shutdown.py. Python3 required.

shutdown.py

import subprocess
import time
import datetime


def main():
    # Dictionary with strings that can be input and the methods that they call.
    options = {
        'H': hibernate,
        'S': shutdown,
        'X': exit
    }

    # Initialise action with an empty string value. This is to prevent our
    # loop below to check an undefined variable on its first run.
    action = ''

    prompt = 'Press H for hibernate, S for shutdown. X to cancel: '

    # Loop until H, S or X is entered in the promt.
    while action not in options:
        action = input(prompt).upper()
    options[action]()


def hibernate():
    # Python has a style guide (PEP8) that enforces a limit of
    # 79 characters per line.
    # Multiple strings witin parentheses will be concatenated into one.
    minutes = getMinutes('In how many minutes should the computer '
                         'be put in hibernate? ')

    seconds = minutes * 60

    endTime = getEndOfWaitTime(seconds)
    print('Computer will hibernate at {0}'.format(endTime))

    # Wait.
    time.sleep(seconds)

    # Call the OS specific shutdown command.
    subprocess.call('shutdown', '/h')


def shutdown():
    minutes = getMinutes('In how many minutes should the computer '
                         'be shut down? ')

    seconds = minutes * 60

    endTime = getEndOfWaitTime(seconds)
    print('Computer will shut down at {0}'.format(endTime))

    # Alternatively use the t flag for shutdown command.
    time.sleep(seconds)

    subprocess.call('shutdown', '/s')


def getMinutes(prompt):
    minutes = None
    # As long as minutes does not evaluate to true, keep on going.
    # Below we cast the string result of input() to an integer.
    # Which, if not valid, will be 0 (false). Non zero integers equal true.
    while not minutes:
        try:
            minutes = int(input(prompt))
        except ValueError:
            minutes = None

    return minutes


def getEndOfWaitTime(seconds):
    now = time.time()
    # Add the amount of seconds passed to the function.
    end = now + seconds
    endTime = datetime.datetime.fromtimestamp(end)
    # Return string formatted as YYYY-MM-DD HH:MM:SS
    return endTime.strftime('%Y-%m-%d %H:%M:%S')


# The main function will only be executed if this script was called directly.
# Like $ python3 shutdown.py
# If it was not contained like this then the prompt would run every time you
# import this file.
if __name__ == '__main__':
    main()