"""구조화 JSON 로깅.

LOG_FORMAT 환경변수로 json | text 선택 가능.
"""
from __future__ import annotations

import json
import logging
import traceback
from datetime import datetime, timezone

_BUILTIN_ATTRS = {
    "args", "created", "exc_info", "exc_text", "filename", "funcName",
    "levelname", "levelno", "lineno", "module", "msecs", "message", "msg",
    "name", "pathname", "process", "processName", "relativeCreated",
    "stack_info", "thread", "threadName", "taskName",
}


class JsonFormatter(logging.Formatter):
    def format(self, record: logging.LogRecord) -> str:
        log_data = {
            "timestamp": datetime.fromtimestamp(record.created, tz=timezone.utc).isoformat(),
            "level": record.levelname,
            "logger": record.name,
            "message": record.getMessage(),
        }
        for key, value in record.__dict__.items():
            if key not in _BUILTIN_ATTRS and not key.startswith("_"):
                try:
                    json.dumps(value)
                    log_data[key] = value
                except (TypeError, ValueError):
                    log_data[key] = str(value)
        if record.exc_info and record.exc_info[0] is not None:
            log_data["exception"] = "".join(traceback.format_exception(*record.exc_info))
        return json.dumps(log_data, ensure_ascii=False)


def setup_logging(
    log_format: str = "json",
    level: int = logging.INFO,
    logger: logging.Logger | None = None,
) -> None:
    target = logger or logging.getLogger()
    if log_format == "json":
        formatter = JsonFormatter()
    else:
        formatter = logging.Formatter(
            "%(asctime)s %(levelname)s %(name)s: %(message)s",
            datefmt="%Y-%m-%dT%H:%M:%S",
        )
    for handler in target.handlers:
        handler.setFormatter(formatter)
    target.setLevel(level)