Solution to Onboarding Project #2

location_to_datetime.py

"""
Location to Datetime CLI

Usage:
    python location_to_datetime.py --coordinates='39.6034810,-119.6822510'
    python location_to_datetime.py --address='278 Bay Ridge Avenue, Brooklyn, NY, 11209'
    python location_to_datetime.py --address='New York' --from-time='2017-08-08' --from-address='Egypt'
    python location_to_datetime.py --address='New York' --from-time='2017-08-08T10:20:23' --from-address='Egypt'
    python location_to_datetime.py --address='New York' --to-json
    python location_to_datetime.py --address='New York' --format-str='YYYY-MM-DD HH:mm:ss ZZ'

Note:
    Because there is no API key configured, the Google API sometimes returns an error instead of the correct result.
    So just retry. This can be fixed by adding a `&key=<API_KEY>` to the API requests.
"""

import sys
import json
import argparse
import datetime

import requests

import arrow

GOOGLE_TIMEZONE_API_URL = 'https://maps.googleapis.com/maps/api/timezone/json'
GOOGLE_ADDRESS_API_URL = 'https://maps.googleapis.com/maps/api/geocode/json'


def run(coordinates=None, address=None, from_address=None, from_time=None):
    assert (coordinates or address), 'Must provide an address or coordinates value to get a result.'
    assert (from_address and from_time) or (not from_address and not from_time), 'Must provide a from_address and from_time value if you want to convert a datetime.'

    if coordinates:
        try:
            tz = _get_timezone_for_coordinates(coordinates)
        except Exception:
            raise Exception('Could not find timezone for provided coordinates')

    else:
        try:
            tz = _get_timezone_for_address(address)
        except Exception:
            raise Exception('Could not find timezone for provided address')

    if not from_address and not from_time:
        result = arrow.now(tz)

    else:
        try:
            result = _convert_timezone(tz, from_address, from_time)
        except Exception:
            raise Exception('Could not find timezone for provided from_address')

    return result


def _convert_timezone(tz, from_address, from_time):
    from_tz = _get_timezone_for_address(from_address)
    from_datetime = datetime.datetime.fromisoformat(from_time)

    return arrow.get(from_datetime, from_tz).to(tz)


def _datetime_to_json(dt):
    obj = {
        'year': dt.year,
        'month': dt.month,
        'day': dt.day,
        'hour': dt.hour,
        'minute': dt.minute,
        'timezone': dt.strftime('%Z')
    }

    return json.dumps(obj)


def _get_timezone_for_coordinates(coordinates):
    response = requests.get('{}?location={}&timestamp=100'.format(GOOGLE_TIMEZONE_API_URL, coordinates))

    return response.json()['timeZoneId']


def _get_timezone_for_address(address):
    response = requests.get('{}?address={}'.format(GOOGLE_ADDRESS_API_URL, address))
    location = response.json()['results'][0]['geometry']['location']
    coordinates = ('{lat},{lng}'.format(**location))

    return _get_timezone_for_coordinates(coordinates)


def _format_result(result, to_json, format_str):
    if to_json:
        return _datetime_to_json(result)

    if format_str:
        return result.format(format_str)

    return result.isoformat()


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Returns the requested location\'s current time or converts timezones.')
    parser.add_argument('--from-address', type=str, help='Address that you want to convert from, e.g., \'Egypt\'')
    parser.add_argument('--from-time', type=str, help='Date/datetime (in ISO8601 format) that you want to convert.')

    location_group = parser.add_mutually_exclusive_group()
    location_group.add_argument('--coordinates', help='Coordinates string you want to look up the time for, e.g., \'39.6034810,-119.6822510\'')
    location_group.add_argument('--address', type=str, help='Address you want to look up the time for, e.g., \'New York\'.')

    result_format_group = parser.add_mutually_exclusive_group()
    result_format_group.add_argument('--to-json', help='True if you want the result to be a json date object', action='store_true')
    result_format_group.add_argument('--format-str', type=str, help='Specify a format of the result string.')

    args = parser.parse_args()
    print(args)

    try:
        result = run(
            coordinates=args.coordinates,
            address=args.address,
            from_address=args.from_address,
            from_time=args.from_time,
        )

        formatted_result = _format_result(result, args.to_json, args.format_str)

        print(formatted_result)

    except Exception as e:
        print(e, file=sys.stderr)