"""Lambda for expired snapshots removing."""

import logging
import os

import boto3

logger = logging.getLogger()
logger.setLevel(logging.INFO)

client = boto3.client('ec2')
ec2 = boto3.resource('ec2')


def handler(event, context):
    """Lambda handler."""
    volume_tag = os.environ['VOLUME_TAG']

    # Get snapshot ID from SNS event
    snapshot_id = event.split('/')[1]

    snapshot = ec2.Snapshot(snapshot_id)
    volume_id = snapshot.volume_id

    # Get retention
    volume = ec2.Volume(volume_id)
    volume_tags = {v['Key']: v['Value'] for v in volume.tags}
    retention = volume_tags[volume_tag]

    # Get all snapshots for this volume
    all_snapshots = client.describe_snapshots(
        Filters=[
            {
                'Name': 'volume-id',
                'Values': [
                    volume_id,
                ]
            },
        ],
    )
    unsorted_snapshots = [
        (snap['StartTime'], snap['SnapshotId']) for snap in
        all_snapshots['Snapshots']
    ]
    sorted_snapshots = sorted(unsorted_snapshots, reverse=True)
    for snap in sorted_snapshots[int(retention):]:
        delete_request = client.delete_snapshot(SnapshotId=snap[1])
        logger.info('Request {} were sent to delete snapshot {}'.format(
            delete_request['ResponseMetadata']['RequestId'],
            snap[1]
        ))