# A1. This function is only useful for returning a value to 'timeelapsed'. Return the number and unit, using the plural of the unit if the amount is greater than 1.
# Return an empty string if the amount is 0. This function takes advantage of all units in the parent 'timeelapsed' function using 's'.
# Input example: 1, 'seconds'. Abbreviations are not accepted.
# Output example: '1 second'
def handle_plurals(amount, unit):
    if amount == 1:
        return '1 '+unit[0:len(unit)-1]
    elif amount == 0:
        return ''
    else:
        return str(amount) + ' ' + unit

# A0. Format an amount of elapsed time.
# Input: value, an int or float.
# unit, a string for the unit used by the value. that can be the full name ("milliseconds") or an abbreviation ("ms").
# Only milliseconds and seconds are supported, because these are the only common output units. Milliseconds will be converted to seconds.
#
# Output: The formatting and conversion ratios are the same as the built-in timesince and timeuntil filters: a human-readable string such as '5
# seconds' or '1 month, 17 days'. The only behavioral difference is that seconds will be shown instead of rounded to 0 minutes, and if the value is
# less than a second, there will be up to three decimal places. Only the two largest adjacent units are shown. Weeks, however, will be shown only when
# they are the largest unit. This function uses 365-day years and 30-day months.
#
# Template syntax example: {{ stopwatch_result | timeelapsed:"ms" }}
def timeelapsed(value, unit):
    # Convert to seconds. If the value is more than 1 second, then round down to integer seconds.
    if (unit == "milliseconds" or unit == "ms") and value > 1000:
        value //= 1000
    else:
        if (unit == "milliseconds" or unit == "ms") and value < 1000:
            value /= 1000
            return str(value) + ' seconds'
    seconds = value % 60
    value //= 60
    minutes = value % 60
    value //= 60
    hours = value % 24
    value //= 24
    # If weeks are the largest unit, then use mod 7. If months or years are the largest unit, then use mod 30.
    if value < 30:
        days = value % 7
        value //= 7
        weeks = value % 7
        months = 0
        years = 0
    else:
        days = value % 30
        value //= 30
        weeks = 0
        months = value % 12
        years = value // 12
    years_string = handle_plurals(years, 'years')
    months_string = handle_plurals(months, 'months')
    weeks_string = handle_plurals(weeks, 'weeks')
    days_string = handle_plurals(days, 'days')
    hours_string = handle_plurals(hours, 'hours')
    minutes_string = handle_plurals(minutes, 'minutes')
    seconds_string = handle_plurals(seconds, 'seconds')
    if years_string != '':
        if months_string != '':
            return years_string + ', ' + months_string
        else:
            return years_string
    elif months_string != '':
        if days_string != '':
            return months_string + ', ' + days_string
        else:
            return months_string
    elif weeks_string != '':
        if days_string != '':
            return weeks_string + ', ' + days_string
        else:
            return weeks_string
    elif days_string != '':
        if hours_string != '':
            return days_string + ', ' + hours_string
        else:
            return days_string
    elif hours_string != '':
        if minutes_string != '':
            return hours_string + ', ' + minutes_string
        else:
            return hours_string
    elif minutes_string != '':
        if seconds_string != '':
            return minutes_string + ', ' + seconds_string
        else:
            return minutes_string
    else:
        return seconds_string