"""Простой in-memory rate limit (на процесс)."""

from __future__ import annotations

import time
from collections import defaultdict
from threading import Lock


class RateLimiter:
    def __init__(self) -> None:
        self._hits: dict[str, list[float]] = defaultdict(list)
        self._lock = Lock()

    def hit(self, key: str, *, limit: int, window_sec: float) -> bool:
        """True если запрос разрешён, False если превышен лимит."""
        now = time.monotonic()
        with self._lock:
            bucket = self._hits[key]
            cutoff = now - window_sec
            self._hits[key] = [t for t in bucket if t >= cutoff]
            if len(self._hits[key]) >= limit:
                return False
            self._hits[key].append(now)
            return True


limiter = RateLimiter()


def client_ip(request) -> str:
    forwarded = (request.headers.get("X-Forwarded-For") or "").split(",")[0].strip()
    if forwarded:
        return forwarded
    peer = request.remote
    return str(peer or "unknown")


def allow(request, bucket: str, *, limit: int = 20, window_sec: float = 60.0) -> bool:
    ip = client_ip(request)
    return limiter.hit(f"{bucket}:{ip}", limit=limit, window_sec=window_sec)