"""Structured JSON logging with request correlation."""

from __future__ import annotations

import logging
import sys
import time
import uuid
from contextvars import ContextVar
from typing import Any

_request_id: ContextVar[str] = ContextVar("request_id", default="-")


class JsonFormatter(logging.Formatter):
    def format(self, record: logging.LogRecord) -> str:
        import json

        payload: dict[str, Any] = {
            "ts": time.strftime("%Y-%m-%dT%H:%M:%S", time.gmtime(record.created))
                 + f".{int(record.msecs):03d}Z",
            "level": record.levelname,
            "logger": record.name,
            "msg": record.getMessage(),
            "request_id": _request_id.get(),
        }
        for key in ("document_id", "latency_ms", "status", "n_keys", "detail"):
            val = getattr(record, key, None)
            if val is not None:
                payload[key] = val
        if record.exc_info:
            payload["exc"] = self.formatException(record.exc_info)
        return json.dumps(payload, ensure_ascii=False)


def configure_logging(level: str = "INFO", json_output: bool = True) -> None:
    root = logging.getLogger()
    root.handlers.clear()
    handler = logging.StreamHandler(sys.stdout)
    if json_output:
        handler.setFormatter(JsonFormatter())
    else:
        handler.setFormatter(
            logging.Formatter("%(asctime)s %(levelname)-7s %(name)s | %(message)s")
        )
    root.addHandler(handler)
    root.setLevel(level.upper())
    # uvicorn duplicates access logs through its own handlers.
    for noisy in ("uvicorn.access", "uvicorn.error"):
        logging.getLogger(noisy).handlers.clear()
        logging.getLogger(noisy).propagate = True


def new_request_id() -> str:
    rid = uuid.uuid4().hex[:16]
    _request_id.set(rid)
    return rid


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