"""Lambda send_failure function module."""
import json

from config import app_logger as logger
from confluent_kafka import Producer
from config import BROKER_SERVERS
from config import DEAD_LETTER_KAFKA_TOPIC


def delivery_report(err, msg):
    """Log delivery results from callbacks for each message produced, triggered by flush()."""
    if err is not None:
        logger.exception('Message delivery failed: {}'.format(err))
    else:
        logger.info('Message delivered to {} [{}]'.format(msg.topic(), msg.partition()))


def handler(event, context):
    """Lambda entry point."""
    try:
        logger.info('Starting to write failed event to Kafka topic.')
        producer = Producer({'bootstrap.servers': BROKER_SERVERS, 'security.protocol': 'SSL'})

        # Asynchronously produce a message, the delivery report callback
        # will be triggered from poll() above, or flush() below, when the message has
        # been successfully delivered or failed permanently.
        producer.produce(
            DEAD_LETTER_KAFKA_TOPIC, json.dumps(event).encode('utf-8'), callback=delivery_report)
        # Wait for any outstanding messages to be delivered and delivery report callback.
        producer.flush()
        logger.info(f'Successfully wrote failed message to Kafka topic: {DEAD_LETTER_KAFKA_TOPIC}')
        return {'status': 'success'}
    except Exception as err:
        logger.exception(str(err))
        raise err