"""
kafka.py - tests the local kafka broker
"""
import datetime
import json
import os

from kafka import KafkaProducer, KafkaConsumer, TopicPartition


kafka_host = os.environ.get('KAFKA_HOST', 'localhost')
kafka_port = os.environ.get('KAFKA_PORT', '9092')

TOPIC = os.environ.get('KAFKA_TOPIC', 'test')
URL = '{}:{}'.format(kafka_host, kafka_port)
CLIENT_ID = os.environ.get('KAFKA_CLIENT_ID', 'tester')


class JsonSerializer(object):
    @staticmethod
    def serialize(value):
        return json.dumps(value).encode('utf-8')

    @staticmethod
    def deserialize(value):
        return json.loads(value.decode('utf-8'))


class Tester(object):
    """
    Component that provides a produce and consume behavior
    """
    def produce(self):
        """
        Produces a message on kafka with the current datetime
        """
        producer = KafkaProducer(
            bootstrap_servers=[URL],
            client_id=CLIENT_ID,
            value_serializer=JsonSerializer.serialize,
            api_version=(0, 10, 1),
            batch_size=0,
            acks='all'
        )

        message = datetime.datetime.now().isoformat()
        future_metadata = producer.send(TOPIC, message)
        producer.flush()
        metadata = future_metadata.get(timeout=10)
        print('Produced this message (offset={}): {}'.format(metadata.offset, message))
        producer.close()

        return metadata

    def consume(self, metadata):
        """
        Consumes a message
        """
        consumer = KafkaConsumer(
            bootstrap_servers=URL,
            client_id=CLIENT_ID,
            value_deserializer=JsonSerializer.deserialize,
            api_version=(0, 10, 1)
        )

        partition = TopicPartition(TOPIC, 0)
        consumer.assign([partition])
        consumer.seek(partition, metadata.offset)
        message = next(consumer)
        print('Consumed this message (offset={}): {}'.format(metadata.offset, message))
        consumer.close()


def main():
    """
    main entrypoint
    """
    tester = Tester()
    message_info = tester.produce()
    tester.consume(message_info)


if __name__ == "__main__":
    main()