"""
This module implements simple helper functions for managing service instance objects
"""
__author__ = "VMware, Inc."

import atexit
import ssl
from pyVim.connect import SmartConnect, Disconnect


def connect(args):
    """
    Determine the most preferred API version supported by the specified server,
    then connect to the specified server using that API version, login and return
    the service instance object.
    """

    service_instance = None

    # form a connection...
    try:
        context = None
        if hasattr(ssl, 'SSLContext'):
            context = ssl.SSLContext(ssl.PROTOCOL_TLS)
            if args.disable_ssl_verification:
                context.verify_mode = ssl.CERT_NONE
            else:
                context.verify_mode = ssl.CERT_REQUIRED
                context.load_verify_locations(args.vcenter_cert_path)

        service_instance = SmartConnect(
            host=args.host,
            user=args.user,
            pwd=args.password,
            port=args.port, 
            sslContext=context)

        # doing this means you don't need to remember to disconnect your script/objects
        atexit.register(Disconnect, service_instance)
    except IOError as io_error:
        print(io_error)

    if not service_instance:
        raise SystemExit("Unable to connect to host with supplied credentials.")

    return service_instance