from typing import Any, cast, Union

from Crypto.Cipher import AES

BM2_ENCRYPTION_KEY = b"\x6c\x65\x61\x67\x65\x6e\x64\xff\xfe\x31\x38\x38\x32\x34\x36\x36"

AesBlockSize = 16


def create_aes(key: bytes = BM2_ENCRYPTION_KEY) -> Any:
    return AES.new(key, AES.MODE_CBC, bytes([0] * AesBlockSize))


def pad_to_block(x: bytes) -> bytes:
    required_size = (len(x) + (AesBlockSize - 1)) // AesBlockSize * AesBlockSize
    return x.ljust(required_size, b"\x00")


def encrypt(data: bytes, key: bytes = BM2_ENCRYPTION_KEY) -> bytes:
    return cast(bytes, create_aes(key).encrypt(pad_to_block(data)))


def decrypt(encrypted_data: Union[bytes, bytearray], key: bytes = BM2_ENCRYPTION_KEY) -> bytes:
    return cast(bytes, b''.join(create_aes(key).decrypt(bytes(encrypted_data[i:i + AesBlockSize])) for i in range(0, len(encrypted_data), AesBlockSize)))