#! /usr/bin/python
#
# Copyright (c) 2021 Gavin D. Howard
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# Stolen from http://stackoverflow.com/a/3041990/3281147 and modified for my
# purposes.

import sys
import signal
import argparse

def sighandler(signum, frame):
	raise Exception("timeout")

def query(question, default=None, timeout=0):
	"""Ask a yes/no question via raw_input() and return their answer.

	"question" is a string that is presented to the user.
	"default" is the presumed answer if the user just hits <Enter>.
		It must be "yes" (the default), "no" or None (meaning
		an answer is required of the user).

	The "answer" return value is True for "yes" or False for "no".
	"""

	valid = {"yes": True, "y": True, "ye": True,
			 "no": False, "n": False}
	if default is None or default == "":
		prompt = " [y/n]"
	elif default == "yes" or default == "y":
		prompt = " [Y/n]"
	elif default == "no" or default == "n":
		prompt = " [y/N]"
	else:
		raise ValueError("invalid default answer: '{}'".format(default))

	if timeout < 0:
		raise ValueError("timeout must be positive or zero")

	signal.signal(signal.SIGALRM, sighandler)

	try:
		while True:

			if timeout != 0:
				signal.alarm(timeout)

			sys.stdout.write(question + prompt + ': ')
			choice = input().lower()

			signal.alarm(0)

			if default is not None and default != '' and choice == '':
				return valid[default]
			elif choice.casefold() in valid:
				return valid[choice.casefold()]
			else:
				sys.stdout.write("Please respond with 'yes' or 'no' "
				                 "(or 'y' or 'n').\n")

	except Exception:
		sys.stdout.write('{}\n'.format(default))
		return valid[default]

if __name__ == "__main__":

	parser = argparse.ArgumentParser(description='Provide a yes/no prompt and return the answer')
	parser.add_argument('--default', action='store', default='', nargs='?', help='the default answer')
	parser.add_argument('--timeout', action='store', default=0, type=int, nargs='?',
	                    help='how long to wait; 0 means wait forever')
	parser.add_argument('query', action='store', help='the query to show the user')

	args = vars(parser.parse_args())

	ret = query(args['query'], default=args['default'], timeout=args['timeout'])

	sys.exit(not ret)