"""SmartEDT 后端服务入口。

主要职责：
- 加载配置与初始化日志
- 初始化数据库 schema/TimescaleDB
- 构造核心服务（仿真、监控、鉴权/RBAC）
- 挂载 HTTP/WebSocket 路由并启动 uvicorn
"""

from __future__ import annotations

import argparse
import asyncio
import logging
import multiprocessing
import platform
import sys
from pathlib import Path

# 修复 Windows 下 psycopg 异步连接的 Event Loop 问题
if platform.system() == "Windows":
    # 1. 强制设置 SelectorEventLoopPolicy
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
    
    # 2. Monkeypatch 阻止 uvicorn 覆盖策略 (uvicorn 默认在 Windows 上强制使用 Proactor)
    # 这对 psycopg 3 (SQLAlchemy async) 是必须的，因为 Proactor 不支持 add_reader/add_writer
    original_set_policy = asyncio.set_event_loop_policy
    def patched_set_policy(policy):
        # 如果尝试设置 Proactor，则忽略并保持 Selector
        if isinstance(policy, asyncio.WindowsProactorEventLoopPolicy):
            return
        original_set_policy(policy)
    asyncio.set_event_loop_policy = patched_set_policy

import uvicorn
from dotenv import load_dotenv
from fastapi import FastAPI, WebSocket

from contextlib import asynccontextmanager

from backend.config.settings import load_settings
from backend.database.engine import create_engine, create_session_factory
from backend.database.schema import init_schema, init_timescaledb
from backend.services.broadcaster import Broadcaster
from backend.services.simulation_manager import SimulationManager
from backend.services.server_monitor import ServerMonitorService
from backend.services.unity_socket_client import UnitySocketClient
from backend.device.mock_vehicle import MockVehicleDevice
from backend.api import auth_routes, rbac_routes, routes, unity_routes, user_routes, ws
from backend.utils import configure_logging

logger = logging.getLogger("backend")

def _default_backend_log_file() -> Path | None:
    """在打包运行态下返回默认日志文件路径；开发态返回 None。"""
    if getattr(sys, "frozen", False):
        exe_dir = Path(sys.executable).resolve().parent
        return exe_dir / "logs" / "backend.log"
    return None

def _force_windows_selector_event_loop_for_uvicorn() -> None:
    """避免 uvicorn 在 Windows 上切换到 ProactorEventLoop（与 psycopg async 不兼容）。"""
    if platform.system() != "Windows":
        return
    try:
        import uvicorn.loops.asyncio as uvicorn_asyncio_loop
    except Exception:
        return

    def _selector_loop_factory(use_subprocess: bool = False):
        return asyncio.SelectorEventLoop

    uvicorn_asyncio_loop.asyncio_loop_factory = _selector_loop_factory

# 全局单例容器（简单实现）
class Container:
    """简易全局容器：集中创建与持有配置、DB 引擎、session 工厂与各服务单例。"""

    def __init__(self):
        load_dotenv()
        self.settings = load_settings()
        configure_logging(
            "INFO" if not self.settings.server.debug else "DEBUG",
            log_file=_default_backend_log_file(),
        )
        
        self.file_root = self.settings.files.root_path
        self.file_root.mkdir(parents=True, exist_ok=True)

        self.engine = create_engine(self.settings.database)
        self.session_factory = create_session_factory(self.engine)
        self.broadcaster = Broadcaster()
        self.unity_client = UnitySocketClient(self.settings.unity.host, self.settings.unity.port)
        
        # 实例化服务
        self.simulation_manager = SimulationManager(
            self.session_factory,
            self.broadcaster,
            unity_client=self.unity_client,
        )
        
        # 实例化监控服务
        self.server_monitor = ServerMonitorService(
            self.session_factory,
            self.broadcaster
        )

container = Container()

@asynccontextmanager
async def lifespan(app: FastAPI):
    """FastAPI 生命周期：启动初始化与停机清理。"""
    # 启动前初始化
    await init_schema(container.engine)
    if container.settings.database.timescaledb:
        try:
            await init_timescaledb(container.engine)
        except Exception as e:
            # 可能是已存在或权限问题，仅打印日志
            logger.warning("TimescaleDB init warning: %s", e)
    
    # 注册默认设备
    mock_dev = MockVehicleDevice(device_id="mock_01")
    await container.simulation_manager.register_device(mock_dev)
    
    # 启动监控服务
    await container.server_monitor.start()

    yield
    
    # 停机清理
    await container.server_monitor.stop()
    await container.simulation_manager.stop()
    await container.engine.dispose()

app = FastAPI(title="SmartEDT Backend", version="0.1.0", lifespan=lifespan)
app.include_router(routes.get_router(simulation_manager=container.simulation_manager, file_root=container.file_root))
app.include_router(auth_routes.get_router(session_factory=container.session_factory))
app.include_router(rbac_routes.get_router(session_factory=container.session_factory))
app.include_router(user_routes.get_router(session_factory=container.session_factory))
app.include_router(unity_routes.get_router(simulation_manager=container.simulation_manager, session_factory=container.session_factory))

@app.websocket("/ws")
async def ws_endpoint(websocket: WebSocket):
    await ws.websocket_handler(websocket, broadcaster=container.broadcaster)


def main() -> None:
    """命令行入口：解析参数并启动 uvicorn。"""
    parser = argparse.ArgumentParser()
    parser.add_argument("--host", default=None)
    parser.add_argument("--port", type=int, default=None)
    parser.add_argument("--debug", action="store_true")
    args = parser.parse_args()

    settings = load_settings()
    host = args.host or settings.server.host
    port = args.port or settings.server.port
    debug = args.debug or settings.server.debug

    _force_windows_selector_event_loop_for_uvicorn()

    if getattr(sys, 'frozen', False):
        uvicorn.run(app, host=host, port=port, log_level="debug" if debug else "info")
    else:
        uvicorn.run("backend.main:app", host=host, port=port, reload=debug, log_level="debug" if debug else "info")


if __name__ == "__main__":
    multiprocessing.freeze_support()
    main()