"""请求上下文中间件与结构化日志。

- `Hunjing-Request-ID`：合法则回显，缺失由服务端生成（UUIDv4，request_ 前缀）。
- `traceparent`：透传 W3C Trace Context；缺失生成新 trace-id（不与业务请求 ID 混用）。
- JSON 结构化日志：Authorization/Cookie/Set-Cookie 等敏感头脱敏。
"""

import json
import logging
import re
import uuid
from typing import Any

from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import Request

from app.core.ids import new_id

REDACTED_HEADERS = {"authorization", "cookie", "set-cookie", "hunjing-csrf-token", "x-api-key"}
_TRACEPARENT_RE = re.compile(r"^[0-9a-f]{2}-[0-9a-f]{32}-[0-9a-f]{16}-[0-9a-f]{2}$")


def _sanitize_headers(headers: Any) -> dict[str, str]:
    return {
        k: ("[REDACTED]" if k.lower() in REDACTED_HEADERS else v) for k, v in headers.items()
    }


class JsonFormatter(logging.Formatter):
    def format(self, record: logging.LogRecord) -> str:
        payload: dict[str, Any] = {
            "ts": self.formatTime(record, "%Y-%m-%dT%H:%M:%S%z"),
            "level": record.levelname,
            "logger": record.name,
            "message": record.getMessage(),
        }
        for key in ("request_id", "trace_id", "method", "path", "status"):
            value = getattr(record, key, None)
            if value is not None:
                payload[key] = value
        if record.exc_info:
            payload["exception"] = self.formatException(record.exc_info)
        return json.dumps(payload, ensure_ascii=False)


def configure_logging(level: str = "info") -> None:
    handler = logging.StreamHandler()
    handler.setFormatter(JsonFormatter())
    root = logging.getLogger()
    root.handlers = [handler]
    root.setLevel(level.upper())


class RequestContextMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next: Any) -> Any:
        request_id = request.headers.get("Hunjing-Request-ID") or new_id("request_", version=4)
        traceparent = request.headers.get("traceparent")
        if traceparent is None or not _TRACEPARENT_RE.match(traceparent):
            traceparent = f"00-{uuid.uuid4().hex}-{uuid.uuid4().hex[:16]}-01"
        trace_id = traceparent.split("-")[1]
        request.state.request_id = request_id
        request.state.trace_id = trace_id

        response = await call_next(request)
        response.headers["Hunjing-Request-ID"] = request_id
        response.headers["traceparent"] = traceparent
        logging.getLogger("hunjing.access").info(
            "request",
            extra={
                "request_id": request_id,
                "trace_id": trace_id,
                "method": request.method,
                "path": request.url.path,
                "status": response.status_code,
            },
        )
        return response


__all__ = ["RequestContextMiddleware", "configure_logging", "_sanitize_headers"]