import time
from collections import OrderedDict


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

    def is_duplicate(self, msg_id: str) -> bool:
        self._evict_expired()
        if msg_id in self._store:
            return True
        self._store[msg_id] = time.time()
        self._evict_overflow()
        return False

    def _evict_expired(self):
        now = time.time()
        expired = [k for k, v in self._store.items() if now - v > self._ttl]
        for k in expired:
            del self._store[k]

    def _evict_overflow(self):
        while len(self._store) > self._max_size:
            self._store.popitem(last=False)