biliBv.py

# (C) 2019-2020 lifegpc
# This file is part of bili.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
# 
# This code can Convert bvid into avid CORRECTLY! QwQ    -- edited by Evira.

XOR_CODE = 23442827791579
MASK_CODE = 2251799813685247
MAX_AID = 1 << 51
ALPHABET = "FcwAPNKTMug3GV5Lj7EJnHpWsx4tb8haYeviqBz6rkCy12mUSDQX9RdoZf"
ENCODE_MAP = 8, 7, 0, 5, 1, 3, 2, 4, 6
DECODE_MAP = tuple(reversed(ENCODE_MAP))

BASE = len(ALPHABET)
PREFIX = "BV1"
PREFIX_LEN = len(PREFIX)
CODE_LEN = len(ENCODE_MAP)
def debv(x: str) -> int:
    assert x[:3] == PREFIX
    x = x[3:]
    tmp = 0
    for i in range(CODE_LEN):
        idx = ALPHABET.index(x[DECODE_MAP[i]])
        tmp = tmp * BASE + idx
    return (tmp & MASK_CODE) ^ XOR_CODE

def enbv(x: int) -> str:
    bvid = [""] * 9
    tmp = (MAX_AID | x) ^ XOR_CODE
    for i in range(CODE_LEN):
        bvid[ENCODE_MAP[i]] = ALPHABET[tmp % BASE]
        tmp //= BASE
    return PREFIX + "".join(bvid)