import asyncio
from typing import Dict, Optional


class DeviceTargetCache:
    def __init__(self):
        self.targets: Dict[str, str] = {}
        self.lock = asyncio.Lock()

    async def get_target(self, device_id: str) -> Optional[str]:
        async with self.lock:
            return self.targets.get(device_id)

    async def set_target(self, device_id: str, target_device_id: str):
        async with self.lock:
            self.targets[device_id] = target_device_id

    async def remove_target(self, device_id: str):
        async with self.lock:
            if device_id in self.targets:
                del self.targets[device_id]

    async def get_all_targets(self) -> list:
        async with self.lock:
            return list(self.targets.items())


# 单例实例
device_target_cache = DeviceTargetCache()