"""Tools file for HassIO."""
import asyncio
from datetime import datetime, timedelta, timezone
import logging
import re

import aiohttp
import async_timeout
import pytz

_LOGGER = logging.getLogger(__name__)

FREEGEOIP_URL = "https://freegeoip.io/json/"

# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
# https://github.com/django/django/blob/master/LICENSE
DATETIME_RE = re.compile(
    r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
    r'[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
    r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
    r'(?P<tzinfo>Z|[+-]\d{2}(?::?\d{2})?)?$'
)


async def fetch_timezone(websession):
    """Read timezone from freegeoip."""
    data = {}
    try:
        with async_timeout.timeout(10, loop=websession.loop):
            async with websession.get(FREEGEOIP_URL) as request:
                data = await request.json()

    except (aiohttp.ClientError, asyncio.TimeoutError, KeyError) as err:
        _LOGGER.warning("Can't fetch freegeoip data: %s", err)

    except ValueError as err:
        _LOGGER.warning("Error on parse freegeoip data: %s", err)

    return data.get('time_zone', 'UTC')


# Copyright (c) Django Software Foundation and individual contributors.
# All rights reserved.
# https://github.com/django/django/blob/master/LICENSE
def parse_datetime(dt_str):
    """Parse a string and return a datetime.datetime.

    This function supports time zone offsets. When the input contains one,
    the output uses a timezone with a fixed offset from UTC.
    Raises ValueError if the input is well formatted but not a valid datetime.
    Returns None if the input isn't well formatted.
    """
    match = DATETIME_RE.match(dt_str)
    if not match:
        return None
    kws = match.groupdict()  # type: Dict[str, Any]
    if kws['microsecond']:
        kws['microsecond'] = kws['microsecond'].ljust(6, '0')
    tzinfo_str = kws.pop('tzinfo')

    tzinfo = None  # type: Optional[dt.tzinfo]
    if tzinfo_str == 'Z':
        tzinfo = pytz.utc
    elif tzinfo_str is not None:
        offset_mins = int(tzinfo_str[-2:]) if len(tzinfo_str) > 3 else 0
        offset_hours = int(tzinfo_str[1:3])
        offset = timedelta(hours=offset_hours, minutes=offset_mins)
        if tzinfo_str[0] == '-':
            offset = -offset
        tzinfo = timezone(offset)
    else:
        tzinfo = None
    kws = {k: int(v) for k, v in kws.items() if v is not None}
    kws['tzinfo'] = tzinfo
    return datetime(**kws)