# Copyright 2015 Egor Tensin <Egor.Tensin@gmail.com>
# This file is licensed under the terms of the MIT License.
# See LICENSE.txt for details.

import logging, time

import vk.api
import vk.error
import vk.user

def format_user(user):
    if user.has_last_name():
        return '{} {}'.format(user.get_last_name(), user.get_first_name())
    else:
        return '{}'.format(user.get_first_name())

def format_user_is_online(user):
    return '{} is ONLINE'.format(format_user(user))

def format_user_is_offline(user):
    return '{} is OFFLINE'.format(format_user(user))

def format_user_last_seen(user):
    return '{} was last seen at {}'.format(format_user(user), user.get_last_seen())

def format_user_went_online(user):
    return '{} went ONLINE'.format(format_user(user))

def format_user_went_offline(user):
    return '{} went OFFLINE'.format(format_user(user))

def user_is_online(user):
    logging.info(format_user_is_online(user))

def user_is_offline(user):
    logging.info(format_user_is_offline(user))
    logging.info(format_user_last_seen(user))

def user_went_online(user):
    logging.info(format_user_went_online(user))

def user_went_offline(user):
    logging.info(format_user_went_offline(user))

def print_status(user):
    if user.is_online():
        user_is_online(user)
    else:
        user_is_offline(user)

def print_status_update(user):
    if user.is_online():
        user_went_online(user)
    else:
        user_went_offline(user)

USER_FIELDS = vk.user.Field.ONLINE, vk.user.Field.LAST_SEEN

def update_status(api, uids):
    return {user.get_uid(): user for user in api.users_get(uids, USER_FIELDS)}

DEFAULT_TIMEOUT=5

def loop_update_status(api, uids, timeout=DEFAULT_TIMEOUT):
    users = update_status(api, uids)
    for uid in users:
        print_status(users[uid])
    while True:
        time.sleep(timeout)
        try:
            updated_users = update_status(api, uids)
        except vk.error.ConnectionError:
            continue
        for uid in updated_users:
            if users[uid].is_online() != updated_users[uid].is_online():
                users[uid] = updated_users[uid]
                print_status_update(updated_users[uid])

if __name__ == '__main__':
    import argparse, sys

    def natural_number(s):
        x = int(s)
        if x < 1:
            raise argparse.ArgumentTypeError()
        return x

    parser = argparse.ArgumentParser(
        description='Track when people go online/offline.')

    parser.add_argument(metavar='UID', dest='uids', nargs='+',
                        help='user IDs or "screen names"')
    parser.add_argument('-t', '--timeout', default=DEFAULT_TIMEOUT,
                        type=natural_number,
                        help='set refresh interval (seconds)')
    parser.add_argument('-l', '--log', type=argparse.FileType('w'),
                        default=sys.stdout,
                        help='set log file path (stdout by default)')
    args = parser.parse_args()

    logging.basicConfig(format='[%(asctime)s] %(message)s',
                        stream=args.log,
                        level=logging.INFO,
                        datefmt='%Y-%m-%d %H:%M:%S')

    api = vk.api.API(vk.api.Language.EN)

    try:
        loop_update_status(api, args.uids, timeout=args.timeout)
    except KeyboardInterrupt:
        pass
    except Exception as e:
        logging.exception(e)
        sys.exit(1)