"""AI 事件 WebSocket 推送端点。

提供:
- /ws/ai-cache/{site_id}?token=xxx — 缓存更新 / 失效事件
- /ws/ai-alerts/{site_id}?token=xxx — AI 告警事件(Phase 3.1)

协议:
- 客户端连接(必须带 token query)→ 服务端校验 JWT → accept →
  订阅 EventBus → 持续 send_json 事件
- 事件格式:{"type": "cache_updated|alert_created|...", "site_id": int, "payload": {...}}
- 服务端关闭或客户端断开时清理订阅

W1-AI-CLOSURE 组 7 安全加固(P0-9):
- 新增 token query 参数,JWT 解码失败 → 关闭(4401)
- site_id 必须与 token 中的 site_id 一致;site_id=-1 全局订阅要求
  token 角色含 super_admin
- 不再允许任何用户监听任意门店的 AI 事件流
"""

from __future__ import annotations

import logging

from fastapi import APIRouter, Query, WebSocket, WebSocketDisconnect, status
from jose import JWTError

from ..ai.event_bus import AIEvent, get_event_bus
from ..auth.jwt import decode_access_token

logger = logging.getLogger(__name__)

ws_router = APIRouter()


_WS_CLOSE_AUTH_FAILED = 4401  # 自定义 close code(WebSocket close codes 4000-4999 给应用使用)


def _authorize_ws(token: str | None, site_id: int) -> bool:
    """校验 WS 连接的 JWT token 与 site_id。

    返回 True 表示通过,False 表示拒绝。
    site_id == -1 时要求 token roles 含 super_admin。
    """
    if not token:
        return False
    try:
        payload = decode_access_token(token)
    except JWTError:
        return False

    token_site_id = payload.get("site_id")
    roles = payload.get("roles") or []
    if not isinstance(roles, list):
        roles = []

    if site_id == -1:
        # 全局订阅(admin-web 全局监控):仅 super_admin
        return "super_admin" in roles

    # 站点订阅:token 的 site_id 必须等于 URL 中的 site_id
    # super_admin 跨站点放行
    return token_site_id == site_id or "super_admin" in roles


@ws_router.websocket("/ws/ai-cache/{site_id}")
async def ws_ai_cache(
    websocket: WebSocket,
    site_id: int,
    token: str | None = Query(default=None),
) -> None:
    """AI 缓存事件推送。

    site_id=-1 表示订阅全局(收所有门店的 cache_updated / cache_invalidated),
    需 super_admin token。
    """
    await _serve_event_stream(websocket, site_id, token=token, endpoint="ai-cache")


@ws_router.websocket("/ws/ai-alerts/{site_id}")
async def ws_ai_alerts(
    websocket: WebSocket,
    site_id: int,
    token: str | None = Query(default=None),
) -> None:
    """AI 告警事件推送(Phase 3.1)。

    site_id=-1 表示订阅全局告警,需 super_admin token。
    事件 type: alert_created / alert_updated / budget_exceeded / circuit_opened。
    """
    await _serve_event_stream(websocket, site_id, token=token, endpoint="ai-alerts")


async def _serve_event_stream(
    websocket: WebSocket,
    site_id: int,
    *,
    token: str | None,
    endpoint: str,
) -> None:
    """共享事件流处理逻辑(含 token 鉴权)。"""
    if not _authorize_ws(token, site_id):
        await websocket.close(code=_WS_CLOSE_AUTH_FAILED, reason="auth required")
        logger.warning(
            "WS %s 鉴权失败: site_id=%s token_present=%s",
            endpoint, site_id, bool(token),
        )
        return

    await websocket.accept()
    # -1 映射为全局订阅(None)
    subscribe_key: int | None = None if site_id == -1 else site_id
    logger.info(
        "WS %s 连接建立: site_id=%s", endpoint, subscribe_key if subscribe_key else "ALL",
    )

    bus = get_event_bus()
    queue = await bus.subscribe(subscribe_key)

    try:
        while True:
            event = await queue.get()
            if event is None:
                break
            await websocket.send_json({
                "type": event.type,
                "site_id": event.site_id,
                "payload": event.payload,
            })
    except WebSocketDisconnect:
        logger.info("WS %s 客户端断开: site_id=%s", endpoint, subscribe_key)
    except Exception:
        logger.exception("WS %s 异常: site_id=%s", endpoint, subscribe_key)
    finally:
        await bus.unsubscribe(subscribe_key, queue)
        try:
            await websocket.close()
        except Exception:
            pass