import sys
import traceback
from datetime import datetime, timezone


class _Logger:
    """원본 DerbyServer LOG 인터페이스를 간소화한 버전.
    LOG.i / LOG.d / LOG.w / LOG.e_no_callstack / LOG.SetPrefix 를 제공한다.
    """

    def __init__(self):
        self._prefix = ""

    def SetPrefix(self, prefix: str):
        self._prefix = prefix

    def _now(self) -> str:
        return datetime.now(timezone.utc).strftime("%Y-%m-%d %H:%M:%S")

    def _write(self, level: str, msg):
        head = f"{self._now()} [{level}]"
        if self._prefix:
            head += f"[{self._prefix}]"
        print(f"{head} {msg}", file=sys.stderr if level in ("WARN", "ERROR") else sys.stdout)

    def d(self, msg):
        self._write("DEBUG", msg)

    def i(self, msg):
        self._write("INFO", msg)

    def w(self, msg):
        self._write("WARN", msg)

    def e(self, msg):
        self._write("ERROR", msg)
        traceback.print_stack()

    def e_no_callstack(self, msg):
        self._write("ERROR", msg)


LOG = _Logger()