"""心跳保活服务：扫描 Agent 池，剔除超时未心跳节点。"""
import logging

import redis.asyncio as aioredis

from app.config import settings
from app.constants import AgentStatus
from app.repository.agent_repo import AgentRepo

logger = logging.getLogger(__name__)


class HeartbeatService:
    def __init__(self, redis: aioredis.Redis, agent_repo: AgentRepo | None = None):
        self.redis = redis
        self.agent_repo = agent_repo or AgentRepo(redis)

    async def scan(self) -> int:
        """扫描并剔除超时 Agent，返回剔除数量。"""
        stale = await self.agent_repo.stale_agents(settings.agent_heartbeat_timeout)
        for aid in stale:
            await self.agent_repo.update_status(aid, AgentStatus.OFFLINE)
            logger.info("heartbeat: agent offline (stale) agent_id=%s", aid)
        return len(stale)