Oleg's Challenge

hour_overlap.py

# 1. Create a Python function that gets an integer between 1 - 12 (as an hour) and returns the exact time in hours
#    and minutes at which the hands of the clock overlap at this hour
#   (for example, for 1, the result will be close to 1:06)
# 2. create a unit test for this function, using 'assert', or the Python 'unittest' framework
# 3. [BONUS]
#    a. add also seconds calculation to the return value of the function.
#    b. calculate the angle of the hands in 360 degrees system
#       taking 12:00 (noon, midnight) as a point of reference
# ATTENTION: You do not need to import any modules to implement this task


DEGREES_PER_MINUTE_RATIO    = 360 / 60
HOUR_RATIO_INCREMENT        =   1 / 12
MINUTES_PER_HOUR            =  60
SECONDS_PER_MINUTE          =  60
ACCURACY                    =   0.001 # set arbitrarily based on a changes in output


def calculate_clock_position(hour_position, minute_position=0):
    '''
    Calculate how far the hour hand moves forward as the minute hand "catches up" to it.

    hour_position   - The ratio from 0 to 1 that represents the position around the clock.
    minute_position - The ratio from 0 to 1 that represents the position around the clock.
    '''
    # minute hand moves forward towards hour hand
    next_minute_position = hour_position
    # the hour hand moves forward in this period
    hour_position += (hour_position - minute_position) * HOUR_RATIO_INCREMENT
    # if we exceed our accuracy this will suffice
    if hour_position - next_minute_position < ACCURACY:
        return (hour_position, next_minute_position)
    else:
        return calculate_clock_position(hour_position, next_minute_position)


def hour_overlap(hour):
    # confirm our value is an integer in the range 1 to 12 inclusively
    assert isinstance(hour, int)
    assert 1 <= hour and hour <= 12

    # the simple case of 12
    if hour == 12:
        return {
            "hours": hour,
            "mins": 0,
            "secs": 0,
            "min_angle": 0
        }

    hour_position, minute_position = calculate_clock_position(hour / 12)

    # calculate minutes, seconds, and angle
    mins = hour_position * MINUTES_PER_HOUR
    secs = mins % 1 * SECONDS_PER_MINUTE
    angle = hour_position * 360

    return {
        "hours": hour,
        "mins": int(mins),
        "secs": int(secs),
        "min_angle": angle # float
    }


def test_dict_instance():
    try:
        res = hour_overlap(1)
        assert isinstance(res, dict)
    except AssertionError as e:
        print("Oh, snap! the test has failed. exception: {}").format(e)


def test_value_one():
    try:
        res = hour_overlap(1)
        assert res['hours'] == 1
        assert res['mins'] == 5
        assert res['secs'] == 27
        assert int(res['min_angle']) == 32
    except AssertionError as e:
        print('Invalid response calculating hour overlap at hour 1.')
        print('{}'.format(e))


def test_value_twelve():
    try:
        res = hour_overlap(12)
        assert res['hours'] == 12
        assert res['mins'] == 0
        assert res['secs'] == 0
        assert res['min_angle'] == 0
    except AssertionError as e:
        print('Invalid response calculating hour overlap at hour 12.')
        print('{}'.format(e))


if __name__ == '__main__':
    for i in range(1, 12):
        print('{hours:0>2}:{mins:0>2}:{secs:0>2} @ {min_angle:06.2f} degrees'.format(**hour_overlap(i)))

    test_dict_instance()
    test_value_one()
    test_value_twelve()