import os
from mmengine.config import Config
from mmengine.runner import Runner

def load_config(config_path):
    """
    Load an MMEngine config file and return the config and Runner.

    Args:
        config_path (str): Path to the config file (e.g., 'configs/my_model/my_config.py').

    Returns:
        cfg (Config): Loaded config object.
        runner (Runner): Runner initialized with the config.
    """
    # Use os.path.splitext to safely get the extension
    base, ext = os.path.splitext(config_path)
    ext = ext[1:]  # Remove the dot from extension

    if ext not in ['py', 'json', 'yaml', 'yml']:
        raise ValueError(f"Unsupported config file extension: .{ext}")

    # Load the configuration using MMEngine
    cfg = Config.fromfile(config_path)

    # Optional: Do any programmatic config updates here
    # e.g., cfg.work_dir = './work_dirs/my_experiment'

    # Initialize the runner with the loaded config
    runner = Runner.from_cfg(cfg)

    return cfg, runner