from dataclasses import dataclass
from typing import Protocol

import numpy as np


@dataclass
class PredictResult:
    """Result of one bbox-prompted segmentation.

    `polygon` is a list of (x, y) pixel coordinates describing the outer
    contour of the largest mask blob. `score` is the model's confidence for
    the selected mask (in [0, 1]).
    """
    polygon: list[tuple[float, float]]
    score: float


class BaseAdapter(Protocol):
    """Minimal adapter contract. Each model family implements this."""

    def load(self, config: str, checkpoint: str, device: str) -> None:
        """Load weights into memory. Called once, lazily on first predict."""
        ...

    def predict_bbox(
        self, image_rgb: np.ndarray, bbox_xyxy: tuple[int, int, int, int]
    ) -> PredictResult:
        """Run segmentation with a bbox prompt, return the best polygon."""
        ...

    def unload(self) -> None:
        """Free GPU memory. Called when the registry evicts this model."""
        ...