"""
DynamoDB Utils
==============

Utils for any dynamodb operations for ows-accounting
"""

import boto3
from boto3.dynamodb.conditions import Attr
from boto3.dynamodb.conditions import Key


def get_table(table_name):
    """Get Dynamodb Table by name.

    Args:
        table_name (str): name of the dynamodb table.

    Returns:
        dynamodb.Table.
    """

    resource = boto3.resource('dynamodb')
    return resource.Table(table_name)


def query_items(
        table, partition_key, partition_key_value,
        sort_key=None, sort_key_value=None, **filters):
    """Get dynamodb items with user_id_type and filters.

    Args:
        table (dynamodb.Table): table object from dynamodb.
        partition_key (str): partition_key.
        partition_key_value (str): value of the partition key.
        sort_key (str): partition sort key.
        sort_key_value (str): partition sort key value.
        filters (dict): optional filters. Example: file_type='txt'.

    Returns:
        list: list of reports dicts. Example:
        [{'user_id_type': '18805L', 'number_format': 'en_US', 'user_params':
        '206__all__en_US__xls', 'period_ids': '206', 'transaction_types':
        'all', 'account_type': 'label', 'status': 'GENERATED',
        'payment_interval': 'month', 'file_type': 'xls',
        'account_id': '18805',
        'download_avro_file_start': '2016-05-26 17:45:45'}]
    """

    filter_expressions = None
    key_condition_expression = Key(partition_key).eq(
        partition_key_value)
    if sort_key and sort_key_value:
        key_condition_expression = (
            key_condition_expression & Key(sort_key).eq(sort_key_value))
    query_params = {
        'KeyConditionExpression': key_condition_expression,
        'ScanIndexForward': False,
        'ConsistentRead': True
    }
    for attribute, value in filters.items():
        if not filter_expressions:
            filter_expressions = Attr(attribute).eq(value)
        filter_expressions = filter_expressions & Attr(attribute).eq(value)

    if filter_expressions:
        query_params['FilterExpression'] = filter_expressions
    return table.query(**query_params).get('Items')