import time


class CommentDeduplicator:
    def __init__(self, max_size: int = 50_000, ttl_seconds: int = 600):
        self._max_size = max_size
        self._ttl = ttl_seconds
        self._cache: dict[str, float] = {}

    def is_duplicate(self, comment_id: str) -> bool:
        self._evict_expired()
        return comment_id in self._cache

    def mark(self, comment_id: str):
        self._evict_expired()
        self._cache[comment_id] = time.time()
        self._evict_oldest_if_needed()

    def _evict_expired(self):
        now = time.time()
        expired = [cid for cid, ts in self._cache.items() if now - ts > self._ttl]
        for cid in expired:
            del self._cache[cid]

    def _evict_oldest_if_needed(self):
        while len(self._cache) > self._max_size:
            oldest = min(self._cache, key=self._cache.get)
            del self._cache[oldest]

    def clear(self):
        self._cache.clear()

    def __len__(self) -> int:
        return len(self._cache)