import os
from itertools import cycle
import gzip


def ror(n, rotations, width):
    return (2**width - 1) & (n >> rotations | n << (width - rotations))


with open("3/withkey/juliakey.txt", "r") as julia_key_file, open(
    "3/withkey/juliaplaintext.txt.gz.enc", "rb"
) as julia_cipher_file:
    julia_key_content = julia_key_file.read()
    julia_cipher_content = julia_cipher_file.read()

key_shift = int(julia_key_content.split()[4])
key_xor = julia_key_content.split()[-1]
print("key shift", key_shift)
print("key xor", key_xor)

result = bytes()
for c_byte, k_byte in zip(julia_cipher_content, cycle(key_xor)):
    tmp = c_byte ^ ord(k_byte)
    # kinda dumb tangent: question mentions that encryption rotates bits but didn't mention which direction
    # imagine spending 3 hours thinking the problem is gzip when it turns out you rotate RIGHT, not left
    result += ror(tmp, 1, 8).to_bytes(1, "big")

# gzip - write as bytes, read with decompression
with open("test.gz", "wb") as f:
    f.write(result)
with gzip.open("test.gz", "r") as gf:
    print("answer starts here-----" + gf.read().decode() + "-----ends here")
os.remove("test.gz")