"""Handle DynamoDB Streams events.

1. Read a set of DDB Streams events.
2. Execute other lambda to handle event.
"""

import boto3
import json

import common_config
import config
from constants import fields
import exceptions


@exceptions.sentry_capture_exception
def handler(event, context):
    """Handle dynamoDB events, for each call the Lambda that saves to DD DB."""
    if event is None or fields.DDB_EVENT_RECORDS not in event:
        return
    client = boto3.client('lambda')
    for record in event[fields.DDB_EVENT_RECORDS]:
        # Get a part of the current record with new values only.
        if fields.DDB_EVENT_RECORD_MAIN not in record:
            continue
        ddb = record[fields.DDB_EVENT_RECORD_MAIN]
        if fields.DDB_EVENT_RECORD_NEW_VALUES not in ddb:
            continue
        new_item = ddb[fields.DDB_EVENT_RECORD_NEW_VALUES]
        common_config.logger.debug('Processing record: %s', new_item)
        # Using synchronous (blocking) invocation here is important - we want
        # to save incoming events/records preserving the order.
        client.invoke(
            FunctionName=config.VO_TO_DD_SYNC_LAMBDA_NAME,
            Payload=json.dumps(new_item).encode()
        )