#!/usr/bin/env python3

"""
Calculates the fraction of a year that the period from today's date to the
given date constitutes, optionally multiplies it with a value, and prints the
result.

E.g. useful to see if a second-hand whole-year gym membership is actually
discounted.
"""

import sys
import datetime

datestr = sys.argv[1]
value = 1
if len(sys.argv) >= 3:
    value = float(sys.argv[2])

d0 = datetime.date.today()
d1 = datetime.datetime.strptime(datestr, "%Y-%m-%d").date()

days_in_year = datetime.date(2, 1, 1) - datetime.date(1, 1, 1)
print(value * ((d1 - d0) / days_in_year))