import time

DEDUP_TTL = 30.0
MAX_DEDUP_ENTRIES = 200

_dedup_cache: dict[int, float] = {}


def is_duplicate(message_index: int) -> bool:
    now = time.monotonic()
    if message_index in _dedup_cache:
        if now - _dedup_cache[message_index] < DEDUP_TTL:
            return True
    _dedup_cache[message_index] = now
    if len(_dedup_cache) > MAX_DEDUP_ENTRIES:
        stale = [k for k, v in _dedup_cache.items() if now - v > DEDUP_TTL]
        for k in stale:
            del _dedup_cache[k]
    return False


def mark_seen(message_index: int) -> None:
    _dedup_cache[message_index] = time.monotonic()


def reset() -> None:
    _dedup_cache.clear()