import threading
from typing import Any, List, Optional
import insightface

import roop.globals
from roop.typing import Frame

FACE_ANALYSER = None
THREAD_LOCK = threading.Lock()


def get_face_analyser() -> Any:
    """
    Initialize and return the face analyser.

    This function ensures that the face analyser is initialized only once,
    using a thread-safe mechanism.

    Returns:
        Any: An instance of the FaceAnalysis class from insightface.
    """
    global FACE_ANALYSER

    with THREAD_LOCK:
        if FACE_ANALYSER is None:
            FACE_ANALYSER = insightface.app.FaceAnalysis(
                name='buffalo_l',
                providers=roop.globals.execution_providers
            )
            FACE_ANALYSER.prepare(ctx_id=0, det_size=(640, 640))
    return FACE_ANALYSER


def get_one_face(frame: Frame) -> Optional[Any]:
    """
    Extract the face with the smallest bounding box from the given frame.

    Args:
        frame (Frame): The image or video frame to analyze.

    Returns:
        Optional[Any]: The face with the smallest bounding box or None if no face is found.
    """
    faces = get_face_analyser().get(frame)
    if not faces:
        return None

    return min(faces, key=lambda x: x.bbox[0])


def get_many_faces(frame: Frame) -> List[Any]:
    """
    Extract all detected faces from the given frame.

    Args:
        frame (Frame): The image or video frame to analyze.

    Returns:
        List[Any]: A list of detected faces or an empty list if no faces are found.
    """
    try:
        return get_face_analyser().get(frame)
    except Exception as e:
        print(f"Error getting faces: {e}")
        return []