convert_from_utc.py

from datetime import datetime, timedelta
from dateutil.tz import tzlocal


def convert_from_utc(input, offset=0, outputstr=True, tz=False):
    '''

    This operation accepts three arguments:

        1. str input: Input with format specified below
        2. int offset: Offset in hour(s). This may be needed for daylight saving. (optional)
        3. bool ouputstr: If True (default), output is a string, else output is of type datetime.datetime
        4. bool tz: If True, return Timezone-aware (only string) output

    RULES:
        Input has to be a string in the following format:
        - yyyy-mm-ddTHH:MM:S.sssZ (There has to be at least one decimal point after second)
        e.g: INPUT: 2020-05-20T12:25:21.123Z

    Output will be in this format:

    - String: yyyy-mm-dd HH:MM:SS {TZ}
        e.g: 2020-05-20 22:25:21
          or 2020-05-20 22:25:21 AEST (if tz=True)   
    - datetime.datetime format

    Test:
    >>> convert_from_utc('2002-01-04T03:15:43.000Z')
    2002-01-04 13:15:43
    >>> type(convert_from_utc('2002-01-04T03:15:43.000Z'))
    <class 'str'>
    >>> type(convert_from_utc('2002-01-04T03:15:43.000Z', outputstr=False))
    <class 'datetime.datetime'>

    '''
    
    # Parse Inputs
    if input == None:
        return None
    input = datetime.strptime(input, '%Y-%m-%dT%H:%M:%S.%fZ')
    offset = timedelta(hours= offset)

    # Calculate time difference between UTC and now,
    # then round to nearest second

    now = datetime.now(tzlocal())
    utc_offset = now.tzinfo.utcoffset(now)
    local_time = input + utc_offset + offset


    if outputstr:
        local_time_str = datetime.strftime(local_time, '%Y-%m-%d %H:%M:%S')
        if tz:
            local_time_str += f' {datetime.now(tzlocal()).tzname()}'
        return local_time_str
    else:
        return local_time