"""

Secret file eraser.

"""

from itertools import islice

from random import random

from .bitmap import Bitmap

def erase(bitmap: Bitmap) -> None:

"""Scramble a previously hidden data."""

if bitmap.reserved_field > 0:

for byte_offset in islice(bitmap.byte_offsets, bitmap.reserved_field):

bitmap[byte_offset] = randomize_lsb(bitmap[byte_offset])

bitmap.reserved_field = 0

print("Erased a secret file from the bitmap")

else:

print("Secret file not found in the bitmap")

def randomize_lsb(value: int) -> int:

"""Set a random bit on the least-significant position."""

return value & ~1 if random() < 0.5 else value | 1