error_count: float
      event_insert_count: float
  
  
  async def handle_event(event: DynamoDBStreamEvent) -> EventHandlerResult:
      """Handles Call Events
  
      Loops through the DynamoDB stream records and handles asynchronous Call
      state mutations.
  
      Manages the Lambda Tumbling Window state to keep track of Call aggregations
  
      :param event: Lambda event
      """
      # pylint: disable=too-many-locals
      stream_deserialized_event = DynamoDBDeserializedStreamEvent(event)
      results: List[Union[Dict, Exception]] = []
  
      appsync_host = str(urlparse(APPSYNC_GRAPHQL_URL).netloc)
      appsync_auth = AppSyncIAMAuthentication(host=appsync_host)
      appsync_transport = AIOHTTPTransport(url=APPSYNC_GRAPHQL_URL, auth=appsync_auth)
      appsync_client = Client(transport=appsync_transport, fetch_schema_from_transport=True)
      async with appsync_client as appsync_session:
          call_event_handler_args = dict(
              appsync_session=appsync_session,
              metrics=METRICS,
              is_sentiment_analysis_enabled=IS_SENTIMENT_ANALYSIS_ENABLED,
          )
          if IS_SENTIMENT_ANALYSIS_ENABLED:
              call_event_handler_args["comprehend_client"] = COMPREHEND_CLIENT
              call_event_handler_args["comprehend_language"] = COMPREHEND_LANGUAGE_CODE
  
          call_event_handler = CallEventHandler(**call_event_handler_args)
          tasks = []
          for record in stream_deserialized_event.records:
              if not is_call_event_record(record):
                  LOGGER.debug("not a call event record - skipping - keys: %s", record.dynamodb.keys)
                  continue
  
              tasks.append(call_event_handler.handle(record=record))
  
          results = await asyncio.gather(*tasks, return_exceptions=True)
  
          event_error_count = 0.0
          event_insert_count = 0.0
          state = {}
          async with CallStateManager(
              event=event,
              dynamodb_table=EVENT_SOURCING_TABLE,
              appsync_session=appsync_session,
          ) as call_state_manager:
              for result in results:
                  if isinstance(result, Exception):
                      event_error_count = event_error_count + 1
                      LOGGER.error("call event exception: %s", result)
                      try:
                          raise result
                      except Exception:  # pylint: disable=broad-except
                          LOGGER.exception("call event exception")
                  else:
                      event_insert_count = event_insert_count + 1
                      if LOGGER.isEnabledFor(logging.DEBUG):
                          result_extra = result if isinstance(result, dict) else {}
                          LOGGER.debug("call event result", extra=result_extra)
  
                      updated_state = call_state_manager.update_state(input_item=result)
                      LOGGER.debug("updated state", extra=dict(updated_state=updated_state))
  
              state = call_state_manager.state
  
          if call_state_manager.has_error:
              event_error_count = event_error_count + 1
  
      return EventHandlerResult(
          {
              "results": results,
              "state": state,
              "event_error_count": event_error_count,
              "event_insert_count": event_insert_count,
          }
      )
  
  
  @METRICS.log_metrics  # type: ignore
  @TRACER.capture_lambda_handler
  @LOGGER.inject_lambda_context
  def handler(event: DynamoDBStreamEvent, context: LambdaContext):
      # pylint: disable=unused-argument
      """Lambda handler
  
      Processes Call events from the DynamoDB stream of the Event Sourcing table
      It manages the mutation of Call state/metadata including transcript and
      sentiment derived from the Call events.
      """
      LOGGER.debug("lambda event", extra={"event": event})
      LOGGER.info("GraphQL endpoint: [%s]", APPSYNC_GRAPHQL_URL)
      LOGGER.info("sentiment analysis enabled: [%s]", IS_SENTIMENT_ANALYSIS_ENABLED)
  
      record_count = len(event.get("Records", []))  # type: ignore
      METRICS.add_metric(
          name="EventBatchCount",
          unit=MetricUnit.Count,
          value=record_count,
      )
      event_result = EVENT_LOOP.run_until_complete(handle_event(event=event))
  
      METRICS.add_metric(
          name="EventInsertErrorCount",
          unit=MetricUnit.Count,
          value=event_result.get("event_error_count", 0.0),
      )
      METRICS.add_metric(
          name="EventInsertCount",
          unit=MetricUnit.Count,
          value=event_result.get("event_insert_count", 0.0),
      )
  
      # Lambda tumbling window state
      incoming_state = event.get("state", {})  # type: ignore
      outgoing_state = event_result.get("state", incoming_state)
  
      LOGGER.debug("state", extra=dict(incoming_state=incoming_state, outgoing_state=outgoing_state))
      return {"state": outgoing_state}
  