"""In-memory sliding-window rate limit (per IP)."""

from __future__ import annotations

import threading
import time
from collections import defaultdict, deque

from app import config

_lock = threading.Lock()
_hits: dict[str, deque[float]] = defaultdict(deque)


def reset() -> None:
    """Clear all tracked hits (tests)."""
    with _lock:
        _hits.clear()


def allow(ip: str, *, now: float | None = None) -> bool:
    """Return True if ``ip`` may proceed; record the hit when allowed.

    Allows when the number of hits in the last 1.0s is strictly less than
    ``settings.rate_limit_per_second``.
    """
    if not ip:
        ip = ""
    limit = config.settings.rate_limit_per_second
    ts = time.monotonic() if now is None else now
    window_start = ts - 1.0

    with _lock:
        q = _hits[ip]
        while q and q[0] <= window_start:
            q.popleft()
        if len(q) >= limit:
            return False
        q.append(ts)
        return True