Hearthstone decklist decode

hs_decode.py

#!/usr/bin/python

# modified for brevity from https://github.com/HearthSim/python-hearthstone/blob/master/hearthstone/deckstrings.py

import base64
from io import BytesIO
from typing import IO, List, Tuple

DECKSTRING_VERSION = 1

CardList = List[int]
CardIncludeList = List[Tuple[int, int]]

def _read_varint(stream: IO) -> int:
	shift = 0
	result = 0
	while True:
		c = stream.read(1)
		if c == "":
			raise EOFError("Unexpected EOF while reading varint")
		i = ord(c)
		result |= (i & 0x7f) << shift
		shift += 7
		if not (i & 0x80):
			break
	return result

def _write_varint(stream: IO, i: int) -> int:
	buf = b""
	while True:
		towrite = i & 0x7f
		i >>= 7
		if i:
			buf += bytes((towrite | 0x80, ))
		else:
			buf += bytes((towrite, ))
			break
	return stream.write(buf)

def parse_deckstring(deckstring) -> Tuple[CardIncludeList, CardList, format]:
	decoded = base64.b64decode(deckstring)
	data = BytesIO(decoded)

	if data.read(1) != b"\0":
		raise ValueError("Invalid deckstring")

	version = _read_varint(data)
	if version != DECKSTRING_VERSION:
		raise ValueError("Unsupported deckstring version %r" % (version))

	format = _read_varint(data)
	try:
		format = format
	except ValueError:
		raise ValueError("Unsupported FormatType in deckstring %r" % (format))

	heroes: CardList = []
	num_heroes = _read_varint(data)
	for i in range(num_heroes):
		heroes.append(_read_varint(data))

	cards: CardIncludeList = []
	num_cards_x1 = _read_varint(data)
	for i in range(num_cards_x1):
		card_id = _read_varint(data)
		cards.append((card_id, 1))

	num_cards_x2 = _read_varint(data)
	for i in range(num_cards_x2):
		card_id = _read_varint(data)
		cards.append((card_id, 2))

	num_cards_xn = _read_varint(data)
	for i in range(num_cards_xn):
		card_id = _read_varint(data)
		count = _read_varint(data)
		cards.append((card_id, count))

	return cards, heroes, format


def write_deckstring(cards: CardIncludeList, heroes: CardList, format: format) -> str:
	data = BytesIO()
	data.write(b"\0")
	_write_varint(data, DECKSTRING_VERSION)
	_write_varint(data, int(format))

	if len(heroes) != 1:
		raise ValueError("Unsupported hero count %i" % (len(heroes)))
	_write_varint(data, len(heroes))
	for hero in heroes:
		_write_varint(data, hero)

	cards_x1, cards_x2, cards_xn = trisort_cards(cards)

	for cardlist in cards_x1, cards_x2:
		_write_varint(data, len(cardlist))
		for cardid, _ in cardlist:
			_write_varint(data, cardid)

	_write_varint(data, len(cards_xn))
	for cardid, count in cards_xn:
		_write_varint(data, cardid)
		_write_varint(data, count)

	encoded = base64.b64encode(data.getvalue())
	return encoded.decode("utf-8")
	
deckstring = 'AAEBAc2xAgjAAe0E7QX3DdYRh6wC8fsCoIADC8kDqwTLBPsMhRDH0wKW6AK0/ALNiQPXiQOfmwMA'
print(parse_deckstring(deckstring))