"""将 Vue 前端构建产物挂载到 FastAPI，实现单端口 Web 访问。"""
from pathlib import Path

from fastapi import FastAPI, HTTPException
from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles


def mount_frontend(app: FastAPI, static_dir: Path) -> bool:
    """挂载 frontend/dist。成功返回 True，目录不存在返回 False。"""
    static_dir = static_dir.resolve()
    index = static_dir / "index.html"
    if not index.is_file():
        return False

    assets_dir = static_dir / "assets"
    if assets_dir.is_dir():
        app.mount("/assets", StaticFiles(directory=assets_dir), name="assets")

    @app.get("/", include_in_schema=False)
    async def serve_index():
        return FileResponse(index)

    @app.get("/{filename}", include_in_schema=False)
    async def serve_root_static(filename: str):
        if filename.startswith("api") or filename in ("docs", "redoc", "openapi.json"):
            raise HTTPException(status_code=404, detail="Not Found")
        file_path = (static_dir / filename).resolve()
        try:
            file_path.relative_to(static_dir)
        except ValueError:
            raise HTTPException(status_code=404, detail="Not Found")
        if file_path.is_file():
            return FileResponse(file_path)
        return FileResponse(index)

    return True