import time
from collections import OrderedDict


class MessageDeduplicator:
    def __init__(self, max_size: int = 10000, ttl_seconds: int = 300):
        self._max_size = max_size
        self._ttl_seconds = ttl_seconds
        self._cache: OrderedDict[str, float] = OrderedDict()

    def is_duplicate(self, msg_id: str) -> bool:
        now = time.time()
        self._evict_expired(now)

        if msg_id in self._cache:
            return True

        self._cache[msg_id] = now

        if len(self._cache) > self._max_size:
            self._cache.popitem(last=False)

        return False

    def _evict_expired(self, now: float):
        expire_before = now - self._ttl_seconds
        expired = [mid for mid, ts in self._cache.items() if ts < expire_before]
        for mid in expired:
            self._cache.pop(mid, None)