from __future__ import annotations

import os
from functools import lru_cache
from pathlib import Path

from huggingface_hub import hf_hub_download

os.environ.setdefault("YOLO_CONFIG_DIR", "/tmp/Ultralytics")

FASTSAM_REPO = "Uminosachi/FastSAM"
FASTSAM_FILENAME = "FastSAM-s.pt"


@lru_cache(maxsize=1)
def load_fastsam_cpu():
    """Carica una sola istanza FastSAM e la mantiene esplicitamente su CPU."""
    from ultralytics import FastSAM

    local_weight = Path(FASTSAM_FILENAME)
    if local_weight.exists():
        weight_path = local_weight
    else:
        weight_path = Path(hf_hub_download(repo_id=FASTSAM_REPO, filename=FASTSAM_FILENAME))
    model = FastSAM(str(weight_path))
    try:
        model.model.to("cpu")
    except Exception:
        pass
    return model