"""Structured JSON logging and request context."""

from __future__ import annotations

import contextvars
import json
import logging
import sys
from datetime import datetime, timezone
from typing import Any


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


class JsonFormatter(logging.Formatter):
    """Render log records as one-line JSON."""

    _reserved = set(logging.makeLogRecord({}).__dict__) | {"message", "asctime"}

    def format(self, record: logging.LogRecord) -> str:
        payload: dict[str, Any] = {
            "timestamp": datetime.now(timezone.utc).isoformat(),
            "level": record.levelname,
            "logger": record.name,
            "message": record.getMessage(),
            "request_id": getattr(record, "request_id", request_id_context.get()),
        }
        for key, value in record.__dict__.items():
            if key not in self._reserved and not key.startswith("_"):
                payload[key] = value
        if record.exc_info:
            payload["exception"] = self.formatException(record.exc_info)
        return json.dumps(payload, default=str, ensure_ascii=False)


def configure_logging(level: str = "INFO") -> None:
    """Configure process logging once."""
    root = logging.getLogger()
    root.handlers.clear()
    handler = logging.StreamHandler(sys.stdout)
    handler.setFormatter(JsonFormatter())
    root.addHandler(handler)
    root.setLevel(level.upper())


def get_logger(name: str) -> logging.Logger:
    return logging.getLogger(name)