import os
from pathlib import Path
from typing import Final, Optional
from dataclasses import dataclass

@dataclass
class AppConfig:
    """
    Central configuration class.
    """
    # Directory Setup
    ARTIFACTS_DIR: Final[Path] = Path("artifacts")
    OUTPUT_DIR: Final[Path] = ARTIFACTS_DIR.joinpath("functiongemma-modkit-demo")
    
    # Model & Data
    HF_TOKEN: Final[Optional[str]] = os.getenv('HF_TOKEN')
    # Defaulting to a real model ID for safety, original was local path '../hf/270m'
    MODEL_NAME: Final[str] = '../hf/270m' 
    DEFAULT_DATASET: Final[str] = 'bebechien/SimpleToolCalling'
    
    def __post_init__(self):
        self.ARTIFACTS_DIR.mkdir(parents=True, exist_ok=True)