#!/usr/bin/python

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# to you under the Apache License, Version 2.0 (the
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import argparse
import json
from dlab.actions_lib import *
from dlab.meta_lib import *
import sys
import boto3
import ipaddress


parser = argparse.ArgumentParser()
parser.add_argument('--subnet_name', type=str, default='')
parser.add_argument('--region', type=str, default='')
parser.add_argument('--vpc_selflink', type=str, default='')
parser.add_argument('--prefix', type=str, default='')
parser.add_argument('--vpc_cidr', type=str, default='')
parser.add_argument('--ssn', type=bool, default=False)
parser.add_argument('--user_subnets_range', type=str, default='')
args = parser.parse_args()


if __name__ == "__main__":
    if args.user_subnets_range == '' or args.ssn:
        empty_vpc = False
        private_subnet_size = ipaddress.ip_network(u'0.0.0.0/{}'.format(args.prefix)).num_addresses
        subnets_cidr = []
        try:
            subnets = GCPMeta().get_vpc(args.vpc_selflink.split('/')[-1])['subnetworks']
        except KeyError:
            empty_vpc = True
            subnets = []
        for subnet in subnets:
            subnets_cidr.append(GCPMeta().get_subnet(subnet.split('/')[-1], args.region)['ipCidrRange'])
        sortkey = lambda addr: \
            (int(addr.split("/")[0].split(".")[0]),
             int(addr.split("/")[0].split(".")[1]),
             int(addr.split("/")[0].split(".")[2]),
             int(addr.split("/")[0].split(".")[3]),
             int(addr.split("/")[1]))
        sorted_subnets_cidr = sorted(subnets_cidr, key=sortkey)

        if not empty_vpc:
            last_ip = int(ipaddress.IPv4Address(sorted_subnets_cidr[0].split('/')[0].decode("utf-8")))
        else:
            last_ip = int(ipaddress.IPv4Address(args.vpc_cidr.split('/')[0].decode("utf-8")))
        previous_subnet_size = private_subnet_size
        for cidr in sorted_subnets_cidr:
            first_ip = int(ipaddress.IPv4Address(cidr.split('/')[0].decode("utf-8")))
            if first_ip - last_ip < private_subnet_size or previous_subnet_size < private_subnet_size:
                subnet_size = ipaddress.ip_network(u'{}'.format(cidr)).num_addresses
                last_ip = first_ip + subnet_size - 1
                previous_subnet_size = subnet_size
            else:
                break

        dlab_subnet_cidr = ''
        if empty_vpc:
            dlab_subnet_cidr = '{0}/{1}'.format(ipaddress.ip_address(last_ip), args.prefix)
        else:
            if previous_subnet_size < private_subnet_size:
                while True:
                    try:
                        dlab_subnet_cidr = '{0}/{1}'.format(ipaddress.ip_address(last_ip + 1), args.prefix)
                        ipaddress.ip_network(dlab_subnet_cidr.decode('utf-8'))
                        break
                    except ValueError:
                        last_ip = last_ip + 2
                        continue
            else:
                dlab_subnet_cidr = '{0}/{1}'.format(ipaddress.ip_address(last_ip + 1), args.prefix)
    else:
        pre_defined_subnet_list = []
        subnet_cidr = args.user_subnets_range.split('-')[0].replace(' ', '')
        pre_defined_subnet_list.append(subnet_cidr)
        while str(subnet_cidr) != args.user_subnets_range.split('-')[1].replace(' ', ''):
            subnet = ipaddress.ip_network(u'{}'.format(subnet_cidr))
            num_addr = subnet.num_addresses
            first_ip = int(ipaddress.IPv4Address(u'{}'.format(subnet.network_address)))
            next_subnet = ipaddress.ip_network(u'{}/{}'.format(ipaddress.ip_address(first_ip + num_addr),
                                                               args.prefix))
            pre_defined_subnet_list.append(next_subnet.compressed)
            subnet_cidr = next_subnet
        existed_subnet_list = []
        response = GCPMeta().get_vpc(args.vpc_selflink.split('/')[-1])['subnetworks']
        for subnet in response:
            existed_subnet_list.append(GCPMeta().get_subnet(subnet.split('/')[-1], args.region)['ipCidrRange'])
        available_subnets = list(set(pre_defined_subnet_list) - set(existed_subnet_list))
        if not available_subnets:
            print("There is no available subnet to create. Aborting...")
            sys.exit(1)
        else:
            dlab_subnet_cidr = available_subnets[0]

    if args.subnet_name != '':
        if GCPMeta().get_subnet(args.subnet_name, args.region):
            print("REQUESTED SUBNET {} ALREADY EXISTS".format(args.subnet_name))
        else:
            print("Creating Subnet {}".format(args.subnet_name))
            GCPActions().create_subnet(args.subnet_name, dlab_subnet_cidr, args.vpc_selflink, args.region)
    else:
        print("Subnet name can't be empty")
        sys.exit(1)