"""请求耗时观测中间件。"""
from __future__ import annotations

import logging
import time

from starlette.middleware.base import BaseHTTPMiddleware

logger = logging.getLogger("api.performance")


class PerformanceMiddleware(BaseHTTPMiddleware):
    """记录接口耗时；日志只包含路径、状态码和耗时，不包含请求参数。"""

    def __init__(self, app, *, slow_ms: float = 500.0):
        super().__init__(app)
        self.slow_ms = slow_ms

    async def dispatch(self, request, call_next):
        started = time.perf_counter()
        response = await call_next(request)
        elapsed_ms = (time.perf_counter() - started) * 1000
        if elapsed_ms >= self.slow_ms:
            logger.warning(
                "slow request path=%s method=%s status=%s elapsed_ms=%.2f",
                request.url.path,
                request.method,
                response.status_code,
                elapsed_ms,
            )
        return response