"""In-memory fixed-window rate limiter, keyed per API key.

Good enough for a single-process gateway; swap for Redis if you scale out.
"""
import time
from collections import defaultdict
from threading import Lock

_windows: dict[int, tuple[int, int]] = defaultdict(lambda: (0, 0))  # key_id -> (window_start, count)
_lock = Lock()


def check(key_id: int, limit_per_minute: int) -> bool:
    """Returns True if the request is allowed."""
    if limit_per_minute <= 0:
        return True
    now = int(time.time() // 60)
    with _lock:
        window, count = _windows[key_id]
        if window != now:
            _windows[key_id] = (now, 1)
            return True
        if count >= limit_per_minute:
            return False
        _windows[key_id] = (window, count + 1)
        return True