from __future__ import annotations
import marshal
import random
import zlib
from . import crypto
from .util import gen_bytes
CIPHER_OPS = ('xor', 'perm', 'rot')

def pack(code_obj, rng: random.Random, layers: int=3) -> tuple[bytes, list[tuple[str, bytes]]]:
    data = marshal.dumps(code_obj)
    data = zlib.compress(data, 9)
    layer_keys: list[tuple[str, bytes]] = []
    for _ in range(layers):
        op = rng.choice(CIPHER_OPS)
        key = gen_bytes(rng, rng.randint(20, 40))
        if op == 'xor':
            data = crypto.stream_xor(data, key)
        elif op == 'perm':
            data = crypto.perm_apply(data, key)
        elif op == 'rot':
            data = crypto.rot_apply(data, key)
        layer_keys.append((op, key))
    return (data, layer_keys)