"""Model loading with mock/real switching based on environment."""

from typing import Union

from config.settings import settings

# Type alias for model stack
ModelStack = Union["MockModelStack", "RealModelStack"]  # noqa: F821

# Lazy singleton
_model_stack: ModelStack | None = None


def get_model_stack() -> ModelStack:
    """Get model stack based on environment configuration."""
    if settings.mock_models:
        from models.mock import MockModelStack

        return MockModelStack().load_all()
    else:
        from models.real import RealModelStack

        return RealModelStack().load_all()


def get_models() -> ModelStack:
    """Get or create the singleton model stack."""
    global _model_stack
    if _model_stack is None:
        _model_stack = get_model_stack()
    return _model_stack


def reset_models() -> None:
    """Reset the model stack (useful for testing)."""
    global _model_stack
    _model_stack = None