datemanip.py

#!/usr/bin/env python
from __future__ import absolute_import, division, print_function, unicode_literals

import arrow
import click
click.disable_unicode_literals_warning = True


def is_weekend(i):
    assert isinstance(i, arrow.Arrow)
    return i.weekday() in (5, 6)


@click.command()
@click.argument("day")
@click.argument("working_days", type=click.IntRange(0, 360))
def datemanip(day, working_days):
    """
    Example:

        > datemanip today 4
        20150831 Mon

    Use in conjunction with `cal -y` for your date manipulation needs.
    """
    if day == "today":
        day = arrow.now()
    else:
        day = arrow.get(day, "YYYYMMDD")
    i = day
    while True:
        i = i.replace(days=+1)
        working_days -= 1

        # Skip weekend
        while is_weekend(i):
            i = i.replace(days=+1)

        # Increment `i` & decrement working_days in lockstep
        if working_days == 0:
            break
    print(i.format("YYYYMMDD ddd"))


if __name__ == "__main__":
    datemanip()