"""Simple in-memory rate limiter per user."""

from __future__ import annotations

import time
from collections import defaultdict
from typing import Annotated

from fastapi import Depends, HTTPException, status

from app.api.deps import require_student
from app.core.schemas import UserProfile


class RateLimiter:
    def __init__(self, max_requests: int, window_seconds: int) -> None:
        self._max = max_requests
        self._window = window_seconds
        self._buckets: dict[int, list[float]] = defaultdict(list)

    def check(self, user_id: int) -> None:
        now = time.time()
        cutoff = now - self._window
        bucket = self._buckets[user_id]
        # purge expired entries
        while bucket and bucket[0] < cutoff:
            bucket.pop(0)
        if len(bucket) >= self._max:
            raise HTTPException(
                status_code=status.HTTP_429_TOO_MANY_REQUESTS,
                detail=f"请求过于频繁，请 {self._window // 60} 分钟后重试",
            )
        bucket.append(now)


_diagnosis_limiter = RateLimiter(max_requests=5, window_seconds=60)


def check_diagnosis_rate_limit(
    user: Annotated[UserProfile, Depends(require_student)],
) -> None:
    _diagnosis_limiter.check(user.id)