"""M6 — SAE: Top mean-activation Sparse Autoencoder feature.

Stub implementation — requires pretrained SAE for LLaVA-1.5.
Raises NotImplementedError unless a SAE checkpoint is provided.
"""

from typing import Optional

import numpy as np

from src.methods.base import SteeringMethod


class SAE(SteeringMethod):
    """SAE — Sparse Autoencoder feature selection (stub)."""

    def __init__(self, sae_checkpoint: Optional[str] = None, **kwargs):
        self.sae_checkpoint = sae_checkpoint
        if sae_checkpoint is None:
            import logging
            logging.getLogger(__name__).warning(
                "SAE (M6) requires a pretrained SAE checkpoint. "
                "Skipped unless --sae-checkpoint is provided."
            )

    @property
    def name(self) -> str:
        return "SAE"

    @property
    def method_id(self) -> str:
        return "M6"

    def extract_vector(
        self,
        h_pos: np.ndarray,
        h_neg: np.ndarray,
        **kwargs,
    ) -> np.ndarray:
        if self.sae_checkpoint is None:
            raise NotImplementedError(
                "SAE (M6) requires a pretrained SAE checkpoint for LLaVA-1.5. "
                "Provide --sae-checkpoint or skip M6."
            )
        # TODO: Implement SAE feature selection when checkpoint available
        raise NotImplementedError("SAE feature extraction not yet implemented.")