"""
FastAPI 应用入口
挂载 v1 API 路由、CORS 中间件、生命周期管理
"""

from __future__ import annotations

import asyncio
import json
import logging
import threading
from contextlib import asynccontextmanager
from pathlib import Path
from typing import AsyncGenerator

from fastapi import FastAPI, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse, JSONResponse, RedirectResponse, Response

from app.config import settings
from app.database import close_db, init_db

_logger = logging.getLogger(__name__)


class BotManager:
    """管理企业微信机器人的生命周期（在后台线程中运行）"""

    def __init__(self):
        self._thread: threading.Thread | None = None
        self._running = False

    def start(self):
        """在后台线程中启动机器人"""
        if self._running:
            _logger.info("企业微信机器人已在运行")
            return
        if not settings.WEWORK_BOT_ENABLED or not settings.WEWORK_BOT_ID or not settings.WEWORK_BOT_SECRET:
            _logger.info("企业微信机器人未配置，跳过启动")
            return

        self._thread = threading.Thread(
            target=self._run_bot, daemon=True, name="wework-bot"
        )
        self._thread.start()
        _logger.info("企业微信机器人已在后台线程启动")

    def _run_bot(self):
        """在线程中运行 bot（需要新建事件循环）"""
        self._running = True
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        try:
            loop.run_until_complete(self._run_bot_async())
        except Exception as e:
            _logger.error("企业微信机器人线程异常退出: %s", e, exc_info=True)
        finally:
            loop.close()
            self._running = False

    async def _run_bot_async(self):
        """异步运行 bot"""
        from app.wework_bot import WeComBotService
        service = WeComBotService()
        await service.start_async()

    async def restart(self) -> dict:
        """重启机器人（先停后启）"""
        was_running = self._running
        # 停止旧的（设置 enabled=False 让旧线程自然退出）
        old_id = settings.WEWORK_BOT_ID
        old_secret = settings.WEWORK_BOT_SECRET
        old_enabled = settings.WEWORK_BOT_ENABLED

        if not old_enabled or not old_id or not old_secret:
            return {"success": False, "message": "请先配置机器人 ID 和 Secret 并启用"}

        # 等待旧线程结束
        if self._thread and self._thread.is_alive():
            # SDK 的 run() 会阻塞，无法从外部优雅停止
            # 通过设置 enabled=False 让下次检查时退出
            _logger.info("等待旧机器人线程结束...")
            # 无法强制停止，提示用户
            if was_running:
                return {"success": False, "message": "旧机器人正在运行，请稍后重试（SDK 不支持强制停止）"}

        # 启动新的
        self.start()
        return {"success": True, "message": "机器人已启动"}

    def get_status(self) -> dict:
        """获取机器人状态"""
        configured = bool(settings.WEWORK_BOT_ID and settings.WEWORK_BOT_SECRET)
        return {
            "enabled": settings.WEWORK_BOT_ENABLED,
            "configured": configured,
            "running": self._running,
            "bot_id": settings.WEWORK_BOT_ID,
        }


# 全局 bot 管理器
bot_manager = BotManager()


@asynccontextmanager
async def lifespan(_app: FastAPI) -> AsyncGenerator[None, None]:
    """
    应用生命周期管理：
    - 启动时：初始化数据目录、验证数据库连接、预热嵌入服务
    - 关闭时：释放数据库连接
    """
    _logger = logging.getLogger(__name__)

    # ── 启动 ──
    settings.ensure_dirs()
    await init_db()

    # 启动企业微信机器人（后台线程）
    bot_manager.start()

    # 预热嵌入服务（懒加载，首次调用时初始化）
    try:
        from app.services.embedding_service import EmbeddingService
        EmbeddingService.get_instance()
    except Exception as exc:
        _logger.warning("嵌入服务预热失败（将在首次使用时重试）: %s", exc)

    yield

    # ── 关闭 ──
    await close_db()


# ──────────────────────────── 创建应用 ────────────────────────────

app = FastAPI(
    title="HuiBrain - 中文直播教育知识库",
    description="基于向量检索的中文直播教育知识库系统，支持直播文字稿导入、OCR 截图识别、语义搜索等功能。",
    version="1.2.0",
    lifespan=lifespan,
)

# ──────────────────────────── CORS 中间件 ────────────────────────────

app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


# ──────────────────────────── 全局异常处理 ────────────────────────────

@app.exception_handler(Exception)
async def global_exception_handler(request: Request, exc: Exception) -> JSONResponse:
    """全局未捕获异常处理"""
    logger = logging.getLogger(__name__)
    logger.error("未处理异常: %s", exc, exc_info=True)
    return JSONResponse(
        status_code=500,
        content={"detail": "服务器内部错误", "message": str(exc)},
    )


# ──────────────────────────── 注册路由 ────────────────────────────

from app.api.v1.pages import router as pages_router
from app.api.v1.search import router as search_router
from app.api.v1.import_export import router as import_export_router
from app.api.v1.images import router as images_router
from app.api.v1.settings import router as settings_router

app.include_router(pages_router, prefix="/api/v1/pages", tags=["知识页面"])
app.include_router(search_router, prefix="/api/v1/search", tags=["语义搜索"])
app.include_router(import_export_router, prefix="/api/v1/import", tags=["导入导出"])
app.include_router(images_router, prefix="/api/v1/images", tags=["图片OCR"])
app.include_router(settings_router, prefix="/api/v1/settings", tags=["系统设置"])


# ──────────────────────────── 健康检查 ────────────────────────────

@app.get("/health", tags=["系统"])
async def health_check():
    """健康检查接口"""
    return {"status": "ok", "version": "1.2.0"}


# ──────────────────────────── 图片文件访问 ────────────────────────────

@app.get("/data/images/{image_name}", tags=["前端"])
async def serve_image(image_name: str):
    """访问 images 目录下的图片文件（用于前端预览）"""
    img_path = settings.images_dir / image_name
    if not img_path.exists():
        return JSONResponse(status_code=404, content={"detail": "图片不存在"})
    return FileResponse(str(img_path))


# ──────────────────────────── 前端页面 ────────────────────────────

@app.get("/favicon.ico", include_in_schema=False)
async def favicon():
    """返回空响应，避免浏览器 404 报错"""
    return Response(status_code=204)


@app.get("/", tags=["前端"])
async def index():
    """返回前端管理页面"""
    static_dir = Path(__file__).parent.parent / "static"
    index_path = static_dir / "index.html"
    if index_path.exists():
        return FileResponse(
            str(index_path),
            headers={"Cache-Control": "no-cache, no-store, must-revalidate"},
        )
    return RedirectResponse(url="/docs")