import asyncio
from datetime import datetime, timezone, timedelta
from app.config import settings
from app.internal.logger import logger
from app.internal import firestore as fstore

SWEEP_INTERVAL = 30  # seconds


async def sweeper_loop():
    """
    Periodically check for nodes that haven't checked in recently
    and mark them offline in Firestore.
    """
    logger.info("Node sweeper started.")
    while True:
        await asyncio.sleep(SWEEP_INTERVAL)
        try:
            await _sweep()
        except Exception as e:
            logger.error(f"Sweeper error: {e}")


async def _sweep():
    threshold = datetime.now(timezone.utc) - timedelta(seconds=settings.node_offline_threshold)

    def _query():
        from app.internal.firestore import db
        return [
            doc.to_dict()
            for doc in db.collection("nodes").stream()
        ]

    nodes = await asyncio.to_thread(_query)
    for node in nodes:
        status = node.get("status", "offline")
        if status == "offline":
            continue

        last_seen_raw = node.get("last_seen")
        if not last_seen_raw:
            continue

        # last_seen may be a Firestore Timestamp, a datetime, or an ISO string
        if isinstance(last_seen_raw, str):
            last_seen = datetime.fromisoformat(last_seen_raw)
        else:
            last_seen = last_seen_raw
        if last_seen.tzinfo is None:
            last_seen = last_seen.replace(tzinfo=timezone.utc)

        if last_seen < threshold:
            node_id = node.get("node_id")
            await fstore.doc_update("nodes", node_id, {"status": "offline"})
            logger.info(f"Node {node_id} marked offline (last seen: {last_seen.isoformat()})")