"""接口限流：Redis 固定窗口计数（Nginx 层之外的第二道，对齐《02-技术文档》4.5）"""
from datetime import datetime

import redis.asyncio as aioredis

from app.core import errors
from app.core.response import BizException


async def hit(redis: aioredis.Redis, key: str, limit: int, window_seconds: int, message: str | None = None) -> None:
    """固定窗口计数，超限抛 1005(HTTP 429)。key 需自带维度与窗口标识。"""
    n = await redis.incr(key)
    if n == 1:
        await redis.expire(key, window_seconds)
    if n > limit:
        raise BizException(errors.RATE_LIMITED, message, http_status=429)


def window_key(window_seconds: int) -> str:
    """窗口标识：分钟 %Y%m%d%H%M / 小时 %Y%m%d%H / 天 %Y%m%d"""
    now = datetime.now()
    if window_seconds >= 86400:
        return f"{now:%Y%m%d}"
    if window_seconds >= 3600:
        return f"{now:%Y%m%d%H}"
    return f"{now:%Y%m%d%H%M}"


async def hit_subject(
    redis: aioredis.Redis, subject: str, action: str, limit: int, window_seconds: int, message: str | None = None
) -> None:
    """按主体（用户ID/设备ID/IP）+ 动作限流：rl:{action}:{subject}:{窗口}"""
    await hit(redis, f"rl:{action}:{subject}:{window_key(window_seconds)}", limit, window_seconds, message)