"""AWS Route 53 Lambda Backup"""
    
    import os
    import csv
    import json
    import time
    from datetime import datetime
    import boto3
    from botocore.exceptions import ClientError
    
    
    # Set environmental variables
    
    s3_bucket_name = ''
    s3_bucket_region = ''
    
    try:
        s3_bucket_name = os.environ['s3_bucket_name']
        s3_bucket_region = os.environ['s3_bucket_region']
    except KeyError as e:
        print("Warning: Environmental variable(s) not defined")
    
    
    # Create client objects
    
    s3 = boto3.client('s3', region_name='us-east-1')
    route53 = boto3.client('route53')
    
    
    # Functions
    
    def create_s3_bucket(bucket_name, bucket_region='us-east-1'):
        """Create an Amazon S3 bucket."""
        try:
            response = s3.head_bucket(Bucket=bucket_name)
            return response
        except ClientError as e:
            if(e.response['Error']['Code'] != '404'):
                print(e)
                return None
        # creating bucket in us-east-1 (N. Virginia) requires
        # no CreateBucketConfiguration parameter be passed
        if(bucket_region == 'us-east-1'):
            response = s3.create_bucket(
                ACL='private',
                Bucket=bucket_name
            )
        else:
            response = s3.create_bucket(
                ACL='private',
                Bucket=bucket_name,
                CreateBucketConfiguration={
                    'LocationConstraint': bucket_region
                }
            )
        return response
    
    
    def upload_to_s3(folder, filename, bucket_name, key):
        """Upload a file to a folder in an Amazon S3 bucket."""
        key = folder + '/' + key
        s3.upload_file(filename, bucket_name, key)
    
    
    def get_route53_hosted_zones(next_zone=None):
        """Recursively returns a list of hosted zones in Amazon Route 53."""
        if(next_zone):
            response = route53.list_hosted_zones_by_name(
                DNSName=next_zone[0],
                HostedZoneId=next_zone[1]
            )
        else:
            response = route53.list_hosted_zones_by_name()
        hosted_zones = response['HostedZones']
        # if response is truncated, call function again with next zone name/id
        if(response['IsTruncated']):
            hosted_zones += get_route53_hosted_zones(
                (response['NextDNSName'],
                response['NextHostedZoneId'])
            )
        return hosted_zones
    
    
    def get_route53_zone_records(zone_id, next_record=None):
        """Recursively returns a list of records of a hosted zone in Route 53."""
        if(next_record):
            response = route53.list_resource_record_sets(
                HostedZoneId=zone_id,
                StartRecordName=next_record[0],
                StartRecordType=next_record[1]
            )
        else:
            response = route53.list_resource_record_sets(HostedZoneId=zone_id)
        zone_records = response['ResourceRecordSets']
        # if response is truncated, call function again with next record name/id
        if(response['IsTruncated']):
            zone_records += get_route53_zone_records(
                zone_id,
                (response['NextRecordName'],
                response['NextRecordType'])
            )
        return zone_records
    
    
    def get_record_value(record):
        """Return a list of values for a hosted zone record."""
        # test if record's value is Alias or dict of records
        try:
            value = [':'.join(
                ['ALIAS', record['AliasTarget']['HostedZoneId'],
                record['AliasTarget']['DNSName']]
            )]
        except KeyError:
            value = []
            for v in record['ResourceRecords']:
                value.append(v['Value'])
        return value
    
    
    def try_record(test, record):
        """Return a value for a record"""
        # test for Key and Type errors
        try:
            value = record[test]
        except KeyError:
            value = ''
        except TypeError:
            value = ''
        return value
    
    
    def write_zone_to_csv(zone, zone_records):
        """Write hosted zone records to a csv file in /tmp/."""
        zone_file_name = '/tmp/' + zone['Name'] + 'csv'
        # write to csv file with zone name
        with open(zone_file_name, 'w', newline='') as csv_file:
            writer = csv.writer(csv_file)
            # write column headers
            writer.writerow([
                'NAME', 'TYPE', 'VALUE',
                'TTL', 'REGION', 'WEIGHT',
                'SETID', 'FAILOVER', 'EVALUATE_HEALTH'
                ])
            # loop through all the records for a given zone
            for record in zone_records:
                csv_row = [''] * 9
                csv_row[0] = record['Name']
                csv_row[1] = record['Type']
                csv_row[3] = try_record('TTL', record)
                csv_row[4] = try_record('Region', record)
                csv_row[5] = try_record('Weight', record)
                csv_row[6] = try_record('SetIdentifier', record)
                csv_row[7] = try_record('Failover', record)
                csv_row[8] = try_record('EvaluateTargetHealth',
                    try_record('AliasTarget', record)
                )
                value = get_record_value(record)
                # if multiple values (e.g., MX records), write each as its own row
                for v in value:
                    csv_row[2] = v
                    writer.writerow(csv_row)
        return zone_file_name
    
    
    def write_zone_to_json(zone, zone_records):
        """Write hosted zone records to a json file in /tmp/."""
        zone_file_name = '/tmp/' + zone['Name'] + 'json'
        # write to json file with zone name
        with open(zone_file_name, 'w') as json_file:
            json.dump(zone_records, json_file, indent=4)
        return zone_file_name
    
    
    ## HANDLER FUNCTION ##
    
    def lambda_handler(event, context):
        """Handler function for AWS Lambda"""
        time_stamp = time.strftime("%Y-%m-%dT%H:%M:%SZ",
            datetime.utcnow().utctimetuple()
        )
        if(not create_s3_bucket(s3_bucket_name, s3_bucket_region)):
            return False
        #bucket_response = create_s3_bucket(s3_bucket_name, s3_bucket_region)
        #if(not bucket_response):
            #return False
        hosted_zones = get_route53_hosted_zones()
        for zone in hosted_zones:
            zone_folder = (time_stamp + '/' + zone['Name'][:-1])
            zone_records = get_route53_zone_records(zone['Id'])
            upload_to_s3(
                zone_folder,
                write_zone_to_csv(zone, zone_records),
                s3_bucket_name,
                (zone['Name'] + 'csv')
            )
            upload_to_s3(
                zone_folder,
                write_zone_to_json(zone, zone_records),
                s3_bucket_name,
                (zone['Name'] + 'json')
            )
        return True
    
    
    if __name__ == "__main__":
        lambda_handler(0, 0)