#! /usr/bin/env python3

"""
Purpose:

Following sample shows you how to create Gateway Load Balance (GWLB) Endpoint
using VPC Endpoint Service Name using Python (Boto3) Library.

Only one subnet per GWLB Endpoint is supported
"""

import argparse
import boto3
import logging
from botocore.exceptions import ClientError

# create required boto3 clients and resources:
ec2 = boto3.client('ec2')


def create_gwlbe(service_name, vpc_id, subnet_ids):
    """
    Creates VPC Endpoint Service.

    Accepts:
    - service_name (str): VPCE Service name.
    - vpc_id : 'vpc-xxxx'
    - subnet_ids (list of str): ['subnet-xxxx'], only one subnet id for GWLBe

    Usage:
    - create_gwlbe('service_name', 'vpc-xxxx', ['subnet-xxxx']
    """
    logging.info("Creating VPC Endpoint of Type GatewayLoadBalancer:")
    try:
        response = ec2.create_vpc_endpoint(
            VpcEndpointType='GatewayLoadBalancer',
            VpcId=vpc_id,
            SubnetIds=subnet_ids,
            ServiceName=service_name
        )
        vpce_id = response['VpcEndpoint']['VpcEndpointId']
        vpce_id_type = response['VpcEndpoint']['VpcEndpointType']
        return response, vpce_id, vpce_id_type
    except ClientError as e:
        logging.error(e)
        return None


def main():
    """
    Creates VPC Endpoint Type GatewayLoadBalancer (GWLBE):

    Accepts:
    --service_name: VPC-E Service name
    --vpc_id: vpc id to with GWLBE is associated
    --subnet_id: list of subnet id. As of now only one subnet id supported for
    GWLBe

    Usage:
    python create_gwlb_endpoint_sample.py \
    --service_name com.amazonaws.vpce.sa-east-1.vpce-svc-05c11ebdfc1b84593 \
    --vpc_id vpc-09a8e887492790aea
    --subnet_id subnet-002136cca79d6bba3
    """
    parser = argparse.ArgumentParser()
    parser.add_argument('--service_name', required=True,
                        help='specify service name', type=str)
    parser.add_argument('--vpc_id', required=True,
                        help='specify vpc id', type=str)
    parser.add_argument('--subnet_id', nargs='+', required=True,
                        help='specify subnet id')

    args = parser.parse_args()

    ############################
    # Define script variables:
    ############################
    service_name = args.service_name
    vpc_id = args.vpc_id
    subnet_id = args.subnet_id
    #############################

    # GWLBE:
    gwlbe1 = create_gwlbe(service_name, vpc_id, subnet_id)
    print(f"GWLBE1 ID: {gwlbe1[1]}")
    print(f"GWLBE1 TYPE: {gwlbe1[2]}")


if __name__ == '__main__':
    main()