"""Lambda delete-intermediate-snapshots module."""
import boto3
import sentry_sdk
from sentry_sdk.integrations.aws_lambda import AwsLambdaIntegration

import config

from common.logic import database # noqa
from common.utils.logger import log as logger # noqa

if config.SENTRY_DSN:
    sentry_sdk.init(
        dsn=config.SENTRY_DSN,
        environment=config.ENVIRONMENT,
        integrations=[AwsLambdaIntegration(timeout_warning=True)]
    )


def assume_source_account_role(account_id, role_name):
    """
    Assume IAM role in source account.

    Args:
    account_id (str): AWS account ID

    Returns:
    dict: dict of AWS credentials
    """
    client = boto3.client('sts')
    assume_role_response = client.assume_role(
        RoleArn=f'arn:aws:iam::{account_id}:role/{role_name}',
        RoleSessionName=config.SERVICE_NAME,
        ExternalId=config.EXTERNAL_ID,
        DurationSeconds=3600
    )
    credentials = assume_role_response['Credentials']

    return credentials


def get_snapshots_to_delete(event, rds_client):
    """
    Determine which snapshots to delete.

    Args:
        event: the lambda event
        rds_client: the RDS client

    Returns:
    list: list of snapshot names to delete
    """
    db_type = event['db_type']
    all_snapshots = database.find_matching_snapshots(
        event['db_name'], db_type, rds_client)

    execution_id = event['execution_id']
    snapshots_to_delete = set()

    for snapshot in all_snapshots:
        snapshot_name = snapshot['DBClusterSnapshotIdentifier'] \
            if db_type == 'cluster' else snapshot['DBSnapshotIdentifier']
        tags = snapshot.get('TagList', [])
        for tag in tags:
            if tag['Key'] == 'execution_id' and tag['Value'] == execution_id:
                snapshots_to_delete.add(snapshot_name)
                break

    return snapshots_to_delete


def handler(event, _context):
    """Lambda entry point."""
    try:
        source_account_role = event.get(
            'source_account_role', config.CROSS_ACCOUNT_BACKUP_ROLE_NAME)
        credentials = assume_source_account_role(
            event['source_account_id'], source_account_role)
        rds_client = boto3.client(
            'rds',
            region_name=config.AWS_DEFAULT_REGION,
            aws_access_key_id=credentials['AccessKeyId'],
            aws_secret_access_key=credentials['SecretAccessKey'],
            aws_session_token=credentials['SessionToken']
        )

        snapshots_to_delete = get_snapshots_to_delete(event, rds_client)

        for snapshot in snapshots_to_delete:
            database.delete_snapshot(
                snapshot, event['db_type'], rds_client, wait=False)
            logger.info(f'Deleted snapshot {snapshot} in account '
                        f"{event['source_account_id']}")
    except Exception as error:
        logger.exception(str(error))
        raise error