"""
MISC skeleton — copy & fill. (p4-team style: oracle, encoding, stego, brute)

p4 'misc' covers a lot: byte-by-byte oracle (heXdump), encoding tricks,
PRNG reversing, image stego, constraint solving. See forensics_skeleton.py
for the generic oracle helper.
"""
import base64
import string


# ---- encoding chain helper (common in misc) ----
def try_decodings(blob):
    """Brute a chain of common decodings to spot a flag."""
    results = []
    data = blob
    for _ in range(3):
        for name, fn in [
            ("b64", lambda d: base64.b64decode(d)),
            ("b32", lambda d: base64.b32decode(d)),
            ("b16", lambda d: base64.b16decode(d)),
            ("hex", lambda d: bytes.fromhex(d.decode())),
        ]:
            try:
                out = fn(data)
                if b"flag" in out.lower() or b"CTF" in out:
                    results.append((name, out))
                data = out
            except Exception:
                pass
    return results


# ---- generic byte-by-byte oracle ----
CHARSET = string.ascii_letters + string.digits + "{}_-!@#$%^&*()+=/."


def recover_oracle(known_start, oracle_fn, stop="}"):
    """oracle_fn(prefix) returns a stable baseline string for a given known prefix."""
    known = known_start
    while stop not in known:
        baseline = oracle_fn(known)
        found = None
        for c in CHARSET:
            if oracle_fn(known + c) == baseline:
                found = c
                break
        if not found:
            known += "?"
            break
        known += found
        print(known)
    return known


if __name__ == "__main__":
    raise NotImplementedError("pick a misc technique and fill it in")