# ------------------------------------------------------------------------
# RF-DETR
# Copyright (c) 2025 Roboflow. All Rights Reserved.
# Licensed under the Apache License, Version 2.0 [see LICENSE for details]
# ------------------------------------------------------------------------
"""Shared logger factory for RF-DETR modules."""

import logging
import os
import sys


class _RFDETRLogger(logging.Logger):
    """Logger subclass that adds a :meth:`warning_once` helper."""

    def __init__(self, name: str, level: int = logging.NOTSET) -> None:
        super().__init__(name, level)
        self._warned_once: set[str] = set()

    def warning_once(self, msg: str, *args: object, **kwargs: object) -> None:
        """Emit *msg* as a WARNING exactly once per unique message string."""
        if msg not in self._warned_once:
            self._warned_once.add(msg)
            self.warning(msg, *args, **kwargs)


def get_logger(name: str = "rf-detr", level: int | None = None) -> _RFDETRLogger:
    """Creates and configures a logger with stdout and stderr handlers.

    This function creates a logger that sends INFO and DEBUG level logs to stdout, and WARNING, ERROR, and CRITICAL
    level logs to stderr. If the logger already has handlers, it returns the existing logger without adding new
    handlers.

    The log level can be specified directly or through the LOG_LEVEL environment variable.

    Args:
        name: The name of the logger. Defaults to "rf-detr".
        level: The logging level to set. If None, uses the LOG_LEVEL environment
            variable, defaulting to INFO if not set.

    Returns:
        A configured _RFDETRLogger instance.
    """
    if level is None:
        level = getattr(logging, os.getenv("LOG_LEVEL", "INFO").upper(), logging.INFO)

    logger = logging.getLogger(name)

    # If the logger was already registered as a plain Logger before this call,
    # upgrade it in-place so warning_once is always available.
    if not isinstance(logger, _RFDETRLogger):
        logger.__class__ = _RFDETRLogger
        logger._warned_once = set()  # type: ignore[attr-defined]

    logger.setLevel(level)

    if not logger.handlers:
        formatter = logging.Formatter(
            "[%(asctime)s] [%(levelname)s] %(name)s - %(message)s", datefmt="%Y-%m-%d %H:%M:%S"
        )

        stdout_handler = logging.StreamHandler(sys.stdout)
        stdout_handler.setLevel(logging.DEBUG)
        stdout_handler.addFilter(lambda r: r.levelno <= logging.INFO)
        stdout_handler.setFormatter(formatter)

        stderr_handler = logging.StreamHandler(sys.stderr)
        stderr_handler.setLevel(logging.WARNING)
        stderr_handler.setFormatter(formatter)

        logger.addHandler(stdout_handler)
        logger.addHandler(stderr_handler)
        logger.propagate = False

    return logger  # type: ignore[return-value]