"""Amazon SQS connector."""
import time

import boto3


def get_sqs_resources():
    """Get SQS client.

    Returns:
         boto3.resources.base.ServiceResource: SQS resource represents
         object-oriented interface of SQS.

    """
    sqs_resource = boto3.resource('sqs')
    return sqs_resource


def get_queue_by_name(queue_name, sqs_resource=None):
    """Get Amazon SQS queue.

    Args:
        queue_name (str): the name of the queue.
        sqs_resource (boto3.resources.base.ServiceResource): optional
            SQS resource.

    Returns:
        boto3.resources.factory.sqs.Queue: Instance of Amazon SQS queue

    """
    sqs = sqs_resource if sqs_resource else get_sqs_resources()
    return sqs.get_queue_by_name(QueueName=queue_name)


def get_queue_number_of_messages(queue):
    """Get Amazon SQS queue ApproximateNumberOfMessages (health check).

    Args:
        queue (boto3.resources.factory.sqs.Queue): the queue.

    Returns:
        int: approximate number of messages

    """
    queue.reload()
    message_count = int(queue.attributes.get('ApproximateNumberOfMessages'))
    if message_count == 0:
        time.sleep(2)
        queue.reload()
        message_count = int(
            queue.attributes.get('ApproximateNumberOfMessages'))
    return message_count


def yield_sublists(src_list, sublist_size):
    """Yield successive sublist_size length chunks from src_list.

    Example usage:
        my_list = [x for x in range(0, 100)]
        for sublist in yield_sublists(my_list, 10):
            print(sublist)

    Args:
        src_list (list): list to divide
        sublist_size (int): size of each sublist returned

    Returns:
        generator: slices of the original src_list

    """
    for i in range(0, len(src_list), sublist_size):
        yield src_list[i:i + sublist_size]


def get_message(queue):
    """Receive 1 message from the queue.

    Args:
        queue (boto3.resources.factory.sqs.Queue): the SQS queue

    Returns:
        boto3.resources.factory.sqs.Message: SQS message or None

    """
    queue.reload()
    messages = queue.receive_messages(
        MaxNumberOfMessages=1, WaitTimeSeconds=20, AttributeNames=['All'])
    if not messages:
        return None
    return messages[0]