import asyncio
import logging
from typing import Any

from fastapi import APIRouter, WebSocket, WebSocketDisconnect

from app.core.logging import logger

router = APIRouter()

# 连接管理器：job_id -> WebSocket 连接集合
_connections: dict[str, set[WebSocket]] = {}
_lock = asyncio.Lock()


async def _broadcast(job_id: str, message: dict[str, Any]) -> None:
    """向订阅该 job 的所有客户端广播消息。"""
    async with _lock:
        conns = _connections.get(job_id, set()).copy()
    if not conns:
        return
    import json
    payload = json.dumps(message)
    disconnected = set()
    for ws in conns:
        try:
            await ws.send_text(payload)
        except Exception:
            disconnected.add(ws)
    # 清理失效连接
    if disconnected:
        async with _lock:
            _connections.get(job_id, set()).difference_update(disconnected)


async def send_progress(job_id: str, **kwargs: Any) -> None:
    await _broadcast(job_id, {"type": "progress", "job_id": job_id, **kwargs})


async def send_epoch_done(job_id: str, **kwargs: Any) -> None:
    await _broadcast(job_id, {"type": "epoch_done", "job_id": job_id, **kwargs})


async def send_completed(job_id: str, **kwargs: Any) -> None:
    await _broadcast(job_id, {"type": "completed", "job_id": job_id, **kwargs})


async def send_error(job_id: str, message: str) -> None:
    await _broadcast(job_id, {"type": "error", "job_id": job_id, "message": message})


async def send_heartbeat(job_id: str) -> None:
    await _broadcast(job_id, {"type": "heartbeat", "job_id": job_id, "timestamp": datetime_now()})


def datetime_now() -> str:
    from datetime import datetime, timezone

    return datetime.now(timezone.utc).isoformat()


@router.websocket("/ws/training/{job_id}")
async def training_websocket(websocket: WebSocket, job_id: str) -> None:
    await websocket.accept()
    async with _lock:
        _connections.setdefault(job_id, set()).add(websocket)
    logger.info(f"客户端已连接到训练 WebSocket (job {job_id})")
    try:
        while True:
            # 保持连接；客户端可发送 "ping" 或取消请求
            data = await websocket.receive_text()
            if data == "ping":
                await websocket.send_text('{"type":"pong"}')
    except WebSocketDisconnect:
        logger.info(f"客户端已从训练 WebSocket 断开 (job {job_id})")
    finally:
        async with _lock:
            _connections.get(job_id, set()).discard(websocket)