# GNU GPLv3, see LICENSE

import sys

from argparse import ArgumentParser

from shamira import generate, reconstruct, SException

def run():

	parser = ArgumentParser()

	subparsers = parser.add_subparsers()

	build_split_parser(subparsers.add_parser("split"))

	build_join_parser(subparsers.add_parser("join"))

	parser.set_defaults(func=lambda _: parser.error("missing command"))

	args = parser.parse_args()

	args.func(args)

def build_split_parser(parser):

	parser.add_argument("-k", type=int, required=True, help="number of shares necessary for recovering the secret")

	parser.add_argument("-n", type=int, required=True, help="number of generated shares")

	encoding = parser.add_mutually_exclusive_group()

	encoding.add_argument("--hex", action="store_true", help="encode shares' bytes as a hexadecimal string")

	encoding.add_argument("--b32", action="store_true", help="encode shares' bytes as a base32 string")

	encoding.add_argument("--b64", action="store_true", help="encode shares' bytes as a base64 string")

	parser.add_argument("secret", nargs="?", help="a secret to be split. Can be provided on the command line,"

		" redirected through stdin, or will be asked for interactively.")

	parser.set_defaults(func=_generate)

def build_join_parser(parser):

	encoding = parser.add_mutually_exclusive_group()

	encoding.add_argument("--hex", action="store_true", help="decode shares' bytes from a hexadecimal string")

	encoding.add_argument("--b32", action="store_true", help="decode shares' bytes from a base32 string")

	encoding.add_argument("--b64", action="store_true", help="decode shares' bytes from a base64 string")

	parser.add_argument("-r", "--raw", action="store_true", help="return the secret as raw bytes")

	parser.add_argument("share", nargs="*", help="shares to be joined. Can be provided on the command line,"

		" redirected through stdin, or will be asked for interactively.")

	parser.set_defaults(func=_reconstruct)

def _generate(args):

	encoding = get_encoding(args) or "b32"

	if args.secret:  # provided as a positional argument

		secret = args.secret

	elif sys.stdin.isatty():  # input from terminal

		secret = input("Enter your secret:\n")

	else:  # redirected from other source

		secret = sys.stdin.read()

	try:

		shares = generate(secret, args.k, args.n, encoding)

		for s in shares:

			print(s)

	except SException as e:

def _reconstruct(args):

	encoding = get_encoding(args)

	if args.share:  # provided as a positional argument

		shares = args.share

	elif sys.stdin.isatty():  # input from terminal

		print("Enter the shares, each on separate line, end with an empty line:")

		shares = []

		while not shares or shares[-1]:

			shares.append(input())

		shares.pop()

	else:  # redirected from other source

		shares = sys.stdin.read().split()

	try:

		print(reconstruct(*shares, encoding=encoding, raw=args.raw))

	except SException as e:

def get_encoding(args):

	if args.hex: return "hex"

	elif args.b32: return "b32"

	elif args.b64: return "b64"

	else: return ""