human_readable_duration_format.py

"""
Your task in order to complete this Kata is to write a function which formats a duration, given as a number of seconds,
in a human-friendly way.

The function must accept a non-negative integer. If it is zero, it just returns "now". Otherwise, the duration is
expressed as a combination of years, days, hours, minutes and seconds.

It is much easier to understand with an example:

format_duration(62)    # returns "1 minute and 2 seconds"
format_duration(3662)  # returns "1 hour, 1 minute and 2 seconds"
For the purpose of this Kata, a year is 365 days and a day is 24 hours.

Note that spaces are important.

Detailed rules
The resulting expression is made of components like 4 seconds, 1 year, etc. In general, a positive integer and one of
the valid units of time, separated by a space. The unit of time is used in plural if the integer is greater than 1.

The components are separated by a comma and a space (", "). Except the last component, which is separated by " and ",
just like it would be written in English.

A more significant units of time will occur before than a least significant one. Therefore, 1 second and 1 year is
not correct, but 1 year and 1 second is.

Different components have different unit of times. So there is not repeated units like in 5 seconds and 1 second.

A component will not appear at all if its value happens to be zero. Hence, 1 minute and 0 seconds is not valid, but it
should be just 1 minute.

A unit of time must be used "as much as possible". It means that the function should not return 61 seconds, but 1 minute
and 1 second instead. Formally, the duration specified by of a component must not be greater than any valid more
significant unit of time.
"""


def format_duration(seconds):
    if seconds == 0:
        return 'now'
    time = {'year': seconds // 31536000}
    seconds = seconds % 31536000
    time['day'] = seconds // 86400
    seconds = seconds % 86400
    time['hour'] = seconds // 3600
    seconds = seconds % 3600
    time['minute'] = seconds // 60
    seconds = seconds % 60
    time['second'] = seconds
    time_array = []
    for key, val in time.items():
        if val == 0:
            continue
        elif val == 1:
            time_array.append(f"{val} {key}")
        else:
            time_array.append(f"{val} {key}s")
    if len(time_array) == 1:
        return time_array[0]
    elif len(time_array) == 2:
        return f"{time_array[0]} and {time_array[1]}"
    else:
        result = ', '.join(time_array[:-1])
        return f"{result} and {time_array[-1]}"