from datetime import datetime, timedelta, timezone

import boto3

class Ec2Instances(object):

    def __init__(self, region):
        print("region "+ region)
        self.ec2 = boto3.client('ec2', region_name=region)

    def delete_snapshots(self, older_days=1):
        delete_snapshots_num = 0
        snapshots = self.get_lambda_created_snapshots()
        for snapshot in snapshots['Snapshots']:
            fmt_start_time = snapshot['StartTime']
            if (fmt_start_time < self.get_delete_data(older_days)):
                self.delete_snapshot(snapshot['SnapshotId'])
                delete_snapshots_num+1
        return delete_snapshots_num

    def get_lambda_created_snapshots(self):
        snapshots = self.ec2.describe_snapshots(Filters=[{'Name': 'description', 'Values': ['Created by Lambda backup function ebs-snapshots']}])
        return snapshots

    def get_delete_data(self, older_days):
        delete_time = datetime.now(tz=timezone.utc) - timedelta(days=older_days)
        return delete_time;

    def delete_snapshot(self, snapshot_id):
        self.ec2.delete_snapshot(SnapshotId=snapshot_id)

def lambda_handler(event, context):
    print("event " + str(event))
    print("context " + str(context))
    ec2_reg = boto3.client('ec2')
    regions = ec2_reg.describe_regions()
    for region in regions['Regions']:
        region_name = region['RegionName']
        instances = Ec2Instances(region_name)
        deleted_counts = instances.delete_snapshots(1)
        print("deleted_counts for region "+ str(region_name) +" is " + str(deleted_counts))
    return 'completed'