"""
logger.py
---------
Logging setup for training and evaluation runs.
"""

import logging
import sys
from pathlib import Path
from typing import Optional


def setup_logger(
    name:     str,
    log_file: Optional[str] = None,
    level:    int = logging.INFO,
) -> logging.Logger:
    """
    Create and configure a logger.

    Args:
        name:     logger name
        log_file: optional path to write logs to file
        level:    logging level

    Returns:
        Configured logger
    """
    logger = logging.getLogger(name)
    logger.setLevel(level)

    # Avoid duplicate handlers
    if logger.handlers:
        return logger

    formatter = logging.Formatter(
        fmt   = "[%(asctime)s] [%(name)s] [%(levelname)s] %(message)s",
        datefmt = "%Y-%m-%d %H:%M:%S",
    )

    # Console handler
    console_handler = logging.StreamHandler(sys.stdout)
    console_handler.setLevel(level)
    console_handler.setFormatter(formatter)
    logger.addHandler(console_handler)

    # File handler (optional)
    if log_file is not None:
        Path(log_file).parent.mkdir(parents=True, exist_ok=True)
        file_handler = logging.FileHandler(log_file)
        file_handler.setLevel(level)
        file_handler.setFormatter(formatter)
        logger.addHandler(file_handler)

    return logger