"""Utils functions related to DynamoDB."""

import datetime

import boto3

from activity_detector import base_config


def set_status(activity_type_name, date, status, timestamp=None):
    """Set status for the activity type in DynamoDB.

    Args:
        activity_type_name (str): the name of the activity type.
        status (str): status to set.
        date (str): date of the interest.
        timestamp (datetime): optional last procssed time, defaults to now
    """
    if not timestamp:
        timestamp = datetime.datetime.utcnow().strftime(
            base_config.STATUS_TIMESTAMP_FORMAT)
    else:
        timestamp = timestamp.strftime(base_config.STATUS_TIMESTAMP_FORMAT)

    client = boto3.client('dynamodb', region_name='us-east-1')
    client.update_item(
        TableName=base_config.DYNAMODB_STATUS_TABLE,
        Key={
            'activity_type_name': {'S': activity_type_name},
            'date': {'S': date}},
        ExpressionAttributeNames={'#status': 'status'},
        UpdateExpression='SET last_processed_timestamp = :d, #status = :s',
        ExpressionAttributeValues={
            ':d': {'S': timestamp},
            ':s': {'S': status}})


def get_status(activity_type_name, date):
    """Get status for the activity type from DynamoDB.

    Args:
        activity_type_name (str): the name of the activity type.
        date (str): date of the interest.

    Returns:
        dict: dictionary of the form: {
            'status': 'PROCESSED',
            'last_processed_timestamp': '1970-01-01'
        }.
    """
    client = boto3.client('dynamodb', region_name='us-east-1')
    response = client.get_item(
        TableName=base_config.DYNAMODB_STATUS_TABLE,
        Key={
            'activity_type_name': {'S': activity_type_name},
            'date': {'S': date}},
        ExpressionAttributeNames={'#status': 'status'},
        ProjectionExpression='#status,last_processed_timestamp')

    if 'Item' not in response:
        return None

    status = response['Item']['status']['S']
    timestamp = response['Item']['last_processed_timestamp']['S']

    return {
        'status': status,
        'last_processed_timestamp': datetime.datetime.strptime(
            timestamp, base_config.STATUS_TIMESTAMP_FORMAT)}