import re

import humanfriendly

SYSTEMCTL_TIMESPAN_RE = re.compile(r'([0-9]+((\s[a-z]*)|([a-z]+)))')


def parse_systemctl_time_delta(time_str: str):
    """
    https://humanfriendly.readthedocs.io/en/latest/api.html?highlight=parse_timespan#humanfriendly.parse_timespan
    """
    time_str = time_str.replace(' left', '').replace(' ago', '')
    spans = []
    for part in re.findall(SYSTEMCTL_TIMESPAN_RE, time_str):
        delta = part[0]
        if 'month' in delta:
            # humanfriendly does not support "months" so we convert it to weeks
            num = int(delta.split(' ')[0])
            delta = f'{num * 4} weeks'
        try:
            spans.append(humanfriendly.parse_timespan(delta))
        except humanfriendly.InvalidTimespan as e:
            return e
    return sum(spans)