"""Structured JSON logging with request-ID correlation."""
from __future__ import annotations

import contextvars
import logging
import sys
import uuid

from pythonjsonlogger import jsonlogger
from starlette.middleware.base import BaseHTTPMiddleware

from .settings import settings

_request_id_var: contextvars.ContextVar[str] = contextvars.ContextVar(
    "request_id", default="-"
)


def get_request_id() -> str:
    return _request_id_var.get()


class RequestIdFilter(logging.Filter):
    def filter(self, record: logging.LogRecord) -> bool:
        record.request_id = _request_id_var.get()
        return True


def configure_logging() -> None:
    """Configure root logger to emit JSON with request_id."""
    root = logging.getLogger()
    # Remove any pre-existing handlers (uvicorn installs its own)
    for h in list(root.handlers):
        root.removeHandler(h)

    handler = logging.StreamHandler(sys.stdout)
    formatter = jsonlogger.JsonFormatter(
        fmt="%(asctime)s %(levelname)s %(name)s %(request_id)s %(message)s",
        rename_fields={"asctime": "ts", "levelname": "level", "name": "logger"},
    )
    handler.setFormatter(formatter)
    handler.addFilter(RequestIdFilter())
    root.addHandler(handler)
    root.setLevel(getattr(logging, settings.log_level.upper(), logging.INFO))

    # Calm down noisy loggers
    logging.getLogger("uvicorn.access").setLevel(logging.WARNING)


class RequestIdMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request, call_next):
        rid = request.headers.get("X-Request-ID") or uuid.uuid4().hex[:12]
        token = _request_id_var.set(rid)
        try:
            response = await call_next(request)
            response.headers["X-Request-ID"] = rid
            return response
        finally:
            _request_id_var.reset(token)