import asyncio
from typing import Optional

from .base import BaseInferenceEngine

_engine: Optional[BaseInferenceEngine] = None
# 懒初始化，确保在事件循环启动后创建
_inference_lock: Optional[asyncio.Lock] = None


def get_engine() -> BaseInferenceEngine:
    if _engine is None:
        raise RuntimeError("推理引擎未初始化，请先调用 init_engine()")
    return _engine


def get_inference_lock() -> asyncio.Lock:
    global _inference_lock
    if _inference_lock is None:
        _inference_lock = asyncio.Lock()
    return _inference_lock


def init_engine(model_path: str, runtime: str = "ultralytics") -> BaseInferenceEngine:
    global _engine
    if runtime == "onnx":
        from .onnx_adapter import OnnxRuntimeAdapter
        _engine = OnnxRuntimeAdapter(model_path)
    else:
        from .ultralytics_adapter import UltralyticsAdapter
        _engine = UltralyticsAdapter(model_path)

    print(f"[mingxi-vision] 加载模型: {model_path}")
    _engine.warmup()
    print(f"[mingxi-vision] 引擎就绪: {_engine.__class__.__name__} · {_engine.model_version}")
    return _engine


def reload_engine(model_path: str, runtime: str = "ultralytics") -> BaseInferenceEngine:
    """热重载模型，调用方必须持有推理锁"""
    global _engine
    _engine = None                    # 释放旧引用，让 GC 回收显存
    return init_engine(model_path, runtime)