"""
DynamoDB Client
=============

Provides dynamodb_resource attribute for connection to AWS DynamDB service.

https://aws.amazon.com/documentation/dynamodb/
"""

import boto3
from botocore.client import Config


dynamodb_resource = boto3.resource(
    'dynamodb', 'us-east-1', config=Config(max_pool_connections=1000))
client = dynamodb_resource.meta.client

ITEM_FIELD = 'Item'


def batch_update_item_fields(
        table, key, verb, expressions, attribute_names, attribute_values,
        batch_size=4000, force=False):
    """Util to update several fields within an item."""
    update_expression = '{} {}'.format(verb, ', '.join(expressions))
    if not expressions or batch_size > len(update_expression) and not force:
        return False

    update_item = getattr(table, 'update_item')
    update_item(
        Key=key,
        UpdateExpression=update_expression,
        ExpressionAttributeNames=attribute_names,
        ExpressionAttributeValues=attribute_values)

    return True