"""前端管理页面的构建与静态挂载。

方案: 不再由 bot 拉起 vite dev server, 而是把构建产物用 FastAPI StaticFiles
挂载到 bot 端口 /learning_chat 路径, 与 API 同源, 无孤儿进程、无 CORS 问题。
前端开发时手动 `npm run dev` 即可(API 已配置 dev proxy)。
"""

import asyncio
from pathlib import Path

from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles
from nonebot import logger

BASE_DIR = Path(__file__).resolve().parent
ADMIN_DIR = BASE_DIR / "web" / "learning-chat-admin"
DIST_DIR = ADMIN_DIR / "dist"

# 参与构建新鲜度检查的源文件(不在 src/ 下的)
SRC_FILES = ("vite.config.ts", "index.html", "package.json")


def _dist_is_stale() -> bool:
    """dist/index.html 不存在, 或比任何源码旧时视为需要重建"""
    dist_index = DIST_DIR / "index.html"
    if not dist_index.exists():
        return True
    dist_mtime = dist_index.stat().st_mtime
    for src_file in (ADMIN_DIR / "src").rglob("*"):
        if src_file.is_file() and src_file.stat().st_mtime > dist_mtime:
            return True
    return any(
        (ADMIN_DIR / name).stat().st_mtime > dist_mtime
        for name in SRC_FILES
        if (ADMIN_DIR / name).exists()
    )


async def build_frontend() -> bool:
    """执行 vite 构建, 返回是否成功"""
    logger.info("群聊学习 | 前端源码已更新, 开始重新构建(约10-40秒)...")
    proc = await asyncio.create_subprocess_exec(
        "npx.cmd",
        "vite",
        "build",
        cwd=str(ADMIN_DIR),
        stdout=asyncio.subprocess.PIPE,
        stderr=asyncio.subprocess.STDOUT,
    )
    output, _ = await proc.communicate()
    if proc.returncode != 0:
        logger.error(
            "群聊学习 | 前端构建失败(%s):\n%s",
            proc.returncode,
            output.decode(errors="ignore")[-3000:],
        )
        return False
    logger.info("群聊学习 | 前端构建完成")
    return True


async def ensure_frontend_ready() -> bool:
    """确保构建产物是最新的, 返回是否可用(最新或已成功重建)"""
    if not _dist_is_stale():
        return True
    return await build_frontend()


def mount_frontend(app) -> None:
    """将构建产物挂载到 bot 端口的 /learning_chat 路径(需在 API 路由注册后调用)。

    history 模式 SPA 需要回退: assets/ 静态挂载 + 真实文件直接返回,
    其余路径(如 /login /config 等前端路由)一律回退到 index.html。
    """
    if not DIST_DIR.exists():
        logger.error("群聊学习 | 前端构建产物不存在, 管理页面不可用")
        return
    assets_dir = DIST_DIR / "assets"
    if assets_dir.exists():
        app.mount(
            "/learning_chat/assets",
            StaticFiles(directory=str(assets_dir)),
            name="learning_chat_assets",
        )
    dist_resolved = DIST_DIR.resolve()

    @app.get("/learning_chat/{full_path:path}")
    async def learning_chat_spa(full_path: str):
        target = (DIST_DIR / full_path).resolve()
        if full_path and target.is_file() and target.is_relative_to(dist_resolved):
            return FileResponse(target)
        # SPA 回退: 前端路由(如 /login /config)全部交给 index.html
        return FileResponse(DIST_DIR / "index.html")

    @app.get("/learning_chat")
    async def learning_chat_root():
        return FileResponse(DIST_DIR / "index.html")

    logger.info("群聊学习 | 管理页面已挂载: http://<host>:<port>/learning_chat/")